| 摘要 |
1413649 Accelerator for pickling bath BASF WYANDOTTE CORP 10 Nov 1972 [11 Nov 1971] 7773/75 Divided out of 1427269 Heading C7E Cleaning of a metal surface by an acid bath is accelerated by adding thereto an additive comprising a nitrite ion source, water and NH 3 . The relative amounts may be 25-35% NO 2 -source, e.g. K, N 9 , or NH4 nitrate, up to 5% ammonia, and 65-75 wt per cent water; 1-4% of the additive is added to an acid bath, e.g. of HNO 3 , used to clean Al, brass or Cu smutted by caustic etching or anodizing. |
