| 摘要 |
PURPOSE:To eliminate the adhesion of corrosion products and reaction residue, by providing chromium oxide converted from a chromium compound with heat on the surface of a substrate for a reaction vessel. CONSTITUTION:A substrate is a reaction vessel, piping or the like for handling corrosive gas. After a chromic acid solution of specific gravity of 1.6-1.7 is applied onto the inner surface of said reaction vessel or piping, the inner surface is heat treated. This cycle is repeated several times, while raising the temp. within the range of a heating temp. of 310-700 deg.C. As a result, a dark green chromium oxide layer is formed on the inner surface. Hereon, a chromium compound, e.g. chromium chloride, chromium nitrate, magnesium chromate or a soluble complex chromium compound, may be used instead of said chromic acid. |
