EXOTHERMIC ELEMENT MATERIAL FOR MOSI2-BASED COMPOSITE CERAMIC HEARTIER FOR USE AT HIGH TEMPERATURE AND PRODUCTION OF THE MATERIAL

摘要

PROBLEM TO BE SOLVED: To obtain an exothermic element material as a composite ceramic with the relative density at a specific level or higher and the average grain size at a specific level or lower, excellent in mechanical strength, high-temperature creep resistance characteristics and high- temperature oxidation resistance, thus usable at ultrahigh temperatures, by dispersing a specific amount of MoB particles in a W-dissolved MoSi₂-type ceramic with part of the Mo in MoSi₂ substituted by W. ;SOLUTION: This exothermic element material is obtained according to the above-mentioned process; wherein, the amount of MoB particles to be added is 5-30 vol.%; this material as composite ceramic is ≥98% in relative density and ≤25 μm in average grain size; the W- dissolved MoSi₂-type ceramic is shown by pref. the formula (Mo_1-XWX)Si₂; the rate (x) if the amount of the W dissolved in the composition is pref. 35-45 wt.%. This material is usable at the temperature of an exothermic element of ≤1,800°C (up to 1,900°C). Specifically, this material is obtained using a cellulose-based binder through extrusion molding, drying, degreasing, sintering and film coating treatment; in this case, the sintering process is carried out at a degreasing rate of ≥80% and at a temperature lower than the heater service temperature so as to afford the sufficiently dense objective material.;COPYRIGHT: (C)1998,JPO