Mamun, Kabir and Stokes, J. (2014) Development of a semi automated dual feed unit to produce FGM coatings using the HVOF thermal spray process. The South Pacific Journal of Natural and Applied Sciences, 32 (1). pp. 18-26. ISSN 1838-837X
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Abstract
The application of functionally graded materials (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. The present study investigates an innovative
modification of a high velocity oxy-fuel (HVOF) 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. 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. In the current research the mixing of different proportions of powders were controlled by a computer using LabVIEW software and
hardware, which allowed the control and repeat-ability of the micro structure when producing functionally graded
coatings.
| Item Type: | Journal Article |
|---|---|
| Subjects: | T Technology > TJ Mechanical engineering and machinery |
| Divisions: | Faculty of Science, Technology and Environment (FSTE) > School of Engineering and Physics |
| Depositing User: | Kabir Mamun |
| Date Deposited: | 10 Nov 2014 02:35 |
| Last Modified: | 11 May 2016 03:05 |
| URI: | https://repository.usp.ac.fj/id/eprint/7738 |
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