ABSTRACT
Wear generates debris. The debris comes in a wide variety of sizes and shapes. Wear debris turns motor oil black. You can see it on your hands if you shake hands with your garage mechanic. The black in used oil is like a pigment — it is nanometer-size colloidal metal particles (and carbon) suspended in the oil. If you take an oil filter apart, you will find other types of wear debris. Some are shiny metal particles visible to the naked eye and in the millimeter size category. If you are in the surface mining business, you will find even larger metal particles in the gravel produced by rock crushers. This is metal that is gouged from the metal jaws in the crusher. In a factory grinding room, dust swept up from the floor and examined in a scanning electron microscope will show perfect micron-size metal spheres from rapidly solidifying drops of molten metal generated by the grinding wheel. Examples of these unique debris particles will be found later in this chapter.
