Supersonic Laser Deposition of Self-Lubricating Coatings

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.

Study on Microstructure and Tribological Performance of Diamond/Cu Composite Coating via Supersonic Laser Deposition

The supersonic laser deposition (SLD) of diamond/Cu composite powder is studied over a range of laser power. The deposition efficiency, coating microstructure, cohesive/adhesive bonding, phase composition, micro-hardness, and tribological property of the diamond/Cu composite coating are investigated. The results indicate that, as laser power is increased, deposition efficiency initially increases and then declines. The diamond particles distribute uniformly in the composite coating. Due to the increase of velocity ratio and total energy by laser irradiation, the cohesive/adhesive bonding of the composite coating is improved. The composite coating can preserve the phase composition of the origin powders due to the relatively low heat input during the SLD process. Slight oxidation of the Cu powder can be detected in the coatings prepared with high laser power, which has adverse effects on material deposition. The SLD-diamond/Cu composite coating has superior wear-resistance because of low friction coefficient, high micro-hardness, and uniformly distributed diamond particles.