| 摘要 |
<p>Polycyclic, condensed, aromatic hydrocarbon cpds. contg. at least one OH gp. bonded directly to a 6C ring, are used as catalytic additives (A), to a nitrate-based aq. bath soln. for electrolytically detaching metal coatings, esp. Ni coatings, from Fe-contg. substrates, esp. steels having a low C content, partic. under 0.1%. (A) pref. consists of one or more of alpha-, beta-naphthol, alpha-, beta-bi-naphthol or their nitro cpds. or alkali-, ammonium- or amine salts, e.g. Na- or ammonium naphtholate or an amino-naphthol. (A) can also be anthrahydroquinone or its alkali-, ammonium- or amine salt. The water-solubility of (A) is improved by mixing with an alcohol or alkaline medium, e.g. NaOH. A pref. bath contains (a) 10-500(100-200) g/l nitrate component, esp. amine nitrate, (b) 0.1-50 g/l (A) esp. 2-5 g/l naphthol or anthrahydroquinone and (c) sufficient HNO3 to set pH 4-10(6-8). (A) are less toxic, corrosive and malodorous than phenol, can be handled more easily and cause less environmental pollution. Short stripping times are achieved without attacking the substrate.</p> |
