| 摘要 |
<p>An aqueous solution for chemically brightening aluminium contains hydrofluoboric acid, nitric acid and a soluble salt of a metal which is displaced in solution by aluminium. The metal may be copper, zinc, silver or cadium; the salt specifically disclosed is copper nitrate. The solution may also contain boric acid, acetic acid, phosphoric acid, ammonia, ammonium salts glycerol, glycols and ethers of the alkylene glycols, e.g. ethylene glycol mono- or diethyl ether. Sulphates, which are objectionable, may be precipitated by barium acetate. Examples are given of compositions suitable for brightening aluminium in two purity ranges. The Provisional Specification also refers to the brightening of aluminium alloys.</p> |
