采用电弧离子镀(AIP)技术在K417G合金表面制备了NiCrAlYSi涂层,利用HRS-2M型往复磨损试验机测试了K417G合金及NiCrAlYSi涂层室温至400℃以下的摩擦磨损特性,利用扫描电镜(SEM),能谱分析(EDS)和X射线衍射(XRD)等手段对合金和涂层的磨损表面形貌和横截面形貌进行观察和分析.结果表明:K417G合金的磨损率低于NiCrAlYSi涂层,300℃以下,合金摩擦系数高于涂层.室温下,合金和涂层磨损机制是疲劳脱层和环境致脆,环境致脆磨损机制源于室温空气中Ni3Al相的环境脆性;磨损过程中,磨损表面形成的新鲜表面中的Ni3Al相中的Al+与水汽反应生成原子态H且逐渐聚集,导致氢致环境脆性,并逐渐作用于磨损表面;磨损表面的裂纹源在γ/γ'界面处形核,裂纹既沿着γ/γ'界面扩展,又进入γ'晶粒,呈现沿晶和穿晶混合状.随磨损温度升高,Ni3Al相的环境脆性消失,合金和涂层磨损表面的环境致脆特征消失,磨损机制转变为黏着、犁沟、块状剥落和氧化磨损机制.
A NiCrAlYSi coating was prepared on the K417G Ni-based superalloy substrate by arc ion plating (AIP) method.Friction and wear behaviors of NiCrAlYSi coating and Ni-based superalloy K417G from room temperature to 400 ℃ were investigated with reciprocating friction and wear tester.Wear surface morphology and cross-sectional morphology of K417G alloy and NiCrAlYSi coating were observed and analyzed by scanning electron microscope (SEM),energy disperse spectroscopy (EDS) and X-ray diffraction (XRD).The result showed that the wear rate of alloy was lower than that of coating.The friction coefficient of alloy was higher than that of coating below 300 ℃.The friction and wear mechanisms of alloy and coating were environmental embrittlement and fatigue delamination at the room temperature.The wear mechanism of environmental embrittlement of alloy and coating was due to environmental embrittlement of Ni3 Al phase in the air at the room temperature.The reaction between Al + from Ni3 Al phase and vapor in the air existing on the fresh surface during the process of friction generated and collected hydrogen atom,which led to H-embrittlement and gradually affected the worn surface.The crack resource on the worn surface formed at the interface of γ/γ'phases in the alloy.The cracks extended along interface of γ/γ'phases and interface of carbide and alloy,and then entered into γ'phase,presenting the mixed intergranular and transgranular.The environmental embrittlement phenomenon disappeared as temperature rose.The adhesion,ploughing,massive spalling and oxidation wear characteristics were showed on the wear surface.
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