Development of TMD-based solid lubrication coatings using magnetron sputtering for aerospace applications

Abstract

This thesis presents the development and comprehensive characterisation of molybdenum disulfide-titanium (MoS₂-Ti) multilayer solid lubricant coatings deposited via PVD - magnetron sputtering, specifically engineered for precision components in missile guidance actuators. Addressing the critical need for reliable solid lubrication in extreme operational environments, the research systematically optimised deposition parameters (argon pressure: 4 bar, flow rate: 10 sccm, substrate-to-target distance: 45 mm) and implemented a custom substrate rotation mechanism to resolve coating non-uniformity. The optimised process yielded near-stoichiometric MoS₂ coatings (Nₛ/Nₘₒ = 1.72) with Ti interlayers, achieving controlled thickness (8–13 μm) and columnar microstructures consistent with literature. Tribological evaluation via pin-on-disc testing demonstrated a 25% reduction in friction coefficient (CoF ≤ 0.02) compared to uncoated 17- 4PH steel, with a 45% improvement during the critical initial 60 seconds of operation, aligning precisely with missile actuator duty cycles. Structural characterisation using XRD and Raman spectroscopy revealed that Ti incorporation promotes amorphous phase formation, enhancing environmental stability while retaining MoS₂’s solid lubrication properties. Wear debris analysis identified self-lubricating transfer layers of compacted MoS₂ particles, explaining periodic friction fluctuations during testing. The study bridges laboratory-scale optimisation to real-world application, validating the coating’s suitability for missile guidance systems. Future work directions include nanoscale microstructure analysis via TEM, humidity resistance studies, and performance validation on actual actuator components. This research establishes a robust framework for deploying advanced solid lubricants in defence applications, offering a viable alternative to conventional lubricants under extreme mechanical and environmental stresses.