First, physical properties Cobalt is a steel gray metallic luster and a hard metal belonging to Group VIII, in the original amount of 58.93, atomic number 27, atomic power to the distribution: 1s 2, 2s 2, 2p 6, 3s 2 , 3p 6 , 3d 7 , 4s 2 . Cobalt has many isotopes, and only 59 Co is an isotope that exists in nature. Cobalt has at least two allotropes: α-Co, which is stable at low temperatures, has a dense hexagonal character, and β-Co, which has a face-centered cubic lattice, which is stable at higher temperatures. The phase change heat of α-Co conversion β-Co is 60 calories, the phase transition temperature is about 430 ° C (also measured as 417 ° C), and the volume is increased by about 0.36%. Cobalt has a melting point of 1495 ° C, a boiling point of 3520 ° C, a heat of fusion of 62 cal/g, and an evaporation heat of 1540 cal/g. The specific heat is related to temperature: 0.103 cal/g at 0 to 100 °C, 0.146 cal/g at 500 °C, 0.185 cal/g at 800 °C, 0.204 cal/g at 1000 °C, and a thermal expansion coefficient of 12.3×10. -6 to 18.1×10 -6 . The specific gravity is 8.8 to 8.9, the Mohs hardness is 5.6, the Brinell hardness is 124, the relative elongation is 5%, and the elastic modulus is 21,530 kg/mm 2 . Tensile strength: The casting is 24.2 kg/mm 2 and the wire is 70 kg/mm 2 . Compressive strength: 85.8 kg/mm 2 for casting and 82.5 kg/mm 2 for wire. Like iron and nickel , cobalt can absorb hydrogen, and the hydrogen that can be adsorbed in the fine powder state and high temperature is 50 to 150 times the volume of cobalt. The hydrogen adsorbed by electrolytic cobalt is 35 times the volume of cobalt. Cobalt also adsorbs CO at normal temperature. The conductivity of cobalt is about 27.6% of copper , the purity is 99.95%, the specific resistance at 20 °C is 6.248×10 -6 ohm·cm, and the temperature coefficient of resistance of cobalt is 0.006 ∕ °C at 0-100 °C. Cobalt is ductile and very magnetic, with a Curie point of 1121 °C. Second, chemical properties Cobalt is a moderately active metal located in the middle of the iron-based element iron-nickel. Cobalt has good corrosion resistance. At room temperature, water, humid air, alkali and organic acids do not work for cobalt. Cobalt is more difficult to dissolve in dilute acid than iron, but when heated, especially when cobalt is heated in powder state, it can react violently with oxygen, sulfur, chlorine and bromine , and can also be combined with silicon, phosphorus , arsenic , antimony and aluminum. A series of compounds are formed which form Fe 3 C-like carbides (Co 3 C) with carbon. ΔG°=-8580-5.76TlgT+8.75T of Co 3 C formed by cobalt and graphite at different temperatures. Cobalt can be dissolved by sulfuric acid, hydrochloric acid and nitric acid to form a divalent cobalt salt, which can react slowly with dilute acetic acid. When the sulfur content exceeds 0.005%, the ductility of cobalt is greatly lowered, and the ingot containing more than 0.015% of sulfur cannot be forged due to the formation of cracks between the crystal grains. The valence of cobalt is 2 or 3. For simple cobalt ions, divalent cobalt is stable and trivalent cobalt ions are unstable. However, for the cobalt complex, the trivalent cobalt is stable. The cobalt potential sequence is located between iron and nickel. In dilute acid, cobalt is less soluble than iron, but is more soluble than nickel. In some cases, cobalt becomes passive in acid or alkali dissolution. The reported cobalt standard electrode potential value or redox potential value is not consistent. Typically -0.277 volts is taken for ECo 2 + ∕Co and +1.808 volts for E Co 3 + ∕ Co 2 + . When neutralized in a 1 N 20 ° C sulfuric acid solution, the overvoltage of hydrogen deposited on the cobalt electrode was -0.22 volts. Bottle Washing Machine,Bottle Cleaning Machine,Bottle Washers,Glass Bottle Washer Jiangsu Hanmo Tecchnology Ltd,.Co , https://www.jshanmotecho.com