Corrosion and Scaling of Metal Pipes in Simulated Geothermal Water

Ryznar index was used to judge the type of the simulated geothermal water. Uniform Ni-P eletroless coating was prepared on 20 steel surface via eletroless plating. Stereomicroscope, immersion test and electrochemical methods were used to study the corrosion and scaling properties of Ni-P electroless coating steel, 304 stainless steel and 20 carbon steel in simulated geothermal water. The results showed that the scales on the surface of Ni-P electroless coating steel were little and dispersed, but those of 304 stainless steel were thick and concentrated. 20 carbon steel showed many scaling and corrosion products. In addition, Ni-P electroless coating steel and 304 stainless steel were not corroded after immersing in simulated geothermal water, but the former had better corrosion resistance in terms of electrochemical tests, because the Ni-P electroless coating steel had smaller corrosion current density and larger impedance value. So the Ni-P electroless coating steel has better anti-scaling and corrosion resistance performance rather than 304 stainless steel and 20 carbon steel.