Enhanced wear property of magnesium alloy with Al+SiC coating by laser cladding
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摘要: 通过脉冲激光器(Nd-YAG)在AZ91D镁合金基底上熔覆Al+SiC粉体。采用扫描电子显微镜、能量色散谱(EDS)和X-射线衍射测定分析熔覆层的显微组织、化学成分和物相组成。研究表明:Al+SiC涂层主要由SiC,b-Mg17Al12及Mg和Al相组成,激光熔覆层与镁合金基底表现出良好的冶金结合。所有样品都具有树枝状结构,且随着SiC质量分数的增大,树枝状和胞状结构的间隔变得更大。熔覆涂层的表面硬度高于基底,并且随着熔覆层中的SiC质量分数的增加而增大,SiC质量分数为40%的熔覆层具有最大的显微硬度,达到180 HV,然而质量分数为10%的熔覆层硬度为136 HV。销盘滑动磨损试验表明,复合涂层中的SiC颗粒和原位合成的Mg17Al12相显著提高了AZ91D镁合金的耐磨损性,其中,SiC质量分数从10%增加到30%过程中磨损体积损失逐渐减少,SiC质量分数在20%~30%时熔覆层具有最好的耐磨性。Abstract: Al+SiC powders were pulse-laser (Nd-YAG) cladded on AZ91D magnesium alloy. The microstructure, chemical composition and phase analyses of the cladding layer were studied by scanning electron microscopy (SEM), energy dispersive spectrometer (EDS) analysis, and X-ray diffraction (XRD) measurement. It can be seen that the composite coating is mainly composed of SiC and b-Mg17Al12 phases, and as well as metal phases of Mg and Al. The laser cladding showed very good bonding with the magnesium alloy substrate. It was found that with increasing SiC mass fraction, the spacing of the dendritic and cellular structure became larger. The surface hardness of cladding coating is higher than that of substrate, and the increase of SiC mass fraction can increase the surface hardness as the coating with 40% SiC particles shows a maximum hardness of about 180 HV, while that of 10% SiC particles is 136 HV. Sliding wear tests conducted in a pin-on-disc wear testing apparatus showed that the composite coating with SiC particles and in situ synthesized Mg17Al12 phase remarkably improved the wear resistance of the AZ91D magnesium alloy. The wear volume loss shows a decrease as the mass fraction of SiC increases from 10% to 30%, the coatings with about 20% to 30% SiC exhibit the best wear resistance.
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Key words:
- laser technology /
- magnesium alloys /
- laser cladding /
- microhardness /
- wear resistance
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