Cobalt-chrome turbines, and many others. The common Co-Cr alloy production requires the extraction of cobalt and chromium from cobalt oxide and chromium oxide ores. Both of the ores need to go through reduction process to obtain pure metals. Chromium usually goes through aluminothermic reduction technique, and pure cobalt can be achieved through many different ways depending on the characteristics of the specific ore. Pure metals are then fused together under vacuum either by electric arc or by induction melting. Due to the chemical reactivity of metals at high temperature, the process requires vacuum conditions or inert atmosphere to prevent oxygen uptake
Cobalt with water and oxygen to brown cobalt(III) hydroxide (Co(OH)). At temperatures of 600–700 °C, CoO oxidizes to the blue cobalt(II,III) oxide (CoO), which has a spinel structure. Black cobalt(III) oxide (CoO) is also known. Cobalt oxides are antiferromagnetic at low temperature: CoO (Néel temperature 291 K) and CoO (Néel temperature: 40 K), which is analogous to magnetite (FeO), with a mixture of +2 and +3 oxidation states. The principal chalcogenides of cobalt include the black cobalt(II) sulfides, CoS, which adopts a pyrite-like structure, and cobalt(III) sulfide (CoS). Four dihalides of cobalt(II) are known: cobalt(II) fluoride (CoF, pink), cobalt(II) chloride (CoCl,