Optimizing processing stability with ionized polymers in magnetorheological finishing fluid

Abstract

Magnetorheological finishing (MRF) is being widely utilized in Semiconductor and optical processing. The properties of the finishing fluid have a great influence on the finishing quality. This study revealed that sodium polystyrene sulfonate (PSS), when employed as a dispersant in the finishing fluid, effectively enhances the polishing performance and maintains the processing stability of the finishing fluid. In the MRF processing, the group with the addition of 0.2 % PSS achieved a reduction in the roughness (Rq) of the fused silica (FS) workpiece to 1.02 nm compared to 4.3 nm in the control group. The PSS elevated the surface potential of abrasive particles, impeding abrasive agglomeration by reinforcing electrostatic repulsion. Simultaneously, the operation life of the finishing fluid significantly extends more than 3 times. The addition of PSS resulted in a significant decrease in the oxidation of Carbonyl iron particles (CIPs). Energy spectrum analysis revealed that diamond abrasives scratched the CIPs. Scratched CIPs were prone to be oxidized to Fe³⁺, thus leading to the significant failure of the finishing fluid. PSS adsorb to particle surfaces, creating steric hindrance that reduces friction between abrasives and CIPs. The MRF fluid with PSS exhibited a notable reduction of Fe³⁺ concentration. Both mechanisms concurrently enhanced the processing stability.