A comparative evaluation of the friction and wear behaviors of 40CrNiMoA steel and Inconel 718 alloy sliding against Si₃N₄ counterparts was conducted over a large temperature range from room temperature (RT) to 800 °C. The temperature-dependent tribological properties associated with the resulting chemical mitigation and structural adaptation of the solid sliding surface were clarified by surface/interface characterizations. The results revealed desirable performance in reducing friction and wear at elevated temperatures, which was associated with the resulting oxide composite film’s adaptive lubricating capability, whereas severe abrasive wear occurred at room/ambient temperatures. The oxidative-abrasive differentials for the two alloys were further discussed by considering the combined effect of temperature and stressed-shearing conditions.

We firstly fabricated a peculiar 3D structure of Bi₂S₃ salix leaf-like nanosheet/TiO₂ nanorod branched heterostructure arrays by a convenient hydrothermal method and discussed their mechanism of improving photoelectrochemical cell (PEC) properties. The salix leaf-like Bi₂S₃ nanosheets (NSs) were grown on TiO₂ nanorod arrays through controlling the molar ratio of EDTA-Na₂/Bi³⁺ and the reaction time. The morphology, crystal structure, microstructure and optical performance of the 3D Bi₂S₃ NS/TiO₂ NRs at different reaction times were investigated. The results show that the branched heterostructure of 3D Bi₂S₃ NS/TiO₂ NR arrays exhibits enhanced photocurrent density and optical absorption, which were attributed to the larger Bi₂S₃ surface area, as well as a direct electron path within the salix leaf-like Bi₂S₃ NS and TiO₂ NR heterojunctions, resulting from more excitation sites of incident light. The photocurrent density of the 3D Bi₂S₃ NS/TiO₂ NR arrays was almost 9 times greater than that of pristine TiO₂ without a branching structure. The results of the present work demonstrate that fabrication of the branched Bi₂S₃ NS/TiO₂ NR heterogeneous structure is a significant fabrication technology with great promise in PECs.

Cross-sectional view FESEM images of (a) TiO₂ NRs, (b) PbS(4)/TiO₂ NRs (the insets show the top-view of the corresponding cross-sectional view FESEM images). 3D schematic diagrams of (c) TiO₂ NRs, (d) PbS(4)/TiO₂ NRs.

TiO₂/CuInS₂/Bi₂S₃ core/shell/shell (CSS) nanorods (NRs) electrodes were synthesized by the successive ionic layer adsorption and reaction (SILAR) method and applied as the photoelectrodes for high performance in a photoelectrochemical (PEC) cell, wherein the narrow bandgap non-toxic materials, CuInS₂ and Bi₂S₃, were selected to expand the light absorption range to the near-infrared region. The uniform Bi₂S₃ layer was directly covered on the previously coated CuInS₂ layer on TiO₂ NRs to prevent the polysulfide electrolytes' corrosion of CuInS₂. The morphology, crystal structure, optical properties and PEC performance of plain TiO₂, single TiO₂/CuInS₂ core/shell (CS) and TiO₂/CuInS₂/Bi₂S₃ CSS NRs were investigated in detail. The deposition cycles of CuInS₂ and Bi₂S₃ on TiO₂ NRs were optimized to enhance the PEC performance of TiO₂/CuInS₂/Bi₂S₃ CSS composites electrodes. The results show that TiO₂/CuInS₂/Bi₂S₃ CSS obtained enhanced photoconversion efficiency (6 times higher than that of plain TiO₂ and 1.5 times than TiO₂/CuInS₂ CS). Therefore, the construction of CSS nanostructured composites electrodes through coupling single core/shell nanostructures with another narrow gap semiconductor shell suggests a promising design for improving the absorption efficiency and PEC performance of photoelectrodes.

Ni–Co–P/Si₃N₄ composite coatings were fabricated over an aluminum–silicon (Al–Si) substrate using a pulse-current electroplating process, in which the rapid deposition of an intermediate nickel–cobalt layer was used to improve coating adhesion. The microstructure, mechanical, and tribological behaviors of the electroplated Ni–Co–P/Si₃N₄ composite coating were characterized and evaluated. The results revealed that the electroplated Ni–Co–P/Si₃N₄ composite coating primarily consisted of highly crystalline Ni–Co sosoloid and P, and a volumetric concentration of 7.65% Si₃N₄. The electroplated Ni–Co–P/Si₃N₄ composite coating exhibited hardness values almost two times higher than the uncoated Al–Si substrate, which was comparable to hard chrome coatings. Under lubricated and dry sliding conditions, the electroplated Ni–Co–P/Si₃N₄ composite coating showed excellent anti-wear performance. Whether dry or lubricated with PAO and engine oil, the composite coating showed minimum abrasive wear compared to the severe adhesive wear and abrasive wear observed in the Al–Si substrate.