Fabrication of Dense, Nonstabilized ZrO2 Ceramics by Hydrothermal Reaction Sintering
Hirano and Somiya1 prepared high density Cr2O3 ceramics by a method known as hydrothermal reaction sintering, in which chromium metal and water are reacted and then sintered under hydrothermal conditions. The reaction is written simply as 2Cr + 3H2O = Cr2O3 +- 3H2. The mechanism of this reaction, however, appears to be complicated because it should involve 1) reaction between Cr and H2O, 2) sintering of formed Cr2O3, and 3) diffusion of H2 out of a capsule, at high temperatures under high pressures. A subsequent study2 that studied the effects of pressure, temperature, and treating period on hydrothermal reaction sintering of Cr2O3 showed less reproducibility of densities and microstructures in the final product. In spite of such difficulties in the mechanism of the reaction, this technique has great merit in preparing a dense, isostatically sintered oxide with fine grains at relatively low temperatures without any additives.
KeywordsHydrothermal Condition Tungsten Wire Fine Tungsten Initial Mole Ratio Great Merit
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