等离子堆焊Stellite合金高温摩擦磨损特性研究

采用等离子堆焊技术在气门用钢基体上制备了Stellite 1和Stellite F合金堆焊层,对堆焊层的金相组织、物相组成和硬度等进行了研究,在MMU-10G高温端面摩擦磨损试验机上考察了不同温度条件对2种堆焊层摩擦磨损性能的影响,并分析了堆焊层的磨损机理.结果表明:高温条件下,随着温度的上升,2种合金堆焊层的摩擦系数增大,磨损体积减小;温度为400℃时,Stellite 1和Stellite F合金堆焊层分别产生了大量的疲劳裂纹和宽大的犁沟,磨损较为剧烈;温度为500和600℃时,2种合金堆焊层磨损机制相似,主要磨损机制分别为疲劳剥落和磨粒磨损;氧化膜的快速形成以及上试样硬度的下降减小了磨损,磨痕中心区域变窄,磨痕边缘的磨屑不断堆积并被碾压产生了严重的黏着磨损,导致摩擦系数增加.

Friction and Wear Characteristics of Plasma Surfacing Stellite Alloys at Elevated Temperatures

Stellite 1 and Stellite F coatings were fabricated on the substrate of valve steel by plasma surfacing. Metallographic structure, phase composition and hardness were analyzed. The tribological properties of the two kinds of the welding coatings were investigated on a MMU-10G friction and wear tester at elevated temperatures. Results indicate that at elevated temperatures, with the rise of temperature, the friction coefficient of both coatings increased whereas the wear volume decreased. At 400 , Stellite 1 and Stellite F coatings were seriously damaged due to the appearance of fatigue cracks and wide furrows. The main wear mechanisms of both the coatings were fatigue flake and abrasive wear at 500 and 600 . The formation of oxide film and the decreasing hardness of the counterparts resulted in less wear and the central area of wear trace becoming narrower. However, wear debris were accumulated and crushed on both sides of the wear trace, leading to a severe adhesive wear which is related to the large friction coefficient.