Abstract

Experimental antifriction aluminum alloys based on an Al–5% Si–4% Cu system with the addition of low-melting components such as Bi, Pb, In, and Cd have been studied. An optimal heat treatment mode has been adjusted, including the hardening at a temperature of 500°С with further aging at 175°С. The tribological testing have been carried out according to a pad–roller scheme (Steel 45 as the material under study) at a pressure of 0.5, 1.0, and 2.0 MPa to simulate the operation of a bearing mount assembly. It is shown that all the experimental alloys have similar tribological properties, but their mechanical characteristics, in particular, hardness, are different. Of greatest importance is an alloy containing cadmium. Using electron microscopy, the topography is studied and the elemental composition is determined for the surfaces of a roller and a pad made of this material before and after tribological testing. A process of active mass transfer in the contact zone under friction is revealed. In this case, the formation of a film consisting of secondary structures on the roller is observed. The film has the following features: an uneven distribution on the surface with a developed relief and a maximum film thickness reaching 200 μm. It is shown that, under the friction conditions that are used, such a film promotes the formation of scuffing. It has been found that the scuffing occurs after testing at a pressure higher than 1 MPa for all the studied experimental alloys. The nanoindentation of a pad performed at a load ranging from 10 to 100 mN has shown an increase in the hardness of a surface layer about 30 μm thick. This could be connected with the hardening of the material owing to plastic deformations in the friction zone.

中文翻译：

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摩擦变形下基于Al–Si–Cu体系的铝合金表面层结构变化研究

摘要

已经研究了基于Al-5％Si-4％Cu体系并添加了Bi，Pb，In和Cd等低熔点成分的实验减摩铝合金。调整了最佳热处理模式，包括在500°С的温度下硬化并在175°С的温度下进一步老化。摩擦测试是根据轧辊计划（钢45为研究材料）在0.5、1.0和2.0 MPa的压力下进行的，以模拟轴承安装组件的运行。结果表明，所有实验合金都具有相似的摩擦学性能，但其机械特性（尤其是硬度）不同。最重要的是含有镉的合金。使用电子显微镜，在进行摩擦学测试之前和之后，研究地形并确定由这种材料制成的辊子和垫板表面的元素组成。揭示了在摩擦作用下接触区中的有效质量传递过程。在这种情况下，观察到在辊上形成了由二级结构组成的膜。该膜具有以下特征：表面上的不均匀分布，具有凸出的浮雕，最大膜厚达到200μm。结果表明，在所用的摩擦条件下，这种薄膜促进了划痕的形成。已经发现，对于所有研究的实验合金，在高于1 MPa的压力下进行测试后会发生划痕。在10到100 mN的负载范围内执行的垫的纳米压痕显示，表面层的硬度增加了约30μm。由于在摩擦区域中的塑性变形，这可能与材料的硬化有关。