| 摘要 |
PROBLEM TO BE SOLVED: To provide a ceramic heater which has specially superior durability with respect to cryogenic cycles and a glow plug equipped with the heater. SOLUTION: A U-shaped exothermic resistor provided with head wires made of tungsten, etc., is obtained by using paste containing prescribed amounts of silicon nitride powder, WC powder, and sintered auxiliary. Then an unbaked ceramic heater is obtained by putting the exothermic resistor thus obtained on a prescribed position between two half molds obtained by using silicon nitride material powder and an sintering auxiliary and pressurizing the resistor. Thereafter, a ceramic heater is obtained by calcining the unbaked ceramic heater and hot-pressing and baking the calcined heater. In the heater, the thicknesses (t) of joining layers formed at the boundaries between the lead wires and exothermic resistor and the ratio of the thicknesses (t) to the shortest distance L from the outer peripheral surfaces of the joining layers to the outer peripheral surface of an insulating ceramic are respectively adjusted to 1μm <=t<=60μm and 0.0009<=t/L<=0.06.
|
