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采用等离子熔凝工艺对汽车发动机用AZ91镁合金进行了表面改性处理,分析了熔凝电流对熔凝改性层显微组织、耐磨性能和耐腐蚀性能的影响。结果表明,等离子熔凝层的物相种类与AZ91镁合金基体一致,都为α-Mg和β-Mg17Al12相;熔凝层中的β-Mg17Al12相含量都要比AZ91镁合金基体中多,且随着熔凝电流的增大,熔凝层中的β-Mg17Al12相含量不断增加;电流为45、55和65A时熔凝层的磨损质量损失都要比AZ91镁合金基体低,且随着电流的增大,熔凝层的磨损质量损失逐渐降低;经过等离子熔凝改性后的合金的耐腐蚀性能得到提高,耐腐蚀性能从高至低依次为:65A熔凝层>55A熔凝层>45A熔凝层>AZ91镁合金基体,腐蚀形貌的观察结果与动电位极化曲线的观察结果一致。
The plasma melting process was used to modify the surface of the AZ91 magnesium alloy for automobile engine. The influence of the melting current on the microstructure, wear resistance and corrosion resistance of the fused modified layer was analyzed. The results show that the phase types of the plasma fusion layer are the same as those of the AZ91 magnesium alloy matrix, and both are α-Mg and β-Mg17Al12 phases. The content of β-Mg17Al12 phase in the fusion layer is larger than that of the AZ91 magnesium alloy matrix With the increase of the melting current, the content of β-Mg17Al12 phase in the fused layer increases continuously. The wear mass loss of the fused layer at 45, 55 and 65A is lower than that of the AZ91 magnesium alloy. With the increase of the current The corrosion resistance of the alloy after plasma fusion modification is improved, the corrosion resistance from high to low is as follows: 65A fused layer> 55A fused layer> 45A fused layer> AZ91 magnesium alloy substrate, the observed results of the corrosion morphology are consistent with those of the potentiodynamic polarization curve.