The Performance Of Reference Electrode And The Sacrificial Anodes In Low Conductivity Water At Room Temperature

Ag/AgCl electrode was of many advantages over others like easy preparation, maintance and applicable in fields, stability and short responsibility. It was referred as a very good candidate of many reference electrode in corrosion measurement of hash environment. In this thesis, Ag / AgCl electrodes are prepared by two techniques 1) electrolytic; 2) powder metallurgy.The potential of Ag/AgCl electrode electrolytically prepared were measured in 0.1 mol/L KCl,0.5 mol/L NaCl,1 mol/L KCl solution and geothermal water of different temperature(relative to SCE). The experimental results indicate the Ag/AgCl reference electrode potential is stable and with short response time. The potential of Ag/AgCl reference electrode made by powder compression preparation were also measured in geothermal water of different temperature. Their potential were stable compared to Ag/AgCl electrode made by electrolytic preparation. when the Ag and AgCl mass ratio of about 8:2, it consisted of best comprehensive properties. From the morphology by SEM,EDS and AFM,about 80 nm thick AgCl film deposited on silver with uniform size for Ag/AgCl reference electrode.In the presence and absence of cathodic protection of 4 types of Al-based sacrifice anode, Corrosion performance of Q235 steel in geothermal at elevated temperature was investigated by various electrochemistry techniques. LY12,6063,496 and Al-Zn-In alloys were selected as sacrificial anode material and electrochemical tests were carried out. The results showed that, the corrosion potential of Al-Zn-In alloy was more negative than Q235 for 120mV and galvanic current density was larger than that of the rest Al alloys. So Al-Zn-In alloy was ideal as sacrificial anode material.Corrosion mechanism of LY12,6063,496 alloys in geothermal water at room temperature and 55℃were studied by polarization curves and electrochemical impedance spectroscopy(EIS) combined with SEM and XRD measurements,the results showed that, a compact passive film appeared on LY12 alloy's surface after immersion at 55℃, the main components of the passive film were pure aluminum and CaCO3.6063 alloy didn't generate passive film, corrosion products on the surface were mainly Al0.90₄Ge0.096,CaCO₃,FeMoO₄.