Serviceable engineering components not only rely on their bulk material properties but also on the design and characteristics of their surface.

This is especially true in wearcresistant components, as their surface must perform many engineering functions in acvariety of complex environments. The behaviour of a material is therefore greatly dependent on the surface of a material, surface contact area and the environment under which the material must operate. The surface of a metallic material is made up of a matrix of individual grains, which vary in size and bond strength depending on the means by which the material was manufactured and on the elements used to form those grains.

The surface of these components may require treatment, to enhance the surface characteristics. Surface treatments that cause microstructure changes in the bulkmaterial include heating and cooling/quenching through induction, flame, laser, and electron beam techniques, or mechanical treatments (one example is cold working). Surface treatments that alter the chemistry of a surface include carburizing, nitriding,

carbonitriding, nitrocarburizing, boriding, siliconizing, chromizing and aluminising

The surface shape or topology depends upon the process used for forming, be it moulding, casting, or cutting and abrading. As shown in figure 1.2 this is often seen microscopiically. The geometrical tecture may be characterized by it’s surface and result from three different components of surface texture (roughness, waviness and Error of form)