| 摘要 |
PURPOSE:To provide stability against thermal hysteresis such as heating, cooling and the like and improve durability in repeated use by molding and sintering zirconia powder to cause a rate of permanent expansion to assume a minus value. CONSTITUTION:A compact containing therein zirconia powder is sintered in a low temperature region below a sintering temperature to provide a refractory having a minus rate of permanent expansion, which refractory is for use. Preferably, zirconia powder having been subjected to stabilization by means of one or more compounds is used as raw material powder. Accordingly, there is a tendency of shrinkage rather than expansion in an initial stage with respect to thermal hysteresis comprising repetition of heating and cooling, so that it takes much time until a rate of expansion is reached, at which cracking is generated and fracture begins to occur. Accordingly, it is possible to provide stability against such thermal hysteresis and improve durability in repeated use. |
