【作者】 刘鹏；

【导师】 张凤林； 周玉梅；

【作者基本信息】 广东工业大学 ， 机械制造及其自动化（专业学位）， 2016， 硕士

【摘要】 AlSiC复合材料具有高比强度和比刚度、导热率以及耐磨性等优异的力学性能和物理性能,被广泛应用于航空航天、汽车、电子、军工等领域；但是由于SiC颗粒增强相的高硬度与铝基体的高塑性,导致这种材料的加工性能较差,尤其当加工高SiC体积分数的AlSiC复合材料,难加工性表现的更加的明显,普通刀具在加工AlSiC复合材料时,刀具磨损严重,材料表面完整性差。钎焊金刚石磨具拥有高出刃、容屑空间大,磨粒结合强度高等特点,因而可以获得高的锋利度,有利于改善AlSiC复合材料的加工性。本研究分别使用单颗粒金刚石工具与单层钎焊金刚石砂轮对SiC体积分数为20%与50%的AlSiC复合材料进行划擦与磨削加工,主要研究内容和相关结论包括以下几个方面：(1)研究了钎焊单颗金刚石划擦加工不同SiC体积分数的AlSiC复合材料的划痕长度、尺寸特征以及三维形貌,分析了划痕的微观结构；研究了钎焊单颗金刚石划擦AlSiC复合材料的去除机理与表面完整性,同时分析了其磨削力特征。通过研究发现,20%的AlSiC复合材料的实际划痕长度大于50%的划痕长度；加工20%的AlSiC复合材料时耕犁作用比加工50%的材料强；发现金刚石磨粒加工AlSiC复合材料主要包括Al基体塑性去除,SiC颗粒破碎,SiC颗粒推挤移动以及SiC颗粒的粉碎化等机制；划擦20%的AlSiC复合材料切向力与法向力大于50%的材料。(2)使用单层钎焊金刚石工具对不同体积分数的AlSiC复合材料进行磨削加工研究了磨削力与磨粒目数、SiC体积分数的关系；分析了不同目数的钎焊金刚石砂轮加工不同SiC体积分数的AlSiC复合材料的表面形貌；观察了不同加工条件下的被加工后的磨屑形态；分析了不同目数钎焊金刚石砂轮的磨削性能及磨损失效形式。得出磨削SiC20%的AlSiC复合材料产生的力大于磨削SiC50%的材料产生的力,并且当金刚石粒度变小时,磨削力呈减小趋势；磨削20%的AlSiC复合材料是以塑性去除为主,而在磨削50%的复合材料是以脆性去除为主；发现了20%的AlSiC复合材料的磨屑为类似锯齿状的半连续磨屑,而50%的AlSiC复合材料多为不规则且较厚的块状磨屑。更多还原

【Abstract】 AlSiC matrix composites has been known for its high specific strength and specific modulus, high wear resistance, high temperature resistance, high thermal conductivity. These excellent properties make AlSiC matrix composites widely application area in aerospace, automotive, electronics and military industry. Nevertheless, the combination of the high hardness of SiC particle and high ductility of the aluminium matrix can make the materials difficult to machine, especially for the composite with higher volume fraction of the SiC particles. Mono layer brazed diamond wheels have the advantages of high bonding strength, high mean protrusion height, etc. In this study AlSiC composites with 20% and 50% volume fraction of SiC particles was machined by by single grain brazed diamond tools and the monolayer brazed diamond wheels. The main research contents and relevant conclusions are as follow:(1) The contact length, dimension characteristics and three-dimensional morphology and the microstructure of scratching grooves on the AlSiC matrix composites with different volume friction of SiC are analyzed. The removal mechanism and surface integrity of the AlSiC composite is also investigaed. Meanwhile, the scratching forces of the single diamond tool on AlSiC is analyzed.. The results shows that the contact length of AlSiC composite with 20%SiC is longer than AlSiC composite with 50% SiC, and the ploughing effect of AlSiC composite with 20% SiC is stronger than that of 50% one. The scratching forces of AlSiC composite with 20% SiC is higher than that of 50% one. Meanwhile, plastic removal of Al, fracture, pushing and pulverization of SiC are the main form of material removal of AlSiC in the grinding.(2) Monolayer brazed diamond wheels are used to grind AlSiC matrix composites. The relationship between grinding forces and diamond grain size, volume friction of particles is investigated. The surface morphology with different volume friction of AlSiC composite and different kinds of tools are observed. In addition, chips morphology of the composite materials are analyzed. The grinding performance and wear forms of the diamond wheel is studied. The results shows that the grinding forces of AlSiC composite with 20% SiC is higher than that of 50% one, in addition, finer mesh size of diamond wheel obtains the lower grinding forces. Plastic removal is account for the grinding mechanism of AlSiC composite with 20%SiC, however, the more brittle removal mechanism is account for AlSiC with 50% SiC. The chip of AlSiC composite with 20% SiCis the curly form and semi-continuous type. But blocky and discontinuous chips were obtained when grinding AlSiC composite with 50% SiC.更多还原