What is the anode and cathode Coatings Coatings, the iron matrix, the zinc,

copper, nickel, chromium, copper-tin alloy plating is a plating part of the kind?
A: According to the coating metal and the substrate between the metal galvanic relation to classification, can be coated into anodic coating and the cathode coating, in general terms, coating metal electrode potential than the base metal electrode potential is negative, called the anode coating, on the contrary, is called the cathode coating. Zinc coating electrode potential than iron substrate electrode potential is negative, so the zinc coating is anodic coatings. Copper, nickel, copper-tin alloy plating potential Tungsten eletrode the potential of the iron matrix is positive. Hence a cathodic coating. For chromium plating according to the standard potential, than iron is negative, however, easy to purify because chrome plating, the potential tends to be positive, it is also part of cathodic coating. With the condition of the metal potential of the different changes, so what are anodic coating or coating the cathode coating may change. For example, in normal conditions, tin plating of iron is the cathode coating, but in the organic acids, it has become anodic coating it.
 Anodic coating and cathodic coatings on the base metal protective effect is how?
A: The anodic coating protection principle is based on the potential of the coating compared to the base metal is negative, its electric melting pressure is large, the corrosion of the anode of the battery, thereby delaying the corrosion of the base metal. Even a slight exposure of the metal substrate, the coating from the protective effect can still, therefore, the number of pores on the anodic coating, the protection performance is minimal, the thickness, the greater the thickness of the coating, protective stronger. Cathodic coatings on metal substrates only play the role of a purely mechanical isolation, not as electrochemical anodic coating protective effect, so be sure to plating porosity rare cases have a protective effect, otherwise the pores in the coating or breakage, corrosion of the base metal as the anode, accelerated corrosion of the base metal. The general porosity of the coating increases with the thickness of the coating decreases, the thicker the coating cathodic protection performance is stronger.