高体积分数SiCp/Al复合材料的制备、拉伸变形和发黑处理的研究

【作者】 罗嗣俊；

【导师】 陈康华；

【作者基本信息】 中南大学 ， 材料学， 2009， 硕士

【摘要】 高体积分数SiCp/Al复合材料具有高热导率、低热膨胀系数、高弹性模量等优异性能,在空间光学及精密仪器构件领域具有广阔的应用前景。针对空间光机结构件应用的需要,本文研究高体积分数SiCp/Al复合材料的浸渗复合制备、拉伸行为和表面发黑处理。通过压缩与拉伸试验及扫描电镜观察,研究了氧化预处理和添加偏磷酸铝粘接剂对SiC预制体的抗压强度和复合材料的力学性能及显微组织的影响,并研究了淬火工艺对复合材料坯体淬火开裂的影响。SiC预制体的抗压强度和复合材料的抗拉强度随氧化预处理中SiC颗粒氧化程度的增加和预制体中偏磷酸铝含量的增加而提高；但氧化预处理温度超过1000℃或偏磷酸铝含量超过2%,复合材料的抗拉强度降低。采用油作为淬火介质,适当提高油温,可以解决较大尺寸高体积分数SiCp/Al复合材料淬火开裂问题。通过拉伸试验和扫描电镜观察,研究了冷热循环处理、预压处理和预制体中添加偏磷酸铝粘接剂对55%volSiCp/Al-10Si-0.7Mg复合材料拉伸行为及显微组织的影响。热处理和预压处理对复合材料的弹性模量影响很小,但可以提高复合材料的弹性极限。SiC预制体中添加偏磷酸铝粘接剂可提高复合材料的弹性模量和弹性极限。通过金相显微镜、扫描电镜和三维视频显微镜观察、XRD分析和反射率测定,研究了高体积分数SiCp/Al复合材料表面硫酸阳极氧化-化学发黑处理。硫酸阳极氧化使复合材料表面形成了Al203阳极氧化多孔膜、裸露的SiC颗粒表面和SiC颗粒周围凹凸不平的粗糙表面三种表面结构。化学发黑过程为：溶液化学反应生成Mn02和C0304的黑色沉淀物,沉积在复合材料经阳极氧化形成的Al203多孔膜内、裸露的SiC颗粒表面上和SiC颗粒周围凹凸不平的粗糙表面上,在复合材料表面形成一层黑色薄膜。通过优化工艺参数,高体积分数SiCp/Al复合材料的发黑表面对波长430-700nm的可见光的吸收率达到90%以上。更多还原

【Abstract】 There are broad applicating prospects to High volume fraction SiCp/Al composites in the fields of space optics and precision instruments for its high performances as such as high thermal conductivity, low thermal expansion coefficient, higher elastic modulus, et al. To apply the composites to structural components of space optics machines, in this dissertation it is studied that infiltration composite preparation, the tensile behavior and the surface blackening of the composites.Compression and tensile test and SEM are made use to investigate the effects on compressive strength of SiCp performs, mechanical performances and microstructure of the composites with preoxidating performs and joining metaphosphoric acid aluminum into performs as binder. It is also studied that the effects on quench cracking of the composites with different quench processes. Compressive strength of SiCp performs and tensile strength of the composites are increasing as both oxidation increatment of SiCp in preoxidation and increased content of metaphosphoric acid aluminum, but tensile strength of the composites will decline when preoxidating temperature exceeds 1000℃or the content of metaphosphoric acid aluminum exceeds 2%. It can be solved that large size of the composites quenched cracking when using oil as a quenching medium and appropriately increasing the oil temperature.The effects of thermal cycling, preloading and metaphosphoric acid aluminum joined into SiCp preforms on tensile deformation behavior and microstructure of 55vol% SiCp/AI-10Si-0.7Mg composites prepared by pressure infiltration are studied through tensile testing and SEM. Study shows that heat treatments and preloading have less influence on elastic modulus of the composites, of which the tensile elastic limit can be improve by them. Joining metaphosphoric acid aluminum into SiCp performs is able to improve both elastic modulus and tensile elastic limit of the composites.Sulfuric acid anodic oxidation-chemical blackening on the surface of high volume fraction SiCp/Al composites is studied through metallographic microscope, SEM, three-dimensional video microscopy, XRD analysis and measuring reflectivity. Sulfuric acid anodic oxidation makes the surface of the composites form three morphologies and structures:A12O3 porous anodic oxidation film, exposed surface of the SiC particles, rough and uneven surface around SiC. Chemical blackening process is as follows:solution of a chemical reaction to generate the black MnO2 and Co3O4 sediments deposites on the three structures, a layer of black film is formed on the surface of the composites. Optimizing process parameters through the orthogonal experiment, the absorption rate of the blackened surface of high volume fraction SiCp/Al composite material to visible light with 430-700nm wavelength is over 90%.更多还原