【作者】 江沣；

【导师】 许少凡；

【作者基本信息】 合肥工业大学 ， 材料学， 2010， 硕士

【摘要】 本课题采用粉末冶金方法制备了以纳米铜、纳米银、微米铜、微米镍为添加剂的四种铜-石墨复合材料试样,首先将添加剂含量为3%的每种复合材料,采用770℃、800℃、830℃、860℃四种烧结温度进行烧结,并依照国家标准中关于电碳制品物理化学性能试验方法的规定,测量了复合材料试样的几项主要性能,进而研究烧结温度对复合材料性能的影响。实验结果表明,随着烧结温度的增加,复合材料的密度、抗弯强度和硬度均增大,电阻率减小,最佳烧结温度为830℃,温度高于830℃后,四种复合材料的强度增加变缓,硬度则出现下降。其次用粉末冶金方法制备了四组添加剂含量不同的纳米铜-铜-石墨、纳米银-铜-石墨、微米铜-铜-石墨、微米镍-铜-石墨复合材料试样,经最佳烧结温度烧结后,根据国家标准测量了试样的密度、电阻率、硬度及抗弯强度,并用金相显微镜、扫描电镜和能谱分析,对它们的显微组织、断口形貌进行观察分析,研究添加剂含量和种类不同时对铜-石墨复合材料静态性能的影响。结果表明,纳米银添加剂能有效提高铜-石墨复合材料的性能,而纳米铜添加剂的效果则不甚理想。微米铜添加剂对铜-石墨复合材料的影响不大,微米镍的加入不利于提高铜-石墨复合材料的导电性。最后,利用摩擦磨损试验机在滑动速度为10m/s,载荷为4.9N的干摩擦条件下,对四种添加剂含量分别为0%,3%,5%的四组复合材料电刷,进行36h机械摩擦磨损试验,测量了各电刷的磨损量和摩擦系数,用金相显微镜观察了它们的磨面形貌。研究结果表明,含添加剂的复合材料电刷的摩擦系数比不含添加剂的复合材料电刷要大;随着添加剂含量的增加,微米镍-铜-石墨复合材料的磨损量增大,其它三种复合材料的磨损量先增大后减小。更多还原

【Abstract】 In this paper, four kinds of specimens of Cu-C composites added by nano-copper , nano-silver, micron-copper , micron-nickel were obtained by powder metallurgy technology. Each kind of specimens with 3% additives was sintered under the temperature of 770℃, 800℃, 830℃, 860℃. The important properties are tested according to the state standard of test method for physical-chemical properties of electrical carbon product in order to study the influence of sintering temperature on the specimens. The result shows that as the sintering temperature increases, the density, bending strength and hardness are all larger while the resistivity reduces. The optimum sintering temperature is 830℃. When the sintering temperature exceeds 830℃, the strength increases slowly and the hardness even becomes smaller.Secondly, nano-copper , nano-silver, micron-copper , micron-nickel with different contents were added into the Cu-C composites . After having been sintered under the optimum sintering temperature, density, electrical resistivity, hardness and bending strength of specimen were tested, then microstructure and fracture surface were observed by metallographic microscope, SEM and EDS. The relationship between the content of additives and static properties was researched. The investigation shows that nano-silver could significantly improve properties of composite. But the effect of nano-copper is not ideal. The micron-copper doesn’t have obvious effects on the properties of composite. The micron nickel will reduce electric conductivity.Finally, friction and wear properties of four kinds of composite brush with 0% additives, 3% additives and 5% additives were tested for 36 hours on dry friction test with the sliding speed of 10m/s and the load of 4.9N. The weight loss of mechanical wear and friction coefficient were measured. The microstructure and wearing surface were observed by the metallographic microscope. The result shows that the friction coefficient of composite brush with additive is larger than that of composite brush without additive. With the increasing of additive, the wear loss of Cu-C composites added by micron-nickel increases while the wear loss of the other three kinds of composites first increases then decreases.更多还原