Manufacture Of Reflective Aluminium Surfaces Using Cold Spray

This research demonstrates the use of a cold spray as an additive manufacturing process to produce reflective aluminium coatings for use with infrared reflectors. Nitrogen was used as a carrier gas, at a variety of different gas temperatures. Following cold spray, the coatings were machined and polished to Sa values of 100-400 nm and characterised with regard to specular and diffuse reflectivity, porosity, surface roughness, and density. The reflectivity of the coatings approached that of bulk material, almost fully dense coatings were obtained, and the coatings were of greater hardness than the bulk material. Higher gas heating temperatures resulted in greater coating densities and surface reflectivities. This work demonstrates that cold spray can be used to coat thin layers of aluminium onto other materials, which can then be polished to form composite reflectors. This provides a novel reflector with the reflectivity of aluminium, and the structural and thermal properties of the substrate material, allowing for greater flexibility in the creation of bespoke reflectors.