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 (300–1200 m/s) jet of small
particles between 1-50 micrometer size 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.
Eliminating the deleterious effects of high temperature on coatings and substrates offers
significant advantages and new possibilities and makes cold spray promising for many
industrial applications.