【摘要】：氫化鋯是空間反應(yīng)堆理想的中子慢化材料,但氫化鋯作為慢化劑在工作溫度范圍內(nèi)存在失氫問題,從而降低其中子慢化效率和服役壽命。通過表面涂覆技術(shù)在氫化鋯表面制備防氫滲透阻擋層可以有效減緩甚至抑制氫化鋯在高溫條件下的失氫現(xiàn)象。目前,在氫化鋯表面制備單一組分的氧化鋯膜層存在相變開裂問題,難以滿足氫化鋯工況要求。通過成分和結(jié)構(gòu)設(shè)計在氫化鋯表面制備復(fù)合氧化鋯膜層成為氫化鋯慢化材料研究的重要方向。本文采用溶膠-凝膠法在氫化鋯表面制備釔穩(wěn)定氧化鋯膜層,分別研究了醇溶劑種類(乙醇、異丙醇、正丙醇、正丁醇)和釔摻雜量對氧化鋯溶膠的膠凝過程、加熱失重轉(zhuǎn)變過程及相轉(zhuǎn)變過程的影響,并借助掃描電子顯微鏡(SEM/EDS)、X射線衍射儀(XRD)、劃痕儀和真空脫氫試驗對溶膠獲得氧化鋯膜層的形貌、相組成、結(jié)合力及阻氫性能進(jìn)行了分析和表征,研究取得的主要結(jié)果如下:隨著溶劑中羥基上碳鏈長度增加,氧化鋯溶膠顏色逐漸加深,氧化鋯溶膠的陳化時間增加,膜層的連續(xù)性、均勻性和完整性得到改善,膜層的厚度、膜層與基體的結(jié)合力以及膜層的PRF值增大。膜層與基體的結(jié)合力介于32~51N之間,膜層的氫滲透降低因子介于8.3~12.5之間,膜層的平均厚度介于4~15μm之間。以正丙醇為溶劑的溶膠所得膜層相對致密,膜層中孔洞和微裂紋缺陷較少,膜層連續(xù)完整。對不同溶劑制備氧化鋯膜層的相結(jié)構(gòu)分析表明,醇溶劑的種類對膜層的相組成沒有顯著影響,四種氧化鋯凝膠制備的膜層均由單斜相氧化鋯(m-ZrO_2)和四方相氧化鋯(t-ZrO_2)組成,并以單斜相氧化鋯為主(m-ZrO_2);膜層中氫化鋯(ZrH_(1.8))的衍射峰強(qiáng)度隨著溶劑中羥基上碳鏈長度的增加而逐漸減弱。選取正丙醇為溶劑,硝酸釔作為釔摻雜劑,采用溶膠-凝膠法制備釔穩(wěn)定氧化鋯膜層。隨著釔摻雜量的增加,溶膠的pH值逐漸減小,電位逐漸增加,氧化鋯溶膠的粘度降低,溶膠的陳化時間增加,進(jìn)而影響氧化鋯溶膠的涂覆性能,造成膜層連續(xù)性、均勻性和完整性產(chǎn)生差異。釔的摻雜使氧化鋯膜層的厚度增加,減少了氧化鋯膜層中裂紋數(shù)量,并使氧化鋯膜層的致密性提升,阻氫性能提高。氧化鋯膜層的平均厚度在8.3~21.4μm之間,結(jié)合力介于33~51N之間,氫滲透因子介于12.5~18之間。對釔摻雜氧化鋯膜層的相結(jié)構(gòu)分析表明,摻雜釔得到的膜層為釔穩(wěn)定的四方相氧化鋯,隨著釔的摻雜量的增加,膜層中單斜相氧化鋯衍射峰強(qiáng)度減弱,四方相氧化鋯衍射峰強(qiáng)度增強(qiáng),釔的摻雜有效抑制了四方相氧化鋯到單斜相氧化鋯的相轉(zhuǎn)變過程。采用溶膠-凝膠法制備釔穩(wěn)定氧化鋯膜層的優(yōu)選技術(shù)方案為:正丙醇鋯、正丙醇、乙酰丙酮、二乙醇胺的體積比為10:9:1:1,n(Zr~(4+)):n(Y~(3+))=88:12,氧化鋯凝膠終點熱處理溫度為600℃。此條件下獲得的釔穩(wěn)定氧化鋯膜層連續(xù)致密,阻氫效果較好,其氫滲透降低因子PRF值為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，

本文編號：2232836