柱状碳化物(Cr,Fe)_7C_3增强Fe基涂层的摩擦磨损性能

Friction and Wear Performance of Carbide(Cr, Fe)_7C_3-reinforced Fe-based Composite Coating

以Cr3C2和Fe-CrNiBSi粉末为原料,采用等离子熔覆工艺在Q235基板上原位制备了柱状碳化物(Cr,Fe)7C3增强Fe基涂层。用光学显微镜、扫描电镜、电子能谱、X射线衍射仪、同步热分析仪及热力学计算,观察分析了初生碳化物(Cr,Fe)7C3在涂层中的生长特征,并考察了该碳化物增强涂层在不同载荷下的干滑动摩擦磨损性能。结果表明:涂层中初生碳化物(Cr,Fe)7C3为六棱长柱状,以外加Cr3C2颗粒为异质形核基底向外发散生长。热力学分析结果表明,Cr3C2颗粒可促进初生碳化物(Cr,Fe)7C3的形成;在碳化物(Cr,Fe)7C3柱体的内部有孔洞,性质较脆,外部有大量裂纹,裂纹源多发生在柱体与柱体的相交处;碳化物(Cr,Fe)7C3增强涂层的耐磨性显著高于无(Cr,Fe)7C3增强的纯Fe-CrNiBSi合金涂层,但由于碳化物(Cr,Fe)7C3柱体的脆性大,断裂韧性较低,在高载荷下其磨损表面出现大量垂直于滑动方向的裂纹。

Carbide （Cr, Fe）7C3-reinforced Fe-based composite coating was fabricated by plasma transferred arc （PTA） cladding with Fe-CrNiBSi and Cr3C2 powder blends. The nucleation and growth of （Cr, Fe）7C3 were observed and analyzed by OM, SEM, EDS, XRD, simultaneous DSC-TGA, and thermo- dynamic analysis （TA）. And the friction and wear performances of （Cr, Fe）7C3-reinforced Fe-based com- posite coating were measured by using M-2000 tester. The SEM results show that plenty of （Cr, Fe）TC3 with long hexagonal shape in-situ grow on the survived Cr3C2 particle. The TA results show that Cr3C2 can effectively act as the substrate for the nucleation of （Cr, Fe）7C3 rod, thus can promote the formation of （Cr, Fe）7C3 rod in the composite coating. Further, there are some holes inside the rod, and some cracks out- side the rod. These cracks always formed near the intersections between rods. During the variable loads dry sliding friction and wear process, the wear resistance of （Cr, Fe）7C3-reinforced coating is higher than that of the pure Fe-CrNiBSi alloy coating. But there are a lot of vertical cracks on the worn surface of （Cr, Fe）7C3 rod along the sliding direction due to the high brittleness and low fracture toughness of the rod.