Suspension plasma sprayed thermal barrier coatings for diesel engines applications

Depleting fossil fuel resources and environmental concerns have compelled to explore new avenues to improve the efficiency of automotive engines. One of the most attractive solutions for decreasing heat losses from the engine and increasing its efficiency is by insulating the hot components of the engines with protective coatings. Thermal Barrier Coatings (TBCs) are highly attractive due to their excellent physical and mechanical properties at elevated temperatures. However, beside low thermal conductivity it seems that other thermal properties as well as the coatings morphology, microstructure, and thickness are equally important. In this study, several TBCs were sprayed and investigated to assess their suitability for diesel engine applications. Suspension Plasma Spraying (SPS) was used to produce different morphologies and layered structures. Microstructure evaluation was done by SEM and coating porosity was measured by both Image Analysis and Water Impregnation. The thermal properties were determined by Differential Scanning Calorimetry and Laser Flash Analysis. The main results are discussed in correlation with their functional properties and the best coatings structure is proposed.