| 摘要 |
PURPOSE:To enable direct coating by preventing generation of yellow rust, by a method wherein a steel material such as soft steel is soldered in the high temp. region of a heating furnace having a non-oxidative atmosphere and, after cooling in the furnace, steam is sprayed in the steam spray chamber directly connected to said furnace to form a relatively stable Fe3O4 thin film. CONSTITUTION:In a soldering furnace 1 consisting of a work charging chamber 2, a preheating chamber 3, a heating furnace 4 and a furnace cooling chamber 5, a shutter 205 is opened to send works into the furnace 1 from a stand-by chamber 203 by a conveyor 6 and the works are preheated in the preheating furnace 3. The furnace 3 is preliminarily held under a non-oxidative atmosphere by the gas from a conduit 303. Succeedingly, the works which were preheated in the furnace 4 brought to a non-oxidative atmosphere by the gas from a conduit 403 are heated to 800-1,200 deg.C to perform soldering in said furnace. Subsequently, the works are cooled to 400-200 deg.C in the chamber 5 having a cooling pipe 502 arranged thereto and steam is sprayed to the cooled works in the steam spray chamber 7 provided to the downstream of a communication chamber 506 to form an Fe3O3 thin film on the surface of each work.
|
