حسن علم خواه

The purpose of this study is to investigate the microstructure and surface properties of titanium-aluminum nitride (TiAlN) nanostructured coatings produced at different deposition temperatures. The TiAlN nanostructured coatings were deposited on nitrided hot-work tool steel (H11) using pulsed direct current plasma assisted chemical vapor deposition method (DCPACVD). The coatings were produced under the same conditions such as duty cycle, frequency and H2/Ar/N2 gas ratio at 33%, 10 kHz and 400/150/50 sccm, respectively. Also the specimens were deposited at temperatures of 470, 485, 500 and 515 °C by PACVD method. TiN coating interlayer was used to improve the adhesion strength of TiAlN coatings to the substrate. FESEM, SEM and XRD devices were used to characterize the coatings and Vickers micro-hardness and scratch test were used to evaluate the mechanical properties and adhesion strength of the coatings. The results indicated that the maximum hardness of TiAlN coating produced at 485 °C. It is attributed to various factors such as lattice parameter, crystallite size and amount of chlorine in the chemical composition of the coating. Also, due to the formation of a nanoscalethin layer of Fe4N at the interface between the coating and the substrate at the temperatures above 500 °C, the adhesion strength of the TiAlN coating reduces. By quantitative evaluation of the adhesion of the coatings, it was found that the coating formed at the temperature of 485 °C withstands the maximum critical load (23 N) of the scratch