Characterization of the Microstructure of Stabilized Zirconia Used on Diesel-Engine Components

摘要

Stabilized ZrO sub 2 coatings have lowered the metal temperature and protected the coated parts against corrosion and thermal load. A coated valve compared to an uncoated one shows up to 50 exp 0 C less metal temperature at normal load. The tested piston (3000 h) does not show any areas of ceramic coating loss at all, but the valve shows loss of a part of the ceramic coating in an area in the center of the valve plate after 500 h. This area corresponds to the diameter of the valve stem and may be due to the temperature distribution. Metallographic examination showed no base metal deterioration. This demonstrated that local coating loss will not necessarily result in damage to metal components. Results have shown that consideration should be given to improve the spraying technique, tailored coating and graded layers regarding temperature stresses in the base metal. It is also believed that a treatment after the coating process will be of advantage. (ERA citation 07:004746)