PVD Al2O3 coated cutting tool

Abstract

The present invention describes a coated cutting tool for metal machining. The coating is formed by one or more layers of refractory compounds of which at least one layer of fine-grained, crystalline γ-phase alumina, Al2O3, with a grainsize less than 0.1 μm. The Al2O3 layer is deposited with a bipolar pulsed DMS technique (Dual Magnetron Sputtering) at substrate temperatures in the range 450° C. to 700° C. preferably 550° C. to 650° C., depending on the particular material of the tool body to be coated. Identification of the γ-phase alumina is made by X-ray diffraction. Reflexes from the (400) and (440) planes occurring at the 2θ0- angles 45.8 and 66.8 degrees when using CuKα radiation identify the γ-phase Al2O3. The alumina layer is also very strongly textured in the [440]-direction. The Al2O3 layer is virtually free of cracks and halogen impurities. Furthermore, the Al2O3 layer gives the cutting edge of the tool an extremely smooth surface finish.

Dependencies are inferred from the claim text.