Cold spray coatings

Cold spray (CS) technique is a process whereby metallic particles are utilized to form coatings using ballistic impact upon substrate materials. This technique is based on the high velocity (300-1500 m/s) impinging of small solid particle (generally 10-50 mm in diameter) on substrates. In this process, the particles are accelerated by the supersonic gas jet at the heated gas temperature, which is usually lower than melting temperature of powder materials. Consequently, this process solved the problem of thermal spraying, such as high temperature oxidation, phase transformation etc. Until now, the CS has a good track record in almost metallic coatings, such as copper, stainless steels, Ni base superalloys etc. Recently, some kinds of ceramics and polymers can be coated by the CS. The CS is expected as not only coating technique but also thick film formative technique. In this article, the present situation and future prospects of the CS are explained.