等离子体源渗氮奥氏体不锈钢的摩擦磨损行为

Friction and Wear Behavior of Plasma Source Nitrided Austenitic Stainless Steel

采用等离子体源渗氮技术对AISI 316奥氏体不锈钢进行450℃×6h改性处理,通过干摩擦磨损试验对比研究了该不锈钢基体和表面改性层在不同载荷下与Si_3N_4陶瓷球摩擦副对磨时的摩擦磨损行为,观察了磨损形貌,并对其磨损机制进行了分析。结果表明:等离子体源渗氮后,试验钢表面形成了厚度约17μm的单一面心立方结构的高氮γ_N相改性层,改性层中氮元素的原子分数为15%~20%,最大显微硬度约1 510HV0.01;与基体相比,在相同载荷下γN相改性层具有相当或更低的摩擦因数,且比磨损率均降低一个数量级以上,耐磨性能显著提高;基体的磨损机制主要为黏着磨损,而γN相改性层在较低载荷(2~4N)下的磨损机制主要为氧化磨损,在较高载荷(6~8N)下的主要为磨粒磨损。

AISI 316 austenitic stainless steel was modified by plasma source nitriding technique at 450℃ for 6 h.The friction and wear behavior of the stainless steel substrate and surface modified layer against Si_3N_4 ceramic ball friction pairs was investigated comparatively under different loads by dry friction and wear tests.The wear morphology was observed and the wear mechanism was analyzed.The results show that a high-nitrogen γN phase layer with single face-centered-cubic structure and thickness of 17μm was prepared on the surface of the tested steel after plasma source nitriding.The atom fraction of nitrogen element ofγN phase layer was 15%-20% and the highest micro-hardness was about 1510 HV0.01.The friction coefficient of theγN phase layer was equivalent to or smaller than that of the substrate under the same load,the specific wear rate was reduced by one order magnitude and the wear resistance was improved.The main wear mechanism of the substrate was adhesive wear.The main wear mechanism of theγN phase layer was oxidative wear under relatively low loads（2-4 N）and abrasive wear under relatively high loads（6-8 N）.