Structural and Mechanical Characterization of Duplex Multilayer Coatings Deposited onto H13 Tool Steel

Abstract

Quenched and tempered H13 tool steel was plasma nitrided and Physical Vapour Deposition (PVD) coated in a hybrid reactor aiming to obtain a TiN/TiC multilayer coating deposited on a plasma nitrided substrate, with a more gentle transition of elastic-plastic properties between the outermost layer of the coating and the substrate. Duplex treatment (plasma nitriding and PVD coating) was carried out in a hybrid reactor. Plasma nitriding preceded the DC triode magnetron sputtering PVD process, conducted inside the same chamber, using CH 4 and N 2 as reactive gases. Multilayer TiN/TiC coatings deposited on a nitrided H13 substrate were obtained. The multilayer coating was composed by a first Ti interlayer to grant adhesion, followed by a second 18.4 at% C TiC layer with a cF8 NaCl type unit cell, then a 41.9 at% N TiN layer and finally an outermost 32.3 at% C TiC layer with the same cF8 NaCl type unit cell. The multilayer coating showed a gentle transition of elastic-plastic properties assessed by the H/E * and the H 3 /E *2 ratios and the elastic recovery as a function of the distance from the surface of the specimen. The adhesion of the multilayered coating to the substrate was greater in the case of the duplex coated specimen as compared to the non duplex treated H13 steel.