国产一级特黄毛片_综合无码日韩人妻AV一区免费_好爽…又高潮了粉色视频_好涨水快流出来了软件下载_被医生按摩玩到高潮视频_は鬼の妊娠を甘露寺蜜_美国欧洲黄色视频免费看_麻豆精品免费在线_欧美日韩成年网站_久久精品国产高清一区二区

Electrical industry

Electrical industry

Copper/steel metal composite material is a combination of copper and steel two metal materials to take advantage of their respective performance advantages A class of metal materials formed by layered combination. After the material is compounded, it can overcome the respective shortcomings of the two metals, Give full play to the advantages of the two, and the special properties after compounding extend the service life of the components and improve the comprehensive economic benefits. Copper has excellent extensibility and excellent electrical and thermal conductivity. It is a commonly used industrial metal material and is widely used in the electrical industry.