Patent attributes
A refined method to produce textured α-Al2O3 layers in a temperature range of from about 750 to about 1000° C. with a controlled texture and substantially enhanced wear resistance and toughness than the prior art is disclosed. The α-Al2O3 layer is deposited 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 being composed of short pulses and purges consisting of Ti/Al-containing pulses and oxidizing pulses. The α-Al2O3 layer according to this invention has a thickness ranging from about 1 to about 20 μm and is composed of columnar grains. The length/width ratio of the alumina grains is from about 2 to about 12, preferably from about 5 to about 8. The layer is characterized by a strong (116) growth texture, measured using XRD, and by low intensity of (012), (110), (113) (024) and diffraction peaks.
