钴粉涂覆石墨对铜基粉末冶金摩擦材料性能的影响

Effect of Cobalt Powder Coated Graphite on Properties of Copper-based Powder Metallurgy Friction Materials

石墨为粉末冶金摩擦材料中的润滑相,但石墨与金属基的润湿角小,结合能力差,在摩擦过程中易发生剥落,造成摩擦系数升高。本文中的试样通过混料、冷压成型及气氛烧结进行制备,混料前对石墨表面使用Co、Co/Ag进行涂覆处理,利用钴粉对石墨的包镶作用,使涂覆后的石墨在摩擦过程中充分发挥润滑作用,研究应用涂覆石墨后对摩擦材料的物理及力学性能、摩擦磨损性能的影响。试验结果表明,石墨表面涂覆Co或Co/Ag后,石墨颗粒与摩擦材料中金属基结合紧密,摩擦材料的剪切强度提升了10.9%;与加入未涂覆处理石墨的摩擦材料相比,摩擦系数的稳定性得到提高,磨耗量降低了8.5%。

Graphite is the lubricating phase in powder metallurgy friction materials,but the wetting angle between graphite and metal base is small,which makes the binding ability of graphite and metal base poor.During friction,graphite particles are easy to peel off from the friction material,resulting in increased friction coefficient.The samples in this paper were prepared by mixing,cold pressing and atmosphere sintering.The graphite surface was coated with Co and Co/Ag before mixing.Due to the coating effect of cobalt powder on graphite,the coated graphite was lubricated during friction.The mechanical and tribological properties of graphite coated friction materials were studied.The experimental results show that the graphite particles were closely bonded with the metal base in the friction material after the graphite surface was coated with Co or Co/Ag.The shear strength of friction material was increased by 10.9%.Compared with uncoated graphite,the friction coefficient stability was improved and the friction loss was reduced by 8.5%.