The protective effect of anodic and negative coatings on the base metal

The protection principle of the anode coating is based on the fact that the potential of the coating is negative compared with the base metal, and its electrolytic pressure is larger, so it becomes the anode in the battery to erode, thus delaying the erosion of the base metal. Even when the base metal is slightly exposed, the coating can still play a protective role, so the number of pores on the anode coating has little effect on the protective function. In terms of thickness, the greater the thickness of the coating, the stronger the protection. The negative coating only plays a purely mechanical isolation role on the base metal, without the electrochemical protection of the anode coating, so it must be in the case of little porosity of the coating to have a protective effect, otherwise, in the pores or damage of the coating, the base metal will be used as the anode of the battery erosion, accelerating the erosion of the base metal. Generally, the porosity of the coating decreases with the increase of the thickness of the coating, so the greater the thickness, the stronger the protection function of the cathode coating.

What is the protective effect of anode coating and cathode coating on the base metal? Sacrificial anode

According to the electrochemical relationship between the coating metal and the base metal, the coating can be divided into anode coating and cathode coating. Under general conditions, when the electrode potential of the coating metal is negative than the electrode potential of the base metal, it is called anode coating; conversely, it is called cathode coating.