| 摘要 |
PROBLEM TO BE SOLVED: To prevent breakdown of a heater due to the low-temperature oxidization of the center thereof while reducing generation of cracks by deflection due to an expansion difference of the heating material by controlling a density difference between the mean density of the whole of a heater containing MoSi2 and density at the center thereof. SOLUTION: A heater material including 70% or more of MoSi2 is temporarily sintered with a temperature pattern obtained by appropriately adjusting the temperature rising speed in a range at 1350-1650 deg.C. Density difference (true density ratio) between the mean density of the whole of the heater material and density at the center thereof corresponding to 1/5 of the diameter of the heater material is restricted to 5% or less, desirably, 3% or less by the controlled temporary sintering. Even in the case of a temporary sintered body having a large diameter, a sintered body capable of restricting a density difference between the center and the peripheral part thereof can be obtained. Density of the whole of the sintered body is evenly raised by electrifying this temporary sintered body for sintering at about 1700 deg.C so as to provide a heater having excellent durability. |
