Patent attributes
A refined method to produce textured α-Al2O3 layers in a temperature range of 750-1000° C. with a controlled texture and substantially enhanced wear resistance and toughness than the prior art is disclosed. The α-Al2O3 layer is formed on a bonding layer of (Ti,Al)(C,O,N) with increasing aluminium content towards the outer surface. Nucleation of α-Al2O3 is obtained through a nucleation step composed of short pulses and purges of Ti-containing and oxidizing steps. The α-Al2O3 layer has a thickness ranging from 1 to 20 μm and is composed of columnar grains. The length/width ratio of the alumina grains is from 2 to 15, preferably 6 to 10. The layer is characterized by a strong (110) growth texture, measured using XRD, and by the low intensity of (012), (104), (113), (024) and (116) diffraction peaks.
