固态复合法制备铝基复合材料及成型研究

发布时间：2018-03-31 05:27

  本文选题：固态复合　切入点：复合材料　出处：《沈阳理工大学》2011年硕士论文

【摘要】：制备复合材料时,根据增强颗粒进入基体时基体的状态,有液态复合或半固态复合之分。但这些复合工艺均存在着增强颗粒与基体间的润湿性差、有害界面反应和颗粒偏聚等问题,极大地影响着复合材料性能的进一步提高和推广应用。为此,作为液态复合和半固态复合概念的自然延伸,本文提出了固态复合的概念,并研究了SiC颗粒增强铝基复合材料的固态复合和压铸成型工艺。 增强颗粒预处理是制备颗粒增强复合材料的前提性工艺步骤之一。通过扫描电镜观察和能谱分析,发现本研究所用SiC颗粒表面吸附或粘附着亚微米级的SiC粉体和少量Fe、Mn、V、Ni等杂质,为此通过酸洗和浸泡冲洗,有效地去除了颗粒表面的这些有害物。另外,为避免在复合坯料熔化时SiC颗粒与铝液发生有害界面反应,对清洗后的SiC颗粒进行了高温氧化处理。氧化增重试验结果表明:经过1000℃6小时的氧化处理,在碳化硅颗粒表面形成氧化层,其厚度经测算约为117nm。 为了研究固态复合时增强颗粒在金属基体中的分布均匀性,把经过清洗和高温氧化处理的SiC颗粒与铝粉用带强制搅拌的混料机进行混合,然后经冷压、热压得到复合坯料。为避免铝颗粒的氧化,在混合过程中混料机中始终通入氩气进行保护。试验结果表明,混料时间1.5小时即可使SiC颗粒均匀分布于铝粉之中。热压的目的是,利用铝粉的高温塑性降低制坯压力;同时可促进SiC颗粒与铝粉颗粒的紧密结合。 将复合坯料加入“贫铝”7090Al合金溶液中进行熔化分散,同时加以电磁搅拌,至半固态时进行压铸成型。试样检测结果表明,采用固态复合工艺,SiC颗粒在基体合金中分布均匀,且结合状况良好,没有发现有害界面反应和颗粒偏聚的现象。试样摩擦磨损实验表明,复合材料摩擦系数较小,摩擦副表面基本无划痕,说明所制备的复合材料具有良好的摩擦性能。
[Abstract]:When the composites are prepared, there are liquid or semi-solid composites according to the matrix state when the reinforced particles enter the matrix.However, these composite processes have some problems such as poor wettability between reinforced particles and matrix, harmful interfacial reaction and particle segregation, which greatly affect the further improvement and application of the properties of composites.Therefore, as a natural extension of the concepts of liquid and semi-solid composites, the concept of solid state composite is proposed, and the solid state recombination and die casting process of SiC particle reinforced aluminum matrix composites are studied.Pretreatment of reinforced particles is one of the process steps for preparing particle reinforced composites.By scanning electron microscope observation and energy dispersive analysis, it was found that the surface of SiC particles was adsorbed or adhered to submicron SiC powder and a small amount of Fe _ 2O _ mn _ (V _ (+)) Ni. These harmful substances were effectively removed by acid pickling and soaking and washing.In addition, in order to avoid the harmful interfacial reaction between SiC particles and molten aluminum when the composite billet melted, the SiC particles after cleaning were oxidized at high temperature.The results of oxidation weight gain test show that after 6 hours of oxidation at 1000 鈩，

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