Ceramic Composite Applications in Diesel Engines — Experiences and Chances

Abstract

Ceramic matrix composite (CMC) material produced by the French company SEP has been applied in a Diesel engine. Hot components in cylinders have been developed to protect metallic components from high thermal loads. A cylinder head plate, a piston cap and a section of the cylinder liner have been designed, produced and mounted. The valves were covered with a 2 mm layer of flame sprayed zirconia. The performance of the SiC/SiC composite material in test runs was good. The head plate and the cylinder liner insert survived more than 200 hours at the full engine load (about 220 kW at 2000 rpm) without problems. Only the more complex piston component did not achieve satisfactory life times during tests.

With respect to engine performance only small effects on exhaust gas temperature and its pollutants could be observed. The engine efficiency was practically unchanged by the ceramic material. The thermal protection of hot metal components could be demonstrated; the temperature of the valve seats was reduced by about 50 K. Considering the limited benefits, which could be verified in this EUREKA-programme, it seems that high quality ceramics like CMC will have difficulties to be introduced as a structural component in an industrial mass product like a Diesel engine. Material costs itself and extensive work still necessary for the industrialization are the key problems. It is more likely that small ceramic parts, which locally fulfill a well defined function, will succeed first.