| 摘要 |
The present invention describes a coated cutting tool for metal machining. The coating is composed of one or more layers of refractory compounds of which at least one layer consists of fine-grained, crystalline gamma -phase alumina, Al2O3, with a grainsize less than 0.1 mu m. The Al2O3-layer is deposited with a bipolar pulsed DMS technique (Dual Magnetron Sputtering) at substrate temperatures in the range 450 DEG C to 700 DEG C, preferably 550 DEG C to 650 DEG C, depending on the particular material of the tool body to be coated. Identification of the gamma -phase alumina is made by X-ray diffraction. Reflexes from the (400) and (440) planes occurring at the 2θ-angles 45.8 and 66.8 degrees when using CuK alpha radiation identify the gamma -phase Al2O3. The alumina layer is also very strongly textured in the Ä440Ü-direction. In contrast to prior art, the Al2O3-layer is virtually free of cracks and halogen impurities and, furthermore, the Al2O3-layer gives the cutting edge of the tool an extremely smooth surface finish which compared to prior art alpha -Al2O3 coated tools, results in an improved surface finish also of the workpiece being machined, and when coated cemented carbide cutting tools according to the invention are used in the machining of steel or cast iron, several important improvements compared to prior art have been observed. <IMAGE> |
