There is little study on the selection of liquid of pre - filming after the acid wash by hydroxy ethidine phosphonic acid (HEDP). Whereas the proper passivation by pre - fihrang is necessary prevent re - rusting of the metal surface after acid wash.

• 羟基乙叉二膦酸酸洗后预膜液的选择较少有人研究,而适当的预膜钝化是防止酸洗后金属表面返锈的必要措施。