无铅铜铋滑动轴承材料力学性能及摩擦磨损特性研究

发布时间：2018-05-03 23:37

本文选题：Bi相 + 石墨　；参考：《合肥工业大学》2012年硕士论文

【摘要】：铅是一种有毒有害元素，随着环保化的发展趋势，产品无铅化势在必行。本文主要以无毒低熔点金元素铋作为软质相、石墨作为辅助固体润滑剂，利用石墨的减摩特性与铋的抗粘着特性的协同作用取代铜铅轴承材料中的铅，实现铜基轴承材料无铅化。采用常规的粉末冶金方法制备了无铅铜铋、铜铋石墨滑动轴承材料，并开展了相关力学性能及不同工况条件下的摩擦学特性研究，利用扫描电子显微镜、光学显微镜、表面形貌轮廓仪等微观分析手段对材料的显微组织结构、断口与磨痕表面形貌、表面轮廓以及磨痕表面的化学组分进行了系统的分析，探讨了无铅铜铋轴承材料的摩擦磨损机理。研究表明，铋含量对无铅铜铋轴承材料力学性能有较大的影响。由于铋为脆性相，且呈薄片网带状分布于铜合金基体晶界处，割裂了铜合金基体的连续性，使得含Bi铜基轴承材料硬度、压溃强度和冲击韧性随Bi含量的增加而明显减小，含Bi铜基轴承材料断口以脆性沿晶断裂为主。当Bi含量大于4wt%后，铜合金基体晶界处富Bi相的薄片网带状分布已较完整，Bi含量的进一步增大，其对铜合金基体的割裂作用不再明显增加，所以材料力学性能的降低趋势减缓。由于摩擦热的作用，摩擦磨损过程中铜铋轴承材料中的低熔点组元铋会在摩擦副表面直接接触区域熔融、析出，降低接触区域的剪切强度，稳定摩擦副的运行，含铋铜基轴承材料体现出较好的减摩、抗粘着特性。但是铋的含量对铜基轴承材料的摩擦学性能影响较大，适宜铋含量的铜铋轴承材料有利于提高其减摩、耐磨、抗粘着性能；添加适宜含量石墨可以进一步改善无铅铜铋轴承材料的减摩、抗粘着性能，提高耐磨性，，由于镀铜石墨和镀镍石墨与铜合金基体结合较好，添加镀铜石墨或者镀镍石墨的铜铋轴承材料的减摩、抗粘着特性更优，铋与石墨在减摩、抗粘着方面有较好的协同作用。
[Abstract]:Lead is a toxic and harmful element. With the development of environmental protection, lead-free products are imperative. In this paper, the non-toxic low melting point gold element bismuth is used as soft phase and graphite as auxiliary solid lubricant. The synergistic effect of anti-friction property of graphite and anti-adhesion property of bismuth is used to replace lead in copper-lead bearing material. Copper-based bearing materials are lead-free. The lead-free copper-bismuth and copper-bismuth graphite plain bearing materials were prepared by conventional powder metallurgy method. The related mechanical properties and tribological properties under different working conditions were studied. The scanning electron microscope and optical microscope were used to study the mechanical properties of lead-free copper-bismuth and copper-bismuth graphite plain bearings. The microstructure of the material, the surface morphology of fracture and wear mark, the profile of the surface and the chemical composition of the worn surface were systematically analyzed by means of surface topography profilometer and other microanalysis methods. The friction and wear mechanism of lead-free copper-bismuth bearing materials is discussed. The results show that the content of bismuth has great influence on the mechanical properties of lead-free copper-bismuth bearing materials. Because bismuth is a brittle phase and distributes along the grain boundary of the copper alloy matrix as a thin mesh, the continuity of the copper alloy matrix is severed, which makes the hardness, crushing strength and impact toughness of the bearing material containing Bi obviously decrease with the increase of Bi content. The fracture surface of bearing material containing Bi copper is mainly brittle intergranular fracture. When the Bi content is more than 4wt%, the distribution of Bi-rich thin strip at the grain boundary of the copper alloy matrix increases further, and the cleavage effect on the copper alloy matrix is no longer significantly increased, so the decreasing trend of the mechanical properties of the material is slowed down. Due to the effect of friction heat, the low melting point component bismuth in the copper-bismuth bearing material will melt and precipitate directly in the contact area of the friction pair during friction and wear, thus reducing the shear strength of the contact area and stabilizing the operation of the friction pair. Bismuth-containing copper-based bearing materials show good anti-friction and anti-adhesion properties. However, the content of bismuth has a great influence on the tribological properties of copper-based bearing materials. The Cu-Bi bearing materials with suitable bismuth content can improve their friction reduction, wear resistance and adhesion resistance. The addition of graphite with proper content can further improve the friction reduction, adhesion resistance and wear resistance of lead-free copper-bismuth bearing materials. The anti-adhesion property of copper-bismuth bearing materials with copper-bismuth coating or nickel-coated graphite is better than that of copper-bismuth bearing materials. Bismuth and graphite have good synergistic effect on antifriction and adhesion resistance.
【学位授予单位】：合肥工业大学
【学位级别】：硕士
【学位授予年份】：2012
【分类号】：TH117;TH133.31

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