CERMET AND HARD METAL COATINGS FOR ADVANCED LARGE DIESEL ENGINES WITH REDUCED POLLUTANT EMISSIONS

Due to the extraordinary requirements in service and operation of high power diesel marine propulsion engines, and to the long working periods as well as harsh operation conditions, a long operation life cycle, reliability and availability must be sustained. In ship diesel engines, wear usually occurs in the top region of the cylinder liner, where the maximum mechanical and thermal load appears. Modem high pressure direct fuel injection engines (i.e. common rail and pump injector systems) in combustion with high rate turbo charging increases the combustion temperature, pressure and flame propagation. Moreover, abrasive wear mechanism occurs due to the high quantity of abrasive particles and carbon depositions on the piston surface, coming from the heavy fuels combustion and oil degradation. Therefore the thermomechanically and tribologically highly loaded top region are subjected to premature local cylinder damage. This leads to the necessity of a reinforcement of the highly loaded areas by means of advanced materials engineering. State of the art is the use of exchangeable cylinder liner top rings made from hardened steel, placed on the highly loaded areas. This solution has the disadvantage that two different components and materials are used, leading to a reduced heat transfer and elaborate construction and assembly. At the IMTCCC, together with the leading Spanish marine engine manufacturer IZAR, an investigation is being developed, in order to obtain a carbon deposition reducing coating insert by means of HVOF thermal spray techniques.