Endurable Thermal Barrier Coatings

AEI was awarded a Phase II SBIR contract in February 2006 by the Department of Defense’s US Army Tank-automotive and Armaments Command for 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 (TBC) to reduce high power density diesel engine component structural temperatures and heat rejection.

AEI’s approach to advancing durability and insulating effectiveness of TBC’s is to use analysis, bench test screening and engine test verification. Analysis includes thermal-structural finite element modeling to estimate temperatures, stresses and insulating effectiveness along with test verification. Bench testing includes small-sized test coupons followed with full-sized component-like coupons to screen potential TBC systems. Engine test verification includes durability, performance and insulating effectiveness demonstrations.
 

Phase I program bench testing results identified TBC surface-coat systems that reduced radiant heat transfer up to 40 % and coating parameter optimization that improved durability by more than 300 %. Two types of surface-coat systems identified included a plasma spray coating and a post-treatment washcoat. Bench test results demonstrated that radiant heat reflective coatings are desirable while radiant heat absorbing coatings are not desirable.

The phase-II program is currently under way with full-sized component-like bench testing and engine component fabrication progressing. Specially designed thermal bench test rigs have been constructed for testing TBC’s for the piston crown, cylinder head firedeck and the engine valve combustion face applications. The bench test rigs are providing transient thermal loading to simulate engine component thermal loading conditions. Demonstration of TBC durability and insulating performance will be carried out in a high powered diesel engine. Insulating effectiveness will be determined by conducting a cooling system energy balance. Thermal insulation performance will include cylinder pressure measurement and heat release analysis to evaluate in-cylinder combustion and heat transfer performance.