Different techniques are usually employed to evaluate the mechanical properties of arc-sprayed coatings. In many situations, comparing properties is complex, and values extracted from tensile tests are required for structural projects. X6CrNi18-8 stainless steel and molybdenum were sprayed onto a mild steel substrate using the electric arc thermal spray technique to discuss this issue. After a detailed microstructure characterization, tensile tests were performed on both coatings to determine the yield strength and total elongation. Easy techniques were also applied: Vickers hardness and Charpy impact test. Tensile tests have shown that applying coatings increased the steel substrate’s total elongation. Molybdenum coating presented a higher impact resistance than the X6CrNi18-8 one, resulting in no correlation between elongation and Charpy values. On the other hand, correlations between hardness and yield strength were identified, opening a discussion on the effects of the microstructure and type of test used.

Mechanical properties, wear resistance and impact resistance of a high-alloy chromium cast iron used in the fabrication of grinding balls have been studied. A rank of tempering heat treatments under several temperatures 500°C, 525°C, 550°C and 575°C was performed after austenitized at 1050°C. The Scanning Electron Microscope (SEM) and X-ray Diffraction (XRD) techniques have been used to characterize the microstructures and identify the phases. The wear balls tests were conducted in a rotating drum with a velocity 0.5 r/s. The tribological tests were carried out by evaluated a weight loss as function time. The measurement of the rebound resilience was determined by Charpy impact tests. The results of XRD showed the presence of the martensite, carbides type M ₇ C ₃ and M ₂ C for all tempering heat treated. The hardness of the sample increased after the tempering and reach nearly 65 HRC at 1050°C. In another hand, it decreased after the tempering treatment it could be explained by precipitation of the carbides type M ₂ C.

Coating efficiency and quality can be significantly improved by carefully optimizing the coating parameters. Particularly in the flame spray method, the oxygen/fuel ratio, which is classified as oxidizing flame stoichiometry (excess oxygen) and reduces flame stoichiometry (excess acetylene), and spray distance are the most critical factors, as they correlate significantly with coating porosity and corrosion performance. Hence, understanding the effects of these parameters is essential to further minimize the porosity, improving the corrosion performance of thermally sprayed coatings. In this work, a NiWCrBSi alloy coating was deposited via the oxyacetylene flame spray/Flexicord-wire (FS/FC) method. The effect of the flame oxygen/fuel ratio and spray distance on the microstructure properties and corrosion behavior of the coatings was investigated. Afterwards, the microstructure, phases’ compositions, spray distance, and corrosion performance were studied. The equivalent circuit model was proposed, and the corrosion mechanism was discussed. The obtained results highlight that the oxygen-to-fuel ratio is a promising solution for the further application of flame spray/Flexicord-wire (FS/FC) cermet coatings in hostile environments. Depending on the flame’s oxygen/fuel ratio, careful selection of the flame stoichiometry provides low porosity and high corrosion performance.