A novel green CeO2 polishing slurry and its chemical mechanical action mechanism for achieving atomic-level smoothing of fused silica glass surfaces

Abstract

Pitch-based tools are integral to computer-controlled optical surfacing (CCOS) for polishing fused silica but face limitations such as low material removal rates (MRR) and challenges in achieving atomic-level smoothing while ensuring environmental sustainability. While chemical mechanical polishing (CMP) excels in processing planar surfaces, it struggles with complex freeform geometries. CCOS addresses this gap with specialized tool head designs that enable precise machining of intricate surfaces. This study introduces an eco-friendly CeO₂-based polishing slurry suited for CCOS with pitch tools. By incorporating green reagents, such as polyethylene glycol (PEG) and ethylene glycol (EG), and minimizing harmful chemical usage, the slurry achieves significant breakthroughs in performance. Experimental results reveal a surface roughness (Sa) of 0.075 nm, meeting atomic-level smoothing standards, alongside an MRR of 40.5 $\mu$m /h, marking substantial improvements over traditional methods. Physicochemical analyses of the CeO₂ abrasives, including particle size, morphology, and Ce element content, revealed that abrasives with sharp edges and high Ce content are key factors for obtaining high surface quality and MRR. Molecular dynamics (MD) simulations highlight the synergistic effects of the components, optimizing chemical-mechanical interactions to enhance surface quality. These findings demonstrate the potential of green polishing technologies in advancing the precision machining of fused silica, particularly for complex geometries. The study provides a sustainable and high-performance solution for achieving atomic-level smoothing, paving the way for broader applications in precision optics.