Failure Reasons of Sacrificial Anodes for Marine Equipment

There are 1 ~ 2mm thick non-metallic deposits on the surface of the sacrificial anode, mainly due to the basic zinc chloride deposits, which cause the insulation of the sacrificial anode surface. There are a lot of iron-rich precipitates in the sacrificial anode structure, which is seriously inconsistent with the high-purity zinc standard; After the sacrificial anode runs for a short time, the self-corrosion surface has the rapid formation of attachments; the harmful elements such as iron, copper and lead in the anode seriously exceed the standard to form a harmful second phase, which makes the sacrificial anode prone to self-corrosion, which leads to the formation of surface deposits. form.

Electrochemical cathodic protection is one of the most effective methods to slow down and prevent corrosion failure of metal equipment. The sacrificial anode method is widely used in cathodic protection of equipment in seawater due to its simple design, convenient installation, and no external power supply.

There are two necessary conditions for the sacrificial anode to function: firstly, the material itself meets the necessary electrochemical properties, and secondly, it has a good electrical connection with the protected device.

A good sacrificial anode material should have the following characteristics: a sufficiently negative anode working potential, in practical applications, the anode potential should remain stable for a long time, and there should be no obvious positive shift with the consumption of the anode;

The anode polarizability is small during the working process; the sacrificial anode material must have a large enough actual electrochemical capacity; there will be no obvious self-corrosion phenomenon, the corrosion products are uniformly activated and dissolved, and no insoluble corrosion products are deposited on the surface. , there is no obvious mechanical shedding and hydrogen evolution self-corrosion, which will not lead to unnecessary loss of current efficiency. Zinc alloy anode has high current efficiency, uniform corrosion, long service life, and is the most widely used sacrificial anode material in seawater environment.