Ultramicrotomy: a novel technique for preparing wear-debris samples for TEM analysis

摘要

During sliding contact, chemical reactions can occur on the mating surfaces. The products of such tribochemical reactions usually are manifested as wear surface films and as wear debris. Characterization of the wear debris is therefore crucial to the understanding of the wear mechanisms. The quantity of wear debris generated from wear-resistant or self-lubricating materials is often insufficient for analysis by conventional techniques. In such instances, transmission electron microscopy (TEM) is ideally suited for wear-debris analysis. Previous authors have employed an extraction replica technique to prepare wear-debris samples for TEM analysis [1,2], This technique involves pressing a piece of softened acetate tape on to the debris. After the tape has hardened, it is stripped from the surface, coated with carbon, and placed on a TEM grid. When the tape is dissolved in acetone, the debris will be left behind in the carbon film. Others have collected the debris by placing a holey carbon-coated TEM grid directly on the wear scar [3], In this technique, the debris sticks to carbon by Van der Waals forces. However, both techniques usually produce insufficient quantities of electron-transparent material. The objective of the current investigation was to examine the feasibility of preparing TEM samples of wear debris by ultramicrotomy, a technique commonly employed for biological samples, but which recently has been used in materials science [4].