Scratch testing of nanocrystalline alumina+titania+zirconia

This work examines nanocrystalline thermal spray coatings prepared under several power and stand off distances. The coating material was nanocrystalline alumina + titania and zirconia (ATZ) powder mixture deposited using an air plasma spray process. The experimental design employs a full factorial method totaling four samples. The mechanical properties of four coatings were compared via scratch and hardness testing. The scratching process was monitored for transverse loads during the test and the variation in load monitored. The profiles of scratches were analyzed using white light interference profilometry and studied further via SEM. The results indicate that the microstructure reflected features observed in the scratch test. It was also shown that the scratch process and morphology depend on the normal load and spray process