| 摘要 |
<p>A method is disclosed for detecting the presence of a chromate coating on the surface of aluminum. The method includes the application of a few milliliters of a liquid composition to the surface of the aluminum. The liquid composition includes one part of potassium permanganate having a concentration of at least 0.5 weight/volume percent and one part of concentrated sodium hydroxide saturated in an aqueous solution. The liquid has a beet-red pigmentation which undergoes a color change to a bright blue-green pigmentation when it reacts with a chromate coating. If no coating is present on the aluminum surface, the liquid will react with the aluminum and the alloys contained therein to produce a beige color.</p> |
