Hull cell test was conducted using steel sheet as substrate in a 250 mL of potassium zinc plating bath with o-chlorobenzaldehyde as primary brightener at 1 A for 5 min. The zinc coatings obtained were treated by low-Cr iridescent passivation after etching in 2wt% dilute HNO3 solution and rinsing. KC1 was gradually added to the passivation bath comprising 5 g/L CrO3 at room temperature (9 °C in winter). The blow-dried passivation film has good adhesion strength but looks hazy when the KC1 content is <10 g/L. The passivation film on the zinc coating electroplated under agitation is totally clear without haze when the KC1 content is up to 20 g/L. The results of heating test showed that the optimal passivation temperature is 25 °C, at which the iridescent passivation films on the zinc coatings prepared in a wide range of current density have strong reddish color in both frontal and oblique views and good adhesion strength.%采用以邻氟苯甲醛作主光剂的氯化钾镀锌液,在250 mL赫尔槽中以1A电流对钢试片镀5 min,经2％(质量分数)稀硝酸出光并水洗后进行低铬彩钝.于冬天室温9℃时在含铬酸酐5g/L的基础钝化液中逐渐加入KCl.当KCl含量低于10g/L时,吹干后的钝化膜附着力好,但发雾严重；当KCl含量达到20 g/L时,搅拌状态下镀得的试片在钝化后完全不发雾.加热试验表明,25℃为最佳钝化液温,可在宽电流密度范围内获得正看与侧看均以色泽浓鲜、偏红且附着力良好的彩钝层.
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