Zinc anode rods are in the form of long rods with a steel core or a weighable steel core part, the steel core can be threaded through the entire rod or into a section. They can be cast or extruded.
Their main uses are the protection of buried structures in the soil and the internal protection of storage tanks. The thickness of sacrificial anode rods varies greatly, and can be made into filaments or rods with a diameter of 70mm. The maximum length of a single anode is 1.5m. Anode quality depends on the alloy. Zinc anodes weigh up to 100kg. If several anodes are provided that are not already cabled together, each anode has core wires at both ends to facilitate connecting them into an anode chain. The anode rod with support on one side can be inserted into the storage tank, with a pipe plug, which can be bolted to the outside of the tank.
Chemical composition of zinc anode rod
| Chemical composition | Al | Cd | Impurities, not more than | ||||
| Fe | Cu | Pb | Si | Zn | |||
| % | 0.3-0.6 | 0.05-0.12 | 0.005 | 0.005 | 0.006 | 0.125 | Margin |
Electrochemical performance of zinc anode rod
| Performance |
open circuit potential -V(SCE) |
working potential -V(SCE) |
actual capacitance A·h/kg |
Current efficiency % |
Dissolution status |
| In seawater | -1.09~-1.05 | -1.05~-1.00 | ≥780 | ≥95 | Corrosion products are easy to fall off, and the surface dissolves evenly |
| In soil | ≤-1.05 | ≤-1.03 | ≥530 | ≥65 | |
|
Note 1: Reference electrode - saturated calomel electrode. Note 2: Medium - artificial seawater is used as the seawater medium; moist soil is used as the soil medium, and fillers are added around the anode. |
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Main performance of zinc anode rod
The extremely high electrochemical performance and the large power generation per unit weight of the anode material are about 3 times that of the zinc anode and 2 times that of the magnesium anode. In seawater and other media containing chloride ions, the performance is good, and the self-regulating ability of the current is strong. The protection period is longer, up to 20 to 30 years, and the phenomenon of "over-protection" generally does not occur.
Scope of application of zinc anode rod
Aluminum alloy sacrificial anodes are suitable for cathodic protection of metal corrosion in ships, mechanical equipment, marine engineering and seaport facilities in seawater, as well as pipelines, cables and other facilities in sea mud.
