Interactions during the chlorination of a copper–zinc alloy

In this paper several aspects involved in the chlorination of a Zn 48% wt.–Cu alloy between 250 and 500 °C are investigated. The starting temperature for the chlorination of the alloy is determined, which is different from those of pure metals. Analysis of the chlorination thermogravimetric curves and reaction products reveal that there are interactions between reactants and products during the reaction, and that volatilization of ZnCl₂ is diminished during the alloy chlorination. Metallic copper is detected at intermediate stages of the chlorination, and this element, which is not present in the initial sample, appears during the chlorination reaction. An oxidation–reduction type reaction between copper chlorides and metallic zinc is proposed to explain the behaviour observed. The occurrence of this reaction at room temperature was confirmed in separate experiments. At the beginning of the reaction, formation of zinc oxichloride was detected that is being formed from the zinc oxide layer that covers the alloy surface. According to the results obtained, a reaction mechanism is presented for the alloy chlorination.