Advantages for automotive industry of plasma spray coating of Ai–Si cast alloy cylinder bores

Abstract

In the automotive industry the need for lower manufacturing costs, the use of fewer strategic materials, andthe need for easier, faster, and more environmentally sound coating processes is growing. This has led to the examination of a plasma powder spray process used in the application of coatings for surface modification. The present paper examines the use of the plasma powder spray process in coating aluminium-silicon cylinder block bores using a rotating plasma gun capable of producing coatings of reliable microstructure and integrity. Properties and microstructures of the applied coatings are presented and test results show that the necessary bond strength of the coating can be achieved without the use of a bond coat. Surface preparation before coating and surface finishing methods after coating are also discussed. Experience in Europe, Japan, and the USA shows that the plasma powder spray process offers a performance proven and cost effective solution for the coating of cylinder bores.