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Cold spray produces high quality coatings for a wide spectrum of applications.
Cold Gas-Dynamic Spray (or simply Cold Spray) is a process of applying coatings by exposing a metallic or dielectric substrate to a high velocity (300 to 1200 m/ s) jet of small (1 to 50 (mu)m) particles accelerated by a supersonic jet of compressed gas. This process is based on the selection of the combination of particle temperature, velocity, and size that allows spraying at the lowest temperature possible. In the cold spray process, powder particles are accelerated by the supersonic gas jet at a temperature that is always lower than the melting point of the material, resulting in coating formation from particles in the solid state. As a consequence, the deleterious effects of high-temperature oxidation, evaporation, melting, crystallization, residual stresses, debonding, gas release, and other common problems for traditional thermal spray methods are minimized or eliminated.
Process history
The cold spray process was originally developed in the mid-1980s at the Institute of Theoretical and Applied Mechanics of the Russian Academy of Science in Novosibirsk by A. Papyrin and colleagues. They successfully deposited a wide range of pure metals, metal alloys, and composites onto a variety of substrate materials, and demonstrated the feasibility of cold spray for various applications. A U.S. patent was issued in 1994, the European patent in 1995.
In the United States, the first research in the field was conducted in 1994-95 by A. Papyrin with a consortium formed under the auspices of the National Center for Manufacturing Sciences (NCMS) of Ann Arbor, Mich.. The membership included major U.S. companies such as Ford Motor Company, General Motors, General Electric - Aircraft Engines, and Pratt & Whitney Division of United Technologies. This consortium established the first U.S. cold spray capability, and the group published property measurements for several cold-sprayed materials.
At the present time, a wide spectrum of research is being conducted at several research centers, including the Institute of Theoretical and Applied Mechanics of the Russian Academy of Science; Sandia National Laboratories; the Pennsylvania State University; ASB Industries Inc., in the United States; the University of Bundeswehr, Germany; and others.
These studies are related to jet gas dynamics, physics of high-speed particle impact, various powder materials, and development...