NOVEL LOW-TEMPERATURE HARD COATINGS FOR LARGE PARTS

Three-dimensional substrates were coated with CrNx by sputtering and with hydrogenated W-C by magnetron sputtering combined with plasma-assisted chemical vapour deposition. Both types of coating were deposited in TriTec 750 sputtering systems. Hydrogenated metal-C coatings with a low coefficient of friction were deposited at substrate temperatures of 180-230-degrees-C using PK 500 magnetron cathodes with additional magnetic field arrays and anodes behind the substrates. The process equipment was scaled up using a modified TriTec 750 system with a maximum coating volume of 0.5 m diameter and 0.5 m height. In this system, CrNx was deposited using two interpole target magnetrons, 0.8 m long and 0.25 m wide, with anodes. The anodes minimize the electron bombardment of the substrates thereby leading to lower substrate temperatures. By the use of electromagnetic coils at the magnetron cathodes, substrate current densities of up to 6.5 mA cm-2 were achieved. For both a pulsed and a scanned d.c. operation of the coils a continuous cleaning of the target, an increased stability of the reactive deposition process and a higher target utilization were achieved. The described process and its related hardware allow the industrial deposition of hard coatings at low temperatures in large volumes up to several cubic metres using magnetron cathodes of 3 m length.