Comparison of surface properties of Ti/TiN, Cr/CrN and CrN/TiN nanolayer coatings applied by CA-PVD method on 304 stainless steel substrates

نوع: Type: thesis

مقطع: Segment: masters

عنوان: Title: Comparison of surface properties of Ti/TiN, Cr/CrN and CrN/TiN nanolayer coatings applied by CA-PVD method on 304 stainless steel substrates

ارائه دهنده: Provider: Mohammad-Rashed Mohammadi

اساتید راهنما: Supervisors: Dr. Hasan Elmkhah

اساتید مشاور: Advisory Professors: Dr. Arash Fattah-alhosseini

اساتید ممتحن یا داور: Examining professors or referees: Dr. Omid Imantalab & Dr. Damavandi

زمان و تاریخ ارائه: Time and date of presentation: 2023/10/14

مکان ارائه: Place of presentation: Room 10

چکیده: Abstract: The aim of this research is to investigate and compare the surface, mechanical, wear and corrosion properties of Ti/TiN, Cr/CrN and CrN/TiN nanostructured multilayer coatings applied by CA-PVD method on 304 stainless steel substrates. Surface engineering technology improves the surface properties, mechanical, abrasion and corrosion of parts and on the other hand, by applying expensive coatings on the surface of cheaper materials¬, increases the economic efficiency of production units¬. The correct choice of coating based on its unique properties, according to the working conditions of the target part, can largely prevent the damage caused by the destruction of the part in the industry. In this research, scanning electron microscope and XRD machine were used for microstructural characterization. The roughness, wettability and adhesive properties of the samples were measured and their hardness was compared with each other. Wear behavior was evaluated in two dry environments (air) and 3.5 wt% sodium chloride (NaCl 3.5 wt%) and their corrosion resistance in 3.5 wt% sodium chloride solution was compared. According to the scanning electron microscopic images, all three coatings showed a dense structure. From the XRD results, it was found that the CrN/TiN coating has an FCC structure, in the Ti/TiN coating, the Ti layer has a hexagonal compact structure (HCP) and the TiN layer has an FCC structure, and in the Cr/CrN coating, the Cr layer has a BCC structure and the CrN nitride layer has FCC structure. In the roughness test, the values of Ra and Rz for the CrN/TiN coating are 0.401 and 3.509, for the Ti/TiN coating the values are 0.624 and 4.300, for the Cr/CrN coating the values are 0.477 and 3.132 and for the substrate they showed values of 0.036 and 0.274. The wetting angle was obtained for Ti/TiN, Cr/CrN and CrN/TiN coatings and the substrate, respectively, 87.88, 81.97, 64.48 and 41.20 degrees, and the almost hydrophobic properties for Ti /TiN and Cr/CrN were shown. Adhesion was evaluated by Rockwell-C indentation and excellent adhesion to the substrate was observed for all three coatings. Cohesion for Cr/CrN coating in Rockwell-C indentation test was lower than the other two coatings, which caused more wear of this coating in the wear test. The hardness of the Ti/TiN, Cr/CrN and CrN/TiN samples and the substrate was 1888.45, 2454.55, 2118.33 and 198 Vickers, respectively. The coefficient of friction in both air and sodium chloride environments was the lowest for Cr/CrN coating compared to the other two coatings, but in the environment of sodium chloride, the substrate had the lowest friction coefficient. Ti/TiN coating in dry environment and CrN/TiN coating in sodium chloride environment had the highest wear resistance. The best corrosion resistance was also observed for Cr/CrN coating with the lowest corrosion current density. All three coatings increased the wear and corrosion resistance of the substrate

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