Microscopic Characteristics and Mechanical Properties of Plasma Sprayed Al₂O₃ Coatings

This study investigates microscale features in plasma sprayed alumina and how they correlate with mechanical property differences at the macroscale. Thick alumina coatings were deposited on aluminum and titanium substrates by atmospheric and low-pressure plasma spraying using α-Al₂O₃ powder as the feedstock. Coating surfaces and cross-sections were examined by FE-SEM, phase distributions were identified by means of EBSD, and porosity was measured via image analysis. Mechanical properties at the micro and macroscale were assessed by nanoindentation, Vickers hardness, and cavitation erosion testing. Relevant test results and observations are presented and discussed in the paper.