290℃純水中におけるセラミックスの腐食挙動

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Recently, advanced ceramics with superior strength and corrosion resistance have been developed. They have a possibility for various engineering applications as structural materials used in high temperature water, such as steam turbine systems or water cooled reactors. Fundamental corrosion behaviors of 14 kinds of sintered polycrystalline ceramic were examined in oxygen-free (less than 20 ppb dissolved oxygen) and oxygenated (about 32 ppm dissolved oxygen) pure water at 290℃ using a refleshed-type autoclave system. Change in weight and surface morphology detected by X-ray diffraction and scanning electron microscopy on the samples corroded for 72 hours were discussed. Silicon carbide showed the best corrosion resistance among the present ceramics. The corrosion resistance of alumina strongly depended on its purity. 99.99 % purity alumina showed high corrosion resistance. For pressure-less sintered and hot-pressed silicon nitride and sialon ceramics, the preferential dissolution of crystalline phase occurred at the surface of the sample and the grain boundary phases remained near the surface. Aluminum nitride formed a thick boehmite layer in the tests. Partially stabilized zirconia, stabilized by 3 mol % yttria, flaked away by accompanying a phase transformation from tetragonal to monoclinic. Many of the non-oxide ceramics, particularly silicon carbide, showed more accelerated dissolution rates in oxygenated water than in oxygen-free water.
社団法人日本材料学会の論文
1989-03-15

290℃純水中におけるセラミックスの腐食挙動

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