Investigation of Stable Al2O3 Scale on Fe-Al Aluminized Coating for Tritium Barrier

It is well known that α-Al₂O₃ phase has stablility performance, high permeation reduction factor and good resistance performance in liquid LiPb, which is considered as the reference tritium barrier coating in future fusion reactor. In order to study the formation mechanism of stable α-Al₂O₃ scales on fusion structure material, the oxidation behavior of Fe-Al aluminized coating on China Low Activated Martensitic （CLAM） steel was investigated under the oxygen partial pressure from 1 Pa to 20 kPa at the temperature of 940-980 ℃. The Al₂O₃ scales were analyzed by thermogravimetric analysis meter, grazing angle X-ray diffractometer, glow discharge spectrometer, focused ion beam and transmission electron microscope. A single continuous Al₂O₃ scales with the maximum thickness of about 2 000 nm was formed on the diffusion Fe-Al aluminized layer. Thermogravimetric analysis results show that the higher oxidation rate constant is achieved while increasing the oxygen partial pressure, and then oxidation rate constant decreases. The phase transformation of Al₂O₃ scales on the surface of Fe-Al aluminized coating was studied during different oxidation time ranges from 3 min to 180 min. The metastable γ-Al₂O₃ and α-（Al0.948Cr0.052）₂O₃ phases is formed in the earlier oxidation process and finally transformed to stable α-Al₂O₃ phase. The features of the transient α-（Al0.948Cr0.052）₂O₃（113） and α-Al₂O₃（113） were detected by GXRD and then confirmed by focused ion beam and transmission electron microscope.     

阻氚用Fe-Al渗铝层表面稳态相Al2O3膜生长机理研究

为阐释Fe-Al渗铝层表面暂态相Al₂O₃膜向稳态相α-Al₂O₃膜的转变机理,探索稳态相α-Al₂O₃膜制备的氧化工艺参数范围,采用掠入射角X射线衍射仪、辉光放电光谱仪、聚焦离子束、透射电镜等,结合热重分析对CLAM钢基体Fe-Al渗铝层在940～980 ℃、1 Pa～20 kPa参数下的氧化生长行为进行了深入表征与机理分析。研究结果表明,在1 Pa～20 kPa氧分压范围内Al₂O₃膜生长初期反应速率常数随着氧分压的升高而增大,而后期反应速率常数反而随之下降;采用掠入射角X射线衍射仪对3～180 min氧化不同时期表面Al₂O₃膜的相结构进行了掠入射角分析,推测Al2O3膜的生长经历了从氧化初期形成暂态相γ-Al₂O₃（15 min）→过渡态相α-（Al_0.948Cr_0.052）₂O₃（30 min）→稳态相α-Al₂O₃（120～180 min）的演变过程,最短相转变时间约60～90 min,连续Al₂O₃膜厚度约2 000 nm;同时,结合聚焦离子束对30、120 min形成的Al₂O₃膜表面进行了精确定向切割制样,并采用透射电镜选区电子衍射分析验证了相转变前Al₂O₃膜结构为过渡态相α-（Al_0.948Cr_0.052）₂O₃（113）,转变后为稳态相α-Al₂O₃（113）,证实了Cr作为第三组元促进暂态相向稳态相α-Al₂O₃的转变规律。     

DBD coupled with MnOx/γ-Al2O3 catalysts for the degradation of chlorobenzene

This paper investigates the degradation of chlorobenzene by dielectric barrier discharge(DBD)coupled with MnOx/γ-Al2O3 catalysts.MnOx/γ-Al2O3 catalysts were prepared using the impregnation method and were characterized in detail by N2 adsorption/desorption,x-ray diffraction and x-ray photoelectron spectroscopy.Compared with the single DBD reactor,the coupled reactor has a better performance on the removal rate of chlorobenzene,the selectivity of COx,and the inhibition of ozone production,especially at low discharge voltages.The degradation rate of chlorobenzene and selectivity of COx can reach 96.3%and 53.0%,respectively,at the specific energy density of 1350 J l-1.Moreover,the ozone concentration produced by the discharge is significantly reduced because the MnOx/Al2O3 catalysts contribute to the decomposition of ozone to form oxygen atoms for the oxidation of chlorobenzene.In addition,based on analysis of the byproducts,the decomposition mechanism of chlorobenzene in the coupled reactor is also discussed.     

Formation mechanism of Al_2O_3/MoS_2 nanocomposite coating by plasma electrolytic oxidation(PEO)

In this study, an Al_2O_3/MoS_2 nanocomposite coating was created on an aluminum 1050 substrate using the plasma electrolytic oxidation method. The zeta potential measurements showed that small MoS_2 particles have negative potential and move toward the anode electrode.The nanoparticles of MoS_2 were found to have a zeta potential of-25 mV, which prevents suspension in the solution. Thus, to produce an Al_2O_3/MoS_2 nanocomposite, one has to use the microparticles of MoS_2. The X-ray diffraction analyses showed that the produced coatings contained α-Al_2O_3, γ-Al_2O_3, and MoS_2, and that the size of MoS_2 particles can be reduced to 30 nm. It was observed that prolonged suspension in the electrolyte results in an enhanced formation of an Al_2O_3/MoS_2 nanocomposite. Using the results, it was hypothesized that the mechanism of the formation of the Al_2O_3/MoS_2 nanocomposite coating on the aluminum 1050 substrate is based on electrical energy discharge.     

α/γ相比率调控对超音速等离子喷涂Al2O3阻氚涂层微结构及性能的影响

采用超音速等离子喷涂技术在中国低活化马氏体钢表面制备不同α/γ相比率的Al₂O₃阻氚涂层,研究了α/γ相比率调控对Al₂O₃涂层微观结构、力学性能和耐电化学腐蚀性能的影响。利用掠入射X射线衍射（GIXRD）和扫描电子显微镜（SEM）表征Al₂O₃涂层的微观结构、粘结拉伸试验法和纳米压痕仪表征涂层的力学性能、动电位极化曲线法测试涂层的耐电化学腐蚀性能。研究结果显示：通过调控特征喷涂参数（CPSP）,Al₂O₃涂层中α相含量从78.6%至24.4%可控调节,且孔隙率从2.8%降低至1.5%;α相含量为78.6%的Al₂O₃涂层硬度为(11.500±0.575) GPa,约为高γ相含量(75.6%)涂层的2倍;且高α相含量(78.6%)涂层的腐蚀电流密度较高γ相含量(75.6%)涂层的腐蚀电流密度低1个数量级。以上结果表明,高α相含量(78.6%)的Al₂O₃涂层具有更优异的力学性能、耐电化学腐蚀性能以及耐Cl^-扩散穿透能力,具有应用于聚变堆结构材料表面阻氚涂层的潜能。     

Degradation and mineralization of ciprofloxacin by gas–liquid discharge non-thermal plasma

A typical quinolones antibiotic ciprofloxacin(CIP) in aqueous solution was degraded by a gas–liquid discharge non-thermal plasma system. The discharge plasma power and the emission intensity of the excited reactive species(RS) generated in the gas phase were detected by the oscilloscope and the optical emission spectroscopy. The effects of various parameters on CIP degradation, i.e. input powers, initial concentrations addition of radical scavengers and p H values were investigated. With the increase of discharge power, the degradation efficiency increased but the energy efficiency significantly reduced. The degradation efficiency also reduced under high concentration of initial CIP conditions due to the competitive reactions between the plasma-induced RS with the degradation intermediates of CIP. Different radical scavengers(isopropanol and CCl_4) on ·OH and H· were added into the reaction system and the oxidation effects of ·OH radicals have been proved with high degradation capacity on CIP.Moreover, the long-term degradation effect on CIP in the plasma-treated aqueous solution proved that the long-lived RS(H_2O_2 and O_3, etc) might play key roles on the stay effect through multiple aqueous reactions leading to production of ·OH. The degradation intermediates were determined by the method of electrospray ionization(+)-mass spectroscopy, and the possible degradation mechanism were presented.     

Low-temperature diffusion in inert-gas bombarded Al2O3

Previous work on diffusion in inert-gas bombarded Al₂O₃ has revealed the presence of four diffusion processes, of which two take place well below the temperatures for self-diffussion, one agrees with self-diffusion, and one occurs at temperatures well above those for self-diffusion. The present work serves to explore in greater detail the two low-temperature processes. It is shown that the first, which is found in -Al₂O₃, Al(OH)₃, and γ-Al₂O₃beginning at about 100° C, is consistent with a range of ΔH's of 28 to 50 kcal/mole. The mechanism of the process is hinted at by the fact that it overlaps the temperatures both for Al(OH)₃decomposition and for point-defect motion in -Al₂O₃; the correlation with point defects is believed, however, to be the more significant. The second process, which is found only in -Al₂O₃ beginning at 500–650° C, implies an essentially single ΔH lying between 69 and 79 kcal/mole. It was suggested previously by Matzke and Whitton on the basis of electron diffraction that the process could be attributed to the amorphous-crystalline transition of -Al₂O₃. Further aspects of low-temperature diffusion in Al₂O₃ were revealed by comparing autoradiographs of specimens of -A₂O₃which were bombarded to various doses and then either heated to 850° C or immersed in unheated 12N NaOH. Thus regions exposed to a high dose and which would be expected to be amorphous, had an increased sticking factor, a greater tendency to lose gas during heating, and an enhanced chemical reactivity.     

Hybrid electric discharge plasma technologies for water decontamination: a short review

Electric discharge plasma (EDP) can efficiently degrade aqueous pollutants by its in situ generated strong oxidative species (·OH, ·O, H₂O₂, O₃, etc) and other physiochemical effects (UV irradiation, shockwaves, local high temperature, etc), but a high energy consumptions limit the application of EDP in water treatment. Some adsorbents, catalysts, and oxidants have been employed for enhancing the degradation of pollutants by discharge plasma. These hybrid plasma technologies offer improved water treatment performance compared to discharge plasma alone. This paper reviews the water decontamination performance and mechanisms of these hybrid plasma technologies, and some suggestions on future water treatment technologies based on discharge plasma are also proposed.     

Fe-Al/Al2O3涂层表面氧化膜的掠入射X射线衍射研究

本文采用掠入射X射线衍射（GXRD）α-2θ扫描模式,进行了掠入射角α为0.1°～5°范围内Fe-Al/Al₂O₃阻氚涂层表面氧化膜的X射线衍射实验。结果表明,随α的增加,表面氧化膜中Al₂O₃相与Fe₃Al相对应的衍射峰强度绝对值增强;α的增加加深了分析区域的深度,引起Al₂O₃相的相对含量下降,导致Al₂O₃相对衍射峰强度降低。对Fe-Al/ Al₂O₃涂层表面氧化膜的掠入射X射线衍射而言,较佳的掠入射角是0.25°,此时对应Al₂O₃相的衍射峰相对强度最高。经比对PDF卡片,表面氧化膜相结构为暂态γ-Al₂O₃（200）。在此基础上建立了GXRD分析Fe-Al/ Al₂O₃涂层表面亚微米氧化膜的相结构组成的快速无损检测方法。     

DBD plasma assisted atomic layer deposition alumina barrier layer on self-degradation polylactic acid film surface

In this work, the plastic of polylatic acid(PLA) film is coated by alumina(Al_2O_3)through dielectric barrier discharge plasma assisted atomic layer deposition(DBD PA-ALD) for the proposal of the barrier property enhancement. The influence of ALD Al_2O_3 thickness on properties of barrier, mechanical, optical and degradation is investigated in detail. It is obtained that the growth rate of Al_2O_3 in DBD PA-ALD is as quick as 0.12 nm/cycle. After coated～40 nm Al_2O_3, the water vapor transmission rate of PLA is reduced by two orders of magnitude.Additionally, it is noticed that the tension strength of the coated film is improved slightly,whereas the light transmission rate is decreased with the increase of Al_2O_3 thickness. The degradation test shows that Al_2O_3 coating almost does not affect the self-degradation rate of PLA film.     

Neutron-irradiation effect in ceramics evaluated from macroscopic property changes in as-irradiated and annealed specimens

Macroscopic length (linear swelling) and thermal diffusivity changes were measured for heavily neutron-irradiated -Al₂O₃, AlN, β-Si₃N₄ and β-SiC that were irradiated under the same capsule to compare the difference between these materials. And in addition, several capsules were irradiated under different temperatures (646–1039 K) and to different neutron doses (0.4–8.0 × 10²⁶ n/m²) in the Japanese experimental fast reactor JOYO. The swelling and the thermal diffusivity of as-irradiated specimens showed some dependence on the neutron-irradiation dose and the irradiation temperature, and that indicates stability under neutron-irradiation environments. Alpha-Al₂O₃ and AlN showed relatively large swelling and degradation of thermal diffusivity than β-Si₃N₄ and β-SiC. This difference is related to the crystal structure of each material. The dependence of swelling on irradiation dose, that is, -Al₂O₃ showed linear inclination but β-Si₃N₄ and β-SiC showed saturation, supports the model of defect structures. In addition, annealing behaviors of swelling and thermal diffusivity were compared to analyze the behavior of defects at higher temperature.     

Evaluation of trans-ferulic acid degradation by dielectric barrier discharge plasma combined with ozone in wastewater with different water quality conditions

In this study, dielectric barrier discharge plasma and ozone(O_3) were combined to synergistically degrade trans-ferulic acid(FA), and the effect of water quality on FA degradation was studied. The results showed that 96.9% of FA was degraded after 40 min treatment by the plasma/O_3 process. FA degradation efficiency increased with the p H values. The presence of suspended solid and humic acid inhibited FA degradation. FA degradation efficiency increased as the water temperature increased to 30 °C. However, the further increase in water temperature was adverse for FA degradation. Effects of common inorganic ions on FA degradation were also investigated. The addition of Cl~- inhibited the FA degradation, whileCO_3~(2-) had both negative and positive influences on FA degradation.NO_3~- andSO_4~(2-) did not have significant effect on FA degradation. Fe~(3+)and Cu~(2+)benefited FA degradation through the Fenton-like and catalytic ozonation reactions.     

Optical properties of γ-irradiated synthetic sapphire and yttria-stabilized zirconia spectroscopic windows

Synthetic sapphire and yttria-stabilized zirconia single-crystals were irradiated by increasing doses of γ-radiation to study the changes of their optical properties. The optical transparency of -Al₂O₃ was nearly constant up to the γ-radiation dose of 150 kGy for the spectral range of 400–1000 nm, while yellowish-brown coloration of (Zr_0.89Y_0.11)O_1.94 appeared for irradiation above 1 kGy. However, after a short-term heating in the temperature of 210^oC stable discoloration of zirconia can be achieved.     

Improving plasma sterilization by constructing a plasma photocatalytic system with a needle array corona discharge and Au plasmonic nanocatalyst

Efficient sterilization by a plasma photocatalytic system(PPS) requires strong synergy between plasma and photocatalyst to inactivate microorganisms while suppressing the formation of secondary pollutants.Here,we report that a PPS constructed from a needle array corona discharge and Au/TiO₂ plasmonic nanocatalyst could remarkably improve the sterilization of Escherichia coli(E.coli) and alleviate formation of the discharge pollutant O₃.At 6 kV,the combination of corona disc...     

Evaluation on a double-chamber gas-liquid phase discharge reactor for benzene degradation

A double-chamber gas-liquid phase DBD reactor (GLDR), consisting of a gas-phase discharge chamber and a gas-liquid discharge chamber in series, was designed to enhance the degradation of benzene and the emission of NOx. The performance of the GLDR on discharge characteristics, reactive species production and benzene degradation was compared to that of the single-chamber gas phase DBD reactor (GPDR). The effects of discharge gap, applied voltage, initial benzene concentration, gas flow rate and solution conductivity on the degradation and energy yield of benzene in the GLDR were investigated. The GLDR presents a higher discharge power, higher benzene degradation and higher energy yield than that of the GPDR. NO₂ emission was remarkably inhibited in the GLDR, possibly due to the dissolution of NO₂ in water. The benzene degradation efficiency increased with the applied voltage, but decreased with the initial concentration, gas flow rate, and gas discharge gap, while the solution conductivity presented less influence on benzene degradation. The benzene degradation efficiency and the energy yield reached 61.11% and 1.45 g kWh^–1 at 4 mm total gas discharge gap, 15 kV applied voltage, 200 ppm benzene concentration, 0.2 L min⁻¹ gas flow rate and 721 μS cm⁻¹ water conductivity. The intermediates and byproducts during benzene degradation were detected by FT-IR, GC-MS and LC-MS primarily, and phenols, CO_x, and other aromatic substitutes, O₃, NO_x, etc, were determined as the main intermediates. According to these detected byproducts, a possible benzene degradation mechanism was proposed.     

30%TBP-煤油循环使用过程中的辐解行为

为了了解溶剂在乏燃料后处理真实使用过程的辐解稳定性,对比研究了30%TBP-煤油-HNO3体系在γ和α的静态累积辐照和动态循环辐照情况下的辐解行为。研究结果表明:静态累积辐照所引起的溶剂辐解产物生成量、钚保留和钌保留等性能的变化比动态循环辐照明显;当辐照吸收剂量达到1.0×105 Gy(相当于动态循环辐照20次)时,静态累积辐照引起的溶剂钚保留值10倍于动态循环辐照,证实了在乏燃料后处理工艺过程中,通过溶剂的酸碱洗涤,去除HDBP、H2MBP等主要辐解产物,可提高溶剂的循环使用寿命。同时研究结果显示,溶剂的α辐照损伤大于γ辐照。     

The effect of gas additives on reactive species and bacterial inactivation by a helium plasma jet

In this paper,the influences of gas doping(O_2,N_2,Air)on the concentrations of reactive species and bactericidal effects induced by a He plasma jet are studied.Firstly,results show that gas doping causes an increase in voltage and a decrease in current compared with the pure He discharge under the same discharge power,which might be attributed to the different chemical characteristics of O_2 and N_2 and verified by the changes in the gaseous reactive species shown in the optical emission spectroscopy(OES) and Fourier transform infrared(FTIR)spectroscopy.Secondly,the concentrations of aqueous reactive oxygen species(ROS) and reactive nitrogen species(RNS) are tightly related to the addition of O_2 and N_2 into the working gas.The concentrations of aqueous NO_2~- and NO_3~- significantly increase while the concentrations of aqueous ROS decrease with the admixture of N_2.The addition of O_2 has little effect on the concentrations of NO_2~- and NO_3~- and pH values; however,the addition of O_2 increases the concentration of O_2~- and deceases the concentrations of H_2O_2 and OH.Finally,the results of bactericidal experiments demonstrate that the inactivation efficiency of the four types of plasma jets is He?+?O_2??He+AirHeHe+N_2,which is in accordance with the changing trend of the concentration of aqueous O_2~-.Simultaneously to the better understanding of the formation and removal mechanisms of reactive species in the plasma–liquid interaction,these results also prove the effectiveness of regulating the concentrations of aqueous reactive species and the bacteria inactivation effects by gas doping.     

CO_2 conversion by thermal plasma with carbon as reducing agent: high CO yield and energy efficiency

A key problem in CO_2 conversion by thermal plasma is suppressing the inverse reactions,CO?+?O?→?CO_2 and CO?+?0.5O_2?→?CO_2, to simultaneously obtain high CO yield and energy efficiency. This can be done by quickly quenching the decomposed gas or rapidly taking away free oxygen from decomposed gas. In this paper, experiments of CO_2 conversion by thermal plasma with carbon as a reducing agent are presented. Carbon quickly devoured free oxygen in thermal plasma decomposed gas, and not only is the inverse reaction completely suppressed, but the discharge energy to form oxygen atoms, oxygen molecular, and thermal energy is also reused.A CO_2 conversion rate of 67%–94% and the corresponding electric energy efficiency of about 70% are achieved, both are much higher than that seen so far by other plasma implementations.     

发酵优化制备L-赖氨酸盐酸盐-13C6、15N2

采用北京棒杆菌（Corynebacterium pekinense）ZLD118（HS^-、AEC^r）发酵制备稳定同位素双标记的L-赖氨酸盐酸盐-¹³C₆、¹⁵N₂。对菌种的发酵培养条件和发酵培养基配方进行优化,采用优化后的发酵工艺制备高丰度稳定同位素¹³C、¹⁵N双标记L-赖氨酸,经离子交换树脂提纯、活性炭脱色精制后,产品的¹³C丰度达98.61%,¹⁵N丰度为98.15%,纯度为98.47%,产率为88.8%。结果表明,该工艺可进一步用于放大制备。     

Post irradiation examination of uranium inclusions in inert matrices.

The inert matrix materials CeO₂, MgO, Y₂O₃, MgAl₂O₄ and Y₃Al₅O₁₂ were selected as candidates for inert matrices for the EFTTRA²-T3 neutron irradiation experiment. Most targets contain 20% enriched ²³⁵U fissile inclusions with an average size of roughly 150 μm. The volume fraction of the fissile phase is either 2.5 vol% UO₂ or 19.6 vol% of Y_5.78UO_x in the inert matrices. The samples were irradiated for 198.9 full power days in the High Flux Reactor in Petten. The calculated burn-up is between 17.3 and 19.5% FIMA. The temperature of the cladding was kept at 600 ± 25 K. A dimensional change of at least +5 % is measured after neutron irradiation for Y₃Al₅O₁₂ and MgAl₂O₄ with macro dispersions of UO₂; the other targets with a macro dispersion of UO₂ show a volume change of less than + 1 vol%. The fractional release of the fission gas Xe is more than 40% for the MgAl₂O₄ and Y₃Al₅O₁₂ matrices with a macro dispersion of UO₂, the other targets show a fractional release of Xe of less than 15%. Cracks are observed in MgO and MgAl₂O₄ targets which is possibly related to the stress caused by swelling of the UO₂ inclusions.