Thermomechanical fatigue characterization of zirconia (8y2o3- zro2) and mullite thermal barrier coatings on diesel engine components: effect of coatings on engine performance

摘要

8%Y2O3-stabilized zirconia (8YPSZ) and mullite (3Al2o3-2Sio2) powders, which were made plasma sprayable by using an organic binder (polyvinyl alcohol), have been plasma spray coated on to the piston head, values and cylinder head of a 3.8KW single-cylinder diesel engine, previously coated with Ni-Cr-Al-Y bond coat. The engine with components coated with 250 um thick 8YPSZ and 1 mm thick mullite thermal barrier coatings has been evaluated for fuel efficiency and for endurance during 500h long rigorous tests. Improved fuel efficiency was shown by the engine with coated components and the results are discussed. The coatings and the coated components have also been examined for phrases, microstructure and chemical composition by X-ray diffractometry (XRD), scanning electron microscopy (SEM) and energy dispersive X-ray analysis (EDAX). Mullite coatings were found to exhibit increased resistance to microcracking with 8YPSZ during the 500 h endurance test.