Amorphous silicon and silicates-stabilized ZrO2 hollow fiber with low thermal conductivity and high phase stability derived from a cogon template

Abstract ZrO 2 fibers are used as refractory materials owing to their excellent thermal resistance and thermal stability. Natural cogon fiber is a type of hollow Gramineae fiber, and usually contains a small amount of amorphous silicon and silicates, such as SiO 2 , MgSiO 3 , CaSiO 4 , and Al 2 SiO 5 , which can effectively avoid the phase transition of ZrO 2 . In this study, hollow ZrO 2 fibers with remarkable thermal insulation and phase stability were synthesized using a cogon fiber template. The results showed that the final ZrO 2 fibers successfully inherited the hollow structure and amorphous substance from the cogon template. The hollow structure of the biomorphic ZrO 2 fiber helped prevent heat flow more efficiently compared to solid fibers and reduced the thermal conductivity to a significant extent. In addition, the amorphous silicon and silicates played an important role in the phase stability of tetragonal ZrO 2 ; the transformation from the tetragonal to monoclinic phase was avoided at room temperature and in humid environment.