Changsheng Deng

Tsinghua University | TH · Institute of Nuclear and New Energy Technology

Very high temperature gas-cooled reactors (VHTR) require uranium carbide (UC) nuclear fuel microspheres with high thermal conductivity and uranium density. However, the traditional internal gelation process for preparing UC microspheres suffers from difficulties such as poor room temperature stability of the carbon black-containing uranium broth, n...

Uranium mono-nitride (UN) microspheres are expected to play an important role in various miniaturization module reactors. The combination of UN core and tri-structural-isotropic (TRISO) coatings will bring improved efficiency and safety. Carbon-containing gel microspheres were prepared by external gelation, followed by carbothermal reduction and ni...

内凝胶工艺由于制备氧化铀微球球形度好而受到广泛关注。但是内凝胶工艺仍存在一些难点，如制备的微球尺寸略有不均，这不利于内凝胶工艺的大规模应用。在本项工作中特引入微流控辅助内凝胶工艺来制备单分散溶胶液滴。单分散溶胶液滴经洗涤、干燥和烧结后即可获得单分散的氧化铀微球。研究表明通过微流控辅助内凝胶工艺可以制备出尺寸变异系数≤1%、球形度 1.01 的单分散氧化铀微球。微流控辅助内凝胶工艺操作简便，在制备高质量核燃料微球方面具有广泛的应用前景。

The microspheres prepared by the microfluidic‐assisted internal gelation process are still challenging to reach the millimeter size due to the large gravity. The gravity would affect the sphericity and size uniformity of microspheres. The improved microfluidic‐assisted internal gelation process is designed and optimized to produce large‐sized monod...

Zirconium nitride is an increasingly attractive material, owning to its wide range of applications. Nitridation with carbon as a reductant is a commonly used process for the preparation of transition metal nitrides. In this study, the nitridation of carbon-containing zirconia gels was studied as a method to synthesize zirconium nitride. The behavio...

ZrO2 microspheres are widely used as a simulant of UO2 in the development of nuclear fuel. However, the cracking of ZrO2 microspheres prepared by internal gelation is still a challenge during drying and sintering processes. To address this issue, we designed and optimized the washing process for obtaining crack‐free ZrO2 microspheres. Through therm...

In this study, we report a novel high-throughput and instant-mixing droplet microfluidic system that can prepare uniformly mixed monodisperse droplets at a flow rate of mL/min designed for rapid mixing between multiple solutions and the preparation of micro-/nanoparticles. The system is composed of a magneton micromixer and a T-junction microfluidi...

The internal gelation process without cooling at room temperature is a significant challenge for the preparation of yttria-stabilised zirconia (YSZ) ceramic microspheres. In this work, a high-throughput and instant-mixing droplet microfluidic system that can prepare monodisperse YSZ ceramic microspheres was constructed. It mixed two stable solution...

Zirconium nitride microspheres with uniform size of ~680 μm, good sphericity, and good integrity were prepared by internal gelation process and two-step nitridation. The effects of carbon black and temperature on stability of sol were investigated. Induction of carbon black decreased stability of sol but the amount of carbon black added has little...

Zirconia (ZrO2) microspheres are of great interest as a surrogate precursor material for preparation of uranium nitride (UN) microspheres in High Temperature Reactor (HTR). However, the crystallite transformation of ZrO2 microspheres in cooling process causes cracking of the microspheres. In our study, crack-free nanocrystalline ZrO2 microspheres w...

寻找到一种室温（25 ℃）下稳定 15 h 不固化且成球较好的胶液配方，利用毛细管微流体装置辅助内凝胶工艺制备出小尺寸（<120 μm）的 ZrO2 陶瓷微球，并对影响 ZrO2 微球尺寸的因素进行分析。结果表明：其它条件相同的情况下，硅油的流量或者粘度越大，ZrO2 微球尺寸越小。胶液的流量越大或者毛细管微流体装置喉口尺寸越大，ZrO2 微球尺寸越大；通过图像识别发现，ZrO2 陶瓷微球的 CV 值都小于 5%，说明该方法制备出的 ZrO2 陶瓷微球尺寸均一；通过 SEM 和 XRD 发现 ZrO2 陶瓷微球致密，呈立方相。

Zirconium compounds has been widely attention over the last decades due to its excellent physical and chemical properties. Zirconium nitride nanopowders were synthesized via a simple direct carbothermic nitridation process of internal gel derived zirconia in the presence of nano-sized carbon black. The effects of reaction temperature, dwell time an...

CeO2–Nd2O3 microspheres were successfully prepared by internal gelation process using M(OH)m and [MCit∙xH2O] (M = Ce³⁺, Ce⁴⁺, and Nd³⁺, Cit is (C6O7H5)³⁻) as precursors. The effects of Nd(NO3)3 content on the stability of precursor solution and on the microstructure of the sintered microspheres were investigated. The gelled microspheres and sintere...

The internal gelation process was combined with a co-axial capillary microfluidic device to prepare monodisperse ZrO2 ceramic microspheres. Large sized gel microspheres in the range of hundreds of micrometers could be produced with the capillary microfluidic device with co-axial flow structure and the large sized outlet tubing. After drying and sin...

Cerium dioxide microspheres were successfully prepared by internal gelation with cerium citrate as the precursor. The effects of solution containing hexamethylenetetramine (HMTA) and urea on the stability of precursor solution and on the sintered microspheres were investigated. The results indicate that the gelled microspheres were composed of [CeC...

Cerium dioxide microspheres were successfully prepared by internal gelation process with copolymerization using acrylic acid. The effects of acrylic acid (AA)/hexamethylenetetramine (HMTA) molar ratio and concentration of solution containing urea and HMTA on the stability of precursor solution and on the prepared microspheres were investigated. The...

ZrO2–ZrC–C (ZrCO) ceramic microspheres were fabricated by a combination of internal gelation and carbothermic reduction. The effects of temperature on carbothermic reduction of ZrO2 and the CO content in the heat treatment atmosphere on the phase composition, microstructure and properties of the microspheres were studied. The effects of different c...

A preliminary study was carried out on preparation of UC-UO2 (UCO) composite ceramic microspheres using fructose as the carbon source by combining internal gelation and carbothermic reduction. The effects of the pH of precursor solution, washing and drying processes on the gel microspheres and sintering process on the UCO sintered microspheres were...

ZrC–ZrO2 composite ceramic microspheres were prepared by internal gelation combined with carbothermic reduction using fructose as a chelating agent and carbon source. Fructose in the precursor solution formed complex with zirconium ions, which was conducive to the refining of the microstructure of the sintered composite. ZrC–ZrO2 composite with ZrC...

UCO ceramic microspheres were fabricated by combination of internal gelation and carbothermic reduction process. The effects of the sintering atmosphere and C/U ratio on the UCO ceramic microspheres were studied. The composition, surface morphology, and microstructure of the sintered UCO ceramic microspheres were analyzed. The results indicated tha...

UO2 microspheres with diameter similar to 650 mu m were prepared by internal gelation process through dissolving, broth solution preparation, dispersing, AWD (aging, washing and drying), calcination, reducing and sintering procedures. The broth solution viscosity changing with standing time at different temperatures was measured by rotary viscosime...

Ceria stabilized zirconia microspheres of about 150 microns were prepared by external gelation. The effect of vibration frequency on jet droplet dispersion and size uniformity was investigated. The diameter variances of microspheres prepared at frequency range of 1300 to 2300 Hz were calculated. The optimal frequency was found to be in good accorda...

Tristructural-isotropic (TRISO) coated fuel particles with spherical ceramic fuel kernels followed by three layers of pyrolytic carbon and one layer of silicon carbide (SiC) is successfully used in high temperature gas cooled reactor (HTGR) system. In this paper, an improved design concept of fully ceramic fuel is proposed. The kernels were coated...

Fabrication of ceria–zirconia (CSZ) microspheres by external gelation (EG) and internal gelation (IG) process was investigated. A nozzle with an inner diameter of 0.2 mm was used for broth dispersion under vibration. The effect of broth flow rate on diameter and sphericity of the microspheres was studied. The microspheres were characterized by ther...

External gelation process was used to prepare ceria-stabilized zirconia (CSZ) microspheres at various conditions. The effects of nozzle inner diameter, broth flow rate and Zr concentration on microsphere diameter, standard deviation (SD) of diameter and sphericity were investigated. The microsphere diameter decreased, while sphericity increased as...

Ceria-stabilized zirconia (CSZ) microspheres of ~100 μm were prepared by external gelation process. The inner diameter of nozzle was 0.2 mm. The key process parameters including broth pH value, Zr concentration, flow rate, and vibration frequency were optimized for precise control of the diameter. The optimum parameters were found to be flow rate o...

ZrO2-ZrC (ZrCO) ceramic microspheres were fabricated by combination of internal gelation and carbothermal reduction process. The internal gelation broth containing carbon powders was prepared and stored at room temperature of 25°C to form a precursor of microspheres. By dropping droplets of the broth into hot silicone, the gel microspheres would so...

ZrO2-ZrC (ZrCO) ceramic microspheres were fabricated by internal gelation and carbothermal reduction. The effect of various carbon sources on the stability of the broth was investigated, the carbon sources which have little effect on the stability of the broth were chosen as the carbon sources for carbothermal reduction, and the component distribut...

Double perovskite Sr2FeMoO6-delta was investigated as cathode material for solid oxide electrolysis cells. After dry-pressing and sintering, cathodes were prepared. The effect of starch contents on pore structures of Sr2FeMoO6-delta cathodes was studied. Porosity of cathodes was measured by the Archimedes method, and the microstructures of Sr2FeMoO...

Double perovskite Sr2FeNbO6 (SFN) powders mixed with La0.9Sr0.1Ga0.8Mg0.2O3-delta (LSGM) were selected as cathode materials for solid oxide electrolysis cells. Different contents of starch were added into SFN-LSGM, followed by dry-pressing at 10 MPa and sintering at 1 400 degrees C for 12 h. Porosities of the SFN-LSGM sample were measured by the tr...

ZrCO (ZrO2-ZrC) ceramic microspheres have been prepared by internal gelation combined with carbothermal reduction process. By dropping the droplets of the cold broth containing carbon powders into the hot silicone, the gel microspheres would solidify within a few seconds by the decomposition of the hexamethylenetetramine (HMTA), and then the gel sp...

The double-layer microspheres containing Co with core-shell structure were prepared by the external gelation process. The effects of the type, concentration and density of gelation agent on the properties of the double-layer gelled microspheres were investigated, and the mechanism of the external gelation process was analyzed. Results show that NaO...

A Ba-Ca-Si-Al system glass sealing material was used in solid oxide electrolysis cell (SOEC). The crystallization of BCSA glass system was investigated. The first step was determining the heat treatment process according to the DSC curve of the base glass. The glass after crystallization were tested by SEM and XRD, and the coefficient of thermal ex...

Alumina ceramic microspheres were prepared via internal gelation process. By dropping sol from a cold broth into hot silicone oil gelled microspheres would solidify within a few seconds by decomposition of hexamethylenetetramine (HMTA). The effect of the broth component on the performance of the broth and gelled microspheres obtained has been inves...

ZrO2 microspheres were prepared with an improved internal gelation process without cooling the precursor solution. The stability of the broth for internal gelation process has been systematically investigated, and the results show that the preparation and storage temperature, the concentration of NO3− and the urea in the broth have important effect...

The charge transfer and mass transfer mechanisms in solid oxide electrolysis cells (SOEC) were modeled including the effect of the three-phase boundary length on the anode concentration overpotential. The numerical results agree well with experimental data. The effects of the anode porosity, the pore radius and the diffusion layer thickness were an...

Double-perovskite Sr2FeNbO6 (SFN) has been introduced to the solid oxide electrolysis cell (SOEC) supported by 8 mol% yttria stabilized zirconia (YSZ) electrolyte (500 μm thick) with the cell composition of SFN-YSZ/YSZ/LSM-YSZ (La0.8Sr0.2MnO3, LSM). Five groups of contrast tests are designed to investigate the differences between SFN and Ni in elec...

A crosslinked anion-exchange membrane (AEM) with an in situ photoswitch was synthesized. The side-chain effects on the properties of the AEM were studied using the same membrane sample in different status. The variances between the different samples were eliminated. The hydroxide conductivity of AEM could be increased by reducing the distance betwe...

A novel cross-linked pyridine anion exchange membrane was synthesized via thermal cross-linking methods. 2,5-bis(2,3,4,5,6-pentafluorophenyl)-1,3,4-oxadiazole (FPOx) and diallyl bisphenol A (DABPA) were reacted to obtain the main polymer chain (MP). MP was substituted with 4-bromopyridine and 4-hydroxypyridine to generate two pyridine polymers conj...

Fluorinated poly(aryl ether oxadiazole), synthesized by the copolymerization of 2,5-bis(2,3,4,5,6-pentafluorophenyl)-1,3,4- oxadiazole and diallylbisphenol A, was used as the main polymer chain (MP). 2-aminoethanesulfonic acid (taurine) was attached to brominated-MPs (Br-MPs) at mild conditions, serving as both cation and anion exchange groups. AIE...

The internal gelation process was used to produce gel microspheres containing Zr. The effect of the broth composition particularly pH value on the stability of the broth and morphology of the dried spheres was investigated. The results indicated that the stability of the broth at room temperature increased with the decrease of the pH of the broth....

The computational fluid dynamics (CFD) simulation was adopted to study the internal flow field in nozzle chamber, which was involved in the casting nozzle in the preparation process of UO2 kernel particles. In particular, the flow flux uniformity analysis of each nozzle, which is the important determinant factor of UO2 kernel size uniformity, was f...

In this study, we synthesized a novel ionic liquid composite electrolyte, and successfully used it in the lithium oxygen battery. The composite electrolyte consisted of lithium salt, hydrophobic ionic liquid, and spiro cyclic quaternary ammonium salt. The electrochemical performance of the electrolyte was examined using the cyclic voltammetry, the...

A novel cross-linked fluorinated poly (aryl ether oxadiazole) s having diallyl methylimidazole groups (FPAEO-DA-x) membranes were prepared via copolymerization, bromination, solution casting and hydroxide exchanging using a thermal cross-linking method. The membrane materials synthesized via copolymerization of 2,5-bis(2,3,4,5,6-pentafluorophenyl)-...

Nanofibers exist ubiquitously in natural extracellular matrix (ECM) of all kinds of human tissues forming hydrated interwoven network. Electrospinning nanotechnology has been proven to be a powerful technique to fabricate controllable nanofibers mimicking the natural ECM structures. Hyaluronic acid (HA), as a critical component of natural ECM, has...

Electrochemical behavior of La0.8Sr0.2FeO3 (LSF) electrode with different porosities under cathodic and anodic current polarization has been investigated by electrochemical impedance spectroscopy and the galvanostatic method. The activation and degradation behavior of the LSF electrode may be related to the partial reduction and oxidation of the Fe...

This paper briefly described the process of UO2 kernels preparation by external-gelation for high temperature gas cooled reactor (HTR) fuel elements at Institute of Nuclear and New Energy Technology, Tsinghua University (INET). Precipitation in the broth preparation and the size control of the products were investigated. The precipitate was analyze...

The aging, washing and drying processes are in sequence accomplished in one device which is suitable for the batched preparation of UO2 gelled spheres (similar to 3 kgU/batch), and also can be used in large-scale production. The inside and outside gelation of gelled spheres are complete and uniform through pre-aging process and heating rate control...

The interface reaction between the BaCaAlSi glass and YSZ electrolyte in the solid oxide electrolysis cell at high temperature was investigated. After the heat treatment for 100 hours at 850 degrees C in oxidizing atmosphere, the glass adheres well with the YSZ electrolyte. The structure of the BaCaAlSi glass has undergone significant structural ch...

Double-perovskite Sr2FexMn1-xNbO6-delta(SFMN) powders applied to the electrodes of solid oxide electrolysis cell (SOEC) was synthesized by solid state reaction. The obtained powder was calcined for 12 h at 1150 degrees C in air. The structure and the morphology of the powder were investigated by X-ray diffraction and scanning electron microscopy. S...

A system of xLa(0.8)Sr(0.2)MnO(3) (LSM)-(100-x)Zr0.92Y0.08O2 (YSZ) (0 <= x <= 100, wt%) composite materials has been studied with regard to its DC conductivity transition, connectivity over the entire composition range. Experimental measurements indicate that the DC conductivity decreases with increasing x, and increases above x=20 over the tempera...

The sintering of the UO2 microsphere prepared by external gelation process in HTGR and its performance were summarized. The UO2 microsphere with crack and flaw was studied and controlled. The macroscopic structure of microspheres after calcination, reduction and sintering, was observed. According to the experimental results, the optimal ratio of hy...

La0.8Sr0.2MnO3(LSM)-coated La0.8Sr0.2FeO3 (LSF) electrodes were prepared via the infiltration of LSM stock solution with different concentrations (0.005, 0.010, 0.020, 0.035 and 0.040 mol/L) into porous LSF electrode. The effect of coating solution concentration on the electrochemical performance was investigated. The results obtained by X-ray diff...

The effect of AlF3 concentration on the microstructures and energy storage properties of barium strontium titanate glass ceramics was studied. Scanning electron microscopy investigations revealed that the addition of AlF3 significantly changed the microstructure morphology of the glass ceramics. Dielectric measurements indicated that the dielectric...

La0.8Sr0.2FeO3 electrodes modified with nanoparticles of La0.8Sr0.2MnO3 (LSF/LSM) were prepared by infiltration method. LSM solution had good wettability on LSF surfaces and good electrochemical compatibility with LSF. The impedance of half-cells incorporating the electrodes was also examined. The deconvolution of the impedance spectrum indicated t...

Uranyl nitrate solution with high uranium concentration and hypostoichiometric c(NO3-)/c(U) ratio (the stoichiometric ratio of c(NO3-)/c(U) is 2 in standard uranyl nitrate solution) is crucial for preparation of qualified UO2 kernels for high temperature gas-cooled reactor. An acid-deficient dissolution process was developed for the preparation of...

Praseodymium doped ceria (PCO) nanorods were successfully introduced into the porous LSM–YSZ composite electrode via an infiltration and in situ hydrothermal synthesis route. The phase, composition, and microstructure of the materials were studied by X-ray diffractometry (XRD), energy dispersion spectrometry (EDS), and scanning electron microscopy (...

In order to satisfy the mass spherical fuel elements (SFE) requirements for the High Temperature gas-cooled Reactor (HTR)–Pebble bed Module (HTR-PM), a modified and optimized fabrication of dense uranium dioxide (UO2) kernel via an acid-deficiency uranium nitrate (ADUN) solution was researched and developed in the institute of nuclear and new energ...

The research of advanced and green energy is getting more and more attention because the status quo of the energy shortage and the environment pollution is worse and worse, lithium-air batteries are attracting considerable interest for their high theoretical specific energy and pollution-free. Nevertheless their performance is restricted by many fa...

Three series of BaO–CaO–SiO2–Al2O3, SrO–SiO2–Al2O3, and SrO–CaO–SiO2–Al2O3 glasses are prepared. Their basic physical properties are measured using dilatometry and differential scanning calorimetry from room temperature to the softening temperature. Their structures are characterized with infrared spectroscopy. The wetting characteristics of all gl...

This report describes the various waste generated in the preparation process of UO2 kernels for HTGR fuel elements by sol-gel method in Institute of Nuclear and New Energy Technology (INET), Tsinghua University. The U-containing liquid waste could be firstly precipitated by a strong alkaline. It is crucial that the precipitate must be treated throu...

Thiswork investigates the effects of alkali solution treatment on the electrochemical activity of the LSM/YSZ electrode for solid oxide fuel cell. The electrode treated by alkali solution exhibits an enhanced electrochemical activity, which is independent of alkali concentration and treatment time. Only surface-segregated Sr species is removed by a...

In order to prepare the dense uranium dioxide (UO 2) kernel for high temperature gas-cooled reactors (HTGR) fuel, the conventional sol-gel processes are optimized and modified. The wet process of modified external gelation of uranium (EGU) is introduced, which includes the dissolution of U 3O 8, i.e. the preparation of acid-deficiency uranyl nitrat...

Double-perovskite Sr2Fe1-xMnxNbO6-δ (x = 0, 0.1, 0.2, 0.3, 0.5, 0.8) (SFMN) powders which will be applied to the electrode of solid oxide electrolysis cells (SOEC) were synthesized by Solid State Reaction Method. The mixed oxide powders SrCO3, Fe2O3, MnO2 and Nb2O5, were homogeneously calcined at different temperatures and in different atmospheres....

A high molecular weight block copolymer dispersant with pigment affinic groups — DISPERBYK163 (BYK163) was chosen to disperse submicron-sized Si3N4 in tert-butyl alcohol (TBA) solvent. The stability of Si3N4 powders in TBA with dispersant BYK163 was studied by sedimentation. To achieve good casting behavior, rheological measurement was employed to...

The electrical resistivity (R) of BaO-CaO-SiO 2-Al 2O 3 (BCSA) based glass, which was used in SOEC, was measured by impedance analyzer from room temperature to sealing temperature, and it was founded that electrical resistivity of all seal glass decreases with temperature. When temperature is lower than the soften temperature of glass, the electric...

The electrochemical behavior of the La0.8Sr0.2MnO3−δ/Zr0.92Y0.08O2 (LSM/YSZ) porous composite anodes in solid oxide electrolysis cell is investigated by impedance spectroscopy over an oxygen partial pressure (pO2) range from 0 to 0.6 × 105 Pa. The differential analysis of impedance spectra (DIS) shows three separate arcs which correspond to three d...

The influence of A-site cation (Ln=La, Pr, Sm) on the crystal structure of Sr-doped ferrite perovskites (Ln0.8Sr0.2FeO3−δ, LnSF) was studied and the results used to interpret the differences in electronic conductivity. The electronic conductivity decreased with decreasing A-site cation radius, i.e. in the order La>Pr>Sm between 573 K and 1173 K, whe...

Glass additive was employed to improve the microstructures and energy storage properties of barium titanate ceramics using liquid phase sintering technology. Microstructural observation indicated that the average grain size reduced obviously with increasing glass concentration. Also, the dielectric constant decreased and the dielectric breakdown st...

The phase development, microstructural evolution and dielectric properties of manganese-doped barium strontium titanate glass ceramics have been studied. The specimens with (Ba,Sr)TiO3 (BST) as the major crystalline phase were prepared by bulk crystallization process. The results show that the dielectric constant and the dielectric loss measured at...

Modified TiO2 films have been prepared by combining commercial titania powders (Degussa P25) with sol-gel made by titanium chloride (Ti-sol). The result shows that clusters are formed by nanoparticles and large pores can be seen on the surface of the TiO2 films. The short circuit photocurrent density and photoelectric conversion efficiency of the s...

Double-perovskite Sr2Fe1–xScxMoO6–δ (x=0, 0.05, 0.1, 0.2, 0.3, 0.4) powders applied to the cathode of solid oxide electrolysis cells were synthesized by the sol-gel citrate combustion method. Initial powders were calcined at different temperatures under different atmosphere (air, H2(4 vol.%)/Ar), and the effects of the preparation process on the st...

High-temperature steam electrolysis (HTSE) is an inverse process of high-temperature solid state fuel cells. The key aspect for the technology application is the materials for electrolysis cells. This review summerizes the merits of the HTSE, and presents the recent development on the HTSE, and summarizes the merits of the HTSE. Also, this review i...

Nanosized TiO2 and Fe-, Zn- and Si- doped TiO2 powders were synthesized by sol-gel method and were characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM) and diffuse reflectance spectroscopy (DRS The photocatalytic activities of the synthesized nanopowders were investigated through the degradation of methyl orange solution...

Tape casting and co-sintering technique were used to fabricate the NiO-YSZ hydrogen electrode substrate cermets of planar solid oxide electrolysis cell. The optimal co-sintering temperature was determined after the curves of sinter shrinkage and TGA/DSC of NiO-YSZ and YSZ were measured. Pore-formers were used to increase the porosity of the hydroge...

In this paper, the structure and basic high temperature physical properties of Ba-Ca-Si-Al system sealing material, which was used in solid oxide electrolysis electrolytic cell (SOEC), were researched. First, the infrared spectra were used to estimate the glass structure and number of non-bridging oxygen (NBO) in as-fabricated glasses with differen...