Zhang Jinglei

Electrochemical corrosion behavior of steel in the juncture area of sea clay and sand

Corrosion behavior of steel in the juncture area of sea clay and sand was studied. The results show that galvanic corrosion occurred between steel samples buried in sea clay and sand, and that the polarity of the galvanic cell reversed after some testing later. The cause of reversing of polarity is discussed.

Electrochemical evaluation of dissolution characteristics of Al-based sacrificial anodes in seawater

The surface dissolution characteristics of Al-based sacrificial anodes in seawater have never been expressed numerically except in words such as uniform dissolution, non-uniform dissolution, serious localized dissolution, etc. An electrochemical method was developed in our laboratory to evaluate the above mentioned characteristics quantitatively. The Al anode samples are polarized to −1000 mv (vs. Ag/AgCl reference electrode) in seawater at 25±1°C, and anodic current-time curves are recorded simultaneously. Then the coulometric density was calculated with the aid of a planimeter. By comparing the coulometric densities of these samples, the surface dissolution characteristics of anodes can be evaluated quantitatively.

Effects of Bi and Ti on electrochemical property of Al-Zn-In sacrificial anode

The effect of trace elements Bi and Ti on the electrochemical property of aluminium sacrificial anode in seawater was studied. Different amounts of Bi and Ti were alloyed with Al-Zn-In to make 9 types of aluminium sacrificial anodes. Anode closed circuit potential, discharge capacities and current efficiencies were measured in the laboratory. The results show that the effect of Bi is greater than that of Ti.

Cathodic protection of A1 hull ship

Heavy paint coating loss and localized corrosion of the Al alloy hull occur red after less than a years service of a ship at sea. Examination and analysis showed that the Mg-basic sacrificial anodes originally used for cathodic protection were not suitable as the resulting −1.3V-plus (vs Ag/AgCl) protection potential for the hull was too negative for the purpose.A new protection system was designed in which the protection current densities were 15mA/m2 for the hull and 350mA/m2 for the propeller. The hull protection potential under actual condition at sea was between −920mV and −1100mV (Ag/AgCl) and the protection efficiency was over 90%. The protection areas were calculated by using the formulas A=1.8×LBP×D+BC×LB×B for the hull and As=2Aas for the propeller.