SiO_2对溶胶-凝胶法制备的ZrO_2纤维相变和微观组织的影响

Effects of silica on phase transformation and microstructure of zirconia fiber

通过氧氯化锆与过氧化氢的反应得到氧化锆溶胶,与SiO_2溶胶混合后,制备了不同SiO_2含量的氧化锆纤维,采用SEM、XRD、DTA、FT-IR、^(29)SiNMR、TEM等对纤维相组成和微观结构进行了系统研究。结果表明,少量SiO_2可以显著提高四方相ZrO_2的稳定性,抑制单斜相的形成,避免纤维"皮芯结构"的形成。此外SiO_2可以有效抑制晶粒长大,从而达到细晶的作用,获得无表面缺陷、致密、柔性的ZrO_2纤维。

Zirconia fibers containing different amount of silica are prepared using zirconium oxychloride,hydrogen peroxide and silica sol as the raw materials and by sol-gel method.SEM,XRD,DTA,FT-IR,29 ^Si NMR and TEM are used to characterize the zirconia-silica fibers.It has been found that silica can significantly stabilize the tetragonal ZrO_2 phase,inhibiting its phase transformation to the monoclinic phase.As the consequence,the formation of sheath-core structure in the zirconia-silica fibers has been prevented.Silica can also effectively inhibit the grain growth,resulting in crack-free,transparent,dense and flexible ceramic fibers.