Acid-Washing Behavior of TiB<sub>2</sub>/MgAl<sub>2</sub>O<sub>4</sub>/MgO Composite Powders

Abstract

Using TiO2B2O3 powders as oxidizer,AlMg powders as reducer,the TiB2 multiphase ceramic are preparated with SHS, and analysed with SEM and XRD.The effect of HCl, H3PO4 to pickling of TiB2-based multiphase ceramics is explored by SEM and XRD analysis. Research suggests that: the main ingredients of TiB2-based multiphase ceramics is TiB2, MgO and MgAl2O4 three phases, few of reaction residual objects and impurities also exists; the multiphase ceramics is forming by many of hexagonal crystal type products and small particles reunion, hexagonal crystal type product is TiB2, small particles may be MgO, MgAl2O4 and other impurities product; MgO can be effectively washed by HCl and H3PO4 , but TiB2 and MgAl2O4 invalid. At room temperature, 30% HCl pickling has the best effect, the concentration of TiB2(ω) is up to 59.3%; the higher of the concentration, the better of acid-effect; In the pickling process, as the temperature rises, the concentration of TiB2 grows, but the temperature should not be too high. When temperature reach 75 °C, HCl volatilizes too quickly and inefficiently. At room temperature, 20% H3PO4 has the best pickling effect, the concentration of TiB2(ω) is up to 52.6%, but the best pickling effect is not well with concentration increasing; as the temperature increasing, purity of TiB2 is also increased; At 70°C, the concentration of TiB2(ω) after H3PO4 pickling is up to 61.9%, refine effect is good.