Ceramic heater

PURPOSE : To provide a ceramic heater which is small in resistance change at a high temp. and is free from crack initiation. CONSTITUTION : A ceramic heater 1 inclydes a support 3 having electric insulativeness and a conductive heater element 2 formed rigidly at the foremost of the support 3. Both the support 3 and heater element 2 consist of a hybrid sinter of conductive MoSi2 and insulative Si2N3, wherein the support 3 is structured so that the MoSi2, particles are divided by the surrounding Si2N3 particles so that insulativeness is generated, while the heater element 2 exhibits conductiveness by surrounding Si2N3 with MoSi2 particles which are continuous. As a sintering aid substance, oxide of rare earth element such as Y2O3 or Yb2O3 and Al2O3 are added to the support 3 and heater element 2. and change in the resistance value resulting from iterative current feed is suppressed by making the Y2O3 or Yb2O3 content as additive of the support 3 larger than that of the heater element 2. Crack initiation is prevented by making the Al2O3 content as additive of the heater element 2 larger than that of the support 3.