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一、前 言 过共晶铝硅合金热膨胀系数小,高温性能优良,耐磨性好,比重小,是理想的内燃机活塞用材料。但当含硅量较高时,合金组织中初晶硅粗大,机加工性不好,影响了这种材料在我国的推广使用。磷酸盐复合细化剂能使含硅量高达17％以上的活塞合金可按共晶Al—Si活塞合金的机加工工艺进行加工。并且这种细化剂与美国专利报导的过共晶铝硅合金细化剂((NaPO_3)_6+Al_2O_3)相比,具有细化效果好,兼有除气作用,且价格低廉。
I. Introduction Hypereutectic Al-Si alloy has small thermal expansion coefficient, high temperature performance, good abrasion resistance, small proportion, which is ideal for piston engine materials. However, when the silicon content is high, the primary silicon in the alloy structure is coarse and the machinability is not good, which affects the popularization and application of this material in our country. The phosphate compound refiner enables the piston alloy containing more than 17% silicon to be machined according to the eutectic Al-Si piston alloy machining process. Compared with the hypereutectic Al-Si alloy refiner ((NaPO_3) _6 + Al_2O_3) reported in the U.S.Patent, the refiner has the advantages of thinning effect, degassing effect and low price.