This work aims to show the characterisation of Cr-V-N coatings, with the varied amounts of Cr and V. CrN, VN and Cr-V-N coatings were deposited onto silicon and XC100 steel substrates by reactive radio frequency magnetron sputtering and characterised with X-ray diffraction, X-ray photoelectron spectroscopies, energy dispersive X-ray spectroscopy, scanning electron microscopy, nanoindentation, pin on disc tribological tests and scratch tests. The residual stress was calculated using the Stoney formula. Compared to the CrN system, the Cr-V-N films presented a rough surface based on pyramidal morphology. A hardness of 19?53 GPa and a friction coefficient of 0?55 were obtained for CrN; in contrast, Cr-V-N coatings presented a weak hardness of 6?23 GPa. In the case of wear against a 100Cr6 ball, the Cr-V-N films were completely removed from the substrate, even though the Cr-V-N coating presented a low friction coefficient (0?39). However, the VN film showed good tribological performance.

In the present study, the effect of thermal treatment on the mechanical and structural properties of chromium carbide coatings with different thicknesses is evaluated. The coatings were deposited by cathodic magnetron sputtering on XC100 steel substrates. Samples were annealed in vacuum, at different temperatures ranging from 700 to 1000°C for 1 h, resulting in the formation of chromium carbides. X-ray diffraction (XRD), microanalysis X/energy-dispersive X-ray spectrometer (EDS), X-ray photoelectron spectroscopy (XPS) and scanning electron microscopy analysis were used to characterise the samples. Mechanical properties were evaluated by nano-indentation tests and the residual stress was calculated with the Stoney formula. The XRD analysis suggests the formation of the Cr 7 C 3 , Cr 23 C 6 carbides at 900°C. For thin films, they transformed totally to ternary (Cr, Fe) 7 C 3 carbides and their partial transformation has been observed in the case of thick films at 1000°C, without the formation of Cr 3 C 2. The EDS and XPS showed the diffusion mechanism between the chromium film and the steel substrate for the Cr, Fe, C, O elements during the annealing treatment. The increase of chromium film thickness from 0.5 to 2.64 µm, contributed to the significant enhancement of mechanical properties such as hardness (H) (from 12 to 26.3 GPa) and Young's Modulus (E) (from 250 to 330 GPa), respectively.

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To evaluate the performance characteristics of various surfaces, a detailed and precise description of the surface's micro-geometry properties is required. In this context, roughness is a reliable indicator of the possible behavior of mechanical piece performance, since distortions on the surface can form a direct cause for cracks or corrosion. As a result, characterization of surface roughness is very important for zero-defect fabrication. This paper investigates the 2D roughness parameters of a 42CrMo4 steel surface before and after nitrocarburizing treatment. The latter was accomplished at 580 °C for 10 hours in a salt bath containing sodium cyanates and potassium carbonates. A surface profilometer was used to analyze the influence of nitrocarburizing treatment on the material's surface roughness parameters behavior. The parameters that comprehensively describes the surface structure, namely the amplitude, spacing, hybrid parameters, and material ratio parameters were highlighted. The results of the experiments indicated that the nitrocarburizing treatment was effective in increasing almost all the 2D roughness parameters of the 42CrMo4 steel surface.

The aim of this paper is to study and analyze the effects of a surface controlled salt bath nitriding on the microhardness of AISI 1045 steel. The nitriding process was implemented in the salt bath component at ten different times (from 1 h to 10 h) when the temperature was constant at (520ºC). The nitriding process repeated of other specimens at the same times, but the temperature was (580ºC).The microstructure of the surface layers was investigated by scanning electron microscopy (SEM) and optical microscopy. Hardness profiles were measured with lowload hardness testing to determine the growth of the case depth after nitriding. Microhardness testing was carried out on samples to investigate the hardness profile at the transition from the compound to the diffusion layer. The microhardness of the surface of the nitrided sample at 520ºC and 580ºC was observed in the range of 318-430 HV0.3 and 329-421 HV0.3, respectively. Experimental results showed that the nitrides ε-Fe2-3(N, C) and γ'-Fe4(N,C) present in the compound layer increase the microhardness , It also showed that the Increasing the salt bath nitriding parameters (treatment time and temperature) increases the surface hardness and hardness profile.