Development of Endurable Thermal Barrier Coatings for Diesel Engine Specific Heat Reduction

The U. S. Army has a need for reliable and durable in-cylinder thermal barrier coatings to reduce high power density diesel engine component structural temperatures and heat rejection. Phase I program bench testing results identified thermal barrier coating topcoat systems that reduced radiant heat transfer by 40 % and improved durability by more than 100 %. Two types of topcoat systems that were identified included a plasma sprayed system and a post-treatment slurry system. Bench test results demonstrated that radiant heat reflective coatings are desirable while radiant heat absorbing coatings are not desirable. It is proposed that further development of advanced top-coated thermal barrier coating systems will proceed by continuing to optimize the substrate plasma sprayed coating and topcoat processes while using bench test coupons that simulate the actual engine components to determine coating durability performance. Specially designed thermal bench test rigs will be constructed for testing thermal barrier coatings for the piston crown, cylinder head firedeck and the engine valve face. The bench test rigs will provide transient thermal loading to approach the engine component thermal loading conditions. Demonstration of thermal barrier coating durability and insulating performance will be performed on a high powered diesel engine.