Yttria-stabilized Zirconia Film Fabricated On The Surface Of Zirconium Hydride By Sol-gel

Zirconium hydride is an ideal neutron moderating material.However,the problem of hydrogen loss from zirconium hydride exists in the range of working temperature,which reduces the neutron moderating efficiency and service life.Preparing hydrogen permeation barrier on the surface of zirconium hydride by surface coating technology is an effective way to reduce even inhibit the hydrogen loss at high temperature.At present,Preparing the anti-hydrogen permeation coating of single component on the surface of zirconium hydride exist cracks on films and has been unable to meet the requirements.Thus,the composite zirconia film need be prepared on the surface of zirconium hydride by composition and structure design,which become an important direction for the study of zirconium hydride.Yttrium stabilized zirconia layers were prepared on the surface of zirconium hydride by Sol-Gel method.The influence of the solvent type?ethanol?isopropanol?N-propanol?N-butanol?and yttrium doping amount on the gelation process,the process of heating weightlessness and the phase transition process of the zirconia sol was studied separately.The phase morphology,phase composition,binding force and anti-permeation of the oxide coatings were measured by X-ray diffraction?XRD?,Scanning Electron Microscopy/ Energy Dispersive X-ray Spectra?SEM/EDS?,Scratch Tester and Vacuum Losing Hydrogen experiment,respectively.Main results are concluded as follows:With the increase of carbon chain length on the hydroxy,the color of the zirconia sol gradually become deeper and deeper,the aging time of the zirconia sol is extended,the continuity,uniformity and integrity get better,and the thickness of the films are improved.At the same time the binding force of zirconia layer enhance,the Permeation Reduction Factor?PRF?of the film layer is increased.The binding force of the zirconia layer changes in the range of 32⁵1N,the PRF of the film varies from 8.3 to 12.5,the average thickness of the zirconia film is between 4 and 15?m.The film of the sol by using n-propanol as solvent has relatively dense,the voids and microcracks are less,the continuity and integrity of the film are better.The phase structure analysis of zirconia film prepared by different solvents indicates,the type of alcohol solvent doesn't have obvirously effect on the phase composition of film,zirconia films from the four kinds of zirconia gels are composed of monoclinic zirconia?m-ZrO₂?and tetragonal zirconia?t-ZrO₂?,and the films is mainly composed of m-ZrO₂.With the increase of the carbon chain length of the hydroxyl on solvent,the diffraction intensity of the zirconium hydride(ZrH_1.8)is gradually weaken.The yttrium stabilized zirconia film was prepared using n-propanol as solvent and yttrium nitrate as yttrium dopant by sol-gel.With the increase of yttrium doping amount,the pH of the sol gradually decrease,the potential of sol gradually increase,the viscosity of the zirconia sol reduce,the aging time of sols increase,which affect the coating performance of zirconia sol,resulting in different film continuity,uniformity and integrity.By doping yttrium the thickness of the zirconia film increaseand the cracks in the zirconia film reduce,the compactness of the zirconia film is promoted,and the property of hydrogen resistance is improved.The average thickness of the zirconia film is between 8.3 and 21.4?m,the binding force of the film range from 33 to 51 N,and the PRF of the film is between 12.5 and 18.The phase structure analysis of the yttrium-stabilized zirconia film shows that the yttrium doped zirconia film is a yttrium stabilized tetragonal zirconia.With the doping amount of yttrium increase,the monoclinic zirconia diffraction intensity decrease and the tetragonal zirconia diffraction intensity gradually increase,and the yttrium effectively inhibits the phase transition from tetragonal zirconia to monoclinic zirconia.The preferred conditions for fabricating yttrium-stabilized zirconia film by Sol-gel is that: the volume ratio o f zirconium n-propanol,n-propanol,acetylacetone and diethanolamine is 10:9:1:1,n(Zr⁴⁺):n(Y³⁺)=88:12,The final heat treatment temperature of the zirconia gel is 600?.At this condition,the film is dense and continuous,the performance of hydrogen resistance shows wel,and the hydrogen permeation reduction factor is 17.7.