Supersonic Laser Deposition of Self-Lubricating Coatings

Abstract

Supersonic Laser Deposition (SLD) is a coating and fabrication process combining cold spray (CS) with laser heating of the deposition zone. Laser heating increases deformation on impact, improving bonding for a given particle velocity, eliminating the need to use helium while retaining the advantages of CS; solid-state deposition, low oxidation and high build rate (≤ 10 kg/hr). Although solid lubricants offer advantages over liquid lubrication, remaining effective over a wide range of operating temperatures and loads, while simplifying sealing, their use is limited by current application methods. SLD enables the deposition of metallic coatings which incorporate solid lubricants into metallic coatings, onto a range of substrates. This paper details the powders and conditions used to deposit nickel/graphite using SLD, and the structure and tribological properties of the coatings produced. Co-efficients of friction below 0.14 were demonstrated for nickel/graphite coatings on aluminium substrates.