Preparation of Nanoabrasive for Magnetorheological Polishing of KDP Crystals

Magnetorheological polishing technology is widely used in the processing of high-precision optical elements. One of the determining factors in the magnetorheological polishing technology is the nature and quality of a nanoabrasive present in a magnetorheological suspension. In this study, a method has been developed for the sol–gel synthesis of amorphous silica nanospheres used as a nanoabrasive for magnetorheological polishing of water-soluble crystals used to manufacture nonlinear optical elements for laser technology. The practical success has been achieved by incorporating the synthesized silica nanoabrasive into a magnetorheological suspension. The physicochemical characteristics of the resulting nanoabrasive have been presented. Electron microscopy data have confirmed the spherical morphology of SiO₂ particles, and it has been found that the particle size distribution varies in a range of 40–60 nm, thus ensuring the uniformity and high quality of treating the surfaces of optical elements with the magnetorheological suspension. The structure-related properties of the SiO₂ nanoabrasive have been studied by X-ray powder diffraction. The incorporation of the SiO₂ nanoabrasive into the magnetorheological suspension has made it possible to achieve the high-quality processing and cleanliness of the surface, as well as to ensure the finishing polishing of the surface of KDP single crystals to roughness values of no more than 6 Å. The results of the work are of interest for optimizing the process and improving the technology of magnetorheological polishing.