Wear, Tribology, Surface Treatment And Coatings

INTRODUCTION

The quality of most metal products based on the condition of their surface and on surface deterioration because ofuse. Surface deterioration is also significant in engineering practice, it is often the major factor limiting the life and the performance of machine components.

The detachment and displacement of metallic particles from a metallic surface might be caused by contact with
1.    another metal (metallic wear or adhesive),
2.    a metallic or a non-metallic abrasive (abrasion), or
3.    Moving liquids or gases (erosion). Generally, Erosion is accompanied by some form of corrosion. The above three types of wears might be subdivided into wear under rolling friction or sliding friction and, further, according to whether lubrication can or cannot be used.

Wear involving a single type is rare, and in most cases both abrasive and adhesive wear occur. Each form of wear is influenced by a variety of conditions including environment, type of loading, relative speeds of hardness, mating parts, temperature, lubricants, surface finish, presence of foreign particles, and compatibility and composition of the mating parts involved. Since in most of the machinery applications wear might rarely be avoided completely even with the best lubrication it is common practice to use a hard metal and a relatively soft one together. The soft material is utilized (as a bearing) for the part which is most economical to replace.