M50 Matrix Sintered with Nanoscale Solid Lubricants Shows Enhanced Self-lubricating Properties Under Dry Sliding at Different Temperatures

Abstract

Self-lubricating materials have attracted enormous interest from manufacturers and researchers around the world recently to enhance the durability and lifespan of mechanical components. Hence, the high-level objective of this study is to provide insight into how TiO2 and graphene (G) nanomaterials (NMs) could contribute toward enhancing replenishment of the self-lubricating layer on the worn surface of M50 matrix to maintain a supply of solid lubricant. Frictional samples were fabricated by spark plasma sintering (SPS), then their tribological properties against Si3N4 balls were evaluated using a pin-on-disk tribometer at various temperatures. The wear mechanisms of the rubbing surfaces were also elucidated using electron probe microanalysis (EPMA), field-emission scanning electron microscopy (FE-SEM), energy-dispersive spectroscopy (EDS), three-dimensional (3D) surface profilometry, and X-ray photoelectron spectrometry (XPS). The results of the tribotests indicated that M50 manufactured with TiO2 and TiO2/G hybrid NMs presented excellent antifriction/wear properties at temperatures of 25–450 °C, in comparison with the reference material (M50 steel). This is mainly because of the nanoscale solid lubricant added into the M50 microstructure. The results highlight a novel self-lubricating technology for M50 steel sintered with NMs for use in manufacturing of mechanical components for aerospace and automobile engines.