水润滑下等离子喷涂Cr_3C_2-NiCr涂层/增韧SiC陶瓷摩擦副的摩擦学特性

Tribological Properties of Plasma-sprayed Cr_3C_2-NiCr Coating against Toughened SiC Ceramics under Water-lubricated Sliding

采用 MM- 2 0 0型摩擦磨损试验机考察了等离子喷涂 Cr3C2 - Ni Cr涂层 /增韧 Si C陶瓷摩擦副在蒸馏水润滑下的摩擦学特性 ,通过对磨损表面形貌和磨屑的电子探针和傅立叶转换红外光谱分析 ,探讨了其磨损机理 .结果表明 :在较低载荷下 ,Si C与水发生摩擦化学反应 ,在磨痕表面生成由 Si O2 和硅胶组成的表面膜 ,从而使得摩擦副呈现出优异的摩擦学特性 ;在较高载荷下 ,Si C陶瓷发生晶粒微观断裂 ,从而使得摩擦系数升高并出现较大波动 ,此时 Cr3C2 - Ni Cr涂层的磨损率显著增大 .

The tribological properties of plasma sprayed Cr 3C 2 NiCr coating sliding against toughened SiC ceramics under water lubricated condition were investigated on an MM 200 friction and wear tester. The morphology of the worn surface and the elemental composition of the wear debris were examined by means of electron probe micro analysis and (Fourier transformed infrared) spectroscopy. It has been found that the friction pair records a friction coefficient below 0.2 and wear rates less than 10 -6 mm 3(Nm) -1 . Under water lubricated condition at a relatively low load, tribochemical oxidation of SiC took place, with the generation of the protective film composed of SiO 2 and SiO 2.nH 2O formed on the worn surface. This contributes to decrease the friction coefficient and wear rate. While under a relatively high load, local grain fracture of SiC ceramics occurred, which accounts for the fluctuation in the friction coefficient and the increase in the wear rates of the Cr 3C 2 NiCr coating.