Pure tungsten is steel-gray to tin-white hard metal, very pure tungsten Available saw sawing (pure tungsten is very brittle and difficult to process). Tungsten has forging, tensile and impact three kinds of processing methods. In all the tungsten bar highest melting point of tungsten metal for 3415 ℃, the lowest vapor pressure, tensile strength up (1650 ℃ when). Corrosion performance is very good, most of the inorganic acid inflicting only minor erosion. In air, pure tungsten surface will form a protective oxide at high tungsten boat will be completely oxidized. To add a small amount of tungsten steel can greatly improve the hardness of steel. High purity tungsten is purity of 99.999% and 99.9999%, denoted 5N and 6N pure tungsten. Pure tungsten various impurity elements should be tungsten cubic (0.1 ~ 1000) × 10-12 between, for some impurity element content, such as radioactive elements, alkali metals, heavy metals and gaseous elements, etc. Also there were special requirements . High-purity tungsten and tungsten silicide for ultra large scale integrated circuit as the resistive layer, a diffusion barrier layer and the metal oxide semiconductor-type transistor connected as a gate material, and materials.
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