Optimization of Pulsed Fiber Laser Texturing for Solid Lubricant Deposition on a Ti/TiN Coated Aerospace Alloy

Abstract

AA2219 is a superior performance Al-base alloy which promises toughness, strength and creep resistance which allows the deposition of titanium nitride (TiN) coating at 200 °C. The present research addresses the issue of poor wear properties of the alloy, using state of the art technologies, to deposit hard and adherent thin TiN layer followed by laser surface texturing. The thickness of sub-micron size coating is determined by appropriate modification of the existing mathematical model and composite microhardness values. Laser energy density of 20.8 J/cm2 and 4 repeated pulses is optimized to produce regular size and shape of micro-holes on TiN-coated samples. Epoxy-based MoS2 lubricant is deposited on laser textured samples to produce ultra-low friction surfaces. The micro-holes act as a micro-reservoir of MoS2 solid lubricant. Field emission scanning electron microscope and optical profilometer were used to estimate the topology, shape, size, and depth of micro-holes. The cross-sectional view shows the successful impregnation of epoxy-based MoS2 due to the chemisorption of functional groups with an Al oxide surface.