This paper concerns a comparative study on the tribological properties of Si₃N₄-10 vol% hBN bearing on GCr15 steel under seawater lubrication and dry friction and fresh-water lubrication by using a pin-on-disc tribometer. The results showed that the lower friction coefficient (around 0.03) and wear rate (10⁻⁶ mm/Nm) of SN10/GCr15 tribopair were obtained under seawater condition. This might be caused by the comprehensive effects of hydrodynamics and boundary lubrication of surface films formed after the tribo-chemical reaction. Despite SN10/GCr15 tribopair having 0.07 friction coefficient in the pure-water environment, the wear mechanismsits were dominated by the adhesive wear and abrasive wear under the dry friction conditions, and delamination, plowing, and plastic deformation occured on the worn surface. The X-ray photoelectron spectroscopy analysis indicated that the products formed after tribo-chemaical reaction were Fe₂O₃, SiO₂, and B₂O₃ and small amounts of salts from the seawater, and it was these deposits on the worn surface under seawater lubrication conditions that, served to lubricate and protect the wear surface.

Green synthesis of lignin-based carbon materials can accelerate the development of energy storage and conversion in supercapacitors. In this work, hierarchical graphenelike carbon was prepared by alkali lignin (AL) pyrolysis at a high temperature of 1700 °C. Accompanied by metal salt catalysis and a nitrogen hybridization reaction, a unique nanostructure of graphitized ALC was obtained with both a well-ordered 2D sheet lamellar structure and a uniform bowl-like porous structure. ALC exhibited a graphenelike lattice structure, a BET specific surface area of 1190 m²·g^–1, and excellent electrochemical performance (104 F·g^–1/0.5 A·g^–1). The study offers a prospective way to the high-value application of industrial lignin in supercapacitor electrode materials.

To improve the mechanical properties and tribological characteristics of boron carbide (B₄C) ceramic, silicon carbide (SiC) as an incorporation phase was added into boron carbide matrix. The results showed that, the incorporation of SiC phase led to denser microstructure and lower porosity. When SiC content was 20 wt.%, the bending strength and fracture toughness of the ceramic composite were 447.6MPa and 7.21 MPa·m^1/2, respectively. Under seawater lubrication, the friction coefficient of B₄C-20%SiC was lowered to 0.052, and the wear rate of ceramic composite was lower than the magnitude of 10⁻⁶mm³/Nm. The excellent tribological performance was attributed to lubricating, cooling of seawater, and tribochemical reaction.

In this paper, the tribological behaviors of Si₃N₄-hBN composites and PEEK materials with pre-corrosion were investigated in seawater and deionized water, respectively. Si₃N₄-hBN composite represented a good seawater corrosion resistance, and a low corrosion rate of 0.0037 g/(m²·h) was obtained for Si₃N₄-hBN composites in seawater. The seawater absorption rate of PEEK material was about 0.726%, and the surface became rougher with pre-corrosion. Si₃N₄-hBN/PEEK pairs presented the friction coefficients of around 0.20, and some reactive products (e.g. SiO₂ and H₃BO₃) formed on the surface. When hBN content was equal to 10wt%, more smooth worn surfaces were presented. And, Si₃N₄-10%hBN/PEEK pair presented the lowest and stable friction behavior. There are little changes for Si₃N₄-hBN and PEEK materials before and after immersed in deionized water. The friction coefficients of Si₃N₄-hBN/PEEK pair were all lowered than 0.1 in deionized water. The corresponding wear rates of pins and discs are all below the order of magnitude of 10⁻⁶ mm³/Nm. The excellent tribological characteristics were attributed to ultra-smooth surfaces (originated from the tribochemical reaction).