| 摘要 |
PURPOSE:To inexpensively and economically form a strong corrosion protective film, by cooling a cast-iron pipe after annealing to control the temp. to the prescribed value, thermally spraying a corrosion-resisting metal on the above pipe, and then coating the thermally sprayed film with a protective material while the above pipe is maintained at the prescribed temp. CONSTITUTION:A cast-iron pipe 1 prepared in a casting stage is annealed in a high-temp. furnace 2. The cast-iron pipe 1 of about 700 deg.C after annealing is subjected to surface preparation by means of air blowing, water cooling, etc., and the temp. of this pipe 1 is finally controlled to about 150-300 deg.C, a temp. at which a thermally sprayed film with high adhesive strength can be formed in the following stage. While rotating this cast-iron pipe 1 on rotating rolls 3, a metal having corrosion resistance, such as Al and Zn, is thermally sprayed by means of a thermal spraying gun 4 to form a thermally sprayed film 5. Subsequently, while this cast-iron pipe 1 is held at the prescribed temp., a protective material, such as paint and coating material, is sprayed on the pipe 1 by using a spray nozzle 6, and then, melting and baking are applied by means of the retained heat of the cast-iron pipe 1, by which a protective film 7 can be applied to the above thermally sprayed film 5. |
