TiAl基复合材料制动盘的摩擦学特性研究

发布时间：2018-06-25 20:01

  本文选题：TiAl基复合材料 + 陶瓷颗粒　； 参考：《济南大学》2017年硕士论文

【摘要】：随着车辆的高速化发展,当今汽车普遍使用的铸铁制动盘已经满足不了对安全性和节约能源的要求。其主要存在两个大问题:一是密度大占据了制动系统的大部分重量,二是铸铁材料的高温工作性能不好、抗热衰退性差。而TiAl基复合材料具有密度小、强度高、高温工作性能好等特点,如果将其用作汽车制动盘材料来代替普通的铸铁将对汽车行业的发展具有重要意义。本文针对汽车制动盘的性能要求对TiAl基复合材料进行了基体成分的设计以及耐磨成分的设计。选取了Ti-60Al-2Cr-2Nb-1B做为基体,添加TiC和Al2O3陶瓷颗粒作为耐磨成分。然后采用真空热压烧结技术制备出性能优良的TiAl基复合材料试样。分别对复合材料试样的物理力学性能、摩擦学性能进行了研究。研究结果表明:随着TiC和Al2O3添加量的增加,TiAl基复合材料相对密度逐渐减小,硬度先增大后减小;TiAl基复合材料抗弯强度随着TiC添加量的增加先增大后减小,并且当TiC添加量为12%时其抗弯强度最优;而随着Al2O3添加量增加复合材料的抗弯强度逐渐减小。又对TiAl基复合材料分别进行了干摩擦磨损、水润摩擦磨损、高温摩擦磨损实验。研究结果表明:干摩擦磨损下,TiAl基复合材料摩擦系数随着TiC和Al203添加量的增加先增大后减小。而磨损率随着TiC和Al203添加量的增加开始呈减小趋势,但是当添加量增加到一定量时,磨损率反而又增大了,并且当TiC和Al203添加量分别为12%和14%时,复合材料的磨损率值最小。复合材料的摩擦系数随着实验转速的升高先增大后减小,磨损率随着实验转速的升高而逐渐增大。其中TiC添加量为12%的TiAl基复合材料的摩擦系数更加稳定;水润摩擦磨损下,TiAl基复合材料的摩擦系数和磨损率相对于干摩擦磨损均有所降低,但是整体摩擦系数值仍能保持在0.3左右。并且TiC添加量为12%时,TiAl基复合材料的磨损率值达到最低;在高温摩擦磨损下,TiAl基复合材料的摩擦系数随着温度的升高而降低,TiC添加量为12%的复合材料磨损率在温度小于300℃时缓慢变化,大于300℃时急剧增大。而Al203添加量为14%的复合材料磨损率在温度小于400℃时缓慢变化,大于400℃时急剧增大。所以TiC添加量为12%的TiAl基复合材料的摩擦系数和磨损率的抗热衰退性能更加优异。利用ABAQUS对TiC添加量为12%的TiAl基复合材料制动盘分别在紧急制动工况和持续制动工况进行了仿真分析。研究结果表明:紧急制动工况下时,TiAl基复合材料制动盘的最大温度达到154.2℃,最大应力达到88.94MPa。复合材料制动盘的最大温度和最大应力都出现在制动中期,温度和应力都经历了开始升高然后小幅度降低的过程;持续制动工况下,复合材料制动盘的最大温度达到166.3℃,最大应力达到138.9MPa。制动温度和应力开始呈上升趋势而后保持一个稳定数值;两种制动工况下,TiAl基复合材料制动盘的径向温度梯度和应力梯度均大于周向。
[Abstract]:With the development of high speed vehicle, the cast iron brake disc which is widely used in automobile nowadays can not meet the requirements of safety and energy saving. There are two major problems: one is that the density occupies most of the weight of the braking system, the other is the poor high temperature working performance of cast iron and the poor resistance to thermal degradation. Tial matrix composites have the characteristics of low density, high strength and good high temperature working performance. It will be of great significance to the development of automobile industry if it is used as brake disc material instead of ordinary cast iron. In this paper, the matrix composition and wear resistance of tial matrix composites are designed according to the performance requirements of automobile brake discs. Ti-60Al-2Cr-2Nb-1B was chosen as matrix and tic and Al _ 2O _ 3 ceramic particles as wear resistant components. The tial matrix composites with excellent properties were prepared by vacuum hot pressing sintering. The physical and mechanical properties and tribological properties of the composites were studied. The results show that the relative density of tial matrix composites decreases with the increase of tic and Al _ 2O _ 3 content, and the flexural strength of TiAl-based composites increases first and then decreases with the increase of tic content. The flexural strength of the composite decreases with the increase of Al _ 2O _ 3 content, and the flexural strength of the composite decreases with the increase of tic content of 12. The experiments of dry friction and wear, wet friction and wear, high temperature friction and wear of tial matrix composites were also carried out. The results show that the friction coefficient of tial matrix composites increases firstly and then decreases with the increase of tic and Al203 content under dry friction and wear. However, the wear rate decreases with the increase of tic and Al203 content, but the wear rate increases with the increase of tic and Al203 content, and the wear rate is the lowest when tic and Al203 content are 12% and 14% respectively. The friction coefficient of the composites increases first and then decreases with the increase of the experimental speed, and the wear rate increases gradually with the increase of the experimental speed. The friction coefficient of tial matrix composites with tic content of 12% is more stable, and the friction coefficient and wear rate of tial matrix composites are lower than those of dry friction and wear under wet friction and wear. But the overall friction coefficient can still be kept around 0.3. The wear rate of tial matrix composites is the lowest when tic content is 12. Under high temperature friction and wear, the friction coefficient of TiAl-based composites decreases with the increase of temperature, and the wear rate of the composites with 12% tic content changes slowly when the temperature is less than 300 鈩，

本文编号：2067306