The Influences of Carbon Fiber and Nano-Silica in the Making of an Asbestos-Free Composite for a Train Brake Lining

Abstract

The brake lining is an important component of a train’s breaking system as a friction material needed to reduce speed of wheel rotation. Brake linings on the market are mostly asbestos-based, which is not very heat resistant and is not suitable for wet conditions. Asbestos brake linings are health endangering, cause slip, and are not environmentally friendly. This research aimed to create a heat and friction resistant, asbestos-free composite for train brake linings. The compositions used in this research are carbon fiber, acrylic fiber, glass fiber, metal fiber, and mineral fiber as reinforcing materials. Phenolic resin is used as the matrix with barium sulfate as the catalyst. Additional materials were used to improve friction and wear resistance, such as graphite, cashew nut particles, acrylonitrile butadiene elastomeric, nano-silica, vermiculite, and calcium hydroxide. Carbon fiber was varied at 0.0, 0.05, 0.10, 0.15, 0.20, 0.25 and 0.30% (w/w). Nano-silica was varied at 0.0, 0.2, 0.4, 0.6, 0.8, and 1.0% (w/w). The composites were made by sintering and physical and mechanical properties were tested according to relevant standards. Carbon fibers from 0.1–0.3 wt.% were introduced to improve temperature endurance and the friction coefficient. In addition, nano-silica loadings from 0–1 wt.% decreased porosity and improved wear endurance. Carbon fibers content between 0.25-0.3 wt.% gave optimal endurance of friction temperature. Nano-silica content between 0.8–1.0 wt.% gave optimal wear endurance. SEM indicated that addition of nano-silica in this composite reduced porosity making the block more dense.