The formation of volatile corrosion products during the mixed oxidation-chlorination of cobalt at 650 C

The reaction of cobalt with 1 pct Cl2 in 1, 10, and 50 pct O2/Ar atmospheres has been studied at 650 C with thermogravimetry and mass spectrometry. The principal vapor species appear to be CoCl2 and CoCl3. In all cases, CoCl2(s) forms at the oxide/metal interface and equilibration of the volatile chlorides with Co3O4 does not occur in the early stages of the reaction. In the 1 pct Cl2 1 pct O2-Ar case, continuous volatilization occurs. In the 1 pct Cl2-10 pct O2-Ar and 1 pct CL2-50 pct O2-Ar cases, volatilization occurs only in the first few minutes of reaction. Afterwards, the reaction is predominantly oxidation.