tag:blogger.com,1999:blog-5312250079221641702024-03-05T03:26:43.613-08:00Thermal Spray using HVOFmamunk2http://www.blogger.com/profile/02444555059459888177noreply@blogger.comBlogger7125tag:blogger.com,1999:blog-531225007922164170.post-16034794278494824002007-05-26T17:17:00.001-07:002007-07-26T07:02:34.983-07:00Pay Pal is convient<!-- Begin PayPal Logo --><a href="https://www.paypal.com/ie/mrb/pal=F2F832ERM744E" target="_blank"><img src="http://images.paypal.com/en_US/i/bnr/paypal_mrb_banner.gif" border="0" alt="Sign up for PayPal and start accepting credit card payments instantly." /></a><!-- End PayPal Logo -->mamunk2http://www.blogger.com/profile/02444555059459888177noreply@blogger.com1tag:blogger.com,1999:blog-531225007922164170.post-33342722452694251442007-05-26T16:19:00.000-07:002007-05-26T16:58:47.779-07:00IMC 24th Conference paper<p class="MsoBodyText2" style="line-height: normal; text-align: center;font-family:arial;"><span style="text-transform: uppercase;font-size:85%;" ><span style="font-weight: bold;">Designing and Integrating a semi automated Powder Feed Device to Produce Functionally Graded Materials (FGM) using the HVOF Thermal Spray Process</span><o:p></o:p></span></p><div style="font-family: arial;"> </div><p class="MsoNormal" style="text-align: justify;font-family:arial;"><span style="font-size:85%;"><b><span style=""><o:p> </o:p></span></b></span></p><div face="arial" style="text-align: justify;"> </div><p class="MsoNormal" style="text-align: center;font-family:arial;"><span lang="EN-GB" style="font-size:85%;">Md. Kabir Al Mamun, Prof. Saleem Hashmi, Dr. Joseph Stokes </span><span style="display: none;" lang="EN-GB"><o:p></o:p></span></p><div style="font-family: arial;"> </div><p class="MsoNormal" style="text-align: justify;font-family:arial;"><span lang="EN-GB" style="font-size:85%;"><o:p> </o:p></span></p><div style="text-align: justify; font-family: arial;"> </div><div style="text-align: center;font-family:arial;"><span lang="EN-IE" style="font-size:85%;">Materials Processing Research Centre, <st1:placename st="on">Dublin</st1:placename> <st1:placetype st="on">City</st1:placetype> <st1:placetype st="on">University</st1:placetype>, <st1:city st="on">Dublin</st1:city> 9, <st1:country-region st="on">Ireland</st1:country-region></span><br /></div><p style="text-align: center;font-family:arial;" class="MsoBodyText"><span lang="EN-IE" style="font-size:85%;">National Centre for Plasma Science & Technology, <st1:place st="on"><st1:city st="on">Dublin City University</st1:city>, <st1:country-region st="on">Ireland</st1:country-region></st1:place></span><span lang="EN-GB" style="font-size:85%;"><o:p></o:p></span></p><div style="text-align: justify; font-family: arial;"> </div><p class="MsoNormal" style="text-align: justify;font-family:arial;"><span lang="EN-GB" style="font-size:85%;"><o:p> </o:p></span></p><div style="text-align: justify; font-family: arial;"> </div><p class="MsoNormal" style="text-align: justify;font-family:arial;"><span style="font-size:85%;"><b><span style=""><o:p> </o:p></span></b></span></p><div style="text-align: justify; font-family: arial;"> </div><h1 style="text-align: justify;font-family:arial;"><span style="font-size:85%;">Abstract</span></h1><div style="text-align: justify; font-family: arial;"> </div><p class="MsoNormal" style="text-indent: 28.8pt; text-align: justify;font-family:arial;"><span style="color: rgb(35, 31, 32);font-size:85%;" lang="EN-IE" ><o:p> </o:p></span></p><div style="text-align: justify; font-family: arial;"> </div><p class="MsoNormal" style="text-indent: 28.8pt; text-align: justify;font-family:arial;"><span style="color: rgb(35, 31, 32);font-size:85%;" lang="EN-IE" >The application of FGMs is quite difficult, but thermal spray processes like Plasma spray have demonstrated their unique potential in producing graded deposits, where researchers have used twin powder feed systems to mix different proportions of powders. </span><span lang="EN-IE" style="font-size:85%;">FGMs vary in composition and/or microstructure from one boundary (substrate) to another (top service surface), and innovative characteristics result from the gradient from metals to ceramics or non-metallic to metals.</span><span lang="EN-GB" style="font-size:85%;"> The present study investigates an innovative modification of a HVOF (High Velocity Oxy-Fuel) thermal spray process to produce functionally graded thick coatings. In order to deposit thick coatings, certain problems have to be overcome. Graded coatings enable gradual variation of the coating composition and/or microstructure, which offers the possibility of reducing residual stress build-up with in coatings.</span></p><div style="text-align: justify; font-family: arial;"> </div><p class="MsoNormal" style="text-indent: 36pt; text-align: justify;font-family:arial;"><span lang="EN-GB" style="font-size:85%;">In order to spray such a coating, modification to a commercial powder feed hopper was required to enable it to deposit two powders simultaneously which allows deposition of different layers of coating with changing chemical compositions, without interruption to the spraying process. Various concepts for this modification were identified and one design was selected, having been validated through use of a process model, developed using ANSYS Flotran Finite Element Analysis.</span><span lang="EN-GB" style="font-size:85%;"> In the current research the </span><span style="color: rgb(35, 31, 32);font-size:85%;" lang="EN-IE" >mixing of different proportions of powders</span><span lang="EN-GB" style="font-size:85%;"> were controlled by a computer using LabVIEW software and hardware, which allowed the control and repeatability of the microstructure when producing functionally graded coatings.<o:p></o:p></span></p><div style="text-align: justify; font-family: arial;"> </div><p class="MsoNormal" style="text-align: justify;font-family:arial;"><span style="font-size:85%;"><b style=""><span lang="EN-GB"><o:p> </o:p></span></b></span></p><div style="text-align: justify; font-family: arial;"> </div><p class="MsoNormal" style="text-align: justify;font-family:arial;"><span style="font-size:85%;"><b style=""><span lang="EN-GB">KEYWORDS: </span></b></span><span lang="EN-GB" style="font-size:85%;">HVOF, FGM, Powder Mixing</span></p><div style="text-align: justify; font-family: arial;"> </div><p class="MsoNormal" style="text-align: justify;font-family:arial;"><span lang="EN-GB" style="font-size:85%;"><o:p> </o:p></span></p><div style="text-align: justify; font-family: arial;"> </div><p class="MsoNormal" style="text-align: justify;font-family:arial;"><span style="font-size:85%;"><b style=""><span lang="EN-GB">1. INTRODUCTION<o:p></o:p></span></b></span></p><div style="text-align: justify; font-family: arial;"> </div><p class="MsoNormal" style="text-align: justify;font-family:arial;"><span style="font-size:85%;"><b style=""><span lang="EN-GB"><span style=""> </span><o:p></o:p></span></b></span></p><div style="text-align: justify; font-family: arial;"> </div><p class="MsoNormal" style="text-indent: 36pt; text-align: justify;font-family:arial;"><span lang="EN-GB" style="font-size:85%;">Thermal spraying can be described as a coating produced by a process in which molten or semi molten particles are applied by impact onto a substrate.</span><span style="color: rgb(35, 31, 32);font-size:85%;" lang="EN-IE" > Functionally Graded Materials (FGMs) are a growing application area with significant promise for the future production of; (a) improved materials and devices for use in applications subjected to large thermal gradients, (b) lower-cost clad materials for combinations of corrosion and strength or wear resistance, and (c) improved electronic material structures for batteries, fuel cells, and thermoelectric energy conversion devices and (d) biomedical implant devices for enhanced bone-tissue attachment. The most immediate application for FGMs is as Thermal Barrier Coatings (TBCs), where large thermal stresses can be minimised. Component lifetimes are improved by tailoring the coefficients of thermal expansion, thermal conductivity, and oxidation resistance.<o:p></o:p></span></p><div style="text-align: justify; font-family: arial;"> </div><p class="MsoNormal" style="text-align: justify;font-family:arial;"><span style="color: rgb(35, 31, 32);font-size:85%;" lang="EN-IE" ><span style=""> </span></span><span lang="EN-IE" style="font-size:85%;">To date the Plasma spray process has produce superior coatings for numerous applications, however the High Velocity Oxy Fuel (HVOF) process provides deposits with lower porosity, higher bond strength and low residual stress build up compared to Plasma techniques, due to its high kinetic energy and low combustion temperature design, hence is overall a more superior deposition process. </span><span lang="EN-GB" style="font-size:85%;">There are large ranges of materials, which have potential to benefit from graded structures yet to be researched. The current study aims to contribute new knowledge in these areas by depositing nickel base alloy/stainless steel functionally graded coatings on steel substrates using the HVOF process. Nickel base alloy/Stainless steel graded coatings are used in the automotive and marine industry not only to increase strength of the coated system but also for corrosion applications. </span><span lang="EN-IE" style="font-size:85%;">Functionally graded materials are those materials used to produce components featuring engineered gradual transitions in microstructure and/or composition, the presence of which is motivated by functional performance requirements that vary with location within a component. With functionally graded materials, these requirements are met in a manner that optimises the overall performance of the component. [<span style="color:blue;">1</span>]. Functionally graded materials have the potential to improve the thermo mechanical characteristics of a component in several ways [<span style="color:blue;">2</span>]. </span><span lang="EN-IE" style="font-size:85%;">Thermal spraying can be used to produce inter layers of FGM coating by two methods; Using premixed powder to produce each different layer and secondly Co-injecting two different powders and varying their relative proportions during deposition. Most</span><span lang="EN-GB" style="font-size:85%;"> researchers [<span style="color:blue;">3-7</span>] have used the former method while producing functionally graded coatings; however the latter method is used in this project. </span><span lang="EN-IE" style="font-size:85%;">However the HVOF does not possess a twin powder feed system, hence such a system was designed to fulfil this application. </span><span lang="EN-GB" style="font-size:85%;">Figure 1 (a) shows a schematic diagram of computer controlled Powder feed system.</span><span lang="EN-GB" style="font-size:85%;"> </span><span lang="EN-IE" style="font-size:85%;">This research will discuss the potential of using the HVOF technique to produce FGMs.</span><span lang="EN-IE" style="font-size:85%;"><o:p></o:p></span></p><div style="text-align: justify; font-family: arial;"> </div><p class="MsoNormal" style="text-indent: 36pt; text-align: justify;font-family:arial;"><span lang="EN-GB" style="font-size:85%;"><o:p> </o:p></span></p><div style="text-align: justify; font-family: arial;"> </div><div style="text-align: justify; font-family: arial;"> </div><p class="MsoNormal" style="text-indent: 36pt; text-align: justify;font-family:arial;"><br /><span lang="EN-GB" style="font-size:85%;"></span><span lang="EN-GB" style="font-size:85%;"><o:p></o:p></span></p><div style="text-align: justify; font-family: arial;"> </div><p class="MsoNormal" style="text-indent: 36pt; text-align: justify;font-family:arial;"><span lang="EN-GB" style="font-size:85%;"><o:p> </o:p></span></p><div style="text-align: justify; font-family: arial;"> </div><p class="MsoNormal" style="text-align: justify;font-family:arial;"><span style="font-size:85%;"><b style=""><span style="" lang="EN-GB">2. FUNCTIONALLY GRADED MATERIALS (FGM)<o:p></o:p></span></b></span></p><div style="text-align: justify; font-family: arial;"> </div><p class="MsoNormal" style="text-align: justify;font-family:arial;"><span lang="EN-IE" style="font-size:85%;"><o:p> </o:p></span></p><div style="text-align: justify; font-family: arial;"> </div><p class="MsoNormal" style="text-align: justify;font-family:arial;"><span style="font-size:85%;"><b style=""><span style="" lang="EN-GB"><span style=""> </span></span></b></span><span lang="EN-GB" style="font-size:85%;">A functionally graded coatings is one in which the composition, microstructure and properties vary gradually from the bond coat to the topcoat </span><span lang="EN-GB" style="font-size:85%;"><span style="">[</span></span><span style=";font-size:85%;color:blue;" lang="EN-GB" >8</span><span lang="EN-GB" style="font-size:85%;"><span style="">]</span></span><span lang="EN-GB" style="font-size:85%;">.<br /></span></p><div style="text-align: justify; font-family: arial;"> </div><p class="MsoNormal" style="text-align: justify;font-family:arial;"><span lang="EN-GB" style="font-size:85%;">.</span></p><div style="text-align: justify; font-family: arial;"> </div><p class="MsoNormal" style="text-align: justify;font-family:arial;"><span style="font-size:85%;"><b><span style="text-transform: uppercase;">3. Model Design and Experimentation<o:p></o:p></span></b></span></p><div style="text-align: justify; font-family: arial;"> </div><p class="MsoNormal" style="text-align: justify;font-family:arial;"><span style="font-size:85%;"><b><span style="text-transform: uppercase;"><o:p> </o:p></span></b></span></p><div style="text-align: justify; font-family: arial;"> </div><p class="MsoBodyText" style="text-align: justify;font-family:arial;"><span style="text-transform: uppercase;font-size:85%;" ><span style=""> </span><span style=""> </span></span><span lang="EN-IE" style="font-size:85%;">In this current research the HVOF thermal sprayed facility used is the manually controlled continuous combustion Sulzer Metco Diamond Jet thermal spray system. Sulzer </span><span style=";font-size:85%;color:black;" >Metco provides a powder feed unit to go with their DJ HVOF Thermal Spray system. The desired powder is fed from the powder feed unit through a carrier gas, to the DJ gun where combustion occurs. Typically nitrogen is used to carry the powder particles. The powder feed unit comprises a hopper assembly, air vibrator, load cell, feed rate meter and control cabinet as shown in </span><span style="font-size:85%;">Figure 2.1-a.<span style="color:black;"> The unit is completely self-contained and is designed to deliver the powder to the gun at a precise flow rate [</span><span style="color:blue;">9</span><span style="color:black;">]. The powder material is placed inside the hopper assembly. Due to action of gravitational force, vibration of air vibrator and nitrogen gas pressure within the chamber powder drops into the powder port shaft (</span>Figure 2.1-b<span style="color:black;">). The nitrogen carrier gas flows through this port shaft and, whilst doing so, carries the powder on its way to the combustion zone of the gun. By adjusting the carrier gas flow meter control, the flow rate of the nitrogen gas is regulated and this is set according to the data outlined in the application charts [</span><span style="color:blue;">10</span><span style="color:black;">]. A switch on the gun activates the powder allowing it to flow from the hopper to the combustion chamber within the DJ gun, and the amount flowing is displayed on the feed rate meter (in gmin<sup>-1</sup> or lbs (hour)<sup>-1</sup>)</span><span style="color:blue;">, </span><span style="color:black;">measured by the load cell provided. The feed rate meter has an accuracy of ± 0.1 gmin<sup>-1</sup> and a range of 0 to 100 gmin<sup>-1</sup>. Further details have been reported by Stokes [</span><span style="color:blue;">11</span><span style="color:black;">], hence will not be expanded upon here.</span></span><span lang="EN-IE" style="font-size:85%;"><o:p></o:p></span></p><div style="text-align: justify; font-family: arial;"> </div><p class="MsoNormal" style="text-align: justify;font-family:arial;"><span style=";font-size:85%;color:black;" ><o:p> </o:p></span></p><div style="text-align: justify; font-family: arial;"> </div><p class="MsoBodyText3" style="text-indent: 36pt; text-align: justify;font-family:arial;"><span lang="EN-GB" style="font-size:85%;">The current research is mainly concerned about the development and re-design of the Hopper unit, which has been detailed on the following sections. Spray parameters for Stainless Steel (Diamalloy 1003) and Nickel base alloy (Diamalloy 2001) were taken from literature [<span style="color:blue;">12</span>].<o:p></o:p></span></p><div style="text-align: justify; font-family: arial;"> </div><p style="text-align: justify;font-family:arial;" class="MsoBodyText2"><span style="font-size:85%;"></span><span style="line-height: 150%;font-size:85%;" ><o:p></o:p></span></p><div style="text-align: justify; font-family: arial;"> </div><p class="MsoNormal" style="text-align: justify;font-family:arial;"><span style="font-size:85%;"><b><span style="text-transform: uppercase;">3.1 p</span></b><b><span style="">roduct<span style="text-transform: uppercase;"> D</span>esign<o:p></o:p></span></b></span></p><div style="text-align: justify; font-family: arial;"> </div><p class="MsoNormal" style="text-align: justify;font-family:arial;"><span style="font-size:85%;"><b><span style=""><o:p> </o:p></span></b></span></p><div style="text-align: justify; font-family: arial;"> </div><p class="MsoBodyText" style="text-align: justify;font-family:arial;"><span style="font-weight: normal;font-size:85%;" ><span style=""> </span></span><span lang="EN-IE" style="font-size:85%;">The overall aim was to design and manufacture a mechanism, which would provide an automated facility to control the proportion of the powder materials from an existing feed unit device (Hopper), in order to produce FGM coatings. The mechanism designed was capable of being integrated into the existing DJ powder feed system. The proposed design where possible interfaced with as much of the existing hardware or software within the facility. To develop a design solution for the current problem certain design specification were considered, such as; Performance, Environmental consideration, Maintenance, Installation, Safety and Manufacturability. <o:p></o:p></span></p><div style="text-align: justify; font-family: arial;"> </div><p class="MsoNormal" style="text-align: justify;font-family:arial;"><span lang="EN-GB" style="font-size:85%;">The lead screw of the linear actuator provides a linear relationship between motor rotation and vertical motion enabling open loop control to be used; that is no sensors are required to define the position of the assembly if the previous amount of motor rotation is known. Due to this linear motion the powder particles are ale to flow to the mixing zone from the Chamber ‘A’ and ‘B’.<br /><o:p></o:p></span></p><div style="text-align: justify; font-family: arial;"> </div><p class="MsoNormal" style="text-align: justify;font-family:arial;"><span style="text-transform: uppercase;font-size:85%;" ><o:p> </o:p></span></p><div style="text-align: justify; font-family: arial;"> </div><p class="MsoNormal" style="text-align: justify;font-family:arial;"><span style="font-size:85%;"><b><span style="text-transform: uppercase;">3.2 </span></b><b style=""><span style="" lang="EN-GB">Modelling and Software Control<o:p></o:p></span></b></span></p><div style="text-align: justify; font-family: arial;"> </div><p class="MsoNormal" style="text-align: justify;font-family:arial;"><span style="text-transform: uppercase;font-size:85%;" ><o:p> </o:p></span></p><div style="text-align: justify; font-family: arial;"> </div><p class="MsoNormal" style="text-align: justify;font-family:arial;"><span lang="EN-GB" style="font-size:85%;">In order to check the effectiveness of the design a finite element analysis was carried out before manufacturing these components using the FLOTRAN CFD ANSYS software the results of which will be described briefly. <span style="">The objective achievement of entire project depends on the controlling software development. Hence this was an important part of the current project. To control the linear motion of the needle shaped bolts Lab VIEW programming software has been used in this current research.<o:p></o:p></span></span></p><div style="text-align: justify; font-family: arial;"> </div><p class="MsoNormal" style="text-align: justify;font-family:arial;"><span lang="EN-GB" style="font-size:85%;"><o:p> </o:p></span></p><div style="text-align: justify; font-family: arial;"> </div><p class="MsoNormal" style="text-align: justify;font-family:arial;"><span style="font-size:85%;"><b style=""><span style="" lang="EN-GB">3.3 Experimental Analysis<o:p></o:p></span></b></span></p><div style="text-align: justify; font-family: arial;"> </div><p class="MsoNormal" style="text-align: justify;font-family:arial;"><span lang="EN-GB" style="font-size:85%;"><o:p> </o:p></span></p><div style="text-align: justify; font-family: arial;"> </div><p class="MsoNormal" style="text-align: justify;font-family:arial;"><span lang="EN-GB" style="font-size:85%;"><span style=""> </span></span><span lang="EN-GB" style="font-size:85%;">The powder flow bench tests were carried out to calibrate the powder flow with the vertical movement of the needles, which are coupled with two linear actuators and controlled with Lab VIEW software from a PC. The bench tests were carried out to calibrate the movements of the bolts inside the powder holders, named as chamber ‘P’ and ‘Q’. These needle shaped bolts moves upwards and downwards according to the users’ requirement inside the chamber. When the bolts are in a fully closed position or zero position, no powder flows. With the increase of the vertical movement powder starts to flow from the chamber into the mixing zone and vice versa.<b style=""> </b><span style=""><o:p></o:p></span></span></p><div style="text-align: justify; font-family: arial;"> </div><p class="MsoBodyText" style="text-indent: 36pt; text-align: justify;font-family:arial;"><span lang="EN-IE" style="font-size:85%;">Initially the dual feed powder holder was placed inside the powder hopper and then needle shaped bolts were placed inside the both chambers. Stainless steel powder (Diamalloy 1003) was poured into the chamber ‘P’ and the hopper cover was attached. After that the linear actuators were coupled with the needles. Variation of vertical movement was carried out controlling from the Lab VIEW Programme to check the flow of powder through the hole at the bottom of the chamber. During this process, powder particles were collected into a pre-weighted container at each stage of vertical increment from the bottom of the powder flow tube. The mass of powder flow was measured over a 10 second time period. Therefore the needle was opened for 10 seconds at every stage of vertical increment and weight of the powder flow was calculated subtracting the weight of the container from the total weight. For each step vertical increment three readings were taken. Next the nickel base alloy Diamalloy 1005 and Diamalloy 2001 were poured separately into the chamber ‘Q’ and the above procedure was repeated. To verify the results, chamber ‘Q’ was filled with Diamalloy 1003 and chamber ‘P’ was filled with Diamalloy 1005 and Diamalloy 2001, to justify if there was any difference between the two chambers results. </span><span lang="EN-IE" style="font-size:85%;">Another test was carried out to check the mixing ability of the re-designed mixing zone. In order to test this, two powders, Diamalloy 1003 (light in coloured compared to Diamalloy 2001) and Diamalloy 2001 powders were poured into chamber ‘P’ and ‘Q’ respectively. During this test the feed unit system and the nitrogen gas flow were operated under running mode. A container was placed to collect the resulting powder mixture from the tube connected to the pick up shaft. Visual inspection was carried out to confirm that the light coloured and dark coloured powder particles were mixed properly.<o:p></o:p></span></p><div style="text-align: justify; font-family: arial;"> </div><p class="MsoBodyText" style="text-indent: 36pt; text-align: justify;font-family:arial;"><span lang="EN-IE" style="font-size:85%;">Post bench test, FGM were deposited by spraying the powders mixture varying the composition from Bond to Top coat. This was used to validate that the device worked where these coatings were analysed using EDX (SEM) technique.</span><span lang="EN-IE" style="font-size:85%;"><o:p></o:p></span></p><div style="text-align: justify; font-family: arial;"> </div><p class="MsoNormal" style="text-align: justify;font-family:arial;"><span lang="EN-GB" style="font-size:85%;"><o:p> </o:p></span></p><div style="text-align: justify; font-family: arial;"> </div><p class="MsoNormal" style="text-align: justify;font-family:arial;"><span style="font-size:85%;"><b style=""><span style="" lang="EN-GB">4. RESULTS AND DISCUSSION<o:p></o:p></span></b></span></p><div style="text-align: justify; font-family: arial;"> </div><p class="MsoNormal" style="text-align: justify;font-family:arial;"><span lang="EN-GB" style="font-size:85%;"><span style=""> </span><o:p></o:p></span></p><div style="text-align: justify; font-family: arial;"> </div><p class="MsoNormal" style="text-indent: 36pt; text-align: justify;font-family:arial;"><span lang="EN-GB" style="font-size:85%;">This section briefly describes all the results and discussion of them related to this research.</span><span lang="EN-GB" style="font-size:85%;"> The following section describes the qualification procedure used to assess the functionality of the Dual Powder Feed device. Hypothesis of the current project was used to control the flow of two different powders at a certain ratios, which would give a desired coating composition as showed in Table 1. To achieve this objective a number of experimental tests were carried out on the current project design; manufacturing and installation processes were carried out. This section describes the calibration test on the design finally chosen to fulfil the project objective.</span><span lang="EN-GB" style="font-size:85%;"><o:p></o:p></span></p><div style="text-align: justify; font-family: arial;"> </div><p class="MsoBodyText" style="text-indent: 36pt; text-align: justify;font-family:arial;"><span lang="EN-IE" style="font-size:85%;">Table 1: Hypothesis of the two different powders flow controlling the vertical movement of the linear actuators ‘A’ & ‘B’.<o:p></o:p></span></p><div style="text-align: justify; font-family: arial;"> </div><p class="MsoBodyText" style="text-align: justify;font-family:arial;"><span lang="EN-IE" style="font-size:85%;"><o:p> </o:p></span></p><div style="text-align: justify; font-family: arial;"> </div><div style="text-align: justify; font-family: arial;"> <table class="MsoNormalTable" style="border: medium none ; margin-left: 0px; border-collapse: collapse; text-align: left; margin-right: 0px;" border="1" cellpadding="0" cellspacing="0"> <tbody><tr style="page-break-inside: avoid; height: 27.2pt;"> <td rowspan="7" style="border-style: solid solid none; padding: 0cm 5.4pt; width: 117pt; height: 27.2pt;" valign="top" width="156"> <p class="MsoBodyText" style="text-align: center;" align="center"><span lang="EN-IE" style="font-size:85%;"><o:p> </o:p></span></p> <p class="MsoBodyText" style="text-align: center;" align="center"><span lang="EN-IE" style="font-size:85%;"><o:p> </o:p></span></p> <p class="MsoBodyText" style="text-align: center;" align="center"><span lang="EN-IE" style="font-size:85%;"><o:p> </o:p></span></p> <p class="MsoBodyText" style="text-align: center;" align="center"><span lang="EN-IE" style="font-size:85%;">Vertical movement of linear actuators (mm)<o:p></o:p></span></p> </td> <td colspan="2" style="border-style: solid solid solid none; padding: 0cm 5.4pt; width: 108pt; height: 27.2pt;" valign="top" width="144"> <p class="MsoBodyText" style="text-align: justify;"><span lang="EN-IE" style="font-size:85%;">Initial position of both needles is close or zero.<o:p></o:p></span></p> </td> <td colspan="2" style="border-style: solid solid solid none; padding: 0cm 5.4pt; width: 197.1pt; height: 27.2pt;" valign="top" width="263"> <p class="MsoBodyText" style="text-align: center;" align="center"><span lang="EN-IE" style="font-size:85%;">Desired composition of FGM coating of different powder (%)<o:p></o:p></span></p> </td> </tr> <tr style="page-break-inside: avoid; height: 19.95pt;"> <td style="border-style: none solid solid none; padding: 0cm 5.4pt; width: 54pt; height: 19.95pt;" valign="top" width="72"> <p class="MsoBodyText" style="text-align: center;" align="center"><span lang="EN-IE" style="font-size:85%;">A<o:p></o:p></span></p> </td> <td style="border-style: solid solid solid none; padding: 0cm 5.4pt; width: 54pt; height: 19.95pt;" valign="top" width="72"> <p class="MsoBodyText" style="text-align: center;" align="center"><span lang="EN-IE" style="font-size:85%;">B<o:p></o:p></span></p> </td> <td style="border-style: none solid solid none; padding: 0cm 5.4pt; width: 93.5pt; height: 19.95pt;" valign="top" width="125"> <p class="MsoBodyText" style="text-align: center;" align="center"><span lang="EN-IE" style="font-size:85%;">P (SS)<o:p></o:p></span></p> </td> <td style="border-style: none solid solid none; padding: 0cm 5.4pt; width: 103.6pt; height: 19.95pt;" valign="top" width="138"> <p class="MsoBodyText" style="text-align: center;" align="center"><span lang="EN-IE" style="font-size:85%;">Q (Nickel base alloy)<o:p></o:p></span></p> </td> </tr> <tr style="page-break-inside: avoid; height: 7.2pt;"> <td style="border-style: none solid solid none; padding: 0cm 5.4pt; width: 54pt; height: 7.2pt;" valign="top" width="72"> <p class="MsoBodyText" style="text-align: center;" align="center"><span lang="EN-IE" style="font-size:85%;">4<o:p></o:p></span></p> </td> <td style="border-style: none solid solid none; padding: 0cm 5.4pt; width: 54pt; height: 7.2pt;" valign="top" width="72"> <p class="MsoBodyText" style="text-align: center;" align="center"><span lang="EN-IE" style="font-size:85%;">0<o:p></o:p></span></p> </td> <td style="border-style: none solid solid none; padding: 0cm 5.4pt; width: 93.5pt; height: 7.2pt;" valign="top" width="125"> <p class="MsoBodyText" style="text-align: center;" align="center"><span lang="EN-IE" style="font-size:85%;">100<o:p></o:p></span></p> </td> <td style="border-style: none solid solid none; padding: 0cm 5.4pt; width: 103.6pt; height: 7.2pt;" valign="top" width="138"> <p class="MsoBodyText" style="text-align: center;" align="center"><span lang="EN-IE" style="font-size:85%;">0<o:p></o:p></span></p> </td> </tr> <tr style="page-break-inside: avoid; height: 7.2pt;"> <td style="border-style: none solid solid none; padding: 0cm 5.4pt; width: 54pt; height: 7.2pt;" valign="top" width="72"> <p class="MsoBodyText" style="text-align: center;" align="center"><span lang="EN-IE" style="font-size:85%;">3<o:p></o:p></span></p> </td> <td style="border-style: none solid solid none; padding: 0cm 5.4pt; width: 54pt; height: 7.2pt;" valign="top" width="72"> <p class="MsoBodyText" style="text-align: center;" align="center"><span lang="EN-IE" style="font-size:85%;">1<o:p></o:p></span></p> </td> <td style="border-style: none solid solid none; padding: 0cm 5.4pt; width: 93.5pt; height: 7.2pt;" valign="top" width="125"> <p class="MsoBodyText" style="text-align: center;" align="center"><span lang="EN-IE" style="font-size:85%;">75<o:p></o:p></span></p> </td> <td style="border-style: none solid solid none; padding: 0cm 5.4pt; width: 103.6pt; height: 7.2pt;" valign="top" width="138"> <p class="MsoBodyText" style="text-align: center;" align="center"><span lang="EN-IE" style="font-size:85%;">25<o:p></o:p></span></p> </td> </tr> <tr style="page-break-inside: avoid; height: 7.2pt;"> <td style="border-style: none solid solid none; padding: 0cm 5.4pt; width: 54pt; height: 7.2pt;" valign="top" width="72"> <p class="MsoBodyText" style="text-align: center;" align="center"><span lang="EN-IE" style="font-size:85%;">2<o:p></o:p></span></p> </td> <td style="border-style: none solid solid none; padding: 0cm 5.4pt; width: 54pt; height: 7.2pt;" valign="top" width="72"> <p class="MsoBodyText" style="text-align: center;" align="center"><span lang="EN-IE" style="font-size:85%;">2<o:p></o:p></span></p> </td> <td style="border-style: none solid solid none; padding: 0cm 5.4pt; width: 93.5pt; height: 7.2pt;" valign="top" width="125"> <p class="MsoBodyText" style="text-align: center;" align="center"><span lang="EN-IE" style="font-size:85%;">50<o:p></o:p></span></p> </td> <td style="border-style: none solid solid none; padding: 0cm 5.4pt; width: 103.6pt; height: 7.2pt;" valign="top" width="138"> <p class="MsoBodyText" style="text-align: center;" align="center"><span lang="EN-IE" style="font-size:85%;">50<o:p></o:p></span></p> </td> </tr> <tr style="page-break-inside: avoid; height: 9.55pt;"> <td style="border-style: none solid solid none; padding: 0cm 5.4pt; width: 54pt; height: 9.55pt;" valign="top" width="72"> <p class="MsoBodyText" style="text-align: center;" align="center"><span lang="EN-IE" style="font-size:85%;">1<o:p></o:p></span></p> </td> <td style="border-style: none solid solid none; padding: 0cm 5.4pt; width: 54pt; height: 9.55pt;" valign="top" width="72"> <p class="MsoBodyText" style="text-align: center;" align="center"><span lang="EN-IE" style="font-size:85%;">3<o:p></o:p></span></p> </td> <td style="border-style: none solid solid none; padding: 0cm 5.4pt; width: 93.5pt; height: 9.55pt;" valign="top" width="125"> <p class="MsoBodyText" style="text-align: center;" align="center"><span lang="EN-IE" style="font-size:85%;">25<o:p></o:p></span></p> </td> <td style="border-style: none solid solid none; padding: 0cm 5.4pt; width: 103.6pt; height: 9.55pt;" valign="top" width="138"> <p class="MsoBodyText" style="text-align: center;" align="center"><span lang="EN-IE" style="font-size:85%;">75<o:p></o:p></span></p> </td> </tr> <tr style="page-break-inside: avoid; height: 5.95pt;"> <td style="border-style: none solid solid none; padding: 0cm 5.4pt; width: 54pt; height: 5.95pt;" valign="top" width="72"> <p class="MsoBodyText" style="text-align: center;" align="center"><span lang="EN-IE" style="font-size:85%;">0<o:p></o:p></span></p> </td> <td style="border-style: none solid solid none; padding: 0cm 5.4pt; width: 54pt; height: 5.95pt;" valign="top" width="72"> <p class="MsoBodyText" style="text-align: center;" align="center"><span lang="EN-IE" style="font-size:85%;">4<o:p></o:p></span></p> </td> <td style="border-style: none solid solid none; padding: 0cm 5.4pt; width: 93.5pt; height: 5.95pt;" valign="top" width="125"> <p class="MsoBodyText" style="text-align: center;" align="center"><span lang="EN-IE" style="font-size:85%;">0<o:p></o:p></span></p> </td> <td style="border-style: none solid solid none; padding: 0cm 5.4pt; width: 103.6pt; height: 5.95pt;" valign="top" width="138"> <p class="MsoBodyText" style="text-align: center;" align="center"><span lang="EN-IE" style="font-size:85%;">100<o:p></o:p></span></p> </td> </tr> <tr style="page-break-inside: avoid; height: 20.35pt;"> <td colspan="5" style="border: 1pt solid windowtext; padding: 0cm 5.4pt; width: 422.1pt; height: 20.35pt;" valign="top" width="563"> <p class="MsoBodyText" style="text-align: center;" align="center"><span lang="EN-IE" style="font-size:85%;">Assumption: travelling distance is 4 mm and time delay for each step is equivalent to eight passes of the spray gun across the front of the substrate.<o:p></o:p></span></p> </td> </tr> </tbody></table> </div><div style="text-align: justify; font-family: arial;"> </div><h3 style="text-align: justify;font-family:arial;"><span lang="EN-GB" style="font-size:85%;">4.1 Simulation Results<o:p></o:p></span></h3><div style="text-align: justify; font-family: arial;"> </div><p style="text-align: justify;font-family:arial;" class="MsoNormal"><span lang="EN-GB" style="font-size:85%;"><o:p> </o:p></span></p><div style="text-align: justify; font-family: arial;"> </div><div style="text-align: justify; font-family: arial;"> </div><p class="MsoNormal" style="text-align: justify;font-family:arial;"><span lang="EN-GB" style="font-size:85%;"><o:p> </o:p></span></p><div style="text-align: justify; font-family: arial;"> </div><div style="text-align: justify; font-family: arial;"> </div><p class="MsoNormal" style="line-height: 150%; text-align: justify;font-family:arial;"><span lang="EN-GB" style="font-size:85%;">This ANSYS simulation was carried out mainly to verify the following two questions; whether the design parts would be able to carry the powders into the mixing zone (inside the parts) where they are supposed to mix, whether the mixed powder particles would then be carried out by the nitrogen gas flow inside the pick up shaft towards the spray gun. During the FEA simulation approach different nitrogen gas pressure ratios (ratio between the top of the pressure inlet tube to pick up shaft, 1:1, 2.25:1 and 1.8:1) were applied and an approximate nitrogen gas pressure ratio was determined to cause powder mixing and to force the mixed powder into the carrier gas flow (nitrogen gas) inside the pick up shaft. To meet the requirements of the current project objective it was necessary to compare with the velocity and particle flow trace found in each of the ANSYS models. Figure 4 shows the flow trace of nitrogen gas and powders for a pressure ratio of 2.25:1 where the optimum maximum velocity was found at the outlet ranged from 130 to 147 m/s and this analysis shows that the powder particles are able to mix with each other in side the mixing zone at a velocity range of 0 to 16 m/s and these were shown to perform better than the previous research [<span style="color:blue;">1</span>].<o:p></o:p><br /></span><span lang="EN-GB" style="font-size:85%;"><o:p></o:p></span></p><div style="text-align: justify; font-family: arial;"> </div><p class="MsoBodyText" style="text-align: justify;font-family:arial;"><span lang="EN-IE" style="font-size:85%;"><o:p> </o:p></span></p><div style="text-align: justify; font-family: arial;"> </div><p class="MsoBodyText" style="text-align: justify;font-family:arial;"><span lang="EN-IE" style="font-size:85%;"><span style="font-weight: bold;">4.2 Bench Tests of Powder Flow</span><o:p></o:p></span></p><div style="text-align: justify; font-family: arial;"> </div><p class="MsoBodyText" style="text-align: justify;font-family:arial;"><span lang="EN-IE" style="font-size:85%;"><o:p> </o:p></span></p><div style="text-align: justify; font-family: arial;"> </div><p class="MsoBodyText" style="text-indent: 36pt; text-align: justify;font-family:arial;"><span lang="EN-IE" style="font-size:85%;">The combine graphical representation of the powder flow through the mixing zone during the 4 mm increment of Needle movement in Chamber ‘A’ and Chamber ‘B’ for all powders.</span><span lang="EN-IE" style="font-size:85%;"> </span><span lang="EN-IE" style="font-size:85%;">From visible observations it was found that the powder particle of Diamalloy 1003 and Diamalloy 1005 are more or less same sized, shape. Diamalloy 1003 and Diamalloy 1005 powders have a tendency to agglomerate due to their fine shape where as Diamalloy 2001 is more granular but flows easier compare to the other two types. However the Diamalloy 2001 flowed at high rate compare to Diamalloy 1003 and Diamalloy 1005. Flowability or Density measurement tests and Optical Microscope Image analysis also confirmed these reasons for difference in flow of each powder.<o:p></o:p></span></p><div style="text-align: justify; font-family: arial;"> </div><p class="MsoBodyText" style="text-indent: 36pt; text-align: justify;font-family:arial;"><span lang="EN-IE" style="font-size:85%;">From the powder flow bench test results it has been determined that during the coating process to get the 100% flow of powder particle vertical increment of the needle shaped bolts was 4 mm from zero position using any Chamber either ‘A’ or ‘B’. Each stage of vertical increment or decrement was 1 mm to achieve 25% powder composition, as 25% is ¼ of 100%. Hence to obtain a 1000 μm (approximately 1 mm) thick coating, the spray gun needs to produce 32 layers on the substrate, which is 16 passes (as each layer is 30 μm thick). Hence the Lab VIEW programme limit switch was designed to send a signal to create the vertical increment or decrement of the needle shaped bolts every 8 layers (1/4 of overall coating thickness). The above procedure is applicable when the flow ability of the two powders is more or less same, for example here, base powder material Diamalloy 1003 and coating powder material Diamalloy 1005.</span><span lang="EN-IE" style="font-size:85%;"><o:p></o:p></span></p><div style="text-align: justify; font-family: arial;"> </div><p class="MsoBodyText" style="text-indent: 36pt; text-align: justify;font-family:arial;"><span lang="EN-IE" style="font-size:85%;"><o:p> </o:p></span></p><div style="text-align: justify; font-family: arial;"> </div><p class="MsoNormal" style="line-height: 200%; font-family: arial; text-align: justify;"><!--[if gte vml 1]><v:shape id="_x0000_s1035" type="#_x0000_t202" style="'position:absolute;margin-left:2.25pt;margin-top:-6pt;" filled="f" strokecolor="blue"> <v:textbox style="'mso-next-textbox:#_x0000_s1035'/"> </v:shape><![endif]--><!--[if !vml]--><!--[endif]--><!--[if gte vml 1]><v:shape id="_x0000_s1037" type="#_x0000_t202" style="'position:absolute;margin-left:375pt;margin-top:176.95pt;width:1in;"><![endif]--><!--[if !vml]--><span style="position: absolute; z-index: 12; margin-left: 499px; margin-top: 235px; width: 102px; height: 30px;font-size:85%;" ></span><!--[endif]--><!--[if gte vml 1]><v:shape id="_x0000_s1036" type="#_x0000_t202" style="'position:absolute;margin-left:15.75pt;margin-top:173.95pt;width:1in;" filled="f"> <v:textbox style="'mso-next-textbox:#_x0000_s1036'/"> </v:shape><![endif]--><!--[if !vml]--><span style="position: absolute; z-index: 11; margin-left: 20px; margin-top: 231px; width: 102px; height: 30px;font-size:85%;" > <table cellpadding="0" cellspacing="0"> <tbody><tr> <td style="border: 0.75pt solid black; vertical-align: top;" height="30" width="102"><!--[endif]--><!--[if !mso]--><span style="position: absolute; z-index: 11;"><br /></span><!--[endif]--><!--[if !mso & !vml]--> <!--[endif]--><!--[if !vml]--></td> </tr> </tbody></table> </span><!--[endif]--><span lang="EN-GB" style="font-size:85%;"><!--[if gte vml 1]><v:shape id="_x0000_i1030" type="#_x0000_t75" style="'width:233.25pt;height:186pt'" ole=""> <v:imagedata src="file:///C:\DOCUME~1\Mamun\LOCALS~1\Temp\msohtml1\01\clip_image013.wmz" title=""> </v:shape><![endif]--><!--[if !vml]--><!--[endif]--><!--[if gte mso 9]><xml> <o:oleobject type="Embed" progid="Word.Picture.8" shapeid="_x0000_i1030" drawaspect="Content" objectid="_1241730414"> </o:OLEObject> </xml><![endif]--><!--[if gte vml 1]><v:shape id="_x0000_i1031" type="#_x0000_t75" style="'width:227.25pt;height:184.5pt'" ole=""> <v:imagedata src="file:///C:\DOCUME~1\Mamun\LOCALS~1\Temp\msohtml1\01\clip_image015.wmz" title=""> </v:shape><![endif]--><!--[if !vml]--><!--[endif]--><!--[if gte mso 9]><xml> <o:oleobject type="Embed" progid="Word.Picture.8" shapeid="_x0000_i1031" drawaspect="Content" objectid="_1241730416"> </o:OLEObject> </xml><![endif]--></span></p><div style="text-align: justify;"> </div><div style="text-align: justify;"> </div><p class="MsoBodyText2" style="line-height: normal; text-align: justify;font-family:arial;"><span style="font-size:85%;"><o:p> </o:p></span></p><div style="text-align: justify;"> </div><p class="MsoBodyText2" style="line-height: normal; text-align: justify;font-family:arial;"><span style="font-size:85%;">But when the flowability of two powders (for example base powder material Diamalloy 1003 and coating powder material Diamalloy 2001) is dissimilar then it is necessary to calibrate the powder composition ratio with the vertical increment or decrement of the needle shaped bolts. For the current research Diamalloy 1003 was used as a base material powder (similar to the substrate). Table 2 shows the vertical increment or decrement of each needle shaped bolt according to the amount (mass) of powder found in the mixture as determined by the powder bench test for Diamalloy 1003, 1005 and 2001. Hence, these increment (or decrement) values for each powder-controlling needle, yields the desired functionally graded coatings.<o:p></o:p></span></p><div style="text-align: justify;"> </div><p class="MsoBodyText2" style="text-indent: 36pt; line-height: normal; text-align: justify;font-family:arial;"><span style="font-size:85%;"><o:p> </o:p></span></p><div style="text-align: justify;"> </div><p class="MsoBodyText2" style="line-height: normal; text-align: justify;font-family:arial;"><span style="font-size:85%;"><o:p> </o:p></span></p><div style="text-align: justify;"> </div><p class="MsoBodyText2" style="line-height: normal; text-align: justify;font-family:arial;"><span style="font-size:78%;">Table 2: vertical increment or decrement composition of needle shaped bolt with different powders, </span><span style="font-size:78%;">the chemical composition of starting powders [<span style="color:blue;">13</span>].</span><span style="font-size:78%;"><o:p></o:p></span></p><div style="text-align: justify; font-family: arial;"> </div> <table class="MsoNormalTable" style="border: medium none ; margin-left: -3.6pt; border-collapse: collapse;font-family:arial;" border="1" cellpadding="0" cellspacing="0"> <tbody><tr style="page-break-inside: avoid;"> <td style="border: 1pt solid windowtext; padding: 0cm 5.4pt; width: 72pt;" valign="top" width="96"> <p class="MsoBodyText2" style="line-height: normal;"><span style="font-size:78%;">Percentage of powder composition<o:p></o:p></span></p> </td> <td colspan="2" style="border-style: solid solid solid none; padding: 0cm 5.4pt; width: 135pt;" valign="top" width="180"> <p class="MsoBodyText2" style="line-height: normal;"><span style="font-size:78%;">Diamalloy 1003<o:p></o:p></span></p> <p class="MsoBodyText2" style="line-height: normal;"><span style="font-size:78%;">(Base powder material)<o:p></o:p></span></p> </td> <td colspan="2" style="border-style: solid solid solid none; padding: 0cm 5.4pt; width: 135pt;" valign="top" width="180"> <p class="MsoBodyText2" style="line-height: normal;"><span style="font-size:78%;">Diamalloy 1005<o:p></o:p></span></p> </td> <td colspan="2" style="border-style: solid solid solid none; padding: 0cm 5.4pt; width: 144pt;" valign="top" width="192"> <p class="MsoBodyText2" style="line-height: normal;"><span style="font-size:78%;">Diamalloy 2001<o:p></o:p></span></p> </td> </tr> <tr style=""> <td style="border-style: none solid solid; padding: 0cm 5.4pt; width: 72pt;" valign="top" width="96"> <p class="MsoBodyText2" style="line-height: normal;"><span style="font-size:78%;">Needle shape bolt either ‘A’ or ‘B’ (%)<o:p></o:p></span></p> <p class="MsoBodyText2" style="line-height: normal;"><span style="font-size:78%;">[Initial position is zero]<o:p></o:p></span></p> </td> <td style="border-style: none solid solid none; padding: 0cm 5.4pt; width: 63pt;" valign="top" width="84"> <p class="MsoBodyText2" style="line-height: normal;"><span style="font-size:78%;">Increment or </span><span style="font-size:78%;">Decrement<o:p></o:p></span></p> <p class="MsoBodyText2" style="line-height: normal;"><span style="font-size:78%;">(mm)<o:p></o:p></span></p> <p class="MsoBodyText2" style="text-align: justify; line-height: normal;"><span style="font-size:78%;"><o:p> </o:p></span></p> </td> <td style="border-style: none solid solid none; padding: 0cm 5.4pt; width: 72pt;" valign="top" width="96"> <p class="MsoBodyText2" style="line-height: normal;"><span style="font-size:78%;">Approximated mass of powder (gm), Time delay, T=10 sec<o:p></o:p></span></p> <p class="MsoBodyText2" style="line-height: normal;"><span style="font-size:78%;">(Data from Figure 5)<o:p></o:p></span></p> </td> <td style="border-style: none solid solid none; padding: 0cm 5.4pt; width: 63pt;" valign="top" width="84"> <p class="MsoBodyText2" style="line-height: normal;"><span style="font-size:78%;">Decrement (mm)<o:p></o:p></span></p> </td> <td style="border-style: none solid solid none; padding: 0cm 5.4pt; width: 72pt;" valign="top" width="96"> <p class="MsoBodyText2" style="line-height: normal;"><span style="font-size:78%;">Approximated mass of powder (gm), Time delay, T=10 sec (Data from Figure 5)<o:p></o:p></span></p> </td> <td style="border-style: none solid solid none; padding: 0cm 5.4pt; width: 63pt;" valign="top" width="84"> <p class="MsoBodyText2" style="line-height: normal;"><span style="font-size:78%;">Decrement (mm)<o:p></o:p></span></p> </td> <td style="border-style: none solid solid none; padding: 0cm 5.4pt; width: 81pt;" valign="top" width="108"> <p class="MsoBodyText2" style="line-height: normal;"><span style="font-size:78%;">Approximated mass of powder (gm), Time delay, T=10 sec (Data from Figure 5)<o:p></o:p></span></p> </td> </tr> <tr style=""> <td style="border-style: none solid solid; padding: 0cm 5.4pt; width: 72pt;" valign="top" width="96"> <p class="MsoBodyText2" style="line-height: normal;"><span style="font-size:78%;">100<o:p></o:p></span></p> </td> <td style="border-style: none solid solid none; padding: 0cm 5.4pt; width: 63pt;" valign="top" width="84"> <p class="MsoBodyText2" style="line-height: normal;"><span style="font-size:78%;">4.00<o:p></o:p></span></p> </td> <td style="border-style: none solid solid none; padding: 0cm 5.4pt; width: 72pt;" valign="top" width="96"> <p class="MsoBodyText2" style="line-height: normal;"><span style="font-size:78%;">80<o:p></o:p></span></p> </td> <td style="border-style: none solid solid none; padding: 0cm 5.4pt; width: 63pt;" valign="top" width="84"> <p class="MsoBodyText2" style="line-height: normal;"><span style="font-size:78%;">4.00<o:p></o:p></span></p> </td> <td style="border-style: none solid solid none; padding: 0cm 5.4pt; width: 72pt;" valign="top" width="96"> <p class="MsoBodyText2" style="line-height: normal;"><span style="font-size:78%;">80<o:p></o:p></span></p> </td> <td style="border-style: none solid solid none; padding: 0cm 5.4pt; width: 63pt;" valign="top" width="84"> <p class="MsoBodyText2" style="line-height: normal;"><span style="font-size:78%;">4.00<o:p></o:p></span></p> </td> <td style="border-style: none solid solid none; padding: 0cm 5.4pt; width: 81pt;" valign="top" width="108"> <p class="MsoBodyText2" style="line-height: normal;"><span style="font-size:78%;">90<o:p></o:p></span></p> </td> </tr> <tr style=""> <td style="border-style: none solid solid; padding: 0cm 5.4pt; width: 72pt;" valign="top" width="96"> <p class="MsoBodyText2" style="line-height: normal;"><span style="font-size:78%;">75<o:p></o:p></span></p> </td> <td style="border-style: none solid solid none; padding: 0cm 5.4pt; width: 63pt;" valign="top" width="84"> <p class="MsoBodyText2" style="line-height: normal;"><span style="font-size:78%;">3.50<o:p></o:p></span></p> </td> <td style="border-style: none solid solid none; padding: 0cm 5.4pt; width: 72pt;" valign="top" width="96"> <p class="MsoBodyText2" style="line-height: normal;"><span style="font-size:78%;">60<o:p></o:p></span></p> </td> <td style="border-style: none solid solid none; padding: 0cm 5.4pt; width: 63pt;" valign="top" width="84"> <p class="MsoBodyText2" style="line-height: normal;"><span style="font-size:78%;">3.50<o:p></o:p></span></p> </td> <td style="border-style: none solid solid none; padding: 0cm 5.4pt; width: 72pt;" valign="top" width="96"> <p class="MsoBodyText2" style="line-height: normal;"><span style="font-size:78%;">60<o:p></o:p></span></p> </td> <td style="border-style: none solid solid none; padding: 0cm 5.4pt; width: 63pt;" valign="top" width="84"> <p class="MsoBodyText2" style="line-height: normal;"><span style="font-size:78%;">3.10<o:p></o:p></span></p> </td> <td style="border-style: none solid solid none; padding: 0cm 5.4pt; width: 81pt;" valign="top" width="108"> <p class="MsoBodyText2" style="line-height: normal;"><span style="font-size:78%;">68<o:p></o:p></span></p> </td> </tr> <tr style=""> <td style="border-style: none solid solid; padding: 0cm 5.4pt; width: 72pt;" valign="top" width="96"> <p class="MsoBodyText2" style="line-height: normal;"><span style="font-size:78%;">50<o:p></o:p></span></p> </td> <td style="border-style: none solid solid none; padding: 0cm 5.4pt; width: 63pt;" valign="top" width="84"> <p class="MsoBodyText2" style="line-height: normal;"><span style="font-size:78%;">3.00<o:p></o:p></span></p> </td> <td style="border-style: none solid solid none; padding: 0cm 5.4pt; width: 72pt;" valign="top" width="96"> <p class="MsoBodyText2" style="line-height: normal;"><span style="font-size:78%;">40<o:p></o:p></span></p> </td> <td style="border-style: none solid solid none; padding: 0cm 5.4pt; width: 63pt;" valign="top" width="84"> <p class="MsoBodyText2" style="line-height: normal;"><span style="font-size:78%;">3.00<o:p></o:p></span></p> </td> <td style="border-style: none solid solid none; padding: 0cm 5.4pt; width: 72pt;" valign="top" width="96"> <p class="MsoBodyText2" style="line-height: normal;"><span style="font-size:78%;">40<o:p></o:p></span></p> </td> <td style="border-style: none solid solid none; padding: 0cm 5.4pt; width: 63pt;" valign="top" width="84"> <p class="MsoBodyText2" style="line-height: normal;"><span style="font-size:78%;">2.20<o:p></o:p></span></p> </td> <td style="border-style: none solid solid none; padding: 0cm 5.4pt; width: 81pt;" valign="top" width="108"> <p class="MsoBodyText2" style="line-height: normal;"><span style="font-size:78%;">46<o:p></o:p></span></p> </td> </tr> <tr style=""> <td style="border-style: none solid solid; padding: 0cm 5.4pt; width: 72pt;" valign="top" width="96"> <p class="MsoBodyText2" style="line-height: normal;"><span style="font-size:78%;">25<o:p></o:p></span></p> </td> <td style="border-style: none solid solid none; padding: 0cm 5.4pt; width: 63pt;" valign="top" width="84"> <p class="MsoBodyText2" style="line-height: normal;"><span style="font-size:78%;">2.50<o:p></o:p></span></p> </td> <td style="border-style: none solid solid none; padding: 0cm 5.4pt; width: 72pt;" valign="top" width="96"> <p class="MsoBodyText2" style="line-height: normal;"><span style="font-size:78%;">20<o:p></o:p></span></p> </td> <td style="border-style: none solid solid none; padding: 0cm 5.4pt; width: 63pt;" valign="top" width="84"> <p class="MsoBodyText2" style="line-height: normal;"><span style="font-size:78%;">2.50<o:p></o:p></span></p> </td> <td style="border-style: none solid solid none; padding: 0cm 5.4pt; width: 72pt;" valign="top" width="96"> <p class="MsoBodyText2" style="line-height: normal;"><span style="font-size:78%;">20<o:p></o:p></span></p> </td> <td style="border-style: none solid solid none; padding: 0cm 5.4pt; width: 63pt;" valign="top" width="84"> <p class="MsoBodyText2" style="line-height: normal;"><span style="font-size:78%;">1.30<o:p></o:p></span></p> </td> <td style="border-style: none solid solid none; padding: 0cm 5.4pt; width: 81pt;" valign="top" width="108"> <p class="MsoBodyText2" style="line-height: normal;"><span style="font-size:78%;">24<o:p></o:p></span></p> </td> </tr> <tr style=""> <td style="border-style: none solid solid; padding: 0cm 5.4pt; width: 72pt;" valign="top" width="96"> <p class="MsoBodyText2" style="line-height: normal;"><span style="font-size:78%;">0<o:p></o:p></span></p> </td> <td style="border-style: none solid solid none; padding: 0cm 5.4pt; width: 63pt;" valign="top" width="84"> <p class="MsoBodyText2" style="line-height: normal;"><span style="font-size:78%;">0<o:p></o:p></span></p> </td> <td style="border-style: none solid solid none; padding: 0cm 5.4pt; width: 72pt;" valign="top" width="96"> <p class="MsoBodyText2" style="line-height: normal;"><span style="font-size:78%;">0<o:p></o:p></span></p> </td> <td style="border-style: none solid solid none; padding: 0cm 5.4pt; width: 63pt;" valign="top" width="84"> <p class="MsoBodyText2" style="line-height: normal;"><span style="font-size:78%;">0<o:p></o:p></span></p> </td> <td style="border-style: none solid solid none; padding: 0cm 5.4pt; width: 72pt;" valign="top" width="96"> <p class="MsoBodyText2" style="line-height: normal;"><span style="font-size:78%;">0<o:p></o:p></span></p> </td> <td style="border-style: none solid solid none; padding: 0cm 5.4pt; width: 63pt;" valign="top" width="84"> <p class="MsoBodyText2" style="line-height: normal;"><span style="font-size:78%;">0<o:p></o:p></span></p> </td> <td style="border-style: none solid solid none; padding: 0cm 5.4pt; width: 81pt;" valign="top" width="108"> <p class="MsoBodyText2" style="line-height: normal;"><span style="font-size:78%;">0<o:p></o:p></span></p> </td> </tr> <tr style="height: 16.5pt;"> <td style="border-style: none solid solid; padding: 0cm 5.4pt; width: 72pt; height: 16.5pt;" valign="top" width="96"> <p class="MsoBodyText2" style="line-height: normal;"><span style="font-size:78%;">Chemical Composition (wt%)<o:p></o:p></span></p> </td> <td colspan="2" style="border-style: none solid solid none; padding: 0cm 5.4pt; width: 135pt; height: 16.5pt;" valign="top" width="180"> <p class="MsoBodyText2" style="line-height: normal;"><span lang="EN-IE" style="font-size:78%;">Cr 17%, Ni 12%, Mo 2.5%, Si 1%, C 0.1%, Fe Bal. (Bond Coat)</span><span style="font-size:78%;"><o:p></o:p></span></p> </td> <td colspan="2" style="border-style: none solid solid none; padding: 0cm 5.4pt; width: 135pt; height: 16.5pt;" valign="top" width="180"> <p class="MsoBodyText" style="text-align: center;" align="center"><span lang="EN-IE" style="font-size:78%;">Cr 21.5%, Mo 9%, Nb 3.6%, Ti <0.4%,></span></p> </td> <td colspan="2" style="border-style: none solid solid none; padding: 0cm 5.4pt; width: 144pt; height: 16.5pt;" valign="top" width="192"> <p class="MsoNormal"><span lang="EN-GB" style="font-size:78%;">Cr 17, Fe 4%, Si 4%, B 3.5%, C 1%, Ni Bal. (Top Coat)<span style=""><o:p></o:p></span></span></p> </td> </tr> </tbody></table> <div style="text-align: justify; font-family: arial;"> </div><p class="MsoBodyText2" style="line-height: normal; text-align: justify;font-family:arial;"><span style="font-weight: bold;font-size:85%;" >4.3 Experimental Results</span><span style="font-size:85%;"><o:p></o:p></span></p><div style="text-align: justify;"> </div><p class="MsoNormal" style="text-align: justify;font-family:arial;"><span style="font-size:85%;"><b style=""><span lang="EN-GB" style="color:blue;"><span style=""> </span><o:p></o:p></span></b></span></p><div style="text-align: justify;"> </div><p class="MsoNormal" style="text-align: justify;font-family:arial;"><span style="font-size:85%;"><b style=""><span lang="EN-GB" style="color:blue;"><span style=""> </span></span></b></span><span lang="EN-GB" style="font-size:85%;">A 1 mm thick Stainless steel substrate has functionally grad coated with Diamalloy 1003 and Diamalloy 2001 using the designed semi automated system and chemical composition of five layers was determined using the energy dispersive X-ray (EDX) spectroscopy. The chemical composition of Diamalloy 1003 and Diamalloy 2001 are shown in Table 2.<o:p></o:p></span></p><div style="text-align: justify;"> </div><p class="MsoNormal" style="text-align: justify;font-family:arial;"><span lang="EN-GB" style="font-size:85%;"><o:p> </o:p></span></p><div style="text-align: justify;"> </div><p class="MsoNormal" style="text-align: justify;font-family:arial;"><span lang="EN-GB" style="font-size:85%;"><span style=""> </span>One can see that Cr 17% is common; for both FGM powders, so Fe and B were used to validate the design from Bond coat to Top Coat. The iron Fe desired amount should figure from 67.4% in the Bond Coat and 4% in the Top Coat. The FGM coating obtained values of 54.47% in the Bond Coat, 37.62 % in the middle of the coating and 24.90% in the Top Coat. For Boron (B) the desired amount was 0% in the Bond Coat and 3.5% in the Top Coat and again 0% was obtained in the Bond Coat, 0 % in the middle of the coating and 37.2% in the Top Coat. This confirms that the proposed design has the potential of producing FGM which is a new venture for HVOF spraying.<o:p></o:p></span></p><div style="text-align: justify;"> </div><p class="MsoNormal" style="text-align: justify;font-family:arial;"><span style="font-size:85%;"><b style=""><span style="" lang="EN-GB"><o:p> </o:p></span></b></span></p><div style="text-align: justify;"> </div><p class="MsoNormal" style="text-align: justify;font-family:arial;"><span style="font-size:85%;"><b style=""><span style="" lang="EN-GB">5. CONCLUSION<o:p></o:p></span></b></span></p><div style="text-align: justify;"> </div><p class="MsoNormal" style="text-align: justify;font-family:arial;"><span style="font-size:85%;"><b style=""><span style="" lang="EN-GB"><o:p> </o:p></span></b></span></p><div style="text-align: justify;"> </div><p class="MsoNormal" style="text-align: justify;font-family:arial;"><span style="font-size:85%;"><b style=""><span style="" lang="EN-GB"><span style=""> </span></span></b></span><span lang="EN-GB" style="font-size:85%;">In this current research, an innovative modification of the HVOF thermal spray process was designed to produce functionally graded coatings. This included design, FEA analysis, calibration and validation of a co-injection semi automated system used to deposit stainless steel/nickel base alloy FGM coatings simultaneously on stainless steel substrate.<span style="display: none;"><o:p></o:p></span></span></p><div style="text-align: justify;"> </div><p class="MsoNormal" style="text-align: justify;font-family:arial;"><span style="display: none;" lang="EN-GB"><o:p> </o:p></span></p><div style="text-align: justify;"> </div><p class="MsoNormal" style="text-align: justify;font-family:arial;"><span style="display: none;" lang="EN-GB"><o:p> </o:p></span></p><div style="text-align: justify;"> </div><p class="MsoNormal" style="text-align: justify;font-family:arial;"><span style="display: none;" lang="EN-GB"><o:p> </o:p></span></p><div style="text-align: justify;"> </div><p class="MsoNormal" style="text-align: justify;font-family:arial;"><span lang="EN-GB" style="font-size:85%;"><o:p> </o:p></span></p><div style="text-align: justify;"> </div><p class="MsoNormal" style="text-align: justify;font-family:arial;"><span style="font-size:85%;"><b style=""><span lang="EN-GB"><o:p> </o:p></span></b></span></p><div style="text-align: justify;"> </div><p class="MsoNormal" style="text-align: justify;font-family:arial;"><span style="font-size:85%;"><b style=""><span lang="EN-GB">REFERENCES</span></b></span><span lang="EN-GB" style="font-size:85%;">:</span></p><div style="text-align: justify;"> </div><p class="MsoNormal" style="text-align: justify;font-family:arial;"><span lang="EN-IE" style="font-size:85%;"><o:p> </o:p></span></p><div style="text-align: justify;"> </div><p class="MsoNormal" style="text-align: justify;font-family:arial;"><span lang="EN-GB" style="font-size:85%;">[1] </span><span lang="EN-IE" style="font-size:85%;">Hasan., “HVOF Thermal Spray Deposition of Functionally Graded Coatings”, Ph.D. Thesis, <st1:place st="on"><st1:city st="on">Dublin City University</st1:city>, <st1:country-region st="on">Ireland</st1:country-region></st1:place>, 2004.</span></p><div style="text-align: justify;"> </div><p class="MsoNormal" style="text-align: justify;font-family:arial;"><span lang="EN-GB" style="font-size:85%;">[2] </span><span lang="EN-IE" style="font-size:85%;">Suresh, A., & Mortensen, A., “Fundamentals of Functionally Graded Materials: Processing and Thermo mechanical Behaviour of Graded Metals and Metal-Ceramic Composites”, The University Press, <st1:city st="on"><st1:place st="on">Cambridge</st1:place></st1:city>, ISBN No 1861250630, 1998.<o:p></o:p></span></p><div style="text-align: justify;"> </div><p class="MsoNormal" style="text-align: justify;font-family:arial;"><span lang="EN-IE" style="font-size:85%;">[3] Khor, K. A., et al., Surface and Coatings Technology, Vol. 130, Issue. 2-3, 2000, pp. 233-239. </span><span lang="EN-GB" style="font-size:85%;"><o:p></o:p></span></p><div style="text-align: justify;"> </div><p class="MsoNormal" style="text-align: justify;font-family:arial;"><span lang="EN-IE" style="font-size:85%;">[4] Khor, K. A., et al., Thin Solid Films, Vol. 368, Issue. 1, 2000, pp. 86-92. </span><span lang="EN-GB" style="font-size:85%;"><o:p></o:p></span></p><div style="text-align: justify;"> </div><p class="MsoNormal" style="text-align: justify;font-family:arial;"><span lang="EN-IE" style="font-size:85%;">[5] Khor, K. A., et al., Surface and Coatings Technology, Vol. 114, Issue 2-3, 1999, pp. 181-186.</span><span lang="EN-GB" style="font-size:85%;"><o:p></o:p></span></p><div style="text-align: justify;"> </div><p class="MsoNormal" style="text-align: justify;font-family:arial;"><span lang="EN-IE" style="font-size:85%;">[6] Hu, W., et al., Surface and Coatings Technology, Vol. 105, Issue 1-2, 1998, pp. 102-108. </span><span lang="EN-GB" style="font-size:85%;"><o:p></o:p></span></p><div style="text-align: justify;"> </div><p class="MsoNormal" style="text-align: justify;font-family:arial;"><span lang="EN-IE" style="font-size:85%;">[7] Lima, C. R. C., & Trevisan, R. E., Journal of Thermal Spray Technology, Vol. 6, Issue 2, 1997, pp. 199-204.</span><span lang="EN-IE" style="font-size:85%;"> </span><span lang="EN-IE" style="font-size:85%;"><o:p></o:p></span></p><div style="text-align: justify;"> </div><p class="MsoNormal" style="text-align: justify;font-family:arial;"><span lang="EN-IE" style="font-size:85%;">[8] Dussoubs, B., et al., “Modelling of Plasma Spraying of Two Powders”, Journal of Thermal Spray Technology, Vol. 10, Issue 1, 2001, pp. 105-110.<o:p></o:p></span></p><div style="text-align: justify;"> </div><p class="MsoNormal" style="text-align: justify;font-family:arial;"><span lang="EN-IE" style="font-size:85%;">[9] </span><span style="font-size:85%;">METCO / Perkin Elmer, Diamond Jet: Powder Feed Unit Manual, 1989.<o:p></o:p></span></p><div style="text-align: justify;"> </div><p class="MsoNormal" style="text-align: justify;font-family:arial;"><span lang="EN-IE" style="font-size:85%;">[10] METCO/ Perkin Elmer, “Diamond Jet Application Data Charts”, <st1:country-region st="on"><st1:place st="on">USA</st1:place></st1:country-region>, 1989.<o:p></o:p></span></p><div style="text-align: justify;"> </div><p class="MsoNormal" style="text-align: justify;font-family:arial;"><span lang="EN-IE" style="font-size:85%;">[11] Stokes, J., “The<span style=""> </span>Theory<span style=""> </span>and<span style=""> </span>Application<span style=""> </span>of<span style=""> </span>the<span style=""> </span>HVOF Thermal Spray Process”, <st1:place st="on"><st1:city st="on">Dublin City University</st1:city>, <st1:country-region st="on">Ireland</st1:country-region></st1:place>, 2003.<o:p></o:p></span></p><div style="text-align: justify;"> </div><p class="MsoNormal" style="text-align: justify;font-family:arial;"><span lang="EN-IE" style="font-size:85%;">[12] </span><span style="font-size:85%;">METCO / Perkin Elmer, “Diamond Jet: Process Manual”, 1989.<o:p></o:p></span></p><div style="text-align: justify;"> </div><p class="MsoNormal" style="text-align: justify;font-family:arial;"><span lang="EN-IE" style="font-size:85%;">[13] METCO/ Perkin Elmer, “Diamond Jet Application Data Charts”, <st1:country-region st="on"><st1:place st="on">USA</st1:place></st1:country-region>, 1989.<o:p></o:p></span></p><div style="text-align: justify;"> </div><p class="MsoNormal" style="text-align: justify;font-family:arial;"><span lang="EN-GB" style="font-size:85%;"><o:p> </o:p></span></p>mamunk2http://www.blogger.com/profile/02444555059459888177noreply@blogger.com0tag:blogger.com,1999:blog-531225007922164170.post-812582636595365492007-05-15T05:37:00.000-07:002007-05-15T05:43:17.715-07:00Coming Soon Article on Thermal SprayComing Soon Article on Thermal Spray using <a href="http://hvof.blogspot.com">HVOF</a><br />Title Name:'DESIGNING AND INTEGRATING A SEMI AUTOMATED POWDER FEED DEVICE TO PRODUCE FUNCTIONALLY GRADED MATERIALS (FGM) USING THE HVOF THERMAL SPRAY PROCESS'<br />By:Md. <a href="http://iward2010.blogspot.com">Kabir Al Mamun</a>, Saleem Hashmi, Joseph Stokes <br />Materials Processing Research Centre, <a href="http://dcu.ie">Dublin City University</a>, Dublin 9, Ireland<br />National Centre for Plasma Science & Technology, Dublin City University, Irelandmamunk2http://www.blogger.com/profile/02444555059459888177noreply@blogger.com0tag:blogger.com,1999:blog-531225007922164170.post-28059206197728804262007-05-15T05:33:00.000-07:002007-05-15T05:36:45.963-07:00IMC 24th Paper writing ProblemHi Joe,<br />I have write the paper (Except the Experiment part (3.4, 4.3) & Conclusion (5) marked with Blue color in word file;Please see attachment).This is (Format/template) almost prepared according to the IMC instruction.But I am afraid about size.They said that it must not be more than 8 pages.In fact I have 19 pages excluding Appendix (which is another 11 pages).I couldn't make it less as if I do so then it will be difficult to understand by the readers.Please help me regarding this problem.<br />Thanks<br />Mamunmamunk2http://www.blogger.com/profile/02444555059459888177noreply@blogger.com0tag:blogger.com,1999:blog-531225007922164170.post-18014545335376150722007-05-13T08:27:00.000-07:002007-05-13T08:28:38.629-07:00Slide Show<div><embed src="http://widget-0c.slide.com/widgets/slideticker.swf" type="application/x-shockwave-flash" quality="high" scale="noscale" salign="l" wmode="transparent" flashvars="cy=lt&il=1&channel=360287970197504268&site=widget-0c.slide.com" style="width:400px;height:300px" name="flashticker" align="middle"></embed><div style="width:400px;text-align:left;"><a href="http://www.slide.com/pivot?ad=0&tt=16&sk=0&cy=lt&th=0&id=360287970197504268&map=1" target="_blank"><img src="http://widget-0c.slide.com/p1/360287970197504268/lt_t016_v000_a000_f00/images/xslide1.gif" border="0" ismap="ismap" /></a> <a href="http://www.slide.com/pivot?ad=0&tt=16&sk=0&cy=lt&th=0&id=360287970197504268&map=2" target="_blank"><img src="http://widget-0c.slide.com/p2/360287970197504268/lt_t016_v000_a000_f00/images/xslide2.gif" border="0" ismap="ismap" /></a></div></div>mamunk2http://www.blogger.com/profile/02444555059459888177noreply@blogger.com0tag:blogger.com,1999:blog-531225007922164170.post-79141573723578858212007-05-12T07:16:00.000-07:002007-05-12T07:28:54.213-07:00Basic Principles of Operations<strong><em><strong>Typical Coating Properties</strong></em></strong><br /><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEg268p-18RgDcUuhnaK9mgXto0DJPMsYMdGe9HnAaKGhFkt2YxT_VKrVN7b0GA6f-oKapnd_Evh34tUhVZWKcdDGSLF1HiFPCd1CXrZY7Ec0vyoageTNCGrhIUOO6nUwwNP9qXAAWfnw_M/s1600-h/SPRAYDRAWING.jpg"><img style="float:right; margin:0 0 10px 10px;cursor:pointer; cursor:hand;" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEg268p-18RgDcUuhnaK9mgXto0DJPMsYMdGe9HnAaKGhFkt2YxT_VKrVN7b0GA6f-oKapnd_Evh34tUhVZWKcdDGSLF1HiFPCd1CXrZY7Ec0vyoageTNCGrhIUOO6nUwwNP9qXAAWfnw_M/s320/SPRAYDRAWING.jpg" border="0" alt=""id="BLOGGER_PHOTO_ID_5063678466790246658" /></a><br />The HVOF unit uses an oxygen-fuel mixture consisting of propylene, propane, or hydrogen, depending on users coating requirements to produce the highest quality coating available today. Fuel gases are mixed in a proprietary siphon system in the front portion of the HVOF gun. The thoroughly mixed gases are ejected from the nozzle and ignited externally to the gun. Ignited gases form a circular flame configuration which surrounds the powdered material as it flow through the gun. Combustion temperature is between 5000F to 6000F depending on fuel. The circular flame shapes the powder stream to provide uniform heating, melting, and acceleration (See Diagram). Pre-selected oxygen, fuel and air values are specified for each material to optimize dwell time in the flame. <br /><br />The key success of HVOF is the extremely High Kinetic Energy that is being produced and transferred between the HVOF unit and the substrate using space-age rocket propulsion technology. Typical velocities approach 5000 fps to over 7200 fps depending on which hardware is selected.With both thermal and kinetic energy, the high velocity particles are practically embedded into the substrate to form a superior coating with the following characteristics: <br /><br />High Density The coatings produced though HVOF develop very high densities because of the high kinetic energy associated with this process.<br /><br />High Bond Strengths (in excess of 12,000 psi)<br /><br />Zero Porosity ( with no interconnecting porosity )<br /><br />Metal Working Capabilities<br /><br />Essentially Stress Free<br /><br />Greater Hardness<br /><br />Greater Thickness<br /><br />Low Thermal Input ( substrate temperature less than 300 degrees F which insures original mechanical properties and with No Stress Relieving Required)<br /><br /><em><strong><a href="http://www.nationalthermospray.com/hvof.htm">Reference:</a></strong></em><br /><br />More Videos Visit at <a href="http://mamunk2.blogspot.com">Videoworld</a>mamunk2http://www.blogger.com/profile/02444555059459888177noreply@blogger.com1tag:blogger.com,1999:blog-531225007922164170.post-40230224450526824682007-05-12T05:58:00.000-07:002007-05-12T07:23:34.546-07:00Thermal Spray with HVOF<a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEg6hxZfurNM8uawFLq0HwCMJ-jrnkmJQvqxaJwdIlqzkDr0zKL44lPU0Nwm_Fd4FYAb1RU5NP5gbwC-i9bCFut9jBl-4jI2cJ2bMS5qVpxt6jJe3oCcxToOUKnc7v5igN9fU-sHtdrehwQ/s1600-h/mixing+device.JPG"><img style="float:right; margin:0 0 10px 10px;cursor:pointer; cursor:hand;" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEg6hxZfurNM8uawFLq0HwCMJ-jrnkmJQvqxaJwdIlqzkDr0zKL44lPU0Nwm_Fd4FYAb1RU5NP5gbwC-i9bCFut9jBl-4jI2cJ2bMS5qVpxt6jJe3oCcxToOUKnc7v5igN9fU-sHtdrehwQ/s320/mixing+device.JPG" border="0" alt=""id="BLOGGER_PHOTO_ID_5063659075012905202" /></a><br />Figure 1: Digital picture of the newly designed dual powder feed device.<br /><br /><em><strong>Design of an Integrated semi-automated Powder Feed Device for HVOF / Plasma Spray Processes to Produce Functionally Graded Materials (FGM) of Ti alloy and HA powders for Biomedical Applications</strong></em><br /><br /><br /><em><strong>By:</strong></em><br />Md. Kabir Al Mamun, Joseph Stokes <br />Materials Processing Research Centre, and<br />National Centre for Plasma Science & Technology, Dublin City University, Ireland<br />email: kabir.mamun2@mail.dcu.ie<br /><br /> <br /><em><strong>Introduction</strong></em>: Functionally Graded Materials (FGMs) are a growing application area with significant promise for the future production of; (a) improved materials and devices for use in applications subjected to large thermal gradients, (b) lower-cost clad materials for combinations of corrosion and strength or wear resistance, and (c) improved electronic material structures for batteries, fuel cells, and thermoelectric energy conversion devices and (d) biomedical implant devices for enhanced bone-tissue attachment. The most immediate application for FGMs is as Thermal Barrier Coatings (TBCs), where large thermal stresses can be minimised. Component lifetimes are improved by tailoring the coefficients of thermal expansion, thermal conductivity, and oxidation resistance. The application of FGMs is quite difficult, but thermal spray processes like Plasma spray have demonstrated their unique potential in producing graded deposits, where researchers have used twin powder feed systems to mix different proportions of powders. FGMs vary in composition and/or microstructure from one boundary (substrate) to another (top service surface), and innovative characteristics result from the gradient from metals to ceramics or non-metallic to metals. <br /><em><br /><strong>Research:</strong></em> The present study investigates an innovative modification of a HVOF (High Velocity Oxy-Fuel) thermal spray process to produce functionally graded thick coatings. In order to deposit thick coatings, certain problems have to be overcome. More specifically these problems include minimising residual stress, which causes shape distortion in as-sprayed components. Graded coatings enable gradual variation of the coating composition and/or microstructure, which offers the possibility of reducing residual stress build-up with in coatings.<br />In order to spray such a coating, modification to a commercial powder feed hopper was required to enable it to deposit two powders simultaneously which allows deposition of different layers of coating with changing chemical compositions, without interruption to the spraying process (Figure 1). Various concepts for this modification were identified and one design was selected, having been validated through use of a process model, developed using ANSYS Flotran Finite Element Analysis. In the current research the mixing of different proportions of powders were controlled by a computer using Lab VIEW software and hardware, which allowed the control and repeatability of the microstructure when producing functionally graded coatings. This research has been carried out on DCU HVOF Feed unit system. However this semi-automated powder feed unit system could be use with Plasma techniques to produce FGM coatings of Ti alloy and HA powders for Biomedical Applications.<br /><br /> <br /><strong></strong><strong></strong><br /><br /><a href="http://www.nationalthermospray.com/hvof.htm"><em><strong>Reference:</strong></em></a>mamunk2http://www.blogger.com/profile/02444555059459888177noreply@blogger.com1