| 摘要 |
<p>Surfaces of articles made from alloys contg. 40-95% Cu, esp. Al-bronze or Al-Ni-bronze are lastingly brightened by treatment with a soln. contg. urea or its S-free deriv. and an acid having a pK value =6, pref. 3-5 (pref. acetic or tartaric acid). This soln. is superior to the normally used dichromate solns. as it is nontoxic, cheap, can be disposed of to sewers, can be used repeatedly upon replenishment of urea and acid, and does not attack the metal.</p> |
