Synthesis and characterization of FeSO4 microcapsules applied in chemical mechanical polishing of single crystal SiC wafers

The chemical mechanical polishing (CMP) of single-crystal silicon carbide (SiC) faces challenges such as low efficiency and limited service life of the polishing liquid. To address these issues, we encapsulated the Fenton reaction catalyst FeSO 4 within melaminated formaldehyde (MF) resin via in-situ polymerization to form microcapsules. During processing, when these microcapsules come into contact with the workpiece surface, they release Fe 2+ ions that participate in the reaction, generating highly oxidizing species that promote efficient interfacial chemical reactions. Compared with other catalysts like Fe 3 O 4 and Fe-C composites, FeSO 4 exists in the polishing slurry as Fe 2+ , which significantly enhances the efficiency of the Fenton reaction. This study systematically investigates the effects of various process parameters (water-oil ratio, stirring rate, core-wall ratio) on the morphology and particle size distribution of FeSO 4 microcapsules. The results demonstrate that under conditions of a water-oil ratio of 1:25, a stirring rate of 450 rpm, and a core-wall ratio of 1:2, the prepared microcapsules exhibit smooth surfaces, uniform particle sizes, and excellent dispersion properties. When the core-wall ratio decreases from 1:1 to 1:3, the permeation resistance of the microcapsules increases by approximately 1.5 times. Fourier Transform Infrared spectroscopy (FT-IR) confirms the encapsulation of FeSO 4 within MF resin. Thermogravimetric analysis (TGA) reveals the good thermal stability of the microcapsules. Friction and wear test results indicate that the wear area under FeSO 4 microcapsule conditions is 12.491 μm², representing a 30 % increase in material removal rate compared to traditional Fenton reaction catalysts.