| 摘要 |
<p>A kinetic or cold spraying apparatus for producing a coating or a structural part includes an outer Laval nozzle (20) and an inner powder feed pipe (18) coaxial with the nozzle (20). The powder to be sprayed is entrained in a first gas jet which is caused to flow through the feed pipe (18) into the Laval nozzle (20), the first gas issuing from the Laval nozzle (20) at supersonic velocity and impacting against a substrate so as to form the coating or structural part. A second gas jet is also accelerated through the Laval nozzle (20), the second gas jet passing around the distal end of the powder feed pipe. The second gas acts as a buffer against collisions of the powder with the divergent section (26) of the Laval nozzle (20). The first gas is preheated upstream of the Laval nozzle (20). The distal end (28) of the pipe (18) terminates in the throat (24) of the Laval nozzle (20) or up to 1 mm away from the throat on either side thereof.</p> |
