Thermal spray apparatus

摘要

Thermal spray apparatus capable of directing plasticized powders against a substrate for deposition of a protective coating thereon is disclosed. Various structural details of the apparatus of the present invention enable the attainment of high particle velocities without melting the particles. The apparatus is built around the concept of reducing the temperature of a hot plasma stream after the hot plasma stream is generated. Particles are injectedinto the hot plasma stream only after the medium is cooled. In detailed embodiments, a generated plasma is cooled by the addition of a diluent gas or by passing the generated plasma through an elongated heat exchanger upstream of the point at which the powders are to be injected.