Tribological Behavior of Multi-walled Carbon Nanotubes Grafted Carbon Fiber-reinforced Friction Material

Abstract

Friction characteristics of multi-walled carbon nanotubes grafted carbon fiber-reinforced friction material (MWCRFM), asbestos fiber-reinforced friction material (AFRFM), and oxidized carbon fiber-reinforced friction materials (OCRFM) are investigated in this work using a wear test apparatus. The surface of carbon fiber (CF) is chemically inert and hydrophobic in nature and possesses poor bonding performance with polymer matrix. Hence, in this work, an attempt is made to improve the bonding behavior between CF and remaining ingredients. CF surface is modified by two surface treatment methods. First, oxidation and second grafting multi-walled carbon nanotubes functionalized (MWCNT-F) on CF surface. CF content after surface modification is taken as (5 wt%) and mixed with remaining ingredients of friction material. Composite sheets are prepared by using hand layup method. Three types of friction materials, (MWCRFM), (AFRFM), and (OCRFM) are developed and analyzed for coefficient of friction and wear rate using wear test apparatus. These materials are also characterized for SEM. MWCNTs-F on CF surface is observed. Sample specimens are cut from the composite sheets and the influence of performance properties like speed, load, and time on friction and wear is studied. The back ground for this research work is to identify the best configuration of materials and surface treatment method on CF for the improvement of tribological properties of friction material. The behavior of the samples is also analyzed using regression analysis L9 (3 × 3) experimental design method for three different loads, time periods, and speeds. The results reveal that braking load and time plays an important role to control the friction and wear characteristics of MWCRFM. It was also observed that MWCNT-F grafted on CF possess less wear rate and high coefficient of friction compared to other formulations of materials.