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怎样通过实验来评定彩涂板化学转化膜的质量

发布者:唐山天物彩板有限    发布时间:2019-09-03 09:28
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怎样通过实验来评定彩涂板化学转化膜的质量

唐山天物彩板专注彩板16年——宜昌彩涂板型号_宜昌彩涂板货源充足   更多信息请拨打网站上方电话咨询了解


  通过实验来评定彩涂板化学转化膜质量的方法主要有

  (1)显微镜法。显徽镜法是通过以金相显微镜或电子显微镜将彩涂板化学转化膜放大到100~1000倍,观察其结晶形状、尺寸大小及排列等微观结构情况。结晶形状以柱状晶为好,结晶尺す小些为好,一般控制在几十微米以下,排列越均匀,孔隙率越小越好。

  (2)厚度(或重量)测定法。将试样浸在75℃,质量分数按国标规定的铬酸溶液中10-15min以去除彩涂板化学膜,然后除去膜层前后的重量差而求得膜重。

  (3)腐蚀性能测定法。腐蚀性能测定法最常用的是按国家标准GB6807-86所规定的进行,可采用3%氯化钠水溶液于15-25℃浸渍,或用硫酸铜溶液点滴,硫酸铜点滴液配方如下:CuSO4:5H1O41g/L,NaCl35g/L,HCl13mL/L。也可以在涂层后通过盐雾试验进行考核耐温热试验或循环周期试验等。

  (4)抗冲击试验法。常常是进行涂装后一起测定,当用49Ncm载荷对涂装后的磷化板进行冲击试验时,当冲击后的样板的反面冲击点不产生放射性裂纹时,即可确定该化学转化膜的质量较好。

  (5)二次附着力测定法。彩涂板化学转化膜涂装后测定的附着力为一次附着力。在一定条件下进行耐温水实验后测定的附着力称为二次附着力。一般是在耐水试验后的样板上用划格法作附着力的测定,以胶带剥离后观察涂膜脱落等级,一般均为平行比较实验。

  (6)膜层孔隙率测定法。取14%的NaCl和3%的铁氰化钾溶液,表面活性剂的质量分数为0.1%的蒸馏水溶液,保存在褐色瓶中24h,用滤纸过滤。使用时将滤纸切成长、宽均为2.5cm的纸片,用塑料镊子将纸片浸入上述溶液中,提出滴净多余试液,将它覆盖在待测的化学膜表面,经过一段时间(1min)后将试纸拿掉,观察膜层表面,有蓝色斑点处表示有孔隙部分。

  (7)化学膜的耐碱性。化学膜在0.1mol/L的氢氧化钠碱液中浸渍、温度25℃,比较5min前后的质量差,可以得到化学膜在碱液中的溶解量。

  (8)化学转化膜的耐酸性。比较彩涂板化学转化膜在pH值为2的酸液中的溶解量,来评价彩涂板化学转化膜的耐酸性。

  (9)化学转化膜P比。P比最初定义为P/(P+H),其中P为磷酸二锌铁,H为磷酸锌,因此P比的高低表示彩涂板化学转化膜中磷酸二锌铁所占比率的高低。P比高的彩涂板化学转化膜,其结晶水不易失水,也不易复水,其耐蚀性比低P比的化学转化膜好。

The main methods of evaluating the quality of chemical conversion membranes by experiments are as follows.
 
 
(1) Microscopic method. By means of metallographic microscope or electron microscope, the chemical conversion film was enlarged to 100-1000 times, and its crystal shape, size and arrangement were observed. The columnar crystal is the best crystalline shape, and the smaller the crystallization ruler is, the better it is. Generally, it is controlled under tens of microns. The more uniform the arrangement is, the smaller the porosity is.
 
 
(2) Thickness (or weight) determination. The samples were immersed at 75 C and the mass fraction was 10-15 minutes in the chromic acid solution prescribed by the national standard to remove the chemical film, then the weight difference before and after the film was removed and the film weight was calculated.
 
 
(3) Corrosion test method. The most commonly used method for determination of corrosion performance is according to the national standard GB6807-86. It can be dipped in 3% sodium chloride solution at 15-25 ~C or dripped with copper sulfate solution. The formula of copper sulfate drip is as follows: CuSO4:5H1O41g/L, NaCl35g/L, HCl13mL/L. It can also be tested by salt spray test or cycle test after coating.
 
 
(4) Impact test method. It is often determined together after coating. When the impact test of the coated phosphating plate is carried out with 49Ncm load, the quality of the chemical conversion film can be determined when the reverse impact point of the impact sample does not produce radioactive cracks.
 
 
(5) Secondary adhesion test. The adhesion of chemical conversion film after coating is determined as primary adhesion. Under certain conditions, the adhesion determined after the experiment of temperature-resistant water is called secondary adhesion. Generally, the adhesive force is measured by the scratch method on the sample after water resistance test, and the film falling off grade is observed after stripping of the tape. Generally, it is a parallel comparative experiment.
 
 
(6) Membrane porosity measurement method. Take 14% NaCl and 3% potassium ferricyanide solution and 0.1% distilled water solution of surfactant. Store in brown bottle for 24 hours and filter with filter paper. When used, the filter paper is cut and grown to 2.5 cm wide. The paper is immersed in the above solution with plastic tweezers. The excess test solution is dripped and covered on the surface of the chemical film to be measured. After a period of time (1 minute), the test paper is removed and the surface of the film is observed. The blue spots indicate the porous part.
 
 
(7) alkali resistance of chemical film. The chemical film was impregnated in 0.1 mol/L sodium hydroxide alkali solution at 25 C. The solubility of the chemical film in the alkali solution was obtained by comparing the quality of the film before and after 5 minutes.
 
 
(8) The acid resistance of the chemical conversion film. The acid resistance of chemical conversion membrane was evaluated by comparing the solubility of chemical conversion membrane in acid solution with pH 2.
 
 
(9) P ratio of chemical conversion film. P ratio was initially defined as P/(P+H), where P is ferrozinc phosphate and H is zinc phosphate. Therefore, the ratio of P indicates the proportion of ferrozinc phosphate in the chemical conversion film. The chemical conversion film with high P ratio has better corrosion resistance than the chemical conversion film with low P ratio.
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