The Laser-assisted Cold Spray process and deposit characterisation

Abstract

Laser-assisted Cold Spray (LCS) is a new coating and fabrication process which combines the supersonic powder beam found in Cold Spray (CS) with laser heating of the deposition zone. LCS combines some advantages of CS: solid-state deposition, high build rate and the ability to deposit metals onto a range of substrates, with reduced operating costs which arise from not using a gas heater and replacing helium with nitrogen as the process gas. A system has been developed to impact metallic powder particles onto a substrate which is locally heated using a diode laser. A pyrometer and control system are used to record and maintain impact site temperature. In this study, < 50 µm powder particles are measured to be traveling at around 400 ms − 1 , and heated to temperatures between 450 °C and 900 °C when they impact the substrates. Build rates of up to 45 g min − 1 were achieved for deposits with less than 1% porosity. Oxygen and nitrogen content in the deposits were measured to be less than 0.6 wt.% and 0.03 wt.% respectively.