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US 7,442,432 B2Granted
Alumina layer with controlled texture
AssigneeSeco Tools AB
InventorSakari Ruppi
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AssigneeSeco Tools AB
InventorSakari Ruppi
Estimating the term…
A new and refined method to produce α-Al2O3 layers in a temperature range of from about 750 to about 1000° C. with a controlled growth texture and substantially enhanced wear resistance and toughness than the prior art is disclosed. The α-Al2O3 layer of the present invention 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 being composed of short pulses and purges consisting of Ti/Al-containing pulses and oxidising pulses. The α-Al2O3 layer according to the present 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 4 to about 8. The layer is characterized by a strong (104) growth texture, measured using XRD, and by low intensity of (012), (110), (113), (024) and (116) diffraction peaks.
Cutting tool insert comprising a substrate at least partially coated with a coating with a total thickness of from about 10 to about 40 μm of one or more refractory layers of which at least one layer is an alumina layer, said alumina layer being composed of columnar α-Al2O3 grains with texture coefficients
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