彩钢板涂层前表面处理化成段缺陷及原因

首先检查彩钢板化学转化膜铬含量是否控制在 30~34mg/m之间。另由于化成处理段的缺陷主要是出现完全缺膜、局部缺膜、膜质泛黄和挂灰等几种现象，因此检查时还应该有针对性地进行，检查的取样方法:生产过程中在卷头、卷尾留少量不覆盖有机涂料的化涂板作为检查用取样，并定期送至化涂液厂家检测化涂层铬含量，彩钢板还可采用X射线荧光、衍射、等离子、原子吸收或化学分析法方法测定铬含量。除此之外还可以根据以下所述的表面的膜质情况找出缺陷的成因。

形A完全缺膜原因
(1) 彩钢板磷化液成分比例失调，磷酸二氢盐含量低或游离酸太高;(2)脱脂不净;
(3)化成过程中的环境温度低，时间短;(4)含杂质多，如sO;多;
(5)钢带表面有硬化层。
 B 钢带表面挂灰原因
(1)化学液料盘中沉淀太多，施工时沉淀被搅起，附在钢带上;(2)学液中氧化剂过量;
(3)化学液温度高。
 C化学转化膜泛黄原因
(1) 酸比失调;
(2)化成时环境温度低，时间短;(3)面有过现象;
(4) 氧化剂量少;
(5)Fe2*含量过高;
(6) C1”含量多;

(7)杂质。

Firstly, check whether the chromium content of chemical conversion film of color steel plate is controlled between 30-34mg / m. In addition, due to the defects in the treatment section, there are several phenomena such as complete lack of film, partial film shortage, yellowing of film quality and ash hanging. Therefore, the inspection should be conducted pertinently. The sampling method: in the production process, a small amount of chemical coating plate without covering organic coating shall be left at the coil head and tail for inspection, and the chromium content of chemical coating shall be sent to the manufacturer of chemical coating regularly, The chromium content of color steel plate can also be determined by X-ray fluorescence, diffraction, plasma, atomic absorption or chemical analysis. In addition, the causes of defects can be found according to the film quality of the surface described below.

The reason of complete membrane defect of shape a

(1) The proportion of phosphating solution in color steel plate is out of proportion, the content of dihydrogen phosphate is low or the free acid is too high（ 2) Degreasing is not clean;

(3) The temperature of the environment is low and the time is short（ 4) There are many impurities, such as so; Many;

(5) The steel strip has a hardening layer on the surface.

B. reasons for ash hanging on the surface of steel strip B

(1) Too much precipitation in the chemical liquid tray, which is stirred up during construction, attached to the steel strip（ 2) The oxidant in the study liquid is too much;

(3) The temperature of chemical solution is high.

The reasons of yellowing of C chemical conversion film

(1) Acid ratio is out of order;

(2) The temperature of the environment is low and the time is short（ 3) There is a phenomenon in the surface;

(4) The oxidation dose is low;

(5) Fe2* content is too high;

(6) C1 "content is much;

(7) Impurities.