| 摘要 |
PURPOSE:To dissolve and remove oxide scale on the surface of stainless steel by adding an adhesive to a mixed soln. having a specified composition contg. hydrogen peroxide, phosphoric acid and hydrogen fluoride so as to inhibit the dissolution of the stainless steel in the acid and by applying the resulting pasty acid liq. to the surface of the stainless steel. CONSTITUTION:An adhesive is added to a mixed soln. contg. 1.5-3vol% hydrogen peroxide as 30% soln., 4.5-7vol% phosphoric acid as 1.7 specific gravity soln., and 1-3vol% hydrogen fluoride as 30% soln. to prepare a pasty acid liq. A material which is not decomposed by hydrogen peroxide and gives viscosity to the cleaning soln., e.g., a compound of an alkaline earth metal, colloidal silica powder or activated clay powder is suitable for use as the adhesive. The pasty acid liq. is applied to the surface of stainless steel. Thus, the dissolution of the stainless steel in the acid is inhibited, the corrosion of the weld zone affected by heat at about 650 deg.C by the acid is especially prevented, and oxide scale formed on the surface of the steel is efficiently dissolved and removed. Spattered slag on the weld zone is also removed by efficient cleaning. |
