In Field Electrochemical Detection And Erosion-corrosion Investigation Of Metallic Materials In Marine Environment

On the basis of China's material ambient seawater corrosion network test data accumulated, a great deal of valuable corrosion data has been obtained. National Natural Science Foundation of major projects "in situ material in a natural process of corrosion testing of new technology based on real-time monitoring and application" (No.50499335, 2004.9~2008.7), the main content of this project is "Water environment network typical metal corrosion specimens exposed real-time detection". Focused on the characteristics of Zhoushan seawater with larger concentration of sand and less marine organism, in field corrosion electrochemical detections of metal samples in Zhoushan marine corrosion test station have been implemented. The corrosion behaviors of metal samples both in simulated erosion-corrosion of seawater with sand and in marine erosion-corrosion conditions have been studied. These offer the foundation to investigate and forecast the corrosion performances of materials in marine environment.The in field corrosion electrochemical detections of metal samples in marine environment have been achieved. Potentiostatic square wave and electrochemical impedance spectroscopy (EIS) results reflect the corrosion behaviors of metal samples exposed in different zone and the direct influence of marine environmental factors on the corrosion behaviors. The values of the parameter"B"in polarization resistance formula of Q235 carbon steel, Q235 ultrafine grained steel, 09CuPCrNiRE weathering steel and 09CuPCrNi ultrafine grained high strength steel have been identified, which have an great significance to investigate the corrosion behaviors o f carbon steels and low alloy steels in seawater. And the continuous rules of the samples'corrosion rate changing during exposure have been obtained. The results of carbon steels and low alloy steels immersed samples exposed for 1 and 2 years monitored by electrochemical methods is consistent with that of weight lost methods.The relationships between corrosion rate of the samples and marine environmental factors (such as height of tide, temperature, velocity of seawater and orientation of flow) during the exposure have been studied by gray correlation analysis method. The results show that seawater temperature is the major factor influencing the corrosion rate of the samples exposed in immersed and tidal zone. The extent of tidal height influencing on the tidal zone samples is close to that of temperature.The corrosion behaviors of 3C steel, 10CrMoAl steel, ZHMn55-3-1 copper alloy and HAl77-2 copper alloy have been investigated in different erosion-corrosion conditions of seawater with sand using simulated erosion-corrosion test systems. In the simulating marine velocity range of 0~0.8m/s, the main factor influencing on corrosion rate of 3C and 10CrMoAl steel is velocity of flow, the impact of silt content is not significant. In the test of simulating marine velocity and simulating high-speed erosion-corrosion, the velocity and silt all have an influence on the corrosion behaviors of ZHMn55-3-1 and HAl77-2 copper alloy.The marine erosion-corrosion electrochemical detections of metallic materials have been achieved in Zhoushan marine corrosion test station. The results show that the corrosion rates of 3C steel, 10CrMoAl steel and ZHMn55-3-1 copper alloy augment with the velocity increasing in the velocity range of 1~3m/s, which is consistent with the results of weight lost methods. The erosion-corrosion appearances of materials have further verified the results of electrochemical detections.