Verfahren zur Beschichtung von Substraten mit Aluminiumoxid (Al2O3) und damit beschichtetes Werkstueck

NOVELTY - A substrate is coated with at least partially crystalline aluminum oxide by hollow cathode gas flow sputtering at 400-1000 deg. C exclusive. DETAILED DESCRIPTION - 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. USE - For coating tools and workpieces with hard, insulating, wear resistant aluminum oxide layers for various applications, e.g. as dielectrics or wear protection and friction reducing layers. ADVANTAGE - The hollow cathode gas flow sputtering process permits efficient deposition of high q uality aluminum oxide coatings at least partially in the alpha crystalline phase form, is carried out at relatively low temperature so that tool steel, insulator and glass substrates can be effectively coated, is much less expensive than pulsed sputtering processes, provides a high deposition rate of up to 50 or even up to 100 mu m/hr., allows coating of small substrates or substrates with tips and allows embedding of sensors or sensor layers during coating. DESCRIPTION OF DRAWING(S) - The drawing shows a schematic view of a suitable hollow cathode gas flow sputtering unit. Substrate 10 Heater 12 Hollow cathode arrangement 20 Argon flow 22 Reactive gas (oxygen) 25 Shutter 2