| 摘要 |
1360266 Phosphating compositions PYRENE CHEMICAL SERVICES Ltd 7 Oct 1971 [30 Oct 1970] 46801/71 Heading C7U A phosphating composition comprises an alkali metal or ammonium acid phosphate and an acidifying agent comprising sulphamic acid in an amount such that the aqueous solution has pH 3-6. The phosphate is preferably MH 2 PO 4 where M = K, Na, NH 4 , and the amount of NH 2 SO 3 H is 0À5-10 wt per cent based on the weight of phosphate; where 0À5-3% NH 2 SO 3 H is used, H 3 PO 4 may also be added to provide the desired pH. The composition may also include a surfactant, e.g. a polyoxyalkylenated alkyl phenol or fatty alcohol or an ethylene oxide/ propylene oxide condensate, or an accelerator such as NO 3 -, NO 2 -, ClO 3 -, molybdate, or an aromatic nitro-compound with a phenolic function. A solid composition may be formulated comprising (wt per cent) 75-95 phosphate, 0À4-10 acidifying agent, 0-15 surfactant and 0-10 accelerator; 5-90 g of this is dissolved per litre to give a phosphate concentration preferably of 5-80 g/l. Steel may be treated with the composition, and post-treated in a solution containing hexavalent Cr or hexa- and tri-valent Cr. |
