At present, there is a huge market demand for aluminum sacrificial anodes in China. According to statistics, the demand for sacrificial anodes of an offshore platform is nearly 300 tons, and the quality of anodes used in sea crossing bridges is up to thousands of tons
In addition, China is still a large country of sacrificial anode export, with an average annual anode export of nearly 10000 tons and a huge output value. At present, the mature sacrificial anodes mainly include pure magnesium and magnesium alloy anodes, pure zinc and zinc alloy anodes, aluminum alloy anodes and ferroalloy anodes. Compared with magnesium, zinc and iron-based anodes, aluminum based sacrificial anodes are widely used in cathodic protection systems of ships and structures in marine environment because of their advantages of low density, large electric capacity, long service life, easy availability of raw materials and simple manufacturing process
However, cathodic protection failure often occurs in the practical application of aluminum alloy sacrificial anode
This cathodic protection failure is due to the significant reduction of aluminum anode current efficiency, which can not effectively protect the carbon steel matrix. For sacrificial anode system, the failure is mainly reflected in two aspects: serious self-corrosion of anode and inhibition of anode dissolution
Both of them will reduce the current efficiency of aluminum anode protection, and self corrosion will significantly shorten the service life of the anode
At present, about the improvement of aluminum based sacrificial anode
Most of the research on pole current efficiency focuses on improving the anode material itself
Performance, such as adding an appropriate amount of beneficial elements and reducing harmful impurity elements,
Improve microstructure, etc
However, the protection of aluminum based sacrificial anode
The effect is not only related to the material itself, but also closely related to the service environment of aluminum anode
Tangent correlation
Under actual working conditions, there are many kinds of aluminum based sacrificial anodes
Factors of protection failure, including biological fouling in the marine environment,
It is one of the important reasons for the failure of aluminum anode cathodic protection
This phenomenon of sacrificial anode cathodic protection failure caused by biological fouling is called fouling failure
Marine biological fouling is a phenomenon that seriously affects the performance of components due to the attachment and mass reproduction of marine organisms on man-made components. Metal components in marine environment are often more vulnerable to the corrosion damage of fouling organisms
According to the characteristics of fouling organisms, marine fouling organisms can be divided into three categories: marine microorganisms, such as bacteria, fungi and algae; Marine molluscs, such as sea anemones and sponges; Hard marine animals, such as barnacles, oysters, etc. At present, the research on the harm caused by marine fouling organisms and its protection is mostly focused on ships, pipelines, offshore platforms and other facilities
In addition, some investigations and studies have found that biological fouling will seriously reduce the cathodic protection efficiency of aluminum sacrificial anode materials, especially aluminum based sacrificial anode materials widely used in marine environment
At present, the field investigation and Mechanism Research on the failure of aluminum sacrificial anode materials caused by biological fouling are relatively limited, but this part of the research is very important. For carbon steel substrate, fouling organisms mainly promote
The corrosion process leads to the service failure of carbon steel materials
However, for aluminum sacrificial anode, whether fouling organisms promote corrosion or inhibit corrosion, they will have an adverse impact on the cathodic protection system of sacrificial anode. When the self corrosion of sacrificial anode is intensified, its service life will be greatly reduced. When the anode corrosion is inhibited, the dissolution of anode is blocked, resulting in the ineffective release of cathodic protection current, and its protection efficiency will be significantly reduced. Both of them will cause the decline or even loss of sacrificial anode protection effect. In addition, there are no effective measures to clean the fouling organisms on the surface of sacrificial anode, and the research on the biological fouling protection methods for sacrificial anode is almost blank. Aiming at the aluminum based sacrificial anode materials widely used in marine environment, combined with the previous investigation of marine biological fouling and service of aluminum based sacrificial anode at home and abroad, this paper summarizes the causes and research progress of fouling failure of aluminum based sacrificial anode materials. On this basis, the protection method is discussed, which provides a reference for the research and control of sacrificial anode fouling failure
