This work investigates in situ friction-generated copper nanoparticles at the sliding in the precursor solution of copper formate tetrahydrate and octylamine, which induced by frictional heat, it can effectively mitigate wear while slightly reducing friction coefficient. The frictional heat between tribo-pairs accelerated the decomposition of the precursor into in situ generated copper nanoparticles, as indicated by black stripe regions on the worn surface. This study opened a new strategy to achieve low friction and wear through the thermal decomposition of the liquid lubricants during sliding.
Mechanoluminescence (ML) refers to the unique phenomenon that converts mechanical energy into optical energy. However, at present, there are many kinds of ML generation mechanism models, such as piezoelectric type, triboelectric type, trap-related type, etc., which seriously affect the understanding of the intrinsic mechanism models. Herein, a rare-earth-doped fluoride glass ceramic (Ba 2 LaF 7 :Yb 3+ glass-ceramic, BYG) is developed capable of dual-mode near-infrared ML (NIR ML) via triboelectric and frictional heat pathways. The triboelectric-induced ML arises from interfacial charge transfer between the glass and organic polymer matrices, directly exciting Yb 3+ emission centers. In contrast, frictional heat-induced ML involves the carriers released from oxygen vacancies generated by X-ray irradiation. Such dual-mode NIR ML demonstrates a robust linear correlation with applied stress, enabling the development of a visualized bright-field sensing platform for real-time monitoring of triboelectric potentials and frictional temperatures. Furthermore, this work not only advances the mechanistic understanding of ML but also provides a versatile strategy for indirect optical sensing in ambient environments.
Two-dimension graphene-like covalent-organic frameworks (GCF) nano-sheets were successfully fabricated to evaluate the tribological behavior as lubricant additive in comparison to GO and rGO in PAO 10 oil. The exploration shows that conjugate system of GCF brings p-d feedback coordination to metal ions created by exoelectron, promoting the formation and stability of adsorbed film . The mechanical strength of covalent bond structure in -plane ensures carrying capacity and durability, and the ultrathin layered feature reduces shear stress due to slide effect. Eventually, the excellent reducing friction (up to 53.5%) and anti-wear (up to 95.4%) were achieved at an ultralow dosage of 0.008 wt%. By contrast, dissociation of C–O linkages of rGO and GO induced by tribo-stress and tribo-heat deteriorates its stability and durability.
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