Synthesis of spherical SiO2 powders from water glass and colloidal Sol through ultrasonic spray pyrolysis

• Published in: Hanʼguk Seramik Hakhoe chi 2024, 61(5), 414, pp.811-820
• Main Authors: Kim, Sohyeon, Son, Seunghwan, Han, Kyusung, Hwang, Kwangtaek, Kim, Ungsoo, Kim, Jinho, Choi, Junghoon
• Format: Article
• Language: English
• Subjects: Ceramics; Chemistry and Materials Science; Composites; Glass; Materials Science; Natural Materials; Original Article; 재료공학
• ISSN: 1229-7801; 2234-0491; 2334-0491
• DOI: 10.1007/s43207-024-00383-z

Silicon dioxide (SiO 2 ) is formed via a combination of silicon and oxygen, which are the most abundant elements on Earth. It possesses excellent heat and chemical resistance and can be developed into various types of functional materials. In particular, spherical SiO 2 is extensively utilized in the pre-impregnated materials of printed circuit boards (PCBs) and as a filler in cosmetics. Among the methods used for manufacturing spherical SiO 2 powders, ultrasonic spray pyrolysis (USP) involves the generation of droplets by subjecting a precursor solution to ultrasonic waves. These droplets then undergo a thermal decomposition, resulting in the formation of the final powders. In this study, a low-priced commercial sodium silicate (water glass, Na 2 O 3 Si) was employed as the starting material, and a high-purity colloidal nano-SiO 2 sol was prepared via an ion-exchange resin method. The effects of the rheological properties (dispersion and viscosity), colloidal nano-SiO 2 size, and concentration of the prepared high-purity nano-SiO 2 sol on the shape of the spherical SiO 2 powders synthesized through USP were observed through SEM, PSA, and XRD. The results confirmed that the changes in the colloidal nano-SiO 2 size and surface tension, due to the addition of ethanol to the high-purity nano-SiO 2 sol, had little effect on the physical properties, such as particle size, standard deviation, and roundness of the SiO 2 powders synthesized by USP (USP-SiO 2 ). Moreover, dispersibility alterations were achieved through pH control. Furthermore, concentration of the nano-SiO 2 sol significantly affected the particle size and monodispersity of the final USP-SiO 2 powders.