Grounding Grid Corrosion Protection MG-22 Magnesium Alloy Sacrificial Anode | Service Life 30 Years

Jiaozuo Libo Light Alloy Co., Ltd.

Chang Qing 13939157916

I. Principle of Sacrificial Anode Protection
According to electrochemical principles, when two metals with different electrode potentials are placed in an electrolyte system and connected by a wire, current flows. In this case, the metal with the more negative electrode potential acts as the anode, utilizing the potential difference between the two metals as the current source for cathodic protection. This is the fundamental principle of the sacrificial anode method. See Figure 10-54.
II. Sacrificial Anode Materials
Since the sacrificial anode method provides protection current to the protected metal structure through the consumption of the anode itself, performance requirements are imposed on sacrificial anode materials.
1. Must have a sufficiently negative potential and exhibit minimal polarization during long-term discharge.
2. Corrosion products should not adhere to the anode surface, be loose and easy to fall off, not form a high-resistance hard crust, and be non-polluting.
3. Low self-corrosion and high current efficiency.
4. High current output per unit weight, with uniform current distribution.
5. Good mechanical properties, low cost, and wide availability.
Common sacrificial anodes include magnesium and magnesium alloys, zinc and zinc alloys, and aluminum alloys. Their electrochemical properties are shown in Table 10-59. The electrochemical performance of sacrificial anodes depends on the material composition and impurity content, as specified in standard specifications for sacrificial anodes. Table 10-59 Electrochemical Properties of Sacrificial Anodes Property Unit Zn, Zn Alloy Mg, Mg-Mn Mg-6Al-3Zn Al-Zn-In Relative Density g/cm3 7.1 1.74 1.77 2.83 Anode Open Circuit Potential (SCE) V -1.03 -1.56 -1.48 -1.08 Protective Potential Difference Relative to Iron V -0.20 -0.75 -0.65 -0.25 Theoretical Current Output Ah/g 0.82 2.20 2.21 2.87 In Seawater (3mA/cm2) Current Efficiency % 95 50 55 80 Actual Current Output Ah/g 0.78 1.10 1.22 2.30 Consumption Rate kg/A·a 11.8 8.0 7.2 3.8 In Soil (0.03mA/cm2) Current Efficiency % 65 40 50 65 Actual Current Output Ah/g 0.53 0.88 1.11 1.85 Consumption Rate kg/A·a 17.25 10.0 7.92 4.68