Abstract

The present work characterizes a natural sheep wool and compares its properties to those of a range of three different, well-known organic fibers that are typically used in the friction material production: aramid, cellulose, and polyacrylonitrile (PAN) fibers. The characterization work consisted of the study of the fibers alone, the nonpressed friction materials, and the final railway brake blocks. By these means, it was proven that the wool obtained from latxa sheep (Ovis aries) is a suitable replacement for cellulose because the wool presented slightly better thermal resistance in thermogravimetric analysis, and the particle retention ability of both fibers was similar. The latxa sheep wool was also found to delay the curing reaction to a similar degree as the PAN fiber. Finally, the friction material including sheep wool presented physical and mechanical properties similar to those including cellulose and PAN fibers, and no major differences were found in friction with changing speeds or temperatures. In addition, the inclusion of sheep wool led to the lowest speed and force fade and to a good recovery behavior after the speed and temperature phases, only second to the friction material using PAN fiber. An average spread in the instantaneous friction coefficient and a slightly higher wear are reported for the material containing sheep wool. Finally, no significant differences were found on the friction surfaces or on the wear mechanism when their microstructure was analyzed using scanning electron microscopy.

摘要

目前的工作表征了天然绵羊毛，并将其特性与通常用于摩擦材料生产的三种不同的、众所周知的有机纤维的特性进行了比较：芳纶、纤维素和聚丙烯腈 (PAN) 纤维。表征工作包括单独研究纤维、非压制摩擦材料和最终的铁路制动块。通过这些方法，证明从 latxa 羊（Ovis aries) 是纤维素的合适替代品，因为羊毛在热重分析中表现出稍好的耐热性，并且两种纤维的颗粒保留能力相似。还发现 latxa 绵羊毛延迟固化反应的程度与 PAN 纤维相似。最后，包括羊毛在内的摩擦材料呈现出与包括纤维素和 PAN 纤维在内的摩擦材料相似的物理和机械性能，并且没有发现摩擦随速度或温度变化的重大差异。此外，包含绵羊毛导致最低的速度和力褪色以及速度和温度阶段后的良好恢复行为，仅次于使用 PAN 纤维的摩擦材料。对于含有羊毛的材料，报告了瞬时摩擦系数的平均分布和稍高的磨损。最后，当使用扫描电子显微镜分析它们的微观结构时，在摩擦表面或磨损机制上没有发现显着差异。