镀锌后工件通常在含有铬酐、硫酸和硝酸的溶液中进行钝化处理。随着使用时间的增长,钝化液中锌含量逐渐增多,使溶液的 pH 值逐渐上升。当锌含量大于30克/升时,pH 值迅速升高,溶液往往因此而报废。为此在生产中,常常需要测定钝化液中的锌含量。 Galvanized workpieces are usually passivated in a solution containing chromic anhydride, sulfuric acid and nitric acid. With the growth of the use of time, the zinc content of passivation solution gradually increased, the pH value of the solution gradually increased. When the zinc content is more than 30 g / L, the pH rapidly increases and the solution is often discarded. For this reason, it is often necessary to determine the zinc content of the passivating solution in production.