Considering cold spray for additive manufacturing

Cold spray is beneficial in applications that use heat-sensitive substrate materials or those with difficult-to-reach spray areas. One example involves spraying inside small-diameter, heat-sensitive tubes or bores to provide corrosion resistance. Cold spray produces deposits that are oxide-free and fully dense with acceptable mechanical properties. The process requires heating of a pressurized carrier gas that is passed through a 'DeLaval' convergent-divergent nozzle. The divergent section of the nozzle creates a supersonic gas jet as the carrier gas expands toward the nozzle exit. The spray material is injected into the gas jet either upstream or downstream of the nozzle throat. Each material requires a specific minimum particle velocity to successfully form a well bonded and dense deposit, depending on the process temperature.