Development of Corrosion Preventive Zn-Mg Thermal Sprayed Steel Plate for Oil Storage Tanks--Development of Corrosion Preventive Plate for Oil Storage Tanks-7-

摘要

To develop a corrosion preventive sprayed plate with good workability in welding and stable corrosion protective effect for the bottom plate of industrial oil storage tanks, the properties and working mechanism of Zn-Mg alloy sprayed steel were evaluated and investigated. The main results are as follows:1)The superior corrosion resistance of Zn-Mg alloy sprayed plate was confirmed in the laboratory and oil storage field, including the heat-affected area by 1.2kJ/mmstandard heat input welding.2)Our investigation showed that Zn-Mg alloy prevents oxidation at the outer surface and formation of Zn-Fe alloy at the spray-base metal interface at welding, resulting inhigh corrosion resistance. The preventive mechanism was analyzed in detail by chemical analysis and electrochemical measurements. In short, it is expected that the preventive effect mentioned above stems from the high chemical activity and/or stability of Mg and its compounds.3)From the corrosion test results, enhancement of the corrosion preventive effect was analyzed. The improvement factor to Zn was measured to be six, and the corrosion life time of Zn-Mg sprayed plate was estimated as about 50-60 years. Based on the results above, Zn-Mg sprayed plate was adopted for industrial oil storage tanks.