Thermal reaction of silicon with oxygen in diamond wire saw silicon powder waste: Surface oxidation and interface disproportionation

Abstract

Diamond wire saw silicon powder (DWSSP) waste contains high-purity silicon, which gives it recycling potential for high-value utilization while addressing associated environmental concerns. However, DWSSP waste is highly susceptible to oxidation, and the resultant surface oxide layer significantly impedes both impurity removal and silicon recovery processes. Although an intermediate silicon monoxide (SiO) layer in DWSSP has been preliminarily identified, the dynamic mechanisms governing its formation and evolution under thermal conditions remain poorly understood. This study systematically investigated the thermal oxidation behavior and interfacial reactions of silicon within DWSSP through controlled oxidation experiments and in-situ transmission electron microscopy. The results indicated that silicon oxidation followed parabolic kinetics, with the oxide layer growing simultaneously inward and outward. Higher temperatures accelerated the diffusion-based oxidation process, while a smaller particle size decreased the activation energy, promoting a higher oxidation rate. This work provides direct evidence that SiO accumulated within the oxide layer undergoes interfacial volatilization and disproportionation reactions that ultimately passivate the surface and inhibit further silicon oxidation. This work clarifies the transformation processes occurring within the surface oxide layer during silicon oxidation in DWSSP, laying theoretical groundwork for silicon resource reclamation through DWSSP waste recycling.