Corrosion Research And Life Prediction Of Electricity Metal Materials

In this paper,the corrosion and life prediction of electricity metal materials in Fujian Province are studied.The corrosion rate and corrosion surface morphology of the standard specimens in the real service environments were obtained through the atmospheric corrosion exposure test for the metal material–Q235 carbon steel,pure zinc and red copper commonly used in the power system.At the same time,the neutral salt spray test was carried out to study the corrosion behavior of flat specimen and helix specimen,and the corrosion behavior was analyzed and compared with the atmospheric exposure test,which provided theoretical analysis support for field measurement data.Different electrochemical test methods are used to study the typical polarity reversal of Cu–304 stainless steel galvanic couple and improve the understanding of the potential corrosion hazard which may occur in the power equipment.On this basis,the Geographic Information System(GIS)technology is used to generate the grade distribution map of atmospheric corrosive in Fujian Province,so that the research results are feasible and practical,and provide technical support for the life prediction and safe operation of power equipment.The conclusions and results are as follows:1.Atmospheric corrosion exposure test and neutral salt spray test show that the corrosion rate of the helix-shaped specimens is significantly higher than that of the flat-shaped ones.The factors have a significant effect on the corrosion of metals from the collected climatic and atmospheric environmental parameters of the 16 test places in Fujian province.Typical areas which have high corrosion rate are Pingtan,Zhangzhou(Gulei)and Nanan(Shuitou).The neutral salt spray test show that the corrosion products of the helix and flat shapes present the same compositions,but the two types of standard specimens exhibit different rust layer structures,corrosion product layer formed on the flat specimen is relatively smooth and compact,while the corrosion product layer formed on the helix specimen has more pores and cracks,it is easier for the electrolyte containing corrosive ions to penetrate the rust layer,facilitating further corrosion of the metal substrate,leading to a higher corrosion mass loss.2.Based on the corrosion rate of the standard specimens obtained in 16 test places in Fujian Province and the collected atmospheric environment and climate parameters,the range of atmospheric environmental parameters and metal corrosion rate in the standard ISO9223: 1992 was adjusted or subdivided.The corrosion rate of the standard specimen obtained by the atmospheric exposure test and the collected atmospheric environment and the climate parameters are used for the original database,the range of adjustment or subdivision for the range of data change,and based on the GIS technology,the corrosion grade maps were made for the time of wetness,the concentration of sulfur dioxide,the deposition rate of chloride ion as well as the carbon,zinc and copper of Fujian Province.At the same time,the corrosion rate of the helix specimen was used to determine the atmospheric corrosive grade,and then the highest corrosive grade of carbon steel,zinc and copper was used as the atmospheric corrosive grade,based on the GIS technology the atmospheric corrosive grade distribution map of Fujian Province was made.3.The corrosion rate of zinc was predicted using a Zinc Coating Life Predictor(ZCLP).The results show that,in addition to Fuqing,Xiamen and Nanan areas,the prediction value of corrosion rate of zinc in other 13 places are in good agreement with the measured corrosion rate obtained by the atmospheric corrosion test.the corrosion rate of zinc obtained by the atmospheric corrosion exposure test is reliable.In Fuqing and Xiamen,the error between the predicted value and the measured value is due to the deviation of the environmental monitoring station from the actual test site.4.The typical polarity reversal of the Cu–304 stainless steel galvanic couple(Cu–304SS GC)in Cl-solution with different p H was investigated by open circuit potential(OCP),polarization curve,and galvanic current techniques in conjunction with the scanning vibrating electrode technique(SVET).The results revealed that the typical polarity reversal occurred in Cu–304SS GC in Cl-solution with p H 0,in which the red copper was cathodic to 304 SS,while in the solution with p H 6,4,and 2 the red copper was anodic to 304 SS.