Current Issue : July-September Volume : 2026 Issue Number : 3 Articles : 5 Articles
To address the inherent defects in the fabrication of AlCrN titanium alloy coatings and enhance interfacial bonding strength as well as tribological performance, an AlCrN coating was employed as an absorption layer and subjected to laser shock processing to form an AlCrN/TC4 transition layer. Subsequently, a secondary AlCrN coating was deposited to construct a gradient coating architecture. The surface and cross-sectional morphologies and elemental distributions under varying laser energies were systematically investigated, and the influence of laser energy on the adhesion and wear resistance of the gradient coatings was analyzed. The results demonstrate that with increasing laser impact energy, the thickness of the AlCrN/TC4 transition layer gradually decreases from 3.75 μm to 1.32 μm, accompanied by significant changes in elemental distribution across the surface and cross-section. The interfacial bonding strength of the gradient coating increases substantially from 13.6 N to 43.3 N, while the average friction coefficient rises from 0.436 to 0.507. Concurrently, the wear track depth is reduced, and the wear rate decreases from 86.46 × 10−5 mm3/(N·m) to 7.67 × 10−5 mm3/(N·m). Laser shock peening promotes elemental diffusion, enabling the formation of a diffusion-aided interlayer. The incorporation of this diffused zone facilitates the successful construction of a high-quality TC4 titanium alloy gradient coating, effectively broadening the film–substrate interface, enhancing surface hardness, and significantly improving both interfacial adhesion and wear resistance....
In order to prepare alkyl-functionalized reduced graphene oxide more simply, economically and environmentally, we adopt a two-step method of first reduction and then surface grafting. Graphite oxide (GtO) is first exfoliated to thermally-reduced graphene oxide (TRGO) and then, in a heat-induced solid-state reaction, converted to lauryl-functionalized TRGO (LTRGO). During the second step, lauryl radicals generated from the decomposition of lauroyl peroxide (LPO) open the epoxide rings on TRGO, covalently grafting the alkyl chains. The average water contact angle of LTRGO is 135.5◦, and it disperses stably in base oil without surfactants or other additives. Four-ball test results show when the dosage of LTRGO is 75 mg/L, the average friction coefficient and wear scar diameter of the Formosa Plastics base oil (100 N) are decreased by 20.8% and 15.4%, respectively. The morphology and element analysis after ball-on-disk friction tests showed that the stable LTRGO physical friction adsorption film and metal oxide friction chemical reaction film could be formed between the friction pairs, thus reducing the friction wear....
High-temperature self-lubricating materials with stable tribological performance across a wide temperature range are essential for advanced mechanical systems under extreme conditions. However, balancing mechanical strength and lubrication efficiency remains a key challenge. This study fabricated CoCrFeNiMox-Ni/MoS2-Ag-Cr2O3 composites (x = 0.2, 0.5, 1) via spark plasma sintering, aiming to investigate the effect of Mo content on their microstructure, mechanical properties, and tribological behavior. Microstructural analysis showed that the as-sintered composites mainly consist of FCC phase, Cr2O3, Ag, and Ni/MoS2. Increasing Mo content from 0.2 to 1 wt.% significantly promoted the formation of hard σ-phase intermetallics, leading to increased hardness (up to 546 HV) and yield strength (peaking at 502 MPa). Tribological tests at 25–800 ◦C indicated continuous lubrication behavior in all composites. The minimum friction coefficient was 0.23, and wear rates remained below 10−6 mm3/N·m. In the low-to-medium temperature range, lubrication was dominated by the synergistic effect of Ni/MoS2 and Ag: Ni/MoS2 formed low-shear-strength films, while Ag reduced surface adhesion. Meanwhile, the Mo solid solution strengthened and the σ-phase enhanced wear resistance by improving hardness and inhibiting plastic deformation. At high temperatures, tribochemical reactions generated lubricating films composed of oxides and molybdates, which maintained tribological performance by reducing direct contact between friction pairs. This study demonstrates that Mo-doped high-entropy alloy composites can serve as high-performance wide-temperature self-lubricating materials, providing a basis for designing “matrix-lubricant” systems for extreme-temperature applications....
In the present work, the effect of the composition of the metal binder (Co–Cr, Ni, and NiCr) on the structure and performance properties of WC-based coatings obtained by detonation spraying is investigated. The coatings were characterized using microstructural analysis, EDS mapping, microhardness measurements, tribological testing, and corrosion analysis. The results show that changing the type of binder significantly affects the porosity, distribution of the WC phase, hardness, and tribological behavior of the coatings. The best combination of properties—the lowest coefficient of friction, highest hardness, and the highest corrosion resistance—was obtained for the WC–Co–Cr coating. These results indicate the potential of these coatings for extending the service life of pipeline fittings and equipment in the oil and gas sector....
This study investigates the tribological and electrochemical corrosion behavior of laser-clad nickel–aluminum bronze (NAB) coatings reinforced with WC particles (0, 8, 16 wt.%). Through microstructural characterization and phase analysis, it was found that in the NAB coating containing 16% WC, the WC particles and carbides were uniformly distributed, serving as a reinforcing scaffold. During the friction and wear process, they effectively reduced the contact area between the counter ball and the NAB matrix to a certain extent, smoothing the wear process and resulting in a more stable friction coefficient. Electrochemical testing demonstrates that WC addition significantly enhances corrosion resistance: NAB + 8%WC exhibits a low corrosion current density (icorr), the highest polarization resistance, and the densest protective film. The dual mechanisms—grain boundary blocking and ion channel obstruction—reduce selective Al/Fe leaching and minimize Cl− penetration. The 8% WC formulation optimizes the electrochemical performance, providing excellent corrosion resistance in a simulated marine environment....
Loading....