Study on Determination Method of P Ratio and Crystal Coverage Rate of Phosphating Film on Galvanized Steel Plate

In order to correctly evaluate the phosphating effect on the surface of galvanized steel plate,the two most typical phosphating film evaluation methods,namely P ratio and crystal coverage rate determination method were compared and analyzed.Different methods were used to determine P ratio and crystal coverage rate of phosphating film,respectively.Results showed that when the accuracy of XRD data of phosphating film could not be determined,the method of measuring the diffraction peak area of P phase and H phase was more accurate than that of determining the P ratio.When the XRD data of phosphating film was accurate,the P ratio calculated by directly measuring the diffraction intensity of P phase and H phase was more accurate.When there were many grain shapes and complex grain distribution in SEM morphology,the crystal coverage rate of phosphating film could be measured more accurately according to Q/JL J130012-2018.When the grain distribution was relatively uniform,the crystal coverage rate of the phosphating