Attrition and cryogenic milling production for low pressure cold gas spray and composite coatings characterization

Abstract

Inside the wide field of thermal spray, the possibility to spray ceramic nano-particles by Low Pressure Cold Gas Spray (LP-CGS) represents an interesting and innovative trend. In this work, titanium dioxide TiO2 nanoparticles were mixed with a polymer in order to obtain a tailor-made nanocomposite powder and afterwards cold-sprayed coatings were produced, which might be attractive for their photocatalytic activity. Firstly, two different routes were used to incorporate the ceramic nanoparticles within the polymeric matrix: Attrition Milling (AM) and Cryogenic Milling (CM). Samples composition was not varied, while milling time was changed. The main objective was to investigate the mechanical physical union of TiO2 nanoparticles around polymeric microparticles. The effect of ceramic particles on the structure and morphology of the polymer, as well as the influence of the temperature of the different combining processes were studied. The fundamental properties of the nanocomposite mixture were investigated by Scanning Electron Microscopy (SEM), Laser Scattering (LS Beckman Coulter) and X-ray Diffraction (XRD). Secondly, the best mechanically combined mixture was selected in order to be sprayed by LP-CGS technology. Adequate spraying parameters were chosen in order to develop different composite coatings. Thickness, roughness and porosity of manufactured products were measured.