System, material, and coating considerations for diesel engine TBCs

Thermal barrier coatings (TBCs) have seen widespread use in gas turbines and powder generation equipment, but have seen a much more limited adoption in automotive applications, specifically diesel engines. Initial developments 20 to 30 years ago were never fully realized, but are coming back into the fold. One recent parameter used to evaluate the behavior of these coatings is thermal inertia, which can be used to evaluate the coatings ability to manage thermal loads – both as an insulating material and as a material with low heat capacity. This allows for a large operational "thermal swing" to occur in the engine, which is critical for maintaining cycle efficiency while benefiting from the coating insulating. Variations in thermal inertia can be controlled by air plasma spray (APS) processing, which will be discussed in light of their potential use in diesel engines.