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钳、钨和钨铼合金在高温不能抗氧化,它们组成的热电偶仅限于真空、中性或保护气氛中工作。应用化学蒸汽淀积(CVD)或粉末包渗的方法,在热电极表面施加抗氧化涂层,使其能在高温氧化气氛中使用至极高的温度。涂层的使用寿命决定于涂层厚度和质量。但层厚过厚容易开裂和产生显微裂纹,反而缩短它的使用寿命。在扩散涂层上面附加一层陶瓷涂层封闭原涂层的显微缺陷,可以提高其使用寿命。有涂层的热电偶的热电势,与没有涂层的热电偶基本一致,其误差在容许范围之内。这种热电偶曾在平炉和转炉中进行过钢水连续测温试验,结果出现了乐观的现象。
Clamp, tungsten and tungsten rhenium alloy can not be anti-oxidation at high temperature, their composition of the thermocouple is limited to vacuum, neutral or protective atmosphere work. Application of chemical vapor deposition (CVD) or powder infiltration method, the surface of the hot electrode to apply anti-oxidation coating, it can be used in high temperature oxidation atmosphere to a very high temperature. The service life of the coating depends on the thickness and quality of the coating. But too thick layer thickness easy to crack and produce micro-cracks, but shorten its service life. Adding a layer of ceramic coating on the diffusion coating to close the original coating microscopic defects, can improve its service life. The thermocouple of a coated thermocouple is basically the same as an uncoated thermocouple with an error in the allowable range. This type of thermocouple had been tested for continuous temperature measurement of molten steel in open hearth and converter furnaces and the result was optimistic.