| 摘要 |
PURPOSE:To improve the wear and corrosion resistances of the surface of a metallic pipe by introducing a reactive gas into a hermetically sealed space kept under low pressure and subjecting the surface of the pipe to plasma spraying. CONSTITUTION:A local reaction chamber 2 is placed on the inside of a metallic pipe 1, an exhaust system 8 is worked to keep the chamber 2 under low pressure and a reactive gas is fed from a reactive gas feeder 7. A spraying material having a high m.p. is then plasma-sprayed on the inside of the pipe 1 with a plasma spray gun 3. At this time, the reactive gas is activated by a plasma jet at a high temp., thermally decomposed and brought into a synthesis reaction with the molten spraying material, depositing a reaction product on the inside of the pipe 1. During the plasma spraying, the pipe 1 is rotated and the chamber 2 is moved along the inside of the pipe 1. Thus, the inside of the pipe 1 is coated with a layer 11 of a compound as the reaction product. |
