【作者】 杜素强；

【导师】 高飞； 宋宝韫；

【作者基本信息】 大连交通大学 ， 材料加工工程， 2005， 硕士

【摘要】 研究铜粉在不同的成型压力下的压坯对最终烧结性能和烧结体密度的影响及其作用机理。发现铜粉在成型压力为870 MPa时可以的到最大的烧结体密度。在烧结的过程,通过改变各烧结工艺参数,如温度、升温速度、保温时间和烧结压力等,分析烧结体密度与各工艺参数的关系,提出铜粉的烧结温度应在750℃—800℃之间,烧结压力在2.1 MPa,保温时间以1小时为宜。 在铜粉烧结的基础上,逐渐增加组元,如石墨、SiO₂和增强基体的金属成分—锡、铁等对材料摩擦磨损性能的影响。在铜-石墨材料中,石墨含量从2.5%增加到30%时,在不同摩擦速度下,随着石墨含量的增加,摩擦系数和磨损量减小。在石墨含量低于10%时,摩擦速度对材料的摩擦系数影响明显,且随摩擦速度的提高,磨损量迅速增加。当石墨含量大于15%时,摩擦系数稳定,磨损量并没有随摩擦速度的提高而明显增加。在高速摩擦状态下,石墨和SiO₂的润滑剂性能和摩擦剂性能都下降。铜—石墨材料的摩擦系数随着摩擦速度的增加而缓慢增加;铜—SiO₂的摩擦系数随着摩擦速度的增加而急剧减小。在制动摩擦材料中,用锡和铁增强基体后的磨损率显著减小,摩擦系数的波动变小。石墨和SiO₂的百分含量不宜超过10%,粒度不宜大于0.2～0.315mm。适当细化石墨和SiO₂的粒度有助于稳定摩擦系数和减小磨损率。对同种材料而言,伴随着摩擦系数的升高,磨损率也会有不同程度的增大。 另外,在测量和计算磨损率的过程中,发现现有的磨损率表达方式很多,而在摩擦制动过程中,特别是不同材料进行耐磨性能比较时,应采用“体积/摩擦功”来表示磨损率,并给出了计算公式。更多还原

【Abstract】 Studied the copper powder in different pressure semi-finished product to finally affect the sinter property and density and its mechanism. Discovered the copper powder when takes shape the pressure is 870 MPa may to get the biggest sinter density. In sinter process, through changing the craft parameter, such as the temperature, the elevation speed of temperature, the time of heat preservation and the pressure during sintering and so on, analyzing the relations between the sinter density and various crafts parameter, proposed the copper powder with the temperature supposed 750 ℃ - 800 ℃, the pressure in 2.1 MPa, and the time of heat preservation is suitable to take 1 hour.Under the foundation of the copper powder sintering, added new ingredients gradually, such as graphite, SiO₂ and enhancement substrate metal ingredients-tin, iron and so on, studied the influence of these ingredients to friction coefficient and wear rate. In the copper - graphite material, the friction coefficient and the wear rate reduces under the different rubbing speed when the graphite content increases from 2.5% to 30%. When the graphite content is lower than 10%, the influence of rubbing speed is obvious to the material friction coefficient, and also along with rubbing speed enhancement, wear rate rapidly increase. When the graphite content is bigger than 15%, the friction coefficient is stable; the wear rate has not obviously increased along with the rubbing speed enhancement. Under the high-speed friction condition, the lubricant performance of graphite and the friction performance of SiO₂ are all dropping. The friction coefficient of copper - graphite material slowly increases with the rubbing speed increasing; the friction coefficient of copper - SiO₂ but reduces suddenly along with the rubbing speed increases. In the braking material, when the tin and other hard enhancement substrate added, the wear rate is remarkably reduced, and the friction coefficient fluctuates slightly. The graphite and the SiO₂ percentage not suitably surpasses 10%, the granularity not suitably is bigger than 0.2 -0.315mm. The suitably thin the granularity ofgraphite and SiO₂ is helpful to the stable friction coefficient, and reduces the rate of wear. To the homogeneous material, with the elevating of the friction coefficient, the wear rate also can have the varying degree increasing.In addition, in the measurement and the course of wear rate calculation, find there are a lot of wear rate expression ways. In the course of rubbing to the brake, especially when different materials carry on wear-resisting performance and compare, it should adopt "volume /friction energy ", and the formula is testified.更多还原