溶胶pH值对氢化锆表面阻氢膜层性能的影响

目的采用溶胶-凝胶法在氢化锆表面制备氧化锆阻氢膜层,探究溶胶p H值对阻氢膜层性能的影响。方法以正丙醇锆为前驱体,通过滴加盐酸分别得到p H值为1、3、5、7、9的溶胶。利用扫描电子显微镜(SEM)、激光共聚焦显微镜(CLSM)和X射线衍射仪(XRD),分析了氧化锆膜层的截面形貌、表面形貌和物相组成,并利用真空脱氢实验测试了膜层的阻氢性能。结果溶胶p H值影响溶胶的涂覆性能,致使氢化锆基体表面所得膜层的连续性、均匀性及厚度存在差异。溶胶pH值的变化对形成膜层的物相组成没有显著影响,所得膜层由单斜相氧化锆(m-ZrO2)和四方相氧化锆(t-ZrO_2)组成。当p H值在1～9范围内时,随着溶胶pH的增加,膜层中t-ZrO_2的体积分数和PRF值均呈现出先升高后降低的变化趋势,t-ZrO_2的体积分数介于13.16%～46.84%之间,膜层的PRF值介于10.13～19.46之间。结论溶胶pH值影响溶胶的涂覆性能,进而影响膜层质量、膜层中各物相的含量以及膜层的阻氢效果。当溶胶p H值为3时,溶胶涂覆性能良好,所得氧化锆膜层均匀、连续,膜层较厚且致密,膜层中t-ZrO_2的体积分数最大,为46.84%,同时膜层的氢渗透降低因子(PRF值,Permeation Reduction Factor)达到最大值19.46。

Effect of Sol pH Values on Properties of Hydrogen Resistance Films on the Surface of Zirconium Hydride

The work aims to prepare ZrO2 films on the surface of zirconium hydride, so as to investigate the effects of Sol pH on hydrogen resistance films. With zirconium n-propoxide as precursor, the sol with pH values of 1, 3, 5, 7 and 9 was obtained by adding hydrochloric acid. The cross-sectional morphologies, surface morphologies and phase composition of the as-prepared ZrO2 coatings were investigated by scanning election microscopy (SEM), confocal laser scanning microscope (CLSM) and X-ray diffraction (XRD), respectively. Hydrogen permeation resistance performance was characterized by vacuum dehydrogenation experiment. The pH of precursor solution had a considerable influence on the film properties and caused difference to the continuity, uniformity and thickness. In contrast, there was no significant change in phase composition, and the ZrO2 films obtained at varied pH mainly consisted of monoclinic phase (m-ZrO2) and tetragonal phase (t-ZrO2) zirconia. The volume fraction of t-ZrO2 and permeation reduction factor (PRF) value of the film exhibited a downward parabolic trend when the pH value was increased from 1 to 9, and the volume fraction of t-ZrO2 and PRF value varied in the range of 13.16% to 46.84% and 10.13 to 19.46, respectively. The pH values of precursor solutions has a considerable effect on the paintability of the sol, thus exerting a direct effects on the quality, phase composition and hydrogen permeation resistance of the ZrO2 films. Particularly, the optimized ZrO2-film coated zirconium hydrides are obtained at the pH value of 3, and the thick films are dense, continuous and uniform, where the max volume fraction of t-ZrO2 and PRF (permeation reduction factor) value are 46.84% and 19.46, respectively.