ZrB_2-SiC复合陶瓷发热体的电性能与发热体表面温度之间关系的研究

Relationship between electric properties and surface temperature of ZrB_2-SiC composite ceramic heating element

按照ZrB2和SiC的质量比为7525配料,混料、烘干、热压烧结后,经线切割加工成ZrB2-SiC复合陶瓷直型发热体,研究了发热体的物相组成、微观形貌及在空气和氩气气氛下发热温度随电流电压的变化规律。结果表明,ZrB2-SiC复合陶瓷由均匀分布在ZrB2基体晶界处的SiC颗粒和尺寸小于10μm的等轴状基体ZrB2颗粒组成;在空气和氩气气氛下,ZrB2-SiC复合陶瓷发热体的温度均随电流、电压及加热时间的延长呈稳步增大趋势,同时空气气氛下发热体的电阻随温度升高而增大,并呈现线性变化;在空气和氩气气氛下,ZrB2-SiC复合陶瓷发热体表面温度分别达到1800和2200℃。同时,与铬酸镧和氧化锆发热体相比,其电压、电阻变化较小,电流较大。

ZrB2-SiC composite ceramic straight heating elements were prepared using ZrB2 and SiC as starting materials （the mass ratio of ZrB2 SiC=75 25）,mixing,drying,hot pressing sintering,and then lin-ear cutting.The phase compositions and microstructure of the heating elements,and the change of heating temperature with current and voltage in air and Ar atmosphere were researched.The results show that：（1） ZrB2-SiC composite ceramics are composed of SiC grains （well distributed around the crystal boundaries of ZrB2）and the equant ZrB2 grains （＆lt;10 μm）;temperature of the heating element rises gradually with voltage and electric current increasing and heating period prolonging in air and Ar atmosphere.Mean-while,in air,the heating element resistance increases with temperature rising linearly;in air and Ar atmos-phere,the surface temperatures of the heating elements reach 1 800 and 2 200 ℃,respectively.Compared with the chromate lanthanum and zirconia heating elements,the voltage and resistance change of the de-veloped ones are smaller and the current change is larger.