利用电化学检测技术判定冷轧汽车板磷化膜的质量。利用恒电流/恒电位仪, 测试磷化膜在磷酸盐溶液中的开路电位与时间的关系曲线, 根据该曲线出现拐点的时间结合生产经验可以判定磷化膜的质量。结果表明, 磷化膜质量与曲线上拐点出现时间密切相关, 拐点出现越晚, 膜质量越好, 拐点出现的时间t≤300 s时, 磷化膜质量差; 拐点出现时间700 s＜t≤1 000 s时, 磷化膜质量好; 拐点出现时间t＞1 000 s时, 磷化膜质量很好。

The quality of phosphate coatings on cold rolled automobile steel sheets was judged by electrochemical technology. The relation currve between the open circuit potentials of phosphate coatings and time was tested in phosphate solution by constant current/potentiostat. The quality of phosphate coatings was determined at the inflection point time of the curve. The results indicates that when inflection point time(t)≤300 s, the quality of phosphate coatings is weak; when 300 s＜t≤700 s, the quality of phosphate coatings is common; when 700 s＜t≤1 000 s, the quality of phosphate coatings is good; when t＞1000 s, the quality of phosphate coatings is excellent.