The design of a novel interpenetrating network hydrogel inspired by the microscopic architecture of natural cartilage based on a supramolecular sodium alginate (SA) nanofibril network is reported in this paper. The mechanical strength and toughness of the poly(vinyl alcohol) (PVA) hydrogel were significantly improved after being incorporated with the alginate nanofibril network. The multiple hydrogen bonds between PVA chains and alginate fibers provided an efficient energy dissipation, thus leading to a significant increase in the mechanical strength of the PVA/SA/NaCl hydrogel. The PVA/SA/NaCl hydrogel demonstrated superior water-lubrication and load-bearing performance due to noncovalent interactions compared with pure PVA hydrogels. Moreover, the bioactivity of the PVA/SA/NaCl hydrogel was proved by the MC3T3 cell proliferation and viability assays over 7 days. Therefore, alginate fiber-enhanced hydrogels with high strength and low friction properties are expected to be used as novel biomimetic lubrication materials.

High performance polymer matrix composites with low friction and wear rate are of urgent requirement in sliding bearings and gaskets. In this study, the PTFE/MoS₂ composites were prepared and the effect of testing temperature on the tribological properties were investigated. Results show that the friction coefficient and wear rate are approximately (0.14–0.19) and (4.18–13.38 × 10⁻⁴ mm³/Nm) at testing temperatures from 25 to 250 °C, respectively. At testing temperatures above 200 °C, the coefficient of friction of the composite with the addition of MoS₂ is lower than that of pure PTFE, while the wear rate of the composite material with the addition of 2 wt.% and 5 wt.% MoS₂ is lower than that of pure PTFE at temperatures above 150 °C. At low testing temperatures (25–100 °C), the main wear mechanism is that of slight abrasive wear, while from 150 °C to 250 °C, the main wear mechanism transformed to fatigue and severe abrasive wear.

With the rapid development of the aerospace, automobile, and ocean industries, there is an urgent need for the fabrication of high-performance polymer matrix composites with low friction and wear in wide temperature ranges. In this paper, polytetrafluoroethylenes (PTFEs) doped with polyether-ether-ketone (PEEK), carbon fiber (CF), and TiC were prepared, and the effects of testing temperatures from room temperature to 250 °C in air conditions were investigated. The results showed that the friction coefficient of the PTFE matrix composites had no obviously changing trend, while the wear resistance properties were significantly improved. Due to the synergistic lubrication and enhancement of CF, PEEK, and TiC, the wear rate for composites with these particles decreased from (2.04–2.72) × 10⁻³ mm³/Nm for pure PTFE to (0.67–1.96) × 10⁻⁴ mm³/Nm. Moreover, the SEM analysis results showed that the main wear mechanisms are fatigue and abrasive wear for the PTFE matrix composites. The results obtained in this study will provide data and technical support for the development of high-performance polymer matrix composites with low friction and wear that can be used over a wide temperature range.

Phenolic-matrix composites possess excellent synergistic effects on mechanical and tribological properties and can be used in the aerospace, medical, and automobile industries. In this work, a series of phenol–formaldehyde resin/hexagonal boron nitride nanocomposites (PF/BNs) were in situ synthesized using an easy method. PF/BN coatings (PF/BNCs) on 316L steels were prepared through a spin-casting method. The wear behaviors of these PF/BNCs were investigated by dry sliding with steel balls. The percentage of BN, the thickness of the coating, and the heat treatment temperature affected the coefficients of friction (COFs) and wear rates of these coatings. After heat treatment at 100 °C, the tribological properties of the PF/BNCs were remarkably improved, which might be attributed to both the transformation of carbon on the worn surfaces from C-O/C=O into C=N, carbide, and other chemical bonds and the cross-linking of the prepolymers.

To improve the tribological characteristics of materials employed in spatial mechanisms, there is a significant requirement to develop solid lubricating composites with superior performance. This study investigates the tribological characteristics of composites consisting of a nickel matrix combined with silver molybdate and barium molybdate. The experimental analysis focuses on evaluating the tribological behaviors of these composites from 25 °C to 800 °C. The findings indicate that the combined application of silver molybdate and barium molybdate resulted in enhanced self-lubricating properties of the composites, particularly at temperatures over 400 °C. The inclusion of both silver molybdate and barium molybdate in the composite resulted in the achievement of a low friction coefficient (0.34–0.5), as well as a wear rate ranging from 0.47 to 1.25 × 10⁻⁴ mm³ N⁻¹m⁻¹, within the temperature range of 400 to 800 °C. Furthermore, an analysis was conducted to examine the wear processes of the composites at various sliding temperatures. This analysis was based on the evaluation of the chemical composition and morphologies of the sliding surfaces, which were verified by scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDS), and Raman spectroscopy.

Biomimetic hydrogel lubrication coatings with high wettability and low friction show great promise in tissue engineering, wound dressing, drug delivery, and intelligent sensing. Inspired by the hierarchical structure of natural cartilage, a layered hydrogel coating was constructed to functionalize rigid polyetheretherketone (PEEK). The layered hydrogel coating features a structural design comprising a top soft layer and a middle robust layer. The porous structure of the top soft hydrogel layer stores water molecules, providing surface lubrication, while the dense structure of the middle robust hydrogel layer offers load-bearing capacity. These synergistic effects of the gradient hydrogel layer endow the PEEK substrate with an ultra-low coefficient of friction (COF~0.010 at 5 N load), good load-bearing capacity (COF~0.031 at 10 N load), and excellent wear resistance (COF < 0.05 at 5 N load after 20,000 sliding cycles). This study introduces a novel design paradigm for robust hydrogel coatings with exceptional lubricity, displaying the potential application in cartilage replacement materials.