In situ synthesis of titanium-aluminides in coating with supersonic free-jet PVD using Ti and Al nanoparticles

This paper presents supersonic free-jet PVD (SFJ-PVD) as a new coating technology for structural materials. In SFJ-PVD, coating film is formed by high velocity impact of solid nanoparticles to base materials. This method is composed of evaporation and deposition processes. In the evaporation process, the source material evaporates to form nanoparticles in an inert gas atmosphere. In the deposition process, nanoparticles are deposited on base materials to form coating film with supersonic gas flow. The gas flow is generated by pressure difference between the evaporation chamber and the deposition chamber. The flow of the gas is accelerated through a specially designed supersonic nozzle at the supersonic flow of 3.6 Mach number. With SFJ-PVD, mixed Ti and Al nanoparticles produce high-density coatings of titanium-aluminides without voids and cracks. They synthesize titanium-aluminides on the substrate at 800 K.