hassan elmkhah

This paper aims to study the tribological and electrochemical properties of the CrN/AlCrN nano-layer deposited on H13 tool steel. Arc physical technique was employed to deposit multilayer coating. X-ray diffraction technique, thermionic and field emission scanning electron microscopy and energy dispersive spectroscopy have been used to determine the characteristics of the samples. To study the samples' wear behavior, coating adhesion, and surface hardness, reciprocating wear test, Rockwell-C test, and microhardness Vickers tester were employed, respectively. The measured values of the coefficient of friction and the calculated wear rates showed that the CrN/AlCrN multilayer coating has a much higher wear resistance than the uncoated sample. The coefficient of the friction of the coated sample was 0.53 and that of the uncoated sample was 0.78. Moreover, the wear rate of the coated H13 steel was about 127 times lower than the bare H13 steel sample. The results obtained from electrochemical impedance spectroscopy and polarization tests demonstrated that the corrosion current density of the H13 steel sample was 8 μA/cm2 and that of the CrN/AlCrN multilayer-coated sample was 3 μA/cm2. In addition, the polarization resistance of the treated and the substrate specimens was estimated at 4.2 and 2.7 kΩ.cm2, respectively.

The principal goal of this research is to produce a CrN/Cu multilayer coating and a CrN single-layer coating and also compare their electrochemical and antibacterial behavior. In this investigation, the coatings were applied to the stainless steel substrate by cathodic arc evaporation a sub-division of physical vapor deposition (CAE-PVD). The present phases were characterized and the thickness of the coatings was measured using X-ray diffraction (XRD) and field emission scanning electron microscopy (FE-SEM), respectively. Rockwell-C tester was used to evaluate the adhesion quality. Also, to evaluate the mechanical properties of the coatings such as modulus of elasticity and hardness, a nanoindentation test was used and the indentation effect and coating topography were evaluated using atomic force microscopy (AFM). Studying the electrochemical behavior of the coatings was done using electrochemical impedance spectroscopy (EIS) and potentiodynamic polarization (PDP) tests in Ringer's solution. The results of EIS tests showed that the CrN coating had higher polarization resistance in comparison to the CrN/Cu coating and an increasing trend of polarization resistance related to both coatings was identified by rising the time of immersion. Also, using the PDP curves, the CrN and CrN/Cu coating current densities were estimated at 1.835×10-8 and 2.088×10-8, respectively. The antibacterial activity of CrN and CrN/Cu coatings was evaluated by the spot-inoculation method. The results of the antibacterial test indicated that compared to CrN coating, CrN/Cu coating had a better impact on the control of the bacteria growth.

In this study, CrN/ZrN multilayer nanostructured coatings with different bilayers (10, 20, and 30) were created by the cathodic arc evaporation. The electrochemical behavior of samples was evaluated by polarization and impedance spectroscopy tests in the Ringer medium and the pin on disk test was used to investigate the tribological behavior of the samples. The results of measurements showed that the electrochemical and tribological behavior of the coatings depends on the number of bilayers and by rising the number of bilayers, the coating shows higher corrosion resistance and better tribological performance. Field emission scanning electron microscopy (FE-SEM) images of the specimens after exposure to the corrosion medium showed that the number of surface cavities were formed by the coating that had the highest number of bilayers comparing with other coatings were quite fewer in number and smaller in diameter. The results of the pin on disk test showed that by increasing the number of bilayers from 10 to 30, the coefficient of friction and wear rate decreased and the 30L coating ‌showed better wear resistance.

The main purpose of this investigation is to assess the effect of post-deposition annealing treatment on the electrochemical behavior of TiN coating developed on AISI 304 stainless steel substrate using cathodic arc evaporation physical vapor deposition (CAE-PVD). Post-annealing treatment at 400 ºC was performed on the coated substrate for 1 h. The studied samples were characterized using X-ray diffraction (XRD), scanning electron microscope (SEM), potentiodynamic polarization (PDP), and electrochemical impedance spectroscopy (EIS) tests. The preferred orientation of TiN (111) was identified by XRD patterns and the crystallinity of the coating increased after annealing treatment. SEM observations indicated that TiN coatings free of cracks were successfully developed on the substrate. The electrochemical measurements elucidated that the annealed coating had better corrosion resistance compared to that of the as-deposited coating with a lower current corrosion density. This investigation implied that improved corrosion performance of the TiN coating can achieved by performing post-deposition annealing treatment.

In this study, TiN coatings were deposited on Ti-6Al-4V alloy surface using cathodic arc evaporation (CAE) deposition process at three different bias voltages (-150, -200 and -250 V) applied to the substrate. In this regard, the effect of bias voltage on the microstructure and corrosion behavior of coatings was studied. The microstructure of the coated specimens was analyzed by scanning electron microscopy (SEM), X-ray diffraction (XRD) and atomic force microscopy (AFM). The corrosion behavior of the coatings was studied by potentiodynamic polarization (PDP) experiments and electrochemical impedance spectroscopy (EIS) in the simulated media. Studies on SEM images showed that formed coatings at bias of -200 V exhibited the least amount of needle like cavities (0.4%) and macroparticles. Studying the effect of bias voltage on the corrosion behavior of the coatings deposited at three bias voltages showed that the maximum corrosion resistance was obtained at -200 V and this voltage had the least current density in polarization measurements (5.59×10-7 A/cm2). So, it was considered as the optimal bias voltage.

In this investigation, Ti/TiN nanolayer and TiN single layer coatings were coated on substrate of AISI 316L stainless steel by applying physical vapor deposition (PVD) using the type of cathodic arc evaporation (CAE). The evaluation of microstructure were carried out using x-ray diffraction (XRD), nanoindentation, atomic force microscopy (AFM) as well as scanning electron microscopy (SEM). Polarization and impedance tests were utilized to study the coatings corrosion behavior in the simulated body solution (SBF) in different immersion times. Utilizing CAE technique, high density and adhesion Ti/TiN nanolayer and TiN single layer coatings were successfully made. The corrosion results showed that Ti/TiN nanolayer coating had an exceptionally high polarization resistance compared to 316L substrate and TiN single layer coating. Furthermore, the corrosion results indicated the desired corrosion behavior in the nanolayer coating towards the single layer within the SBF, as a result of the distinct layers presence resulting in a barrier against penetration of the corrosive media.

In this paper, corrosion behavior of single and multilayer (TiN, CrN and TiN/CrN) deposited coatings on Ni-Cr dental alloy in artificial saliva using cathodic arc evaporation-physical vapor deposition (CAE-PVD) technique were investigated. The corrosion behavior of uncoated and coated Ni-Cr prosthetic dental alloy has been investigated electrochemically in addition to the other way represented by the quantity measurement of corrosion products which is resulted from the Ni-Cr dental alloys. Fusayama artificial saliva has been utilized as media for measuring all electrochemical behaviors. The surfaces of samples have been analyzed using X-ray diffraction (XRD), energy dispersion spectroscopy (EDS), and scanning electron microscopy (SEM). The results indicated that the coating procedure that has applied to Ni-Cr dental alloy may change wettability by decreasing the hydrophilicity of the surface. The results indicated that the strongest hydrophobic character is exhibited by CrN coating. Potentiodynamic polarization and Nyquist plots showed that CrN coating had an exceptionally high polarization resistance compared to Ni-Cr dental alloy, TiN and TiN/CrN coatings.

The purpose of this paper is a qualitative evaluation of the mechanical properties of titanium aluminum nitride (TiAlN) hard nanostructured coatings applied on cutting tools using X-ray diffraction (XRD). Deposition of TiAlN and TiN nanostructured coatings were carried out by a pulse DC plasma-assisted vapor deposition (DC-PACVD) and a high power impulse magnetron sputtering (HIPIMS) machines. At first, for enhancement the adhesion of TiAlN nanostructured coating on the steel substrate, TiN inter-layer was deposited for the all samples. Nano-indentation, micro-hardness tester, and field emission scanning electron microscope (FE-SEM) were used in order to measured and compare the qualitative results with the real and experimental values. The results indicate that XRD pattern and their analysis can be a suitable qualitative method to evaluate the mechanical properties of the coatings. The lattice parameter, micro-strain, residual stress, texture coefficient, the crystal grain size and density of dislocation are used to demonstrate the relationship between the mechanical properties of the coatings and the XRD patterns. As a result, this method can be used as non-destructive and inexpensive method for quantitative comparison and evaluation of mechanical properties of thin film materials.