Huyuan Sun

The Corrosion Performance of Galvanized Steel in Closed Rusty Seawater

The corrosion performance of galvanized steel in closed rusty seawater (CRS) was investigated using weight loss, Tafel polarization curve, and electrochemical impedance spectroscopy. Scanning electron microscopy (SEM) and energy dispersive spectroscopy (EDS) were carried out for morphological and chemical characterization of the rust layer absorbed on the zinc coating. Effects of temperature and hydrostatic pressure on corrosion resistance of galvanized steel were studied. Results indicated that rust layer could induce pitting corrosion on the zinc coating under the Cl− erosion; high temperature accelerated the corrosion rate of zinc coating and inhibited the absorption of rust layer; the polarization resistance () of galvanized steel increased with the increase of hydrostatic pressure in CRS.

Corrosion Inhibition of Gemini Surfactant for Copper in 3.5% NaCl

A new gemini surfactant containing long chain alkyl ammonium headgroups have been used as corrosion inhinbitor for copper in 3.5% NaCl solution. The weight loss and electrochemical methods results showed that presence of inhibitor greatly decrease corrosion rate, gemini surfactant acted as an excellent corrosion inhibitor with inhibition efficiency greater than 96% at an optimum concentration of 30 mg·L-1. X-ray photoelectron spectroscopy reveals that the gemini surfactant molecules adsorb onto the copper surface through the two ammonium head groups (N+).

Effects of Zn(OH)2 on Corrosion Behavior of Hot Dipped Zn Coating in Freshwater

The corrosion behavior of hot dipped Zn coating in freshwater with and without Zn(OH)2 was investigated through weight loss test, polarization curve and impedance spectroscopy. The morphology of the corroded hot dipped Zn coating was analyzed by SEM, meanwhile, the effect of Cl- on corrosion behavior of hot dipped Zn coating in saturated Zn(OH)2 solution was examined using polarization curve. It was found that corrosion product Zn(OH)2 accelerate the corrosion of coating, Cl- promoted dissolution of anodic coating and incrSubscript texteased the conductance of the solution, and the worst corrosion resistance of coating is Cl-concentration of 1%.

Corrosion performance of zinc coated steel in seawater environment

Considering the continuous exploitation of marine resources, it is very important to study the anticorrosion performance and durability of zinc coated streel (ZCS) because its increasing use as reinforcements in seawater. Tafel polarization curves and linear polarization curves combined with electrochemical impedance spectroscopy (EIS) were employed to evaluate the corrosion performance of ZCS at Qingdao test station during long-term immersion in seawater. The results indicated that the corrosion rate of the ZCS increased obviously with immersion time in seawater. The corrosion products that formed on the zinc coated steel were loose and porous, and were mainly composed of Zn5(OH)8Cl2, Zn5(OH)6(CO3)2, and ZnO. Pitting corrosion occurred on the steel surface in neutral seawater, and the rate of ZCS corrosion decreased with increasing pH.

A Smart Marine Corrosion Sensor Used in Marine Survey

A smart marine corrosion sensor, as a ship carried equipment, was developed by the authors to measure corrosion potential and corrosion current of materials in seawater. Measuring principle and characteristics of the corrosion sensor are described in the paper. This corrosion sensor, named FS-1, developed by the authors under the aid of 863 research project, had been used to investigate the seawater’s corrosivity in the autumn open cruise, which was performed by Science I Research Vessel in November 2009.

The Electrochemical Analysis of Trace Titanium Addition to the High Pure Zinc Electrode in Seawater

High pure zinc with trace titanium of various contents was prepared by the method of master alloy preparation, and electrochemical characteristic difference in seawater was discussed. The result reveals that there is a minimum of self corrosion current density at 0.04% titanium content in high pure zinc in seawater of Qingdao seashore, and trace addition of titanium may increases the potential stability but not change the corrosion behavior of high pure zinc in seawater.

Research of Corrosion Monitoring System for Metal Coatings

A metal coating corrosion monitoring system (CMS) based on corrosion potential was introduced. It’s working principle, especially the design and selection of soft and hardware and the main technical specifications. The system has the characters of real-time monitoring of changes in corrosion potential status of coatings, automatically storing corrosion information and alarming according to corrosion degree in monitoring sites.

Finite Element Method Simulation of 35# Steel Cathodic Protection Models in the Seawater

Physical models of cathodic protection (CP) for copper protected by 35# steel and for 35# steel protected by aluminum sacrificial anode respectively in seawater were built in this study. Weak form of Laplace equation was deduced to make finite element method (FEM) numerical calculation conveniently. Then, potential distribution of each physical model was computed by FEM following with measured experiments for validation. Typical FEM simulated data along X-axis and Y-axis of physical models agree well with measured experimental data. For 35# steel protected by aluminum sacrificial anode models, normal cathodic protection, over-protected (OP) and under-protected (UP) models were built, respectively. The results demonstrated that it should be feasible of CP for copper by 35# steel and for 35# steel by aluminum sacrificial anode respectively, and FEM could afford well forecast for CP design in engineering.