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目的 厚膜电阻在电热膜方面的应用越来越广,而对于多孔陶瓷基体表面的厚膜电阻抗氧化性能的研究尚不多见.方法 通过恒温氧化实验研究了TiB2掺杂对不锈钢厚膜电阻在400、500、600、700℃下抗氧化性能的影响,采用XRD、SEM和EDS等方法分析了未掺杂及TiB2掺杂两种厚膜电阻的相组成和显微组织.结果 两种厚膜电阻的氧化动力学曲线均符合类抛物线模型,即(△w)n=kt.在400℃下,两种厚膜电阻的指数n均为4,掺杂TiB2电阻膜的氧化速率常数K1为1955.8 g4/(m8·h),而未掺杂TiB2电阻膜的氧化速率常数K2为4694.9 g4/(m8·h),这是由于掺杂TiB2厚膜电阻的致密度较高,使得厚膜电阻的抗氧化性能得以提高.高于500℃时,两种厚膜电阻的指数n均为2,掺杂TiB2厚膜电阻的氧化速率常数大于未掺杂厚膜电阻.这是由于TiB2氧化致使膜层内部出现间隙,膜层内部氧化严重(氧化产物主要为TiO2、B2O3、Fe2O3以及(Fe0.6Cr0.4)2O3),厚膜电阻抗氧化性能降低.结论 不锈钢厚膜电阻中掺杂TiB2可在400℃下提高膜层的抗氧化性能,而在500℃以上的高温环境下却有损于膜层的抗氧化性能.

Thick film resistor is increasingly applied to electrothermal films,but oxidation resistance of thick film resistor on the surface of porous ceramic substrate was seldom studied.The oxidation resistance of stainless steel thick-film resistor at 400 ℃,500℃,600℃ and 700 ℃ was studied by doping TiB2 ceramic powder.The phase structure and microstructure of the thick-film resistors not doped with and doped with TiB2 were studied by means of XRD,SEM and EDS.Oxidation kinetics curves of the two thick-film resistors conform to the parabolic law ((Aw)n=kt).The index n of the two thick-film resistors was 4,and the oxidation rate constant (K1) of TiB2-doped thick-film resistors was 1955.8 g4m8h-1 at 400℃,while the oxidation rate constant (K2) of TiB2-free thick-film resistors was 4694.9 g4.m-8.h-1 since higher compactness of TiB2-doped thick-film resistors contributed to higher oxidation resistance.The index n of the two thick-film resistors was 2 at the temperature above 500 ℃,and the oxidation rate constant of TiB2-doped thick-film resistors was higher than that of the TiB2-free one,since gaps were present in the film as a result of TiB2 oxidation.The oxidation resistance of thick-film resistors reduced in case of severe oxidation in the film (oxidation products were mainly (TiO2,B2O3,Fe2O3 and (Fe0.6Cr0.4)2O3).In stainless steel thick-film resistors,the doping of TiB2 can improve oxidation resistance of the film at 400 ℃,but damage oxidation resistance of the film at temperature above 500 ℃.