| Analysis of High Temperature Stability of White Amorphous Si–O–C(–H) Ceramics in Terms of Structure Evolution and Photoluminescence Degradation |
| Masaki NARISAWA |
| Osaka Prefecture University |
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wo kinds of white Si−O−C(−H) ceramic powders, named S900 and S1100, were prepared from cross-linked polysiloxane particles with an averaged diameter of 6 m [1, 2]. S900 was the product obtained in a hydrogen gas flow at 900 ¡ÆC with a holding time of 1h, whereas S1100 was the product obtained at 1100 ¡ÆC with a holding time of 3h. In an Ar gas flow, heat stability of the powders on graphite boats were examined at a temperature range of 1200−1600 ¡ÆC. S900 was colored brown and black after the heat treatment at 1200 and 1400 ¡ÆC. On the other hand, color of S1100 was changed to light grey after the heat treatment at 1400 ¡ÆC. PL intensity of S900 substantially decreased at 1200¡ÆC, whereas that of S1100 decreased at 1400¡ÆC (Figure 1). Substantial mass loss of the powders occurred beyond 1500 ¡ÆC, which was accompanied by fusing of individual particles at the contact points. At 1600 ¡ÆC, precipitation of cristobalite was observed (Figure 2), and particles were completely fused together. From viewpoints of mass loss, XRD patterns and aggregate formation process, there were no major differences between S900 and S1100, although difference in color and PL was obvious. The white Si−O−C(−H) ceramic would be useful as basic parts of thermal protection systems available at relatively low costs [3], like High-Temperature Reusable Surface Insulation (HRSI) tiles.
References:
[1] M. Narisawa, S. Watase, K. Matsukawa, T. Dohmaru, K. Okamura, Bull. Chem. Soc. Japan 85 (2012) 724.
[2] M. Narisawa, K. Terauds, R. Raj, Y. Kawamoto, T. Matsui, A. Iwase, Scripta Materialia 69 (2013) 602.
[3] M. M. Opeka, I. G. Talmy, J. A. Zaykoski, J. Mater. Sci., 39 (2004) 5887.
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