球形石墨增强银-石墨复合材料的摩擦学行为

来源期刊:中国有色金属学报(英文版)2020年第8期

论文作者:孙阳 王艳 李云 周科朝 张雷

文章页码:2177 - 2187

关键词:银-石墨复合材料;石墨形貌;磨损性能;显微组织;磨损机制

Key words:Ag-graphite composite; graphite morphology; wear resistance; microstructure; wear mechanism

摘    要:采用粉末冶金技术分别制备球形石墨(SG)和鳞片石墨(FG)增强的银-石墨复合材料。并用销-盘式摩擦磨损仪在大气环境和3.0 N的载荷下研究石墨形貌对银-石墨复合材料(Ag-SG和Ag-FG)摩擦学行为的影响。结 果显示,Ag-FG的最低磨损率为3.5×10-5 mm3/(N·m),而Ag-SG的最低磨损率比Ag-FG低一个数量级,为1.6×10-6 mm3/(N·m)。Ag-SG和Ag-FG显著不同的摩擦学行为与亚表面裂纹的形成有关。在摩擦过程中,片状石墨的边缘容易发生应力集中,导致Ag-FG亚表面产生裂纹和严重的剥层磨损。然而,在Ag-SG中,球形石墨能有效抑制裂纹的萌生和扩展,从而使银-石墨复合材料具有优异的耐磨性能。

Abstract: Two kinds of Ag-graphite composites reinforced with spherical graphite (SG) and conventional flake graphite (FG) were prepared by powder metallurgy technology. The effect of graphite morphology on the tribological behavior for the Ag-SG and Ag-FG under the dry sliding wear was investigated with a pin-on-disk tribometer at a load of 3.0 N in atmosphere condition. The results indicated that the minimum wear rate of 3.5×10-5 mm3/(N·m) for Ag-FG was achieved and it reduced by nearly an order of magnitude, reaching 1.6×10-6 mm3/(N·m) for the Ag-SG. The obviously different tribological behaviors between the Ag-SG and Ag-FG were closely related to the formation of cracks in the sub-surface. The stress concentration tended to generate at the edges of flake graphite during sliding process, which resulted in the cracks and severe delamination wear of Ag-FG. However, no cracks were found around the spherical graphite in Ag-SG. The spherical graphite can effectively inhibit the initiation and propagation of cracks, achieving high wear resistance.

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