碳化硅颗粒增强镁基复合材料的制备与性能研究

发布时间：2019-07-06 18:39

【摘要】：由于镁合金在室温及高温下表现出低的硬度，低的强度，耐蚀性差等性能阻碍了其在工业中的应用，采用添加增强体来制备增强镁基复合材料可以很好的改善镁合金基体的综合力学性能。本文采用SiC颗粒作为增强体制备了SiCp/AZ91D镁基复合材料，系统的研究SiC颗粒增强镁基复合材料的增强机理，微观组织结构，，断口形貌，综合力学性能。本文采用不同制备工艺制备复合材料，分别采用挤压铸造法和重力铸造法制备SiCp/AZ91D镁基复合材料，采用正交实验的方法研究了颗粒含量，颗粒尺寸，浇注温度，挤压压力对复合材料性能的影响，并通过极差分析方法分析得出了影响因素的显著性顺序及最优化的实验参数。重力铸造主要研究颗粒含量，颗粒尺寸，浇注温度对材料性能的影响，结合金相组织，断口形貌，力学性能，从微观角度研究了颗粒增强的机理，材料的断裂机制，显微组织。并对挤压铸造法和重力铸造法制备复合材料的密度，抗拉强度，伸长率，硬度等力学性能及微观组织进行对比分析，实验结果表明采用挤压铸造法制备的SiC颗粒增强AZ91D复合材料的综合力学性能较重力铸造法制备的复合材料的综合力学性能更加优良。着重研究挤压铸造法制备SiCp/AZ91D镁基复合材料中颗粒含量及挤压压力对材料显微结构及力学性能的影响，实验结果表明，当挤压压力一定时，随着颗粒含量的增加材料的硬度呈上升趋势，而伸长率呈下降趋势，抗拉强度先增大后减小。当颗粒含量一定时，随着挤压压力的增大材料的抗拉强度及伸长率先增大后减小，当挤压压力为100MPa时达到最高。在最优的实验参数下，采用挤压铸造制备SiCp/AZ91D镁基复合材料，并对复合材料进行固溶与时效处理，研究结果表明，固溶时效后材料的力学性能有了很大的提到。热处理之前抗拉强度为193.1MPa，热处理之后抗拉强度为231.5MPa，提高了19.9%，热处理之前伸长率值为4.32%，热处理之后为5.38%，提高了24.5%，热处理之前硬度值为73.23HB，热处理之后硬度值为81.13HB，提高了10.8%。
文内图片：

图片说明：HFC-134a气瓶
[Abstract]:Due to the low hardness, low strength and poor corrosion resistance of magnesium alloy at room temperature and high temperature, the application of magnesium alloy in industry is hindered. The comprehensive mechanical properties of magnesium alloy matrix can be improved by adding reinforcements to prepare reinforced magnesium matrix composites. In this paper, SiCp/AZ91D magnesium matrix composites were prepared by using SiC particles as reinforcement system. The strengthening mechanism, microstructure, fracture morphology and comprehensive mechanical properties of SiC particles reinforced magnesium matrix composites were systematically studied. In this paper, SiCp/AZ91D magnesium matrix composites were prepared by different preparation processes, and SiCp/AZ91D magnesium matrix composites were prepared by squeeze casting and gravity casting, respectively. the effects of particle content, particle size, pouring temperature and extrusion pressure on the properties of the composites were studied by orthogonal experiment, and the significant order of influencing factors and the optimized experimental parameters were obtained by means of extreme difference analysis. Gravity casting mainly studied the effects of particle content, particle size and pouring temperature on the properties of the material. Combined with metallographic structure, fracture morphology and mechanical properties, the mechanism of particle reinforcement, fracture mechanism and microstructure of the material were studied from a microscopic point of view. The mechanical properties and microstructure of the composites prepared by squeeze casting and gravity casting were compared and analyzed. The experimental results show that the comprehensive mechanical properties of SiC particle reinforced AZ91D composites prepared by squeeze casting are better than those prepared by gravity casting. The effects of particle content and extrusion pressure on the microstructure and mechanical properties of SiCp/AZ91D magnesium matrix composites prepared by squeeze casting were studied emphatically. the experimental results show that when the extrusion pressure is constant, the hardness of the material increases with the increase of particle content, while the elongation decreases, and the tensile strength increases at first and then decreases. When the particle content is constant, the tensile strength and extension of the material increase at first and then decrease with the increase of extrusion pressure, and reach the highest when the extrusion pressure is 100MPa. Under the optimal experimental parameters, SiCp/AZ91D magnesium matrix composites were prepared by squeeze casting, and the solid solution and aging treatment of the composites were carried out. the results show that the mechanical properties of the composites after solid solution aging are greatly mentioned. The tensile strength before heat treatment is 193.1 MPA, the tensile strength after heat treatment is 231.5 MPA, the tensile strength is increased by 19.9%, the elongation value before heat treatment is 4.32%, after heat treatment is 5.38%, the increase is 24.5%, the hardness value before heat treatment is 73.23HB, and the hardness value after heat treatment is 81.13HB, which is 10.8%.
【学位授予单位】：中北大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：TB333

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