烧结气氛论文烧结工艺对铜基粉末冶金摩擦材料性能的影响.doc

烧结气氛论文：烧结工艺对铜基粉末冶金摩擦材料性能的影响【中文摘要】随着我国铁路运输业的飞速发展,列车运行速度一提再提,这就对制动摩擦材料提出了更为苛刻的要求。铜基粉末冶金摩擦材料因其具有高的机械强度、高导热性和优良的摩擦磨损性能而成为高速列车制动闸片的首选材料,如何通过制备工艺和原料体系的改进提高材料的耐温性能和摩擦稳定性一直是人们研究的重点。本文通过采用不同的烧结工艺制备了铜基粉末冶金摩擦材料,研究不同烧结温度和烧结气氛对材料显微组织、物理机械性能和摩擦磨损性能的影响,并探讨了材料在不同制动条件下的摩擦磨损行为及机理,结果表明：(1)铜基粉末冶金摩擦材料中各组元分布均匀,组元间接触紧密,鳞片状石墨垂直于压制方向呈层状分布,SiO2以黑色大颗粒状镶嵌于铜基体内。随的烧结温度提高,材料中各组元间的孔隙减少,当达到一定程度后,孔隙不再减少；烧结气氛对材料的形貌无明显影响。(2)烧结工艺对材料的物理-机械性能影响较大。随烧结温度的提高,采用N2和N2+H2混合气制备材料的密度先升后降,抗压强度较大,且随之呈上升趋势；H2气氛制备材料的密度呈下降趋势,抗压强度与其他两种气氛下制备的相比显著降低,且呈下降趋势。(3)相同制动压力下,材料的摩擦系数随的转速的提高先升高后降低,磨损量随着转速的提高逐渐增加；在较低转速时,磨损以粘着磨损为主,随着转速提高,磨损逐渐表现为氧化磨损和疲劳磨损。N2+H2混合气氛烧结材料在较低转速下具有较好的摩擦性能,磨损量很低,且随烧结温度提高呈下降趋势；N2气氛烧结材料在较高转速下摩擦性能较好,摩擦稳定性好,而且磨损量也较低。(4)在一定转速下,随着制动压力的提高,材料的摩擦系数呈下降趋势,摩擦稳定性系数先升高后下降,磨损量显著增加；较低压力时,磨损主要由粘着机理控制,较高压力时,磨损主要表现为疲劳磨损和剥层脱落。N2+H2混合气氛烧结材料在高制动压力下具有较好的摩擦性能,摩擦稳定性最高,磨损量最小,且随烧结温度升高先减少后增加,在1000时最低。【英文摘要】With the development of train transport, the requirements are stiffer and stiffer in the properties of the braking materials by the speed improvement. Because of the high mechanical strength, high conductibility and excellent friction and wear properties, Cu-based P/M friction materials have been the leading material for friction brake of high-speed train.Cu-based P/M friction material has been made by different sintering process. The effect of sintering temperature and atmosphere on the micro-structure, physical and mechanical properties and friction and wear properties of material have been investigated, and the friction and wear behavior and mechanism in the different braking conditions have been discussed. The results show:(1) Scaly graphite and SiO2 are well-distributed in Cu-based P/M materials. With the increasing of sintering temperature, the pore volume between different components decreases gradually till reached a certain degree. Sintering atmospheres have no effect on the micro-structure of materials.(2) Sintering process have important effects on the physical and mechanical properties of materials. With the increasing of sintering temperature, the densities of materials sintered in N2 andN2+H2 atmosphere increases firstly and decreases then, but the densities in H2 trends to decrease; the compressive strength of materials sintered in N2 and N2+H2 are higher than that in H2.(3) On the same braking pressure, with speed increased, the frictional coefficient increases firstly and decreases then, but the wear volume increases gradually. The slipping speed changes, the wear mechanism changes also. At low speeds, adhesion wear is the main mechanism, but oxidation and fatigue wear takes on priority at high speeds. The materials sintered in the N2+H2 atmosphere have the best frictional property at low speeds, besides, the wear volumes are the lowest and decreases with the increasing sintering temperature. The materials sintered in the N2 atmosphere have the best frictional property at high speeds, and with high frictional stability and lower wear volume at the same time.(4) At the certain speed, with braking pressure increased, the frictional coefficient trends to decrease, frictional stability increases firstly and decreases then, but the wear volume increases greatly. On low pressures, the main wear mechanism is adhesion wear, but fatigue and flake wear are the main mechanism on high pressures. The materials sintered in the N2+H2 atmosphere have the best frictional property on high pressure, the highest frictional stability and the lowest wear volumes, besides, with sintering temperature increased, the wear volume decreases firstly and increases then, and has the lowest value in the sintering temperature of 1000.【关键词】烧结气氛 烧结温度 粉末冶金 铜基摩擦材料 摩擦磨损【英文关键词】sintering atmosphere sintering temperature powder metallurgy Cu-based friction material friction and wear【目录】烧结工艺对铜基粉末冶金摩擦材料性能的影响摘要6-7ABSTRACT7-8目录9-12第一章 绪论12-251.1 高速列车发展概述12-131.2 摩擦材料概述13-161.2.1 摩擦材料的种类13-151.2.1.1 有机摩擦材料13-141.2.1.2 铸铁141.2.1.3 粉末冶金摩擦材料14-151.2.1.4 碳/碳复合材料151.2.2 摩擦材料技术要求15-161.3 粉末冶金摩擦材料16-231.3.1 粉末冶金摩擦材料组成16-191.3.1.1 基体组元171.3.1.2 摩擦组元17-181.3.1.3 润滑组元18-191.3.2 粉末冶金摩擦材料种类19-221.3.2.1 铜基粉末冶金摩擦材料19-201.3.2.2 铁基粉末冶金摩擦材料20-211.3.2.3 铁-铜基粉末冶金摩擦材料211.3.2.4 其它金属基粉末冶金摩擦材料21-221.3.3 粉末冶金摩擦材料在铁道车辆上的应用22-231.4 选题意义和主要工作23-25第2章 试验设计和研究方法25-302.1 材料组成和制备工艺252.1.1 材料组成252.1.2 制备工艺252.2 试验方案25-262.3 性能检测手段26-302.3.1 密度和孔隙率27-282.3.2 硬度282.3.3 抗压强度282.3.4 组织结构和表面形貌分析28-292.3.5 摩擦表面成分及相结构分析292.3.6 摩擦磨损性能测试29-30第3章 材料的物理机械性能及组织结构研究30-383.1 烧结温度和气氛对材料密度和孔隙率的影响30-323.2 烧结温度和气氛对材料抗压强度的影响32-333.3 烧结温度和气氛对材料硬度的影响33-343.4 烧结温度和气氛对材料组织结构的影响34-363.5 本章小结36-38第4章 材料的摩擦磨损性能研究38-614.1 不同温度烧结材料的摩擦磨损性能研究38-534.1.1 转速对材料摩擦磨损性能的影响38-474.1.1.1 转速对材料摩擦系数的影响39-404.1.1.2 不同转速下摩擦系数的稳定性研究40-414.1.1.3 转速对材料磨损量的影响41-434.1.1.4 摩擦磨损机理分析43-474.1.2 制动压力对材料摩擦磨损性能的影响47-534.1.2.1 压力对材料摩擦系数的影响48-494.1.2.2 不同制动压力下摩擦系数的稳定性研究49-504.1.2.3 压力对材料磨损量的影响50-524.1.2.4 摩擦磨损机理分析52-534.2 不同气氛烧结材料的摩擦磨损性能研究53-604.2