【作者】 王雪峰；

【导师】 刘昌明；

【作者基本信息】 重庆大学 ， 材料加工工程， 2009， 硕士

【摘要】 本文研究了Al-19Si-3Mg、Al-21Si-5Mg、Al-21Si-5Mg-1Cu-1Ni-0.2Ti-0.4Mn三种自生颗粒增强过共晶铝硅合金基复合材料和一种外加SiC颗粒增强铝硅合金基复合材料的浆料制备和成形工艺,设计了一套可行的离心成形模具,采用商业软件ProCAST对离心成形凝固过程及其温度场进行了模拟,模拟结果表明640℃以上的浇温在300r/min,400r/min的转速条件下铸件能完全充型,这对设计离心成形工艺具有很高的参考价值。采用对Al-19Si-3Mg浆料浇注温度730℃、模具温度500℃、离心机转速800r/min(代号a),对Al-21Si-5Mg浆料浇注温度725℃、模具温度300℃、离心机转速400r/min(代号b1)和浇注温度780℃、模具温度400℃、离心机转速400r/min(代号b2)两种,对Al-21Si-5Mg-1Cu-1Ni-0.2Ti-0.4Mn浆料浇注温度794℃、模具温度300℃、离心机转速400r/min(代号c1)和浇注温度757℃、模具温度100℃、离心机转速400r/min(代号c2)两种,对ZL104基体浆料浇注温度640℃、模具温度400℃、离心机转速400r/min(代号d),对外加SiC颗粒增强铝硅合金基复合材料的浆料浇注温度720℃、模具温度600℃、离心机转速800r/min(代号e)共七种可行的离心成形工艺成功成形了七个刹车盘零件。对零件解剖后进行了T4和T6热处理,在盘状零件不同的径向位置进行取样,制作了63个试样。观察了这些试样的微观组织,发现Si含量越高初晶硅颗粒的体积分数越高;Mg含量为3%的试样中均未发现Mg2Si颗粒,而Mg含量为5%的试样中均明显发现Mg2Si颗粒;浇注温和模具温度度越低,初晶硅颗粒的粒径越小;固溶和时效处理使基体中的网状共晶组织转变成了短棒状,并出现棱角钝化、圆润化趋势。测试并比较了它们的耐磨性和硬度,发现增强相颗粒越小,颗粒体积分数越高,耐磨性越好;材料中的位错密度越高,其硬度越高。研究结果表明Al-21Si-5Mg-1Cu-1Ni-0.2Ti-0.4Mn材料在757℃浇温、100℃模温和离心机转速400r/min条件下浇铸,并进行T6热处理,可得到最高的硬度,(达HRB89.6),和较好的耐磨性,(在自行设计的耐磨性实验设备上磨损量为16.9mg),是一种做刹车盘的优良材料。更多还原

【Abstract】 In this paper,slurry preparation and forming processes of three autogenous particle reinforced hypereutectic Al-Si alloy matrix composites, which were Al-19Si-3Mg, Al-21Si-5Mg and Al-21Si-5Mg-1Cu-1Ni-0.2Ti-0.4Mn, and a SiC particle reinforced Al-Si alloy matrix composites were studied. A feasible centrifugal casting mould was designed. And the centrifugal casting process and the temperature field of aluminum alloy brake disk and the mould were simulated by using commercial software ProCAST, the result of which indicated that when the pouring temperature was more than 640℃, and the centrifugal rotational speed was 300r/min or 400r/min, a full-filled casting could be obtained. This result was valuable for designing the forming processes.Seven feasible centrifugal casting forming processes, which were pouring temperature 730℃, mould temperature 500℃, centrifugal rotational speed 800r/min (marked‘a’) for Al-19Si-3Mg; pouring temperature 725℃, mould temperature 300℃centrifugal rotational speed 400r/min (marked‘b1’) and pouring temperature 780℃, mould temperature 400℃, centrifugal rotational speed 400r/min (marked‘b2’) for Al-19%Si-5%Mg; pouring temperature 794℃, mould temperature 300℃, centrifugal rotational speed 400r/min (marked‘c1’) and pouring temperature 757℃, mould temperature 100℃, centrifugal rotational speed 400r/min (marked‘c2’) for Al-21Si-5Mg-1Cu-1Ni-0.2Ti-0.4Mn; pouring temperature 640℃, mould temperature 400℃centrifugal rotational speed, 400r/min (marked‘d’) for ZL104; pouring temperature 720℃, mould temperature 600℃, centrifugal rotational speed 800r/min (marked‘e’) for SiC particle reinforced Al-Si alloy matrix composites, were used to form seven brake disks successfully. Everyone of those disks were dissected into three parts, the first one of which would directly dissect again while the second one of which would be T4-heat treated, and the third one would be T6-heat treated. Then samplinged those bake disks at different radial positions, and 63 samples were obtained.After observing the microstructure, we found that the more the percentage composition of Si, the more the volume fraction of primary crystal Si particles, and that there wasn’t Mg2Si particles in those samples in which the percentage composition of Mg was 3% while there were obviously in those samples in which the percentage composition of Mg was 5%. We also found that the lower the pouring temperature and mould temperature, the smaller the primary crystal Si particles; and that T4 and T6 heat treatment translated the reticular eutectic structure in the matrix into short-pole-like shape.After testing and comparing the wear-resisting property and hardness of those samples, we found that the smaller the strengthen particles and the more the volume fraction of strengthen particles, the better the wear-resisting property, and that the higher dislocation density, the higher the hardness.This research indicated that when the pouring temperature was 757℃, the mould temperature was 100℃, and the centrifugal rotational speed was 400r/min, the material Al-21Si-5Mg-1Cu-1Ni-0.2Ti-0.4Mn could get the highest hardness, which was HRB 89.6, and a good wear-resisting property, the wearing quantity of which was 16.9mg tested by the equipment for wear resisting property experiment designed by ourself after T6 heat treatment. So it was an excellent material for forming brake disk.更多还原