Corundum dissolution in concentrated sodium hydroxide solution

摘要

The corundum (α-alumina) core has been considered as a suitable candidate for investment casting of holow, high pressure turbine engine airfoils due to its excelent properties. However, the efifciency of removing alumina cores in concentrated caustic solution cannot meet the needs of industrial production. In this paper, the effects of temperature and initial solution concentration on dissolution ofα-alumina were studied by the classical weight-loss method. The fractal kinetic model was developed in order to describeα-alumina dissolution, assuming that the nonporous particles shrank during reaction process. The results show that the dissolution rate increases with increasing reaction temperature and initial solution concentration. Especialy, the initial solution concentration has a signiifcant inlfuence onα-alumina dissolution rate at a higher reaction temperature. The activation energies decrease with increasing initial solution concentration, and the chemical reaction is the rate-controling step.