METHOD FOR COATING SUBSTRATES WITH ALUMINUM OXIDE (Al 2?O 3?) AND COATING A WORK PIECE USING SAID METHOD

摘要

A substrate is coated with at least partially crystalline aluminum oxide by hollow cathode gas flow sputtering at 400-1000 deg C exclusive. An Independent claim is also included for a tool or workpiece which is completely or partially coated by the above process. Preferred Features: The coating temperature is less than 900 (especially less than 600) deg C, the atmosphere comprises argon containing 0.5-2% oxygen, the pressure is 0.1-10 hPa, the hollow cathode (20) is spaced by 1-10 cm from the substrate (10) and the substrate (10) is negatively biased at 10-1200 V by connection to a direct voltage source, a bipolar pulsed source or a medium or high frequency source.