| Contraposing current severe haze state in China,it is very imperative matter that we should develop clean energy.Nuclear energy is an effective way to solve this problem,whose fusion reaction can release massive energy.Li-6 is a significant clean energy source for long-term sustainable development in the future.However,tritium has the potential for β-radioactivity,and the concentration of Li-6 in the ocean is very important.The fuel of fusion reaction is tritium,which is inexhaustible and unlimited on earth.However,there are still some permeation problems existing in system,including tritium production,usage,storage,transportation technic,fusion tritium production cladding and fuel cycle technology.At present,most of metal material used resistance to tritium adopt 316L stainless steel because of its better property.Compared with other metal materials,tritium permeability is lower.316L stainless steel is a fusion reactor cladding promising one of the candidate structural materials.But due to 316L stainless steel resistance tritium permeation effect still can not meet the current needs.Therefore,now focus on the study of metal materials with low tritium permeability of the surface coating of materials,domestic and foreign resistance to tritium osmosis coating has carried out a lot of research work,prepared a variety of coating materials successfully,which were mainly classified into titanium-based ceramics,aluminides,silicides and oxides.In this paper,a typical sample of Al2O3/Fe-Al composite coating tritium process system was prepared on the surface of 316L stainless steel the pack cementation aluminizing-in-situ oxidation process developed as the research object.The permeation at low tritium pressure(0.1-10Pa)performance.Since the tritium is radioactive,the experimental process uses a deuterium similar to the tritium chemical properties,and the temperature of the Al2O3/Fe-Al composite coating under low deuterium pressure(0.1-10Pa)Deuterium concentration distribution of deuterium samples;Then,the qualitative distribution curve(U-t)of the deuterium concentration of the hot-injected deuterium samples was measured by Glow Discharge Spectrometer(GDEOS);The deuterium-containing samples were prepared by the method of quantitatively absorbing deuterium and quadrupole mass spectrometer(QMS),and the deuterium content was measured by GDOES.The quantitative relationship between deuterium and GDOES was obtained;On the basis of this,the quantitative distribution curve(QDP)of the depth distribution of deuterium concentration in Fe-Al/Al2O3 composite coating under low deuterium pressure(0.1-10Pa)can be obtained.According to the distribution of deuterium in the material,Concentration distribution characteristic equation,characteristic solution,calculation and fitting to obtain the diffusion coefficient of each layer of material and the solubility of deuterium on the surface of alumina,so as to provide an important basis for the infiltration model of tritium process system.The research content of this paper is mainly from the following aspects:① Quantitative calibration of deuterium element by quadrupole mass spectrometer.First,the quantitative analysis of the four-mass spectrometer(QMS)was carried out.Six different pressure ranges were taken in the experiment:the deuterium pressure Pi was injected at one time until the pressure was reduced to P2,and the pressure change data were automatically recorded by the pressure sensor.Using the formula V·lnP1/P2=C·(t2-t1) to get flow guide self-made hole C(3.60E-2、3.61E-2、3.60E-2、3.60E-2、3.59E-2、3.60E-2 cm3/s);Then according to changes in pressure data,flow guide C(P1-P2)is obtained;Finally,the deuterated gas volume N=(P1-P2)*V is obtained by using the pressure difference(P1-P2),And the calibration coefficientβ((Pa.cm3).(A.s)-1)(N=2.76E11*A+1.36)of the integral area A and the deuterium gas N is obtained by linear fitting.② Preparation of Deuterium and Ti Films by Pure Alumina Sheet.Alumina due to high resistance to tritium permeability factor(PRF),alumina through high temperature,high deuterium pressure for a long time infiltration,alumina dissolved less deuterium atoms,therefore,is not suitable for the production of standard samples;by magnetron sputtering method Ti-Mo film samples,after high temperature,high vacuum degassing activation,the surface Ti has a high activity,can quickly combined with deuterium,in particular the use of magnetron sputtering method in the Ti-Mo film surface plating Ni,more conducive to maintaining the activity of Ti,according to the characteristics of Ti-Mo film successfully prepared a standard sample TiDx(x=0.0058、0.01、0.0016、0.0048).③ Qualitative Analysis of Thermal Injected Deuterium by FeAl/Al2O3 and Quantitative Conversion of Concentration Depth Distribution.In order to make the existing glow discharge spectrometer(GDOES)on the deuterium element(D)can both qualitative and quantitative.The voltage signal value U(V)of the standard gaseous discharge spectrometer(GDOES)is plotted as the coordinate Y-axis,and then the deuterium atoms in the standard TiDx are the same as those of the titanium atom.The ratio of D/Ti to the voltage signal value U(V)of the glow discharge spectrometer(GDOES)is obtained by linearly fitting the two to the coordinate X-axis(Y=1.17E5*X-65.5),and the quantitative analysis of the deuterium element by the glow discharge spectrometer.The deuterium samples with hot implanted deuterium pressure(0.1-10)Pa,temperature(320-450)℃ and holding time(0-48)h were prepared by using self-developed thermal injection deuterium deuterium test device.Spectrophotometer(GDOES)was used to quantitatively analyze the variation of deuterium concentration and its depth distribution over time in alumina and Fe-Al transition layer.④ Parameter Analysis and Parameter Solving of Permeation Model of Tritium Process.According to the analysis of the permeability model parameters in the tritium process system,the diffusion coefficient of deuterium in the layers of alumina,Fe-Al transition layer and the solubility of deuterium on the alumina surface are required.Based on the semi-infinite plate model in TMAP7 and the error function(?).the curve of the concentration distribution near the coating is found,and then the diffusion coefficient D(T=320℃,7.14E-18 m2/s、T=400℃,6.43E-17 m2/S、T=450℃,5.79E-16m2/s),The solubility Ks(T=320℃,Ks=1.34E-04 mol/m3*MPa、T=400℃,Ks=1.90E-04 mol/m3*MPa、T=450℃,Ks=5.45E-04 mol/m3*MPa)of deuterium on the alumina surface was obtained using the formula Cs = Ks x Pn,The diffusion coefficient D and the surface solubility Ks of deuterium in standard alumina are close to those in the literature,which indicates that the parameters of Al2O3/Fe-Al composite coating obtained by this method have high reliability. |
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