The effect of SiO ₂ -doped boron nitride multiple coatings on mechanical properties of quartz fibers

SiO ₂ -doped boron nitride multiple coatings (SiO ₂ /BN multiple coatings) were prepared on quartz fibers surface at 700 °C. Single fiber tensile test was employed to evaluate fiber tensile strength; Scanning Electron Microscopy (SEM) and Transmission Electron Microscopy (TEM) were employed to evaluate morphology and structure of the fibers. Fiber tensile test results indicated that the strength of quartz fibers with SiO ₂ /BN multiple coatings was about twice of the fibers with BN coatings and original fibers which were heated at 700 °C for 10 h. The SiO ₂ /BN multiple coatings would provide compressive stress on quartz fibers, which would help to seal the defects on fiber surface. Furthermore, TEM images showed that the nano-SiO ₂ powders crystallized in advance of quartz fibers, which would suppress crystallization of quartz fibers and reduce damage from crystallization. Thus, nano-SiO ₂ powders would help to keep mechanical properties of quartz fibers.