The effect of post-deposition annealing treatment on the electrochemical and tribological behavior of multilayer CrN/CrAlN coating deposited by a physical vapor deposition method

نوع: Type: thesis

مقطع: Segment: PHD

عنوان: Title: The effect of post-deposition annealing treatment on the electrochemical and tribological behavior of multilayer CrN/CrAlN coating deposited by a physical vapor deposition method

ارائه دهنده: Provider: Yemurai Vengesa

اساتید راهنما: Supervisors: Dr. Arash Fattah-Alhossieni

اساتید مشاور: Advisory Professors: Dr. Hassan Elmkhah, Dr. Omid Imantalab

اساتید ممتحن یا داور: Examining professors or referees: Dr. Massoud Atapour, Dr. Kourosh Jafarzadeh

زمان و تاریخ ارائه: Time and date of presentation: Wednesday 1july 2022 at 2pm

مکان ارائه: Place of presentation: Amphitheater

چکیده: Abstract: Cathodic arc evaporated coatings contain residual stress due to the difference in the thermal coefficient between the substrate and the coating. Furthermore, the coating also contains defects such as pinholes and macroparticles which can be detrimental to the mechanical, tribological, and electrochemical properties of the deposited coatings. Post-deposition annealing has been proven to improve the properties of the material due to its ability to reduce residual stress and defects. The study aims to find the optimal annealing temperature for CrN/CrAlN coating and also evaluate the effect of annealing on the phases, hardness, wear, and corrosion. In this study, CrN/CrAlN multilayer coating was deposition AISI 304 substrates using the cathodic arc evaporation physical vapor deposition method (CAE-PVD). Thereafter, the samples were annealed in a vacuum furnace at 400, 500, 600, and 700 ℃. Characterization techniques were used to evaluate the effect of annealing on the mechanical properties, tribological behavior, and electrochemical properties of CrN/CrAlN multilayer coating. X-ray diffraction (XRD) was used to identify the phases, texture coefficient, and crystallite sizes. A scanning electron microscope (SEM) was used to analyze the surface morphology and also used to analyze the cross-section morphology. Energy Dispersive X-Ray Analysis (EDX) was utilized to analyze the elementary composition of the coating. An atomic force microscope (AFM) was used to analyze the surface topography and the roughness of the coating. The contact angle technique was used to evaluate the wettability of the coating. Rockwell-C adhesion test was used to evaluate the quality of the adhesion between the coating and the substrate. Nanoindentation test was used to investigate the evolution of the mechanical properties of the coating. The wear rate and wear morphology were characterized using a ball-on disk tribometer in ambient air and Ringer's solution. The electrochemical properties of the coating were investigated using electrochemical impedance spectroscopy (EIS). The results indicated that with increasing post-deposition annealing treatment temperature a hexagonal Cr2N phase increased. The residual stress decreased from -398 MPa to -218 MPa. Moreover, annealing resulted in the coalescence of macroparticles. The results indicated that the surface roughness increased as the annealing temperature increased due to the coalescence of microparticles. In addition, the wettability of the annealed samples decreased as the annealing temperature increased due to the increase in the roughness and Cr2N phase. The quality of the adhesion was satisfactory (HF1-HF2). The hardness decreased from 19 to 17 GPa and was attributed to the increase in crystallite size and the decrease in the residual stress as the annealing temperature increased from room temperature to 700 ºC. The sample annealed at 400 ℃ had the lowest wear rate in ambient air and Ringer's solution of 6.43×10-5 and 3.04×10-5 mm 3 /Nm, respectively due to optimum ratio of CrN and Cr2N, minimum crystallite growth, and optimum adhesion strength. Based on the EIS results, the sample annealed at 700 ºC had the highest corrosion resistance in Ringer's and 3.5 wt % NaCl among the annealed sample, with polarization resistance of 39 and 33 MΩ.cm2 which can be attributed to the existence of Cr2N, and the increase in the crystallite size of the multilayer coating. These results suggest that annealing can improve the properties and performance of CrN/CrAlN coating

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