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采用预置式两步激光熔覆的方法在汽车发动机用AZ91合金表面进行了等离子喷涂+激光熔覆改性处理,通过金相、扫描电镜、XRD、硬度和极化曲线等测试手段,研究了激光熔覆Al-Si层的显微组织和耐腐蚀性能。结果表明,激光熔覆层主要由α-Al和(α-Al+β-Si)共晶组织组成;激光熔覆层的显微硬度要高于等离子喷涂层,且两种涂层的显微硬度都要高于基体合金;改性层和基体合金的耐腐蚀性能从高至低依次为:激光熔覆层>等离子喷涂层>AZ91合金。
The surface of AZ91 alloy for automotive engine was plasma sprayed and laser cladding modified by the preset two-step laser cladding method. The metallographic, SEM, XRD, hardness and polarization curves were used to study the effects of Microstructure and Corrosion Resistance of Laser Clad Al-Si Layer. The results show that the laser cladding layer mainly consists of α-Al and (α-Al + β-Si) eutectic. The laser micro-hardness of the laser cladding layer is higher than that of the plasma sprayed layer. The hardness is higher than that of the matrix alloy; the corrosion resistance of the modified layer and the matrix alloy from high to low are as follows: laser cladding layer> plasma sprayed layer> AZ91 alloy.