EXPERIMENTAL DETERMINATION OF THE LIQUIDUS SURFACE (1473 K) IN Cu-ZnO-SiO_2-O SYSTEM AT VARIOUS OXYGEN PARTIAL PRESSURES

摘要

Thermodynamic information of the Cu-ZnO-SiO_2-O system has significant importance for high temperature industries. By employing the equilibration/quenching/EPMA technique, phase relation and liquidus surface of the Cu-ZnO-SiO_2-O system at 1473 K has been systematically studied at various oxygen partial pressures (pure argon and 0.21 atm). No ternary compound was found. A pseudo-ternary phase diagram (Cu_20-ZnO-SiO_2) was used to represent the liquidus of Cu-ZnO-SiO_2-O system in equilibrium with air (P_(O_2) = 0.21 atm). Two univariant equilibria (SiO_2 + Zn_2SiO_4 + Oxide liquid, and Zn_2SiO_4 + ZnO + Oxide liquid) were found in the experiments. The phase equilibria of the Cu-ZnO-SiO_2-O system in equilibrium with copper has also been studied at a fixed mole ration between SiO_2 and SiO_2+ ZnO. With increasing SiO_2 content in initial pellets, the concentration of Cu in liquid oxide phase decreases rapidly. Solubility data of Cu in solid phases of Zn_2SiO_4, ZnO and SiO_2 is also reported.