Views: 1 Author: Site Editor Publish Time: 2022-06-07 Origin: Site
Tungsten, a metallic element. Atomic number 74, atomic weight 183.84. Steel gray or silver-white, with high hardness and high melting point, and is not eroded by air at room temperature; the main use is for the manufacture of filaments and high-speed cutting alloy steel, superhard molds, and also used in optical instruments and chemical instruments. China is the world's largest tungsten storage country.
Nickel, a nearly silver-white, hard, ductile, and ferromagnetic metal element that is highly polished and resistant to corrosion. Nickel is a ferrophilic element. It contains the highest nickel in the earth's core and is a natural nickel-iron alloy.
Copper is the earliest metal used by humans. As early as prehistoric times, people began to mine open-pit copper mines and use the obtained copper to make weapons, utensils and other utensils. The use of copper had a profound impact on the progress of early human civilization. Copper is a metal found in the earth's crust and oceans. The content of copper in the earth's crust is about 0.01%, and in individual copper deposits, the content of copper can reach 3% to 5%.