不同成分Al-Mg3Sb2复相涂层的组织和性能

目的研究Mg_3Sb_2含量对Al-Mg_3Sb_2复相涂层组织、耐蚀性和硬度的影响,对比纯Al涂层和添加不同含量Mg_3Sb_2涂层性能的差异。方法采用氧乙炔火焰喷涂技术和自制的Mg_3Sb_2粉末,在AZ31B镁合金表面制备不同成分的Al-Mg_3Sb_2复相涂层。采用扫描电镜(SEM)观察了涂层的微观组织,利用X射线衍射仪(XRD)分析了球磨粉末和涂层的物相组成,通过电化学工作站(CHI660e)对试样在3.5%Na Cl溶液中进行电化学腐蚀性能测试,并用显微硬度计测试了涂层的硬度。结果经火焰喷涂之后,获得了不同成分的Al-Mg_3Sb_2复相涂层,涂层中的物相主要为Al和Mg_3Sb_2。当Mg_3Sb_2的质量分数为40%和60%时,涂层组织致密,气孔、裂纹等组织缺陷较少。Tafel极化曲线测试中,随着第二相Mg_3Sb_2质量分数的增加,涂层的腐蚀电位逐渐正移。当质量分数达到80%时,其腐蚀电位为-0.9819 V,比纯Al涂层正移417.3 m V,腐蚀电流密度为0.048×10-3 A/cm2,约是纯Al涂层的1/2。显微硬度结果显示随着Mg_3Sb_2含量的增加,涂层的硬度逐渐提高,当质量分数达到80%时,涂层的平均硬度达到334.2HV,是纯Al涂层的6.79倍。结论Mg_3Sb_2的加入可以获得组织较好的涂层,随着其含量的增加,涂层的耐蚀性和显微硬度逐渐提高。

Structure and Properties of Al-Mg3Sb2 Multi-phase Coatings with Different Composition

The work aims to study effects of Mg3Sb2on structure, corrosion resistance and hardness of Al-Mg3Sb2mul-ti-phase coatings, and compare properties differences between pure Al coating and those with different contents of Mg3Sb2. The Al-Mg3Sb2multi-phase coatings with different compositions were prepared on the surface of AZ31B magnesium alloy by using oxy acetylene flame spraying and homemade Mg3Sb2powder. Microstructure of the coatings was observed by using SEM;phase composition of ball milling powder and coatings was analyzed by using XRD; electrochemical corrosion performance test was performed to the samples in 3.5% NaCl solution through electrochemical workstation (CHI660e); and hardness of the coat-ings was tested by microhardness tester. The Al-Mg3Sb2multi-phase coatings with different composition were obtained after flame spraying. The coatings had dense structure, and were subject to a few structural defects including pores and cracks when mass fraction of Mg3Sb2was 40% and 60%, respectively. The phases in the coatings were mainly Al and Mg3Sb2. Tafel polariza-tion curve test showed that corrosion potential of the coatings gradually shifted positively with the increase of second phase Mg3Sb2. As the mass fraction of Mg3Sb2reached 80%, the corrosion potential was ?0.9819 V, which was 417.3 mV higher than that of pure Al coating, and corrosion current density of the coatings was 0.048×10?3A/cm2, which was approximately 1/2 of that of the pure Al coating. Microhardness test showed that hardness of the coatings gradually increased with the increase of Mg3Sb2content. When the content of Mg3Sb2was 80%, the average hardness of the coatings reached 334.2HV, which was 6.79 times of that of the pure Al coating. The addition of Mg3Sb2can contribute to better coatings. The corrosion resistance and mi-crohardness of the coatings gradually increase with the increase of Mg3Sb2content.