Wear properties of MOCVD-grown aluminium oxide films studied by cavitation erosion experiments

Thin aluminium oxide films are of interest due to many technical applications, such as hard coating, electrical insulator, or antireflective coating. It is obvious for such applications that the used films should have a good contact with the substrate underneath, be well adhering and be mechanically resistant. Therefore, cavitation experiments according to the ASTM G32-92 standard were now used to study the adhesion and wear resistance of CVD-grown aluminium oxide films. It is shown that amorphous alumina films (0.75 μm thick) which are grown in a hot wall reactor on steel are enduring the cavitation erosion better than the clean and uncovered steel, and are thus very promising for technical applications. After 30 min cavitation, no damages are observed on the coated samples by SEM while uncoated steel is clearly damaged. After 180 min, the mass loss of the specimen caused by cavitation erosion is more than 7 times lower than the one of coated steel.