Mo-12Si-8.5B-ZrO_(2)(Y_(2)O_(3))复合材料在空气和真空中的干摩擦学行为

Dry tribological behaviours of Mo-12Si-8.5B-ZrO_(2)(Y_(2)O_(3))composites in air and vacuum

纳米ZrO_(2)(Y_(2)O_(3))强韧化的双尺度Mo-12Si-8.5B复合材料具有优异的力学性能,但在25~1000℃范围处于空气和真空下的干滑动摩擦学性能尚不清楚。采用销−盘式摩擦磨损试验,比较研究Mo-12Si-8.5B-2.5%ZrO_(2)(Y_(2)O_(3))/Si_(3)N_(4)配对副的干摩擦学性能。结果表明:在空气中,随着测试温度的增加,摩擦因数先增加后减小,800℃时达到最小值(为0.28);复合材料的磨损率在25~600℃时为6.02~69.4×10^(−6) mm^(3)/(N·m),800~1000℃的磨损率增加到8.7×10^(−3)~95×10^(−3) mm^(3)/(N·m)。在真空中,从25℃升高到400℃时,摩擦因数从0.62逐渐降低至0.49,600℃时急剧增加到1.04,而在800℃和1000℃时摩擦因数又分别降低到0.82和0.51,此时磨损率从常温的8.62×10^(−4) mm^(3)/(N·m)减小到1000℃的1.61×10^(−4) mm^(3)/(N·m)。在空气环境下,复合材料的磨损机制主要为黏着磨损,高温时还伴随着氧化磨损。在真空中,复合材料在低温时的磨损机制主要为黏着磨损,高温时磨损机制表现为黏着磨损、犁削磨损和轻微的氧化磨损。

A bimodal grain size Mo-12Si-8.5B composite strengthened and toughed with nano-ZrO_(2)(Y_(2)O_(3))exhibits excellent mechanical properties.However,the dry friction and wear of the composite at 25−1000℃in air and vacuum are not clear.The dry tribological behaviours of the Mo-12Si-8.5B-2.5%ZrO_(2)(Y_(2)O_(3))composite against Si_(3)N_(4) were comparatively investigated.The results show that the friction coefficient increases first and then decreases with the increase of the test temperature in air,and reaches the lowest value of 0.28 at 800℃.The wear rates of the composite are 6.02×10^(−6)−69.4×10^(−6) mm^(3)/(N·m)at 25−600℃,and increases to 8.7×10^(−3)−95×10^(−3) mm^(3)/(N·m)at 800−1000℃.In vacuum,the friction coefficient decreases from 0.62 to 0.49 when the temperature increases from 25℃to 400℃,and then increases sharply to 1.04 at 600℃,then decreases again to 0.82 and 0.51 at 800℃and 1000℃,respectively,and the wear rate decreases from 8.62×10^(−4) mm^(3)/(N·m)at 25℃to 1.61×10^(−4) mm^(3)/(N·m)at 1000℃.In air,the wear mechanism of the composites is adhesive wear,and accompanies with oxidation wear at high temperature.In vacuum,the wear mechanism of the composites at low temperature is adhesive wear,while exhibits the characterizations of adhesive wear,micro-ploughing wear and slight oxidation wear at high temperature.