Double layer aluminum alloy composite sacrificial anode

Abstract

This invention relates to a double layer Al alloy compound sacrificial anode composed of two kinds of Al-base sacrificial anode materials, in which, the components of the outer layer in weight proportion are: Zn 2.5-3.5%, Ga 0.05-0.20%, In 0.01-0.05%, Sn 0.01-0.03%, Bi 0.005-0.05% and Al, the components of the internal layer include: Zn 2.5-7.0%, In 0.018-0.05%, Cd 0-0.02%, Sn 0-0.075%, Mg 0-1.5%, Si 0-0.15%, Ti 0-0.08% and Al, which utilizes the advantages of the two kinds of Al anodes to use the outer Al anode to provide larger protection current at the beginning to polarize the steel structure swiftly and generate a surface deposition layer quickly so as to reduce the current desity necessary for stable polarization, after the consumption, the internal anode can protect the steel structure under rather small current.

Description

technical field [0001] The invention relates to an improvement technology of a composite sacrificial anode, in particular to a double-layer aluminum alloy composite sacrificial anode, which is suitable for cathodic protection of large-scale marine steel structures such as seaports, docks and ocean platforms. Background of the invention [0002] When designing cathodic protection, the protection current density is a very important parameter, and the protection current density required by steel structures in different periods varies greatly. Generally speaking, when the steel structure is just launched into the water, that is, the initial stage of polarization, the required protective current density is relatively high. After the initial stage, the required protective current density of the steel structure will be greatly reduced. In the actual marine engineering design, the design value of the protection current density required at the initial stage is generally twice the des...

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Problems solved by technology

[0006] 1. Magnesium alloy is flammable, so molten salt and sulfur powder must be used for protection during smelting and casting. The production and manufacturing process is relatively complicated, and it pollutes the environment, which is not conducive to the health of operators

[0007] 2. Magnesium alloy anodes have small capacitance and low current efficiency, and the market price is higher than that of aluminum-based anodes. Therefore, in terms of cost of use, magnesium alloy anodes have no advantages at all.

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