Feasibility Study of GaN Coatings by Cold Spray Technique

Gallium nitride (GaN) is a nitrided ceramic material used for its photocatalic properties. Conventional manufacturing processes are all under high temperatures which contribute to increase the cost of the manufactured structure. Cold spray (CS) process appears to be promising alternative technique with no risk of oxidation, thermal degradation, grain growth and low energy consumption. In this study, the feasibility of formation of GaN coatings on stainless steel (SUS304), aluminum alloy 1070 (A1070) and ITO glass was investigated by a downstream injection low pressure cold-spray system. Further, optical microscopy, SEM (scanning electron microscopy), X-ray Diffraction (XRD) and transmission electron microscopy (TEM) were used to characterize the coated surfaces. The deposition of GaN particles on all three substrates were observed to be due to a pseudo deformation of the agglomerated GaN particles. And the deposition results showed a saturation limit to the coating thickness with the number of repeated passes. According to the mass method, the deposition efficiency of GaN particles was enhanced with the increase of the particles and substrate temperature. Besides, the XRD spectra of the coating and the powder indicated that no phase transformation took place during the spray process.

Keywords: Gallium nitride, Cold spray, Pseudo deformation