abstract |
The invention relates to a metal treatment fluid, with a pH-value in the range from 5.5 to 8.5, comprising a combination of (a) one or several carboxylic acids, or carboxylic acid amides, (b) one or several organophosphonic acids, (c) a buffer system for the given pH-range and (d) one or several nitrogen compounds, selected from organic amines or nitrogen-containing heterocycles. |