Multi-scale synergistic reinforcement and performance control of PVA/fiber binary system in preparation of fused silica via gel method

Gel casting faces challenges like low strength, non-uniformity and long cycles in making large fused silica parts. To address these issues, this study addresses challenges by introducing a composite reinforcement system of silica fibers and polyvinyl alcohol (PVA). The system enhances the green body strength, shortens the processing time, and improves the axial uniformity of the material through multi-scale synergistic effects. Specifically, PVA enhances particle connectivity and green body stiffness through chemical bonding, while silica fibers form a 3D network for physical toughening. This multi-scale interaction increases green body flexural strength to 1254.6 kPa, 2.8 times that of the unreinforced system. Silica fibers also create micro-channels that accelerate moisture diffusion, shortening drying time. Fibers anchor with PVA to construct a 3D network that blocks large-particle sedimentation, homogenizing nanoparticle distribution. These effects collectively reduce axial variations in specific surface area and porosity, enabling uniform composition and density from slurry to sintered body. After sintering optimization (1350°C, 30 min), excellent fiber-nanoparticle integration is achieved, producing a fused silica component with a 4:1 aspect ratio, high axial density uniformity, and over 90% optical transmittance. A decimeter-scale fused silica compound eye lens with precise imaging capability was successfully fabricated, demonstrating the system’s practical potential.