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In general, the improvement of mechanical and tribological properties of functional surfaces is achieved by mechanical, thermal, or thermochemical treatments. In the present work, the advancement of the aforementioned properties is carried out using the boriding process. This experimental work aims to study the effect of single-phase Fe2B layer thickness on the EN-GJL-250 cast iron tribological behavior through optimized lubrication under normal load of 60 N at 100 °C. The specimens were borided at 950 °C for 1 and 4 h by a pack-boriding method using a mixture of B4C 85 wt% and Na2CO3 15 wt%. Advanced experimental techniques and comprehensive surface and tribological evaluations were used in this study: The surfaces of the samples were characterized by XRD, SEM, and microhardness measurements. A scratch test and a Daimler-Benz Rockwell C Adhesion Test were used for adhesion testing, and tribological tests were performed using an alternative tribometer. The XRD analysis revealed the formation of a monophase Fe2B layer, as evidenced by the results obtained. The optimum tribological behavior was obtained at a temperature of 950 °C/4 h, showing a remarkable reduction in wear rate of about 300 times compared to both the treatment at 950 °C/1 h and the unborided state. [ABSTRACT FROM AUTHOR]

Various concentrations of Mg2+ substitutional doped ZnS nanoparticles (Zn MgxS, x = 0, 0.02, 0.07, and 0.1) were prepared by adopting the solvothermal method, using ethanol as the solvent at 135°C. The obtained micro/nanoparticles were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), and room temperature photoluminescence (PL) spectroscopy. XRD revealed the conservation of the host ZnS crystal phase after the substitution of Zn2+ by Mg2+ but was accompanied by a weak decrease of the lattice parameter. SEM analysis showed the formation of aggregated particles that were evenly distributed. PL spectra exhibited a near-band-edge (NBE) emission centered at 430 nm, and another band at 585 nm, related to sulfur defects; moreover, no shift occurred when x increased. To explain this finding, computational density functional theory (DFT) calculations were performed, revealing constant gap energy after substitution was maintained at the point G, whereas the density of stats of both CV and BV were reinforced near the band gap. [ABSTRACT FROM AUTHOR]

The tribological performance of the tungsten carbide substrate (WC‐Co), improved by ceramic coatings, is still being reported in new studies that have been carried out to date. It has become a hot research topic that are widely applied in hard material research, especially in the tools manufacturing fields. This study was conducted to investigate the wear characteristics of a commercial cemented carbide tool (WC‐Co) coated with a physical vapor deposition chromium‐vanadium nitride film (CrVN), followed by a boriding process as a final thermochemical treatment. Tested in dry sliding contact against an alumina ball as a static partner, the tribological responses of the specimen were analyzed and compared with an uncoated specimen. Friction coefficients, calculated from volume loss, were around .58 for all specimens except the uncoated specimen at 10 N of applied load. Wear scar analyses revealed the occurrence of several wear mechanisms that is polishing, oxidation, wear debris formation, surface binder removal, grain fragmenting, and grain pull‐out. [ABSTRACT FROM AUTHOR]