| 摘要 |
Chromium is electrodeposited from a chromium plating bath, e.g containing chromic acid with sulphate and silicofluoride ions, in which is maintained a composition comprising (1) a sulphonated 2-alkylimidazole and (2) a disulphonated alkyl diphenyl oxide, e.g. in the amount of 0.001-1.0 g/1, as an anti-misting agent and fume suppressant. Compound (1) preferably has the formula: <FORM:1079647/C6-C7/1> wherein Ar is a phenyl or naphthyl ring incorporated into the imidazole structure through vicinal C atoms of the ring; M is a cation selected from H, NH4 and metals such as Na, K, Li, Cr, Ca, Sr, Ba, Mg, Ni, Fe or Cu; R' is alkyl containing 3-18 C atoms, R" is H, alkyl, aryl, aralkyl, omega-sulphonated alkyl or sulphonated aryl or aralkyl; R'" is H, alkyl or aralkyl; Y is a water soluble anion such as bromide, iodide, sulphate, acetate, metho/etho-sulphate, citrate or perchlorate; and a is 0 or 1. Compound (2) preferably has the formula: <FORM:1079647/C6-C7/2> wherein R is an alkyl group containing 6-18 C atoms, X is a cation selected from H, NH, and metals such as specified above for M; and n is 0 or 1. The composition, when stored, may additionally contain a chromate or dichromate to inhibit fungus or mould growth, and sodium bicarbonate as release agent for pellet compositions.
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