Development of Supersonic Free-Jet PVD with nano-sized culsters

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Ti-Al and TiN nano-composite coatings are prepared by depositing nano-clusters with supersonic free-jet PVD (SFJ-PVD). The authors have developed SJF-PVD as a new coating method in which a coating film is formed by depositing nano-clusters with very high velocity onto a substrate. The high velocity of nano-clusters is produced by the supersonic gas flow of inert gas. The gas flow is generated by pressure difference between evaporation and deposition chambers and accelerated to supersonic velocity (Mach 3.6) by specially designed supersonic nozzles. A smooth, compact and defect-free microstructure is formed both at the interface between substrates and coating films and inside the coating films. The microstructures of Ti-Al and TiN coatings have very fine grain size. It is confirmed with nano-indentation hardness tester that graded coatings of Ti/Ti-Al and Ti/TiN have graded hardness corresponding to the graduation of composition.