Tribological Optimization of Self-Lubricating SiC/MoS₂ Hybrid Aluminium Matrix Composites via Laser Surface Texturing and Graphite Infiltration

Introduction: Sliding-contact aluminium components frequently suffer premature failure due to high friction and wear, limiting their use in bearing, brake, and clutch applications. Hybrid metal matrix composites that combine structural reinforcement with intrinsic lubrication offer a promising route to overcome this limitation, yet the interplay between reinforcement composition and tribological response remains insufficiently quantified.

Methods: Aluminium matrix composites reinforced with silicon carbide (6–26 wt.%) and molybdenum disulfide (1.5–9.5 wt.%), with 1 wt.% magnesium as a wetting agent, were fabricated via two-step stir casting. Surfaces were subsequently laser-textured and graphite-infiltrated to promote lubricant retention. Tribological behaviour was assessed through pin-on-disc and dry sand abrasion tests across varying loads, supported by SEM analysis of worn surfaces; hardness and tensile testing characterized bulk mechanical response.

Results: MoS₂ addition up to 5.5 wt.% reduced the coefficient of friction from 0.68 to 0.38 and lowered wear rate by approximately 41%, with SEM revealing a transition toward more stable, lubrication-dominated sliding. SiC-rich compositions showed superior wear resistance under high contact loads via an abrasion-driven mechanism, while MoS₂-rich compositions performed best under moderate, friction-critical loads. Laser texturing combined with graphite infiltration improved lubricant entrapment and friction stability over extended cycles, without compromising strength: hardness and tensile strength reached 118 HV and 196 MPa at 21 wt.% SiC.

Conclusions: SiC and MoS₂ can be co-engineered within a single hybrid composite to deliver load-adaptive tribological performance alongside structural integrity, offering a design framework for self-lubricating components in aerospace and automotive sliding-contact systems.