Abrasive wear of texture-controlled CVD α-Al2O3 coatings

In the present study the wear resistance of some CVD α-Al2O3 coatings with different growth textures, i.e. 〈0001〉, 〈101¯2〉 and 〈101¯4〉, and a κ-Al2O3 coating have been investigated using a micro-abrasion test with diamond particles as the abrasive medium. The results show that the softer κ-Al2O3 coating shows a higher wear rate as compared with the textured α-Al2O3 coatings. Of the latter coatings, the 〈101¯4〉 textured α-Al2O3 coating shows the lowest wear rate while the 〈0001〉 and 〈101¯2〉 textured α-Al2O3 coatings show similar wear rate. Two different dominant wear mechanisms, i.e. micro cutting and micro chipping, were observed and the latter mechanism is believed to control the wear rate of the Al2O3 coatings investigated. The results obtained are discussed in relation to the dominant wear mechanisms of the coatings identified using scanning electron microscopy.