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The impact of process variables on the chemical vapour deposition of silicon carbide
Thesis (PhD)--University of Pretoria, 2012.
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| Format: | Thesis |
| Language: | Eng |
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University of Pretoria
2013
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| _version_ | 1867613521475272704 |
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| access_status_str | Open Access |
| author2 | De Villiers, Johan Pieter |
| author_browse | De Villiers, Johan Pieter |
| author_facet | De Villiers, Johan Pieter |
| collection | Thesis |
| dc_rights_str_mv | © 2012 University of Pretoria. All rights reserved. The copyright in this work vests in the University of Pretoria. No part of this work may be reproduced or transmitted in any form or by any means, without the prior written permission of the University of Pretoria. |
| description | Thesis (PhD)--University of Pretoria, 2012. |
| format | Thesis |
| id | oai:repository.up.ac.za:2263/31597 |
| institution | University of Pretoria (South Africa) |
| language | Eng |
| last_indexed | 2026-06-10T12:37:28.126Z |
| license_str | Other — see source repository |
| provenance_str_mv | Harvested via OAI-PMH from UPSpace — University of Pretoria Institutional Repository |
| publishDate | 2013 |
| publishDateRange | 2013 |
| publishDateSort | 2013 |
| publisher | University of Pretoria |
| publisherStr | University of Pretoria |
| record_format | dspace |
| source_str | UPSpace — University of Pretoria Institutional Repository |
| spelling | oai:repository.up.ac.za:2263/31597 The impact of process variables on the chemical vapour deposition of silicon carbide De Villiers, Johan Pieter robert.cromarty@up.ac.za Cromarty, Robert Douglas Methyltrichlorosilane Triso Spouted bed Chemical vapor deposition Free silicon mechanical properties Deposition efficiency Deposition rate Morphology Silicon carbide UCTD Thesis (PhD)--University of Pretoria, 2012. High temperature gas cooled nuclear reactors often make use of Tristructural Isotropic (TRISO) coated fuel particles. In these particles, a layer of silicon carbide plays the key role of providing mechanical strength and acting as a diffusion barrier so preventing the release of fission products. TRISO particles are produced by a chemical vapor deposition (CVD) process in a spouted bed coater. Operating conditions of chemical vapor deposition processes are known to influence the properties of the deposited material. In the case of silicon carbide deposited by pyrolysis of methyltrichlorosilane (MTS) in a hydrogen atmosphere, process parameters that may influence the properties of the silicon carbide deposited include deposition temperature, MTS concentration and hydrogen flow rates. In this study the coating process was investigated using a laboratory scale spouted bed CVD coater. In all the test work conducted, carbon coated zirconia particles were used as a starting material. Only silicon carbide was deposited during these trials. Process parameters investigated were temperature, MTS concentration and hydrogen flow rate. The range investigated was 1250 °C to 1550 °C for temperature, 0.5 % to 2.5 % for MTS concentration and 10.0 l.minute-1 to 15.0 l.minute-1 for hydrogen flow. This covered the range that is typically used for small-scale production coaters. Two different gas inlet configurations, a conventional water cooled inlet and an inlet without any cooling, were used in the investigation. Properties of the coating process, such as the deposition rate and coating efficiency, as well as material properties were measured. Material properties investigated included: density, crush strength, micro-hardness, fracture toughness, nano-hardness, Young’s modulus, elemental composition, phase composition and microstructure. It was found that, of the variables investigated, temperature had the strongest effect while hydrogen flow rate had the least effect on material properties. There was considerable variability in all measured parameters; this introduced considerable uncertainty into the predicted effects of process conditions on material properties. Materials Science and Metallurgical Engineering unrestricted 2013-09-10T07:01:46Z 2013 2013-09-10T07:01:46Z 2013-05-30 2012 2013-05-30 Thesis Cromarty, R.D. 2012, The impact of process variables on the chemical vapour deposition of silicon carbide, PhD thesis, University of Pretoria, Pretoria, viewed yymmdd <http://hdl.handle.net/2263/31597> B13/9/1049 B13/9/1049 http://hdl.handle.net/2263/31597 Eng © 2012 University of Pretoria. All rights reserved. The copyright in this work vests in the University of Pretoria. No part of this work may be reproduced or transmitted in any form or by any means, without the prior written permission of the University of Pretoria. application/pdf University of Pretoria |
| spellingShingle | Methyltrichlorosilane Triso Spouted bed Chemical vapor deposition Free silicon mechanical properties Deposition efficiency Deposition rate Morphology Silicon carbide UCTD The impact of process variables on the chemical vapour deposition of silicon carbide |
| title | The impact of process variables on the chemical vapour deposition of silicon carbide |
| title_full | The impact of process variables on the chemical vapour deposition of silicon carbide |
| title_fullStr | The impact of process variables on the chemical vapour deposition of silicon carbide |
| title_full_unstemmed | The impact of process variables on the chemical vapour deposition of silicon carbide |
| title_short | The impact of process variables on the chemical vapour deposition of silicon carbide |
| title_sort | impact of process variables on the chemical vapour deposition of silicon carbide |
| topic | Methyltrichlorosilane Triso Spouted bed Chemical vapor deposition Free silicon mechanical properties Deposition efficiency Deposition rate Morphology Silicon carbide UCTD |
| url | http://hdl.handle.net/2263/31597 |