Friction-induced rehybridization of hydrothermal amorphous carbon in magnesium silicate hydroxide-based nanocomposite

Herein, a hydrothermal amorphous carbon-coated nano-magnesium silicate hydroxide core-shell structure (MSH@C) was synthesized in subcritical water. The structure, phase and chemical composition of nanocomposite powders were characterized by Scanning electron microscope , Transmission electron Microscope, X-ray diffractometer, X-ray photoelectron spectrometer and Raman spectrometer. The tribological tests of nanoparticles as lubricant additives were carried out in order to study the effect of friction on the phase transition and structural ordering of the hydrothermal amorphous carbon in nanocomposite powders. The results show that nano-MSH@C nanoparticles exhibit excellent friction reduction and anti-wear performances. EDS and Raman analyses show that a discontinuous sp 2 -rich tribofilm is formed on the worn surface. The tribofilm formed on the worn surface not only undergoes the phase transformation from sp 3 to sp 2 but also has a higher structural order. The degree of friction-induced rehybridization is proportional to the wear resistance of nanoparticles. The pathway of friction-induced rehybridization and the enhancement of the structural order of the hydrothermal amorphous carbon are attributed to the friction-induced dehydrogenation reaction and the adaptively sliding oriented rearrangement. The tribological mechanism of MSH@C as lubricant additive is mainly ascribed to the shear-induced transfer of the friction-induced loose tribofilm.