高温自润滑TiAl基复合材料轴承摩擦学设计与耐磨性研究

发布时间：2018-05-17 12:57

  本文选题：Ti-Al基复合材料 + 轴承　； 参考：《济南大学》2014年硕士论文

【摘要】：由于Ti-Al合金具有高温力学性能好、比强度高等优点，适用于真空、航空航天等特殊领域，但是其脆性大、耐磨性差，限制了其应用。本文拟采用合金化方法提高其力学性能，通过在TiAl基体中添加Cr、Nb等元素提高其强韧性，添加固体润滑剂（CaF2、BaF2）改善其摩擦磨损性能。 采用真空热压烧结方法制备出轻质、耐磨的Ti-Al基自润滑轴承材料。通过对轴承材料的摩擦学设计、材料的制备、力学性能测试，探讨了该自润滑轴承材料的摩擦磨损性能。 制备出力学性能和摩擦磨损性能良好的滑动轴承材料，并研究了该材料的密度、抗弯强度、硬度、断裂韧性等力学性能。研究发现：随着固体润滑剂的增多，复合材料的密度呈现出先增大后减小的趋势；材料的硬度随着固体润滑剂的增多逐渐下降，未添加润滑剂时，基体材料的硬度为51HRC，而添加质量分数为15%固体润滑剂后，硬度下降到37HRC。在润滑剂添加量为0~10%内，弯曲强度和断裂韧性均随着润滑剂的增多而上升，而当固体润滑剂添加量超过10%时，材料的弯曲强度和断裂韧性均随着润滑剂的增多而下降。 分别在室温和650℃下，对自润滑Ti-Al基复合材料的摩擦磨损性能进行了研究。研究发现，摩擦因数随着固体润滑剂的增多而下降，CaF2和BaF2起到了良好的润滑作用，而且Ti-Al基复合材料在高温下的摩擦磨损性能优于室温下。分别添加质量分数为10%和12%的固体润滑剂时，材料的综合性能较好，微观磨损形貌较平整，摩擦磨损性能较好。在650℃高温下，当润滑剂BaF2-CaF2质量分数为10%时，材料的磨损率能最低，达到0.29×107cm3N-1m-1。在650℃下，分别研究了磨损率和摩擦系数随着转速和载荷的变化规律。发现：磨损率、摩擦因数均随转速的增大而增大，磨损率、摩擦因数均随载荷的增大而增大。通过分析Ti-Al基复合材料的微观磨损形貌，发现其主要磨损形式为黏着磨损，还有一定的表面变形。 通过Solidworks三维建模和ANSYS仿真分析，在600℃下，20MPa压力下，，对比研究了Ti-Al基自润滑材料和淬硬轴承钢GCr15（滑动表面度0.003~0.01mm的硬铬）的摩擦磨损性能。研究发现：Ti-Al基自润滑材料的摩擦性能也是极其优越的，在摩擦一段时间后，Ti-Al材料产生的最大温度值比淬硬轴承钢要小近3倍，最大应力值小2.5倍。
[Abstract]:Ti-Al alloy is suitable for vacuum, aerospace and other special fields because of its good mechanical properties at high temperature and high specific strength. However, its brittleness and poor wear resistance limit its application. In this paper, alloying method is used to improve the mechanical properties of TiAl. The strength and toughness of the composites are improved by adding CrNb and solid lubricant CaF2BaF2) to improve their friction and wear properties. Ti-Al-based self-lubricating bearing materials with light weight and wear resistance were prepared by vacuum hot pressing sintering. The friction and wear properties of the self-lubricating bearing material were discussed by tribological design, preparation of the material and testing of the mechanical properties. A sliding bearing material with good mechanical properties and friction and wear properties was prepared and its mechanical properties such as density bending strength hardness and fracture toughness were studied. It is found that the density of composites increases first and then decreases with the increase of solid lubricants, and the hardness of composites decreases with the increase of solid lubricants. The hardness of the matrix material is 51 HRC, but the hardness of the matrix material decreases to 37 HRC after adding 15% solid lubricant. The flexural strength and fracture toughness of the material increased with the increase of lubricant, but when the amount of solid lubricant was more than 10%, the flexural strength and fracture toughness of the material decreased with the increase of lubricant. The friction and wear properties of self lubricating Ti-Al matrix composites were studied at room temperature and 650 鈩

本文编号：1901468