Pure metals and their alloys tend to react with environment become a chemical union with the elements of a corrosive medium to form stable compounds similar to those found in nature. Metal then will loss occurs in this way, the compound formed is referred to as the corrosion product and the metal surface is spoken of as being corroded.
The Corrosion reaction actually is a complex phenomenon that may take any one or more of several forms. The corrosion usually confined to the metal surface, and this is called general corrosion. But it sometimes occurs along grain boundaries or other lines of weakness because of a difference in resistance to attack or local electrolytic action. To control the corrosion people just try to limited the acceleration of corrosion by modified to metal like using chrome plating or anodizing metal.
In most liquid system condition, the corrosion reaction is divided into an anodic portion and a cathodic portion, occurring simultaneously at discrete points on metallic surfaces. Flow of electricity from the anodic as negative ion to the cathodic areas act as positive pole may be generated by local cells set up either on a single metallic surface or between dissimilar metals.
The corrosion flow of metals applies specifically to chemical or electrochemical attack. The deterioration of plastics and other nonmetallic materials, which are susceptible to swelling, crazing, cracking, softening, etc., is essentially physiochemical rather than electrochemical in nature. Nonmetallic materials can either be rapidly deteriorated when expose to a particular environment or ata the other extreme, be practically unaffected. Under some condition a nonmetallic may show evidence of gradual deterioration. However, it is seldom possible to evaluate its chemical resistance by measurements of weight loss alone, as is most generally done for metals.
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The Corrosion reaction actually is a complex phenomenon that may take any one or more of several forms. The corrosion usually confined to the metal surface, and this is called general corrosion. But it sometimes occurs along grain boundaries or other lines of weakness because of a difference in resistance to attack or local electrolytic action. To control the corrosion people just try to limited the acceleration of corrosion by modified to metal like using chrome plating or anodizing metal.
In most liquid system condition, the corrosion reaction is divided into an anodic portion and a cathodic portion, occurring simultaneously at discrete points on metallic surfaces. Flow of electricity from the anodic as negative ion to the cathodic areas act as positive pole may be generated by local cells set up either on a single metallic surface or between dissimilar metals.
The corrosion flow of metals applies specifically to chemical or electrochemical attack. The deterioration of plastics and other nonmetallic materials, which are susceptible to swelling, crazing, cracking, softening, etc., is essentially physiochemical rather than electrochemical in nature. Nonmetallic materials can either be rapidly deteriorated when expose to a particular environment or ata the other extreme, be practically unaffected. Under some condition a nonmetallic may show evidence of gradual deterioration. However, it is seldom possible to evaluate its chemical resistance by measurements of weight loss alone, as is most generally done for metals.
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