Method and apparatus for low pressure cold spraying

Abstract

A cold spraying process for forming a coating of powder particles sprayed in a gas substantially at ambient temperature onto a workpiece is improved by placement in a low ambient pressure environment in which the pressure is substantially less than atmospheric pressure. The low pressure environment acts to substantially accelerate the sprayed powder particles, thereby forming an improved coating of the particles on the workpiece. The low ambient pressure environment is provided by a vacuum tank coupled to a vacuum pump and having both the workpiece and a cold spray gun located therein. The cold spray gun is coupled to a source of pressurized inert gas as well as to a feeder for providing a flow of the powder to be sprayed. A gas compressor downstream of the vacuum pump compresses gas from the vacuum tank for recycling to the source of pressurized gas. The source of pressurized gas is coupled to the cold spray gun where it may be heated by passing through a heating coil coupled to a source of electrical power, before being sprayed from a nozzle onto the workpiece. An arrangement of valves and injection ports enables the powder flow to be introduced at a selected one of a plurality of locations along the heating coil and the nozzle.

Dependencies are inferred from the claim text.