Research progress on preparation and surface modification techniques of spherical silica micropowder

SHEN Wangqiang; REN Nianzu; YE Junliang; ZHANG Shenming; GUO Minna; WEI Guangyao

doi:10.13732/j.issn.1008-5548.2025.04.005

Abstract：Significance Spherical silica micropowder has garnered significant attention as an inorganic filler due to its high thermal conduc-tivity,excellent dielectric properties,good chemical stability,etc.These superior characteristics have led to its widespread application in various fields,including copper-clad laminates,epoxy resin encapsulants,coatings,cosmetics,drug delivery,catalysis.With continuous technological advancements and increasing demands from downstream industries,the quality require-ments for silica micropowder are becoming more stringent.The excellent performance of spherical silica micropowder has driven its growing market demand,making it a key focus for the future development of silica micropowder techniques. Progress Current research on spherical silica micropowder mainly focuses on its preparation methods and surface modification techniques.Preparation approaches can be broadly classified into two categories:physical and chemical methods.Physical methods,such as flame melting and plasma processing,have been employed to produce high-purity,uniformly sized particles.For instance,a study used angular silica micropowder as a raw material to produce spherical silica micropowder through flame fusion.Chemical methods,including sol-gel,microemulsion,chemical precipitation,spray drying,and vapor phase pro-cesses,have also been widely studied.For instance,a study used tetraethyl orthosilicate as the raw material and hydrochloric acid as the catalyst to synthesize spherical silica micropowder via the sol-gel method.Researchers have further innovated by exploring new silica sources and optimizing existing preparation processes,providing references for the preparation of spherical silica micropowder.For example,researchers used rice husks as the silica source and polyethylene glycol as the solvent to syn-thesize spherical silica micropowder via microwave-assisted sol-gel synthesis. In terms of surface modification,techniques such as organic modification,chemical etching,and polymer grafting are widely used.Silane coupling agents are the most commonly used modifiers.Initially,single-type silane coupling agents were generally applied,but combinations of multiple agents have been shown to enhance their properties.In a study,three different silane cou-pling agents,KH550,KH560,and phenyltrimethoxysilane,were combined to synthesize tri-functional modified spherical silica micropowder.The results indicated that these modifying agents introduced reactive groups to the spherical silica micropowder,enhancing its interfacial compatibility and adhesion with the epoxy resin matrix.Additionally,researchers have employed chemi-cal etching on the surface of micropowder to create more active sites,thereby enhancing the modification effect.For example,researchers treated spherical silica micropowder with a hot NaOH solution.The results showed that the NaOH treatment improved the surface activity and hydroxylation of the spherical silica micropowder,increasing the number of anchoring points and enhancing the dispersion of nanoparticles within the matrix. Conclusions and Prospects Numerous advancements have been made in the preparation and modification of spherical silica micropowder.Techniques such as flame melting,plasma processing,sol-gel,microemulsion,and precipitation methods can all produce spherical silica micropowder with high purity and uniform particle size.However,chemical methods often face chal-lenges related to complex processes,demanding preparation conditions,and environmental pollution,limiting their large-scale production.Physical methods,though simpler and more scalable,have more stringent requirements for temperature and equip-ment.Moreover,these methods demand high-quality natural quartz,which poses significant challenges due to the limited avail-ability of ore sources,thereby hindering sustainable production.Consequently,existing preparation technologies require further refinement for industrial-scale applications.Moreover,with the growing awareness of environmental protection,the environmen-tal impact and sustainable development strategies in the production process of spherical silica micropowder have become increas-ingly important.Future studies should prioritize the development of green and efficient preparation technologies.In terms of sur-face modification,silane coupling agents remain the most commonly used modifiers.Although the modification effects are rela-tively ideal,their high cost exerts considerable pressure on production cost control.To address this,future research should focus on developing new types of modifiers,optimizing modification processes,and conducting in-depth research on modifica-tion mechanisms.