Mechanical Properties of V-O-N Coatings Synthesized by Cathodic Arc Evaporation.

The V-O-N coating set was produced at different relative oxygen concentrations of O2(x) = O2/(N2 +O2) using cathodic arc evaporation. The aim of the research was to determine the effect of oxygen on coating properties. The coatings' composition and structural properties (X-ray diffraction (XRD), scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDX)) and mechanical properties-hardness, adhesion, and wear resistance (nano-indenter, scratch tester, ball-on-disc tester)-were extensively investigated. EDX and XRD analyses indicate that in coatings formed with a relative oxygen concentration in the range of 20-30%, the oxygen concentration in the coating increases dramatically from approximately 16 at.%. to 63 at.%, and the nitrogen concentration drops from about 34 at.% up to 3 at.%. This may indicate greater activity of oxygen compared to nitrogen in forming compounds with vanadium. The occurrence of the V5O9 phase belonging to the Magnéli phases was observed. Microscopic observations indicate that the number of surface defects increases with the oxygen concentration in the coating. The opposite effect is characterized by mechanical properties-hardness, adhesion, and wear resistance decrease with increasing oxygen concentration in the coating.

Comparative Investigations of AlCrN Coatings Formed by Cathodic Arc Evaporation under Different Nitrogen Pressure or Arc Current.

Tools and machine surfaces are subjected to various types of damage caused by many different factors. Due to this, the protecting coatings characterized by the best properties for a given treatment or environment are used. AlCrN coatings with different compositions, synthesized by different methods, are often of interest to scientists. The aim of the presented work was the deposition and investigation of two sets of coatings: (1) formed in nitrogen pressure from 0.8 Pa to 5 Pa and (2) formed at arc current from 50 A to 100 A. We study relationships between the above technological parameters and discuss their properties. Coatings formed at nitrogen pressure (pN2) up to 3 Pa crystallize both in hexagonal AlN structure and the cubic CrN structure. For pN2 > 3 Pa, they crystallize in the CrN cubic structure. Crystallite size increases with nitrogen pressure. The coatings formed at different arc currents have a cubic CrN structure and the crystallite size is independent of the current. The adhesion of the coatings is very good, independent of nitrogen pressure and arc current.

Structure and Properties of ZrON Coatings Synthesized by Cathodic Arc Evaporation.

The transition metal oxynitrides are a coating material with decorative features due to their adjustable color and good mechanical properties. The purpose of the research was to study the effect of the relative oxygen concentration O2(x) = O2/(N2 + O2) in particular on adhesion, but also on the color, structural and mechanical properties of ZrON coatings synthesized by cathodic arc evaporation on HS6-5-2 steel substrates. The surface morphology, phase and chemical composition and mechanical properties were determined using scanning electron microscopy, X-ray diffraction, wavelength dispersive X-ray spectroscopy, nanoindentation and scratch test. It was found that color of the coatings changed from light yellow for ZrN first to gold and then to graphite for Zr-O phase with increase of oxygen concentration. X-ray diffraction patterns showed that the phase separation of ZrN and ZrO2 occurred for about 35 at.% of oxygen in the coating. Increase in oxygen concentration in the coatings led to decrease in crystallite size from about 20 nm for ZrN to about 5 nm for coatings with about 35 at.% of oxygen and about 25 at.% of nitrogen. An increase in hardness from about 26 GPa for ZrN to about 30 GPa for coating with small concentration of oxygen (about 9 at.%) and then decrease to about 15 GPa was observed. Adhesion of Zr-O-N coatings demonstrated strong dependence on oxygen concentration. Critical load for ZrN is about 80 N and decreases with oxygen concentration increase to about 30 N for ZrO2.

Effect of Silicon Concentration on the Properties of Al-Cr-Si-N Coatings Deposited Using Cathodic Arc Evaporation.

The current market requirements are related to the introduction of new protective coatings for tools and machine parts with much better performance properties. These requirements are met by the AlCrSiN coatings; however, knowledge on the adhesion of these coatings to the substrate, as well as on their corrosion resistance, is deficient. The article presents the results of technological works on the coating deposition from AlCrSi cathodes with a silicon concentration from 0 at% to 10 at% by the cathodic arc evaporation and the results of systematic studies of their structure, mechanical, tribological and electrochemical properties. A correlation between the above-mentioned properties and the silicon concentration in the AlCrSiN coatings has been found and discussed. The coatings formed from cathodes containing less than 5 at% Si crystallize in the cubic structure. The size of the crystallites decreases with the silicon concentration increase. The coatings are characterized by a high hardness with a maximum of about 37 GPa (2 at% Si). The adhesion of the coatings is almost independent of the concentration of silicon. The wear rate is about one order of magnitude higher for coatings deposited from cathodes with a silicon concentration of 5 at% and 10 at% compared to a coating with a lower silicon concentration. This finding is consistent with the results of corrosion resistance studies. The coating deposited from the cathode with 10 at% of silicon exhibits the best anticorrosion properties against the salt solution.

Effect of Metallic or Non-Metallic Element Addition on Surface Topography and Mechanical Properties of CrN Coatings.

Alteration of the phase composition of a coating and/or its surface topography can be achieved by changing the deposition technology and/or introducing additional elements into the coating. Investigation of the effect of the composition of CrN-based coatings (including AlCrN and CrON) on the microparticle height and volume, as well as the construction of correlations between the friction coefficient at the microscale and the geometry of microparticles, are the goals of this study. We use atomic force microscopy (AFM), which is the most effective method of investigation with nanometer resolution. By revealing the morphology, AFM allows one to determine the diameter of the particles, their heights and volumes and to identify different phases in the studied area by contrasted properties. The evaluation of the distribution of mechanical properties (modulus of elasticity E and microhardness H) on the surfaces of multiphase coatings with microparticles is carried out by using the nanoindentation method. It is found that the roughness decreases with an increase in the Al concentration in AlCrN. For the CrON coatings, the opposite effect is observed. Similar conclusions are valid for the size of the microparticles and their height for both types of coating.