Anti-scaling characterization of PTFE/PPS composite coating in the geothermal water environment

The anti-scaling performance of 304 stainless steel pipe, epoxy-silicone coating, polyphenylene sulfide (PPS) coating and polytetrafluoroethylene (PTFE)/PPS coating was studied by the methods of image binarization processing, scanning electron microscopy, energy dispersion spectrometry, electrochemical test and so on. The results indicate that the scale formed on the different coatings consisted of a needle-like substance and its main components are CaCO₃. The surface energy of PTFE/PPS coating is lower than that of PPS coating, which could restrain effectively the scaling nucleus to form on the sample surface and affect the growth way of nucleus. After the samples were immersed in the static simulated geothermal water for 10 days, the mass of scaling on the PTFE/PPS coating surface was equal to 37.3% with respect to that on the 304 stainless steel. Furthermore, PTFE/PPS coating has a better anti-corrosion performance in the simulated geothermal water.