Tribological Study of TiN Nano Structured Films Deposited on Plasma Nitrided H11 Steel by Pulsed DC PACVD

Abstract

In recent years, plasma-assisted chemical vapor deposition (PACVD) has been introduced as a suitable technique to deposit hard coatings on to tools of complex geometries. This study focuses on the influence of process parameters during plasma nitriding and TiN coatings, such as duty cycle, treatment time and temperature parameters on the properties of nanostructured binary layers. To improve performance and the quality of the samples, a duplex process combining a plasma nitriding (PN) pre-treatment and a plasma-assisted chemical vapour deposition (PACVD) was applied on the steel surface. A mixture of H2, N2, Ar and TiCl4 was used to deposit a thin film of TiN on H11 steel. The microstructural, mechanical and tribological properties of the coating were investigated using X-Ray diffraction, scanning electron microscopy, atomic force microscopy combined with nanoindentation and pin-on-disc measurements. The results indicate that the small grain size was obtained at low duty cycle (33%) and increased with increasing of the duty cycle to 60 %. Calculated roughness of surface for duty cycle 50 % was 72 nm.