球团硅相增强ZA35合金基复合材料及其耐磨性

ZA 35 ALLOY BASED COMPOSITE REINFORCED BY NODULAR SILICON PHASEAND ITS WEAR RESISTANCE

为了提高锌铝合金在干摩擦条件下的耐磨性以进一步拓宽其应用范围，在ＺＡ３５合金中加入２．５％～５．５％Ｓｉ，并用自制钠盐变质剂对含硅合金进行处理，制得变质硅相增强ＺＡ３５合金基复合材料。经显微观察发现，这种含硅合金中的初生硅相在钠作用下可由块状变成球团状，在球团硅相的表面辐射分布有杆状硅相。将球团硅相从合金中分离出后对其外貌进行的电镜观察和对合金中的球团硅深腐蚀得到的年轮结构分析表明，球团硅是一个多面多晶体，共晶硅在垂直于多面体的某些小晶面杆状生长。对球团硅增强的ＺＡ３５合金进行摩擦试验，发现这种合金中的初生硅由于有辐射杆状硅的作用在干摩擦时不易脱落。和ＺＡ３５合金以及含块硅的ＺＡ３５合金相比，这种锌基复合材料具有更高的耐磨性。

A kind of modified silicon phase reinforced ZA35 alloy based composite was prepared by adding 2.5%～5.5% Si to the alloy and then treating it with modifying agent containing sodium in order to improve the wear resistance performance of zinc aluminium alloy and to widen its application in industry. It was discovered that the shape of primary silicon phase in this alloy was changed from blocky to nodular under the action of sodium. Further observation of the morphology of nodular silicon through scanning electron microscope (SEM) and analysis of the growth ring structure of nodular silicon obtained by deep etching showed that this nodular silicon phase was a polyhedron of silicon on which to every facet there corresponds a pyramid crystal. The results of dry friction test showed that the primary silicon can be firmly embedded in metal matrix and be not exfoliated during dry friction and the nodular silicon reinforced ZA35 alloy base composites have higher wear resistance performance than ZA35 alloy has.