β-Ga ₂ O ₃ , a semiconductor material, has attracted considerable attention given its potential applications in high-power devices, such as high-performance field-effect transistors.

This paper presents the influence of an inorganic Al₂O₃ layer over MoS₂ particles on the tribological performance of electroless Ni–P–MoS₂/Al₂O₃ composite coatings fabricated without using surfactants. The Al₂O₃-coated MoS₂ particles were prepared by a heterogeneous nucleation process. The dry sliding tests of the composite coatings were tested against a WC ball. SEM was used to observe the surface morphology of particles, composite coatings, and worn surfaces. The results indicate that the coverage of an Al₂O₃ coating on MoS₂ particles significantly affects the surface morphology, frictional coefficient and wear loss of the composite coatings. The incorporation of Al₂O₃-coated MoS₂ particles with lower coverage (up to 7% of Al₂O₃) could obtain compact surface structure of composite coatings, which contribute to reduced wear loss. However, higher coverage would lead to loose surface structure of the composite coatings, and thus increase their wear loss.