How to Determine Coating Porosity by Electrolytic Coloring

       The distribution, shape and size of pores can be directly displayed by electrolytic coloring. The schematic diagram of the testing device is shown in Figure 8-2. The sample size is 40mmx60mm. The test solution (taking aluminum as an example) is an aqueous solution of K3Fe(CN)610g/L+K4Fe(CN)6.3H2O10g/L+NaCI60g/L, and the test temperature is 16℃～28.5℃. The test method is as follows;



(1) Spray aluminum with a thickness of 0.05mm to 0.07mm on the iron plate, and make a standard size sample according to the regulations.

(2) Immerse the filter paper in the test solution, as shown in Figure 8-2, place the filter paper between the cathode and the coating, and place a weight on it to ensure good contact.

(3) Direct current electrolysis was applied, the current density was 2 mA/cm2, and the time was 5 min.

(4) After electrolysis, take out the filter paper. The pores in the spray coating are accurately colored on the corresponding positions of the filter paper. The pores are dark blue, and the rest are blue. Check the number of pores with the naked eye or a 20x magnifying glass to get the pores. Rate.