Wear-Related Topography of Ion-Bombarded Surfaces

Experimental data on surface topographical properties are presented for case-hardened materials which had been nitrided by both the glow discharge and ammonia gas processes. Included are the effects of growth, sputtering, nitriding exposure time, and initial surface conditions. Digital encoding equipment has been built to gather and store the large quantity of profilometer data needed to describe surface properties, for subsequent computer analysis. Results are given of these analyses, yielding parameters such as peak densities and radii, and composite indices derived from these parameters, governing lubrication regime, type of asperital deformation, and microcontact area and density. The data show that both nitriding time and initial roughness are significant in determining the relative merits of the final surfaces for friction and wear. Examples are also given of scanning electron microscope photographs of the same surfaces, revealing a texture beyond the resolving power of a profilometer. This is not expected to exercise a major influence on wear characteristics.