氢化锆表面溶胶—凝胶法制备钇稳定氧化锆膜层
发布时间：2018-09-09 15:56
【摘要】：氢化锆是空间反应堆理想的中子慢化材料,但氢化锆作为慢化剂在工作温度范围内存在失氢问题,从而降低其中子慢化效率和服役寿命。通过表面涂覆技术在氢化锆表面制备防氢渗透阻挡层可以有效减缓甚至抑制氢化锆在高温条件下的失氢现象。目前,在氢化锆表面制备单一组分的氧化锆膜层存在相变开裂问题,难以满足氢化锆工况要求。通过成分和结构设计在氢化锆表面制备复合氧化锆膜层成为氢化锆慢化材料研究的重要方向。本文采用溶胶-凝胶法在氢化锆表面制备钇稳定氧化锆膜层,分别研究了醇溶剂种类(乙醇、异丙醇、正丙醇、正丁醇)和钇掺杂量对氧化锆溶胶的胶凝过程、加热失重转变过程及相转变过程的影响,并借助扫描电子显微镜(SEM/EDS)、X射线衍射仪(XRD)、划痕仪和真空脱氢试验对溶胶获得氧化锆膜层的形貌、相组成、结合力及阻氢性能进行了分析和表征,研究取得的主要结果如下:随着溶剂中羟基上碳链长度增加,氧化锆溶胶颜色逐渐加深,氧化锆溶胶的陈化时间增加,膜层的连续性、均匀性和完整性得到改善,膜层的厚度、膜层与基体的结合力以及膜层的PRF值增大。膜层与基体的结合力介于32~51N之间,膜层的氢渗透降低因子介于8.3~12.5之间,膜层的平均厚度介于4~15μm之间。以正丙醇为溶剂的溶胶所得膜层相对致密,膜层中孔洞和微裂纹缺陷较少,膜层连续完整。对不同溶剂制备氧化锆膜层的相结构分析表明,醇溶剂的种类对膜层的相组成没有显著影响,四种氧化锆凝胶制备的膜层均由单斜相氧化锆(m-ZrO_2)和四方相氧化锆(t-ZrO_2)组成,并以单斜相氧化锆为主(m-ZrO_2);膜层中氢化锆(ZrH_(1.8))的衍射峰强度随着溶剂中羟基上碳链长度的增加而逐渐减弱。选取正丙醇为溶剂,硝酸钇作为钇掺杂剂,采用溶胶-凝胶法制备钇稳定氧化锆膜层。随着钇掺杂量的增加,溶胶的pH值逐渐减小,电位逐渐增加,氧化锆溶胶的粘度降低,溶胶的陈化时间增加,进而影响氧化锆溶胶的涂覆性能,造成膜层连续性、均匀性和完整性产生差异。钇的掺杂使氧化锆膜层的厚度增加,减少了氧化锆膜层中裂纹数量,并使氧化锆膜层的致密性提升,阻氢性能提高。氧化锆膜层的平均厚度在8.3~21.4μm之间,结合力介于33~51N之间,氢渗透因子介于12.5~18之间。对钇掺杂氧化锆膜层的相结构分析表明,掺杂钇得到的膜层为钇稳定的四方相氧化锆,随着钇的掺杂量的增加,膜层中单斜相氧化锆衍射峰强度减弱,四方相氧化锆衍射峰强度增强,钇的掺杂有效抑制了四方相氧化锆到单斜相氧化锆的相转变过程。采用溶胶-凝胶法制备钇稳定氧化锆膜层的优选技术方案为:正丙醇锆、正丙醇、乙酰丙酮、二乙醇胺的体积比为10:9:1:1,n(Zr~(4+)):n(Y~(3+))=88:12,氧化锆凝胶终点热处理温度为600℃。此条件下获得的钇稳定氧化锆膜层连续致密,阻氢效果较好,其氢渗透降低因子PRF值为17.7。
[Abstract]:Zirconium hydride is an ideal neutron moderating material for space reactors, but zirconium hydride as moderator has the problem of losing hydrogen in the range of working temperature, thus reducing the efficiency and service life of the moderator. The preparation of hydrogen permeation barrier layer on zirconium hydride surface by surface coating technology can effectively slow down or even inhibit the loss of hydrogen in zirconium hydride at high temperature. At present, the phase transition cracking problem exists in the preparation of single component zirconia film on the surface of zirconium hydride, which is difficult to meet the requirements of zirconium hydride operating conditions. The preparation of composite zirconia film on zirconium hydride surface by composition and structure design has become an important research direction of zirconium hydride moderating material. In this paper, yttrium stabilized zirconia films were prepared on zirconium hydride surface by sol-gel method. The gelation process of zirconia sol by alcohol solvent (ethanol, isopropanol, n-butanol) and yttrium doping was studied. The effect of heating weightlessness transition and phase transition process on the morphology and phase composition of zirconia film was obtained by scanning electron microscope (SEM/EDS) X-ray diffraction (XRD), scratch and vacuum dehydrogenation test. The main results are as follows: with the increase of the length of carbon chain in the hydroxyl group, the color of zirconia sol gradually deepens, the aging time of zirconia sol increases and the film layer is continuous. The uniformity and integrity were improved, the thickness of the film, the adhesion between the film and the substrate and the PRF value of the film were increased. The adhesion force between the film and the substrate is between 32N and 51N, the hydrogen permeation reduction factor of the film is between 8.3ng and 12.5, and the average thickness of the film is between 40.15 渭 m. The film layer obtained by using n-propanol as solvent is relatively compact, and the defects of pores and microcracks in the film layer are less, and the film layer is continuous and complete. The phase structure analysis of zirconia films prepared by different solvents showed that the types of alcohol solvents had no significant effect on the phase composition of the films. The films prepared by four kinds of zirconia gels were composed of monoclinic zirconia (m-ZrO_2) and tetragonal zirconia (t-ZrO_2). The diffraction peak intensity of zirconium hydride (ZrH_ _ (1.8) in the film decreases with the increase of the length of carbon chain in the hydroxyl group. Yttrium stabilized zirconia film was prepared by sol-gel method using n-propanol as solvent and yttrium nitrate as yttrium dopant. With the increase of yttrium doping amount, the pH value of the sol decreases, the potential increases gradually, the viscosity of zirconia sol decreases and the aging time of the sol increases, which affects the coating performance of zirconia sol and results in the continuity of film layer. Uniformity and integrity vary. The doping of yttrium can increase the thickness of zirconia film, reduce the number of cracks in zirconia film, improve the density and hydrogen resistance of zirconia film. The average thickness of zirconia film is between 8.3 渭 m and 21.4 渭 m, the binding force is between 33 ~ 51N, and the hydrogen permeation factor is between 12.5 ~ (18). The phase structure analysis of yttrium doped zirconia film shows that the yttrium doped zirconia film is a yttrium stable tetragonal zirconia film. With the increase of yttrium doping amount, the diffraction peak intensity of monoclinic phase zirconia decreases. The intensity of tetragonal zirconia diffraction peak is enhanced and the phase transition from tetragonal zirconia to monoclinic zirconia is effectively inhibited by yttrium doping. The optimal technique for preparing yttrium stabilized zirconia film by sol-gel method is as follows: zirconium n-propanol, acetylacetone, diethanolamine: 10: 9: 1: 1 (Zr~ (4): n (Y3) = 8812. The final heat treatment temperature of zirconia gel is 600 鈩，
本文编号：2232836
[Abstract]:Zirconium hydride is an ideal neutron moderating material for space reactors, but zirconium hydride as moderator has the problem of losing hydrogen in the range of working temperature, thus reducing the efficiency and service life of the moderator. The preparation of hydrogen permeation barrier layer on zirconium hydride surface by surface coating technology can effectively slow down or even inhibit the loss of hydrogen in zirconium hydride at high temperature. At present, the phase transition cracking problem exists in the preparation of single component zirconia film on the surface of zirconium hydride, which is difficult to meet the requirements of zirconium hydride operating conditions. The preparation of composite zirconia film on zirconium hydride surface by composition and structure design has become an important research direction of zirconium hydride moderating material. In this paper, yttrium stabilized zirconia films were prepared on zirconium hydride surface by sol-gel method. The gelation process of zirconia sol by alcohol solvent (ethanol, isopropanol, n-butanol) and yttrium doping was studied. The effect of heating weightlessness transition and phase transition process on the morphology and phase composition of zirconia film was obtained by scanning electron microscope (SEM/EDS) X-ray diffraction (XRD), scratch and vacuum dehydrogenation test. The main results are as follows: with the increase of the length of carbon chain in the hydroxyl group, the color of zirconia sol gradually deepens, the aging time of zirconia sol increases and the film layer is continuous. The uniformity and integrity were improved, the thickness of the film, the adhesion between the film and the substrate and the PRF value of the film were increased. The adhesion force between the film and the substrate is between 32N and 51N, the hydrogen permeation reduction factor of the film is between 8.3ng and 12.5, and the average thickness of the film is between 40.15 渭 m. The film layer obtained by using n-propanol as solvent is relatively compact, and the defects of pores and microcracks in the film layer are less, and the film layer is continuous and complete. The phase structure analysis of zirconia films prepared by different solvents showed that the types of alcohol solvents had no significant effect on the phase composition of the films. The films prepared by four kinds of zirconia gels were composed of monoclinic zirconia (m-ZrO_2) and tetragonal zirconia (t-ZrO_2). The diffraction peak intensity of zirconium hydride (ZrH_ _ (1.8) in the film decreases with the increase of the length of carbon chain in the hydroxyl group. Yttrium stabilized zirconia film was prepared by sol-gel method using n-propanol as solvent and yttrium nitrate as yttrium dopant. With the increase of yttrium doping amount, the pH value of the sol decreases, the potential increases gradually, the viscosity of zirconia sol decreases and the aging time of the sol increases, which affects the coating performance of zirconia sol and results in the continuity of film layer. Uniformity and integrity vary. The doping of yttrium can increase the thickness of zirconia film, reduce the number of cracks in zirconia film, improve the density and hydrogen resistance of zirconia film. The average thickness of zirconia film is between 8.3 渭 m and 21.4 渭 m, the binding force is between 33 ~ 51N, and the hydrogen permeation factor is between 12.5 ~ (18). The phase structure analysis of yttrium doped zirconia film shows that the yttrium doped zirconia film is a yttrium stable tetragonal zirconia film. With the increase of yttrium doping amount, the diffraction peak intensity of monoclinic phase zirconia decreases. The intensity of tetragonal zirconia diffraction peak is enhanced and the phase transition from tetragonal zirconia to monoclinic zirconia is effectively inhibited by yttrium doping. The optimal technique for preparing yttrium stabilized zirconia film by sol-gel method is as follows: zirconium n-propanol, acetylacetone, diethanolamine: 10: 9: 1: 1 (Zr~ (4): n (Y3) = 8812. The final heat treatment temperature of zirconia gel is 600 鈩，
本文编号：2232836
本文链接：https://www.wllwen.com/shekelunwen/minzhuminquanlunwen/2232836.html
