Development of a glass-ceramic composite reinforced with β-wollastonite synthesized via a hydrothermal method

Abstract

β-Wollastonite (β-CaSiO₃) microfibers were successfully synthesized using a one-step, template-free hydrothermal reaction involving calcium nitrate and sodium metasilicate in an alkaline medium. The synthesis of microfibers was completed at 220 °C within only 240 minutes under an autogenous pressure of 19 bar. This method avoids the formation of xonotlite as an intermediate phase, eliminating the need for subsequent calcination to achieve wollastonite. X-ray diffraction (XRD) confirmed the β-wollastonite phase, while post-calcination analyses indicated enhanced crystallinity and structural characteristics. Scanning electron microscopy (SEM) revealed a needle-like morphology, and N₂ adsorption-desorption analysis demonstrated a developed surface area of 26 m²g^-1 with notable mesoporosity. These advantageous features facilitated the integration of β-wollastonite into the synthesis of a glass-ceramic composite, which was characterized for its morphological, structural, textural, and in vitro bioactivity properties. The composite was prepared by mixing β-wollastonite and bioactive glass powders in a 1:4 mass ratio, followed by compaction through uniaxial pressing and sintering at 1000 °C for various time intervals. For comparison, compacted pure bioactive glass samples were also sintered under identical conditions. Structural, morphological, textural, and in vitro bioactivity characterizations demonstrated that the incorporation of β-wollastonite led to a more uniform and narrower pore size distribution and promoted neck formation between particles, indicating its potential for bone regeneration applications.