Test materials and methods:
Three hot-dip hot-dip coatings, such as hot-dip galvanizing, zinc-aluminum alloy, and Zn-55Al-Si, were used on the industrial production line. Table 1 lists the main indicators. A 2 year real sea exposure test was conducted at the Zhoushan Seawater Corrosion Testing Station: 500mm long coated steel wire samples were degreased, cleaned, dried and weighed, and both edges were sealed with epoxy resin and horizontally fixed in the polychloroprene. The frames made of vinyl plates are insulated from each other in a cage and are fully immersed at a minimum height of 1.5 meters below the water surface. After undergoing various cycles of full leaching, the samples were removed, cleaned and dried and subjected to weightless corrosion tests and tensile strength tests. Using KYKY-1000B scanning electron microscope, the microstructure of the coated steel wire was fully immersed for 18 or 24 months. The working voltage was 20 kV.
Table 1 coated steel wire samples
Micrometer controlled EG&G M173 potentiostat/galvanostat and M276 electrochemical interface were used to measure the polarization of plated steel wire at room temperature. A three-electrode system was used in the experiment. The coated steel wire electrode was encapsulated with PTFE and washed with acetone and distilled water. The exposed area was about 1 cm2. The saturated calomel electrode (SCE) was used as the reference electrode and the platinum electrode was used as the auxiliary electrode. Natural seawater from Zhoushan was used as a test medium and its pH was 8.1. When the weak polarization curve was measured, the sample electrode was first stabilized in seawater for 30 minutes, and a stable corrosion potential, Ecorr, was measured. The cathodic and anodic polarization scans of the sample electrode were performed at a rate of 0.166 mV/s at a starting potential lower than the corrosion potential Ecorr 50 mV. The self-corrosion current density icorr was estimated using a weak polarization curve fitting technique, and the corrosion rate of the coating was evaluated by icorr.