| 摘要 |
PURPOSE:To form a coated film having improved adhesion and durability on a heat-transfer tube, by filling the space extending from the finned part of a heat-transfer tube to be thermally sprayed by plasma to a plasma gun with an oxygen-free atmosphere, and reducing and removing the useless matter in the space. CONSTITUTION:The heat-transfer tube 1 (or finned plate) to be thermally sprayed by plasma is sent into a chamber 4 by means of a tube holder 3, and thermally sprayed by the plasma gun 2. At this time, an inert gas is sent into the space extending from the finned part of the tube 1 to the plasma gun 2 to form an oxygen-free atmosphere, the inert gas is mostly sucked by an exhaust fan 6 through a filter 5, and the discharge of the gas into the atmosphere and the circulation to the chamber 4 are controlled by control valves 7. As a result, the infiltration of oxides into a coated film and the oxidation of the coated film can be controlled, and the coated film having high adhesive strength, durability, and excellent heat radiation efficiency is formed on the heat-transfer tube 1. |
