Semi-metallic Brake Friction Materials Containing ZrSiO4: Friction Performance and Friction Layers Evaluation

Abstract

The effect of ZrSiO 4 (zircon) content on friction performance and friction surfaces of semimetallic brake friction materials is discussed. The experimental results indicate that the varying content of zircon affects the friction performance as well as plays crucial role in the iron film formation on the friction surfaces. The friction layers, formed during friction process, were carefully characterized using scanning electron microscopy with energy dispersive X-ray microanalysis, and X-ray diffraction methods. The phenomenon of two different types of iron film formation (film I and film II) on the friction surfaces is proposed and their formation and destruction mechanism is described. Despite the compositions of both iron films being similar, film I is formed by steel wool itself and film II by the debris from either disc or steel wool. The relationships among formulation, friction performance, and friction surfaces are summarized.