Abstract
A direct observation has been conducted to study the local corrosion of solid silica at the surface of molten silicon. The maximum local corrosion depth of solid silica (linear loss, ΔL/mm) has been measured in relation to various influencing factors. The thermodynamic analysis has been done for the corrosion reactions. Transfer pass of oxygen during corrosion procedure was analyzed based on these thermodynamics and kinetics. Up-and-down oscillation of molten silicon meniscus in the local corrosion zone has been confirmed. It is revealed that the main cause of the local corrosion for solid silica is the Marangoni effect caused by the surface tensions gradient, which is the result of the gradient of oxygen concentration along the meniscus surface of molten silicon formed in the vicinity of SiO2(s)–Si(l)-gas three phases boundary.
