Ceramic and Cermet Coatings for Cylinder Liner in Ultra Light Weight Engines - Novel Processing and Manufacturing of Ceramic Layer Composites

Abstract

Actual requirements in the automotive industry are the reduction of fuel consumption and pollution emission, engine efficiency improvement, as well as cost reduction. Most of these requirements are fulfilled by reducing the total weight of the vehicle. This results in an increasing utilization of light metal components for engine applications. Significant weight savings are obtained by changing the engine block material from cast iron to aluminum or even to magnesium aluminum hybrid constructions. Despite of all advantages the industrial implementation of light metals is often inhibited by their poor surface properties especially concerning wear and tribological behavior. Due to the highly loaded operation conditions a cylinder liner surface reinforcement is necessary. A very promising technological alternative is the internal cylinder reinforcement by using HVOF (high velocity oxygen fuel) sprayed coatings. By using these advanced high energetic coating technologies, material combinations containing solid lubricant ceramic dispersions can be deposited. The thermal spray processes represent a cost effective and flexible solution for ultra light weight engine technology. This research is focused on the development of HVOF sprayed coating systems for cylinder liners, the coating optimization and the cost effective implementation of this hypersonic spray technology in a series production process. It will be shown that cast engine block bores can be directly coated by using an automated HVOF process, obtaining improved coating results. The internal coating process by hypersonic flame spraying is a superior technological alternative to the APS process for high quality cylinder liner and engine crankcase applications.