| Abstract: | Many of the insolubles that occur in automotive and industrial lubricating oils are contaminants originating from the machinery being lubricated or the products of combustion. However, some are deliberately introduced by the manufacturer to improve the performance of the lubricant. Many insolubles are too small to be usefully examined in the optical microscope; the greater resolving power of the electron microscope is needed in order to image them. Mineral oil is however one of the most serious contaminants of the electron microscope vacuum and has necessitated the adaptation of existing preparation techniques or the development of new ones in order to image at high magnification the wide variety of insolubles that are present in many modern lubricants. In this report, we describe and illustrate a range of techniques which permits the imaging, spatial distribution and, in some cases, the size distribution of the particles to be obtained. |
