Comparative Analysis on Several Test Methods of Tin Content in Copper/Tin Plating Coating

In this paper, the contents of main components of copper/tin plating coating on the surface of hydraulic cylinder were compared and analyzed by potassium iodate titration method, inductively coupled plasma atomic emission spectrometry (ICP - AES), scanning electron microscope (SEM/EDS) and X - ray energy spectrometer (EDX). Results showed that the tin contents measured by potassium iodate titration, ICP - AES, SEM/EDS and EDX were (7.30±0.17)%, (7.07±0.15)%, (4.33±0.47)% and(16.69±2.71)% respectively. ICP - AES was based on the spectral analysis of copper/tin plating coating solution, and its test result was similar to the component test result of potassium iodate titration method, which could represent the accurate content of plating coating components; SEM/EDS was a surface analysis method for the plating coating, and the test results were relatively low, reflecting the uneven tin content inside and outside the coating; EDX energy spectrometer was unable to focus and difficult to calibrate. Although the test was fast, the error was large. The test accuracy relied on the calibration of energy spectrometer and the focusing of sample surface. By comparing different test methods, it could be concluded that potassium iodate titration method, ICP - AES and SEM/EDS were all feasible to detect tin content in copper plating coating. Among the three methods, ICP - AES had highest accuracy, SEM/EDS had fastest test speed, potassium iodate titration method had lowest cost and accurate results. This work would provide test basis for field test.