Surface Characterization Techniques for Tribologists: Sample Preparation and Handling

摘要

Tribological properties, particularly boundary lubrication properties, strongly depend on the structure of the friction interface. The objective of surface analysis is to analyze the surface structure as "a field" where tribological phenomena occur. The surface structure under consideration is an important key for investigating reasons why problems occur and acquiring evidence explaining tribological properties. Therefore, test samples used as object of an analysis should offer a tribological field. Also, it should be noticed that under dynamic, that is, tribological, conditions, the surface generally differs from the surface existing under static, that is, analytical conditions. Consequently, a tribologist preparing a sample should know the gap between "dynamic" and "static" conditions and should take conditions of the sample preparation and the analytical objective into consideration. On the other hand, the surface structure under consideration can be roughly subdivided into physical structure and chemical structure. The physical structure includes such parameters as surface profile, thickness, hardness, layered structure, island-type structure, and so on, and the chemical structure consists of structural elements and the state of chemical bonds in the composition. A method of surface analysis should be most suitable for the analysis objective. Both method and apparatus used are discussed. In this connection, the discussion focuses on a plan of a still-better treatment of the tribological field and, in detail, on a method of handling and preparing test samples. A discussion of an analysis of tribological surfaces should include the questions "what?" and "how?" Therefore, the discussion cannot be restricted to a consideration of problems related only to the analysis. If it would be only possible, even a one-sided indication at "this is it" on the questions "what?" or "how?" will make the formulation of an object much easier and an analysis more effective. Many years experience can prompt a tribologist to answer what one should do in a certain place. On the other hand, experience is a preconception. For example, when obtaining results indicating a low coefficient of friction, the majority of tribologists would understand that MoS{sub}2 could be detected in the friction tracks and the case would probably be closed. Whether the conclusion is true and a search for a correct answer is an objective of a surface analysis. In fact, obtaining unexpected results is more interesting than any possibility. Also, such results are valuable, and it is important to consider the field of their occurrence. The authors have been engaged in surface analysis by considering tribological phenomena from a surface chemistry point of view. This is not based only on acquired experience. The most important part of is to perform experiments in surface analysis.