搅拌摩擦加工改性冷喷涂Al-12Si合金涂层的组织和性能

采用冷喷涂在碳钢基体上沉积制备了Al-12Si合金涂层,分别采用平端面和渐开线端面的无针搅拌头以950r/min转速对涂层表面进行搅拌摩擦加工(FSP)改性。采用光镜和扫描电镜对喷涂态和FSP改性后涂层的组织结构进行了表征。结果表明:采用两种搅拌头获得了不同形貌的组织,随着渐开线端面搅拌头的移动,提高了热输入,涂层中组织出现了过热造成的气孔缺陷。Si颗粒在FSP的塑性变形过程中得到了充分的混合,均匀地分散在了涂层中,分析表明沉积粒子的再分布和晶粒的细化能显著提高涂层的表面性能,此外,两种FSP搅拌头改性后涂层表面的硬度分别为113.8HV0.5和125.1HV0.5。

Microstructure and Properties of Cold Sprayed Al-12Si Alloy Coating Followed by Friction Stir Processing

Al12Si alloy coating was deposited onto a mild steel substrate by cold spraying and subsequently modified by friction stir processing (FSP) at a tool rotation speed of 950 r/min using flat and involutes cylinder tools to improve its microstructure and property. The microstructures of the coating after FSP and the ascoldsprayed coating were investigated by optical microscope and scanning electron microscope. The results show that the coating presents different microstructures after two different FSP conditions and pore defects is found in the coating with the involutes cylinder tool because the heat input increases with increasing stirring time. The ascoldsprayed coating contained Si particles at the grain boundaries, and the FSP process could break up and disperse these Si particles more uniformly. It is suggested that the redistribution and grain size refinement of Al12Si particles during FSP could significantly improve the coating performance. The microhardness of the coating modified by the two different tools is 113.8 HV0.5 and 125.1 HV0.5, respectively.