The ultra-low temperature freezing chamber is used for industrial cold treatment, which can freeze various copper sleeve, bearing and other materials. At the same time, attention should be paid to the corrosion of materials to avoid such corrosion.
Therefore, metal corrosion is an electronic factor produced by anode and cathode connected by metal and electrolyte. This factor can be caused by various metals (contact corrosion), structural phase (selective corrosion), ventilation and ion concentration (crevice corrosion and pitting corrosion).
In this process, the metal with lower potential and structural phase act as anode (metal ions exceed electrolyte), while metals with higher potential act as cathode surface (cation decreases from electrolyte). Local anodes and cathodes can also be formed on the same metal surface through different ventilation and precipitation of corrosion products.
In the process of metal corrosion, the electrode potential is the potential of the metal or conductive solid in the electrolyte. The electrode potential can only be measured as the potential of the reference electrode. The specific electrode is an electrode which changes slightly by the external voltage of the potential. The potential of the reference electrode refers to the standard hydrogen electrode.
Self corrosion potential (corrosion potential) refers to the potential produced by electrolyte metal without the influence of external current, and corrosion potential (pitting potential) refers to the critical potential that causes pitting (new hole formation and continuous growth). It is suggested that the re passivation potential refers to the critical potential used to stop the corrosion process and make the hole passivated again. Passivation refers to the process of metal changing from active corrosion state to passive corrosion state. Passivation can be carried out electrochemically or chemically.
When the metal is in a stable environment, the dissolution rate of anode metal decreases, the electrode potential changes according to the change value of noble metal with higher potential, or the concentration of oxidation solution increases, which is called passivity.
A good corrosion resistance of the material in the freezing chamber can reduce the corrosion resistance of the metal surface.