Novel applications of CrN (PVD) coatings deposited at 200 °C

Abstract

CrN (PVD) coatings, deposited at 200 °C in plasma beam sputtering apparatus, were used for selected applications in industry. Using CrN coating, we improved two types of tool: moulds for Al alloy die casting (made of AISI H11 tool steel) and cold forming tools (made of AISI D2 and D3 tool steel). For the first group of tools, it was important that the CrN coating could be successfully used as a hard, oxidation- and corrosion-resistant coating at working temperatures of up to 800 °C; for the second group of tools, the low tempering temperature dictates deposition at 200 °C. The tool life, surface quality of the products and wear mechanisms were studied for the following polished tools (max. diameter, 210 mm): a mould for Al-Si12 die casting of small components of compressors; a combined cold forming and cutting die for mass production of covers for the heating plate of an electric stove; a cold forming deep drawing die for the production of a halogen lamp housing in the electric light industry; a tool set for automatic gradual deep drawing of fancy goods for the shoe and leather industry; a deep drawing die for mass production of the covers of electric motors. All the results show that a CrN coating 4.5–5.5 μm thick with a Cr intermediate layer 0.2 μm thick between the substrate and the coating improved the technological processes and resulted in a noticeable improvement in performance tests. Increased tool life, a higher quality of surface finish of the products and high reliability of CrN coated tools in production were regularly observed during long-term performance tests.