Oxidation protection of carbon fiber by sol-gel derived boron doped yttria stabilized zirconia coatings

The sol-gel approach was utilized to prepare boron doped yttria stabilized zirconia coated carbon fiber and their thermal characteristics were evaluated against yttria stabilized zirconia coated carbon fiber and uncoated fiber. Coated carbon fiber was characterized by TGA, SEM and FT-IR while calcined sols were analyzed by XRD to study the phase composition. Carbon fiber was coated multiple times and the coating thickness was observed to increase with the number of dipping cycles. Nanoparticles obtained by calcining the boron doped yttria stabilized zirconia system, exhibited the cubic phase while pure zirconia nanoparticles represented monoclinic and tetragonal phases. The sol system with Zr: B: Y molar ratio set as 1: 1: 0.14 was observed to provide superior oxidation protection of carbon fiber compared to the conventional yttria stabilized zirconia sol system. The new coating system showed promise concerning oxidation retardation of carbon fiber and its composites at high temperatures.