Effect of moderately high temperature heat treatment on surface morphology and structure of quartz fibers

In this study, quartz fibers were heated at 600 °C, 700 °C, 800 °C and 900 °C for 10 h respectively. Scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray diffraction (XRD) and fiber tensile test were employed to examine the surface morphology, structure and tensile strength of quartz fibers. The SEM images indicated that when fibers were heated up to 600 °C, dot flaws appeared on fiber surface and when the temperature reached 700 °C, new strip flaws appeared on the fiber surface. HR-TEM images showed that when fibers were heated up to 700 °C, some ordered regions (nanometers) appeared on the fiber surface. Furthermore, the nanometer crystallites were found on fiber surface when fibers were heated at 900 °C. The defects on fiber surface, according to fiber tensile test, had a significant effect on mechanical property of quartz fibers and caused drastic reduction in fiber tensile strength. It is considered that the mismatch between the ordered regions and amorphous regions induced new defects on fiber surface, which led to further decrease of fiber tensile strength.

► Nanometer crystallites are detected on heated fiber surface. ► The structure translation causes further decrease of fiber tensile strength. ► Effect of heat-treatment at 600-900 °C on quartz fibers strength is researched.