Electric heater element for high temp. furnaces - using porous zirconia contg. lanthanum chromite at each end near terminals

摘要

Heater element is of a refractory oxide (a) with m.pt. above 2200 degrees C. The aggregate of oxide fibres or grains (a), esp. ZrO2 which is at least partly stabilised, is porous, and its two ends contain a material (b) of low resistivity to the assembly (a,b) has an electric resistivity 100 ohm. cm. at 1000 degrees C. The middle of the element pref. has porosity 50%, whereas the two ends contain equal amts. of ZrO2 and material (b) and with porosity over 30%. Porous aggregates of fibres (a) may be woven or nonwoven, and the ZrO2 (a) pref. has thermal shock resistance above 200 degrees C/minute for min. 20 cycles. The elements can be of different shapes and have high resistance to thermal shock for use above 1200 degrees C in furnaces etc.