Wear characteristics of castings used in internalcombustion engines

Abstract

Castings have been and will continue to be used widely for applications involving wear in the internal-combustion engine. There is, however, a trend towards more sophisticated requirements as the demands on critical components increase. These demands particularly require the use of components with low friction, long wear life, greater temperature stability, and, wherever possible, reduced weight. Light alloys, suitably reinforced and/or surface treated, will become more widely used. However, more traditional materials, including cast iron and steel, will find widespread use for many years, particularly as more durable surface treatments become widely used. Available evidence indicates that surface treatments are used more widely in Europe and Japan than in the UK. Wear occurs by a number of different mechanisms, each of which requires a separate countermeasure. The conditions in the engine are such that, on occasions, a number of different wear mechanisms occur simultaneously, and these may combine with corrosion, which is stimulated by the lubricant and the combustion products. It is important, therefore, to optimize the compositions and microstructures of the castings to produce optimum values of the mechanical and thermal properties which result from them. As the choice of materials increases, it is essential that the solutions to economic requirements do not jeopardize the attainment of the required technical properties. The casting industry has been at the forefront in the development of improved pistons, rings, liners, camshafts, and tappets; to remain in this position, it must keep abreast of the developments taking place in surface treatment and reinforcement in order to achieve the properties required for the 1980s and beyond.