Effects of hydrolysis processing on the character of forsterite gel fibers. Part II: crystallites and microstructural evolutions

Crystallites and microstructural evolutions of the three forsterite fibers derived from three different precursor sols were compared. The formation of crystalline forsterite commenced at a temperature as low as 550 °C in all the fibers. Gel fiber prepared with excess ethanol showed a lower homogeneity and densification; a second phase of magnesia was observed on heating. The water content also affected the grain size and homogeneity of the fired fibers. On heating at 1100 °C, the three forsterite fibers were microporous with grain sizes less than 0.1 μm; further heating at 1300 °C resulted in grain growth up to 0.3–0.5 μm and denser microstructures, depending on the amount of water and ethanol.