Morphology, Structure, and Polishing Performance of Double-Shell P (MMA-MPS)/SiO2/CeO2 Composite Abrasives Controlled by Acid–Base Environment

The double-shell P (MMA-MPS)/SiO 2 /CeO 2 composite abrasive was designed and prepared through the soap-free emulsion polymerization, the sol–gel method, and the in situ chemical precipitation method. Take 3-(methacryloyloxy)propyltrimethoxysilane-modified methyl methacrylate (P (MMA-MPS)) microspheres as the core. The a SiO 2 and b SiO 2 inner shells were coated on the core in acidic and alkaline environments, respectively. The CeO 2 outer shell was then deposited on the inner shell. The morphology, structure, and chemical mechanical polishing performance on KDP crystals of composite abrasives were characterized using SEM, TEM, XRD, FTIR, XPS, and AFM. The results indicate that the P (MMA-MPS)/ a SiO 2 /CeO 2 abrasive possesses the “loose net-like” inner shell of a SiO 2 with the positive charge (-Si-OH 2 + ), leading to the sparser outer shell of CeO 2 and the expanded CeO 2 lattice. After polishing, the surface roughness (Ra) of KDP crystal is 0.69 nm, and the material removal rate (MRR) is 125.6 nm/min. The P (MMA-MPS)/ b SiO 2 /CeO 2 abrasive possesses the “dense strawberry-like” inner shell of b SiO 2 with the negative charge (-Si-O − ), which facilitates the uniform deposition of Ce 3+ through electrostatic adsorption, and forms the dense, complete and highly crystalline outer shell of CeO 2 . The proportion of Ce 3+ is increased by 2.5%. After polishing, the Ra of the KDP crystal further decreases to 0.43 nm, and the MRR increases to 146.2 nm/min. In summary, the comprehensive performance of the P (MMA-MPS)/ b SiO 2 /CeO 2 abrasive is superior to that of the P (MMA-MPS)/ a SiO 2 /CeO 2 abrasive.