Plasma sprayed SiC/Al2O3-8YSZ coatings for high-temperature protection of forging aluminum alloy during ablation

摘要

Nanostructured Al2O3-8YSZ-SiC coatings were successfully fabricated on the forging aluminum alloy by atmospheric plasma spraying using as-prepared nanostructured feedstocks in this paper. The ablation tests for aluminum alloy with and without coatings were carried out using a Metco 9MB plasma gun. The microstructure. phase composition and ablative property (failure lifetime) of the samples before and after ablation were investigated by scanning electron microscope (SEM), X-Ray diffractometer (XRD) and plasma gun. The surface morphologies, cross section and phase compositions of samples with coatings before ablation failure are similar. The failure mode of ceramic coatings after ablation is the generation-propagation of vertical cracks and the intercross of the cracks on orientation of vertical and horizontal. The mud pack pattern in cross section is the typical thermal corrosion morphology for substrate without coatings. The destruction form of substrate with coatings is brittle fracture mildly or plastic deformation. The surface coatings are found to serve as protective coatings in the ablation process.