| 摘要 |
PURPOSE:To inhibit the generation of a spark due to the cell action from occurring, to eliminate the possibility of adversely affecting the quality of a strip and to prolong the life of the roll by thermally spraying nickel on a cast iron roll prior to coating the roll with a specific ceramic material. CONSTITUTION:This immersion roll 1 is used in an alkali salt bath for the acid-washing pretreatment in a continuous sheet annealing line and manufactured by thermally spraying nickel on a cast iron roll 2 to form a nickel layer 3 having >=50mum thickness and then a ceramic material on the nickel layer 3 to form a ceramic layer 4 which has 50 to 200mum thickness and high adhesion strength. This ceramic layer 4 consists of ZrO2 alone or (ZrO2+(25 to 50wt.%) MgO). Further, failures such as penetration of the sodium hydroxide solution to the cast iron roll can be prevented from occurring by sealing the fine communicative holes in the ceramic coating film through subjecting the ceramic layer 4 to sealing treatment with either SiO2 or ZrO2 or a mixture of them. |
