Synthesis and Characterization of Rich Silica Mullite Fibers by Sol–Gel Method Using Aluminum Lactate and Silica Sol

Abstract

Rich silica mullite fibers were prepared from an aqueous solution of aluminum lactate and silica sol by the sol-gel method, in which the Al/Si molar ratio of fibers was 0.64. The aluminum lactate was prepared by mixing aluminum nitrate and lactic acid in the molar ratio of 1:3. The fibers sintered at 1200 • C presented as an amorphous phase, with a rough surface and uniform diameter. Mullite and silica phases were obtained after the fibers were sintered at 1400 • C for 1 h, and the mullite whiskers were observed at the fibers surface, with a high aspect ratio of >10 (about 0.06 µm in diameter). The diameter of the whiskers reached about 0.5 µm at fibers surface when the fibers were sintered at 1600 • C for 1 h.

High‐temperature stable inverse opal photonic crystals via mullite‐sol‐gel infiltration of direct photonic crystals

“…The XRD patterns obtained by annealing the gel confirm an incipient formation of mullite as temperatures as low as 1000°C (Figure ) . Interestingly, the formation of mullite after annealing at 1000°C for 10 hours seems to be more pronounced for the high‐alumina composition, which comprises also traces of crystalline alumina . After fast heating to 1500°C followed by annealing for 10 hours, however, both compositions contain not only mullite but also alumina (delta and alfa) and silica (cristobalite), the latter giving a strong signal.…”