Chapter 5 - Surface Composites by FSP

Abstract

Surface engineering is becoming increasingly important for engineering components which involve surface interactions. The surface of such components is either protected, for example by protective coatings, or modified in a manner that suits the interactions at the surface. Surface hardening of components that are subjected to friction and consequent wear is a common industrial practice. While there are many surface hardening techniques in use they have their own limitations. Surface composites have been emerging as an attractive way to enhance the surface hardness and protect it against wear and tear. Friction stir processing (FSP) has emerged as an effective technique for surface modification and hardening. The technique also allows incorporation of hard ceramic reinforcement into the modified surface to further enhance the hardness. This chapter will deal with such surface composites made by FSP. It should be however, remembered that unless otherwise mentioned specifically, the distinction between surface and bulk composites made by FSP is not absolute and depends on how one perceives the depth to which particles are distributed and the intended application. The processing approaches for making bulk and surface composite by FSP, therefore, also remain the same. These approaches are detailed in Chapter 3, Processing Metal Matrix Composite (MMC) by FSP, and hence, the processing methods of surface composites will be briefly described here.