| 摘要 |
PURPOSE:To prevent cracks on a heating resistor and improve the thermal shock resistance by forming a heater with a ceramic substrate and the heating resistor made of tungsten and molybdenum and specifying the composition of a mullite sintered body constituting the substrate. CONSTITUTION:A ceramic substrate is formed with SiO2, MgO, CaO, and mullite made of Al2O3, SiO2. A high-melting point metal heating resistor mainly made of tungsten and molybdenum is formed on the surface of the ceramic substrate and baked in the reducing atmosphere to obtain a heater. The composition of the mullite sintered body in the substrate is made 93.0wt% or more of the substrate. In the heater thus obtained, the thermal expansion coefficient of the mullite sintered body approximates to that of the tungsten and molybdenum of the heating resistor. No crack thereby occurs on the heating resistor in use for a long time at the high temperature, and the thermal shock resistance is improved.
|
