The reactions of ZrC or ZrN powder and H//2O have been studied at 190 degree -400 degree C under 100 MPa. The reaction of ZrC with H//2O above 240 degree C for 3 h yielded monoclinic ZrO//2 and CH//4, while the reactions of ZrN above 190 degree C for 3 h yielded monoclinic ZrO//2, NH//3 and H//2. The oxidation rate calculated from the weight gain or the integrated peak intensity of the X-ray diffraction were compared with various model functions. A nucleation-controlled model was the best fitted one, while a core-shrinking model fitted as well. This suggested that the reaction was controlled by phase boundary reactions. TEM observation showed that the ultrafine particles about 10 nm nucleated on the surface of Zrn or ZrC grains of about 1-3 mu m.
|Number of pages||8|
|Journal||Yogyo Kyokai Shi/Journal of the Ceramic Society of Japan|
|Publication status||Published - 1988 Jan 1|
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