温成形摩擦界面粉末润滑层宏微观特性的试验研究
Experimental Study on Macro and Micro Characteristics of Powder Lubricant Layer in Frictional Warm Interface
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摘要: 温成形时加入润滑剂,可提高产品质量,降低变形力,延长模具的使用寿命.不同温度下润滑剂的性能不同,也影响加工界面的摩擦特性.通过将松散的石墨粉导入到面接触摩擦副间隙中,可以在轴向载荷和剪切力作用下形成减摩性能良好的粉末层,实现高温和高压成形过程的良好润滑.采用多功能摩擦磨损试验机研究温度对温成形粉末润滑界面的影响,对粉末润滑润滑的摩擦副表面进行电子显微镜观察、三维轮廓分析、能谱分析、元素含量分析及拉曼分析,获得温度影响温成形摩擦特性的现象和机理.结果表明:温度对温成形中粉末润滑界面的摩擦特性有很大影响,不同温度下摩擦系数发生改变,而粉末润滑层的平整性、完整性以及石墨有序化程度也随温度改变,而这些因素都是温度改变粉末润滑效果的内在原因.Abstract: Adding lubricant to warm forming interface can improve the quality of products, reduce the deformation force and extend the life of mold. Lubricant performance is different at elevated temperatures and affect the friction performance of the manufacturing interface. Using loose graphite powder to lubricate the plane contact tribopairs, a powder layer with good anti-friction ability was observed under the effect of axial load and shear. A multifunction tribometer is used to study temperature effect on friction characteristics of the powder lubrication in frictional warm interface. The scanning electron microscope observation, 3-d contour analysis, energy spectrum analysis, elements analysis and Raman analysis were used. The results show that temperature had great influences on friction characteristics of powder lubrication, the friction coefficient and smoothness. The integrity of powder layer and graphite ordering degree varied with temperature. These factors are the internal causes of effect of temperature on powder lubrication.