日本人妻A片成人免费看_天堂在线www官网_欧美日韩国产在线一区_一区二区视频传媒有限公司_国产91色欲麻豆精品一区二区_成人高潮片免费视

　　Metal protection of the purpose, is to control the metal material constituting the metal products due to corrosion caused by consumption, to prevent damage to metal products, thus extending its life. Therefore, in addition to prevent metal corrosion, but also includes protecting the metal sense, so called protective metal. An integrated approach and means in order to achieve the purpose of protection taken is called protection technology.
　　In addition to the correct selection of metal protection methods and rational design of metal material, the surface of the protective layer can be used mainly to deal with electrochemical corrosion protection and media approach.