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Garnet based solid-state electrolyte Li 6.75 La 3 Zr 1.75 Ta 0.25 O 12 (LLZTO) is one of the most promising electrolytes for advanced all-solid-state lithium batteries. However, the ceramic electrolyte is difficult to densify under normal sintering conditions, and hence the Li+ transportation via grain boundary is significantly limited by the loose contact between electrolyte granules, resulting in a high Li+ ionic impedance. Herein, we report a novel 2-step approach to obtain a relatively dense LLZTO ceramic pellet by a special Al-doping method, in which the Al was derived from the erosion of the corundum milling beads by LiOH during ball milling. This approach enables the simultaneous distribution of the aluminum (Al) within the LLZTO lattice and uniformly within the grain boundary, serving as a sintering aid, effectively boosts the fusion of grain boundary and reduced the failure rate during the sintering process. The ceramic pellet had a conductivity of 8.13 × 10−4 S cm−1, higher than that without Al-doping or using Al 2 O 3 as dopant. This method provides an easier way to sinter the garnet ceramic electrolyte. [ABSTRACT FROM AUTHOR]

Synthesis of porous ceramic materials based on fine SiC with sintering silicon oxide and magnesia binders at T = 800–1300 °C is considered. Special attention is paid to the influence of the shape and morphology of the initial powder particles on structural parameters and characteristics of porous ceramic materials. The SiC membranes sintered at 1000–1300 °C had average pore sizes of 0.5–1 μm, open porosity - up to 50 %, bending strength - up to 48.5 MPa and high water permeance - up to 7890 l⋅m−2⋅h−1⋅bar−1. The established filtration efficiency was ∼99 % in the case of screening out model particles of D 50 = 0.5 μm in size with maintaining stable permeance and physico-mechanical characteristics after multiple filtration-regeneration cycles. Comprehension of the initial powders morphology impact on the synthesized porous ceramics parameters makes it possible to forecast and ensure the preset structural, dimensional and physico-mechanical parameters of the materials under study properly. This work can be used for practical low-cost production of highly efficient SiC membranes for micro- and ultrafiltration processes, as well as base for catalysts. [ABSTRACT FROM AUTHOR]

At elevated operating temperatures, a large temperature gradient can cause irreparable damage to the solid oxide fuel cells (SOFCs) stack, eventually interrupting the durability of the stack. Metal substrate support could be used to overcome this challenge. However, the application of metal substrate support poses various challenges such as different thermal expansion coefficients, pore diameters, and complex fabrication techniques. Therefore, a first-ever novel and mechanically strong ferritic stainless-steel metal mesh-supported SOFC design is developed to mitigate these challenges. The metal mesh of 200 μm thickness is laminated with tape-casted green films of anode-support, anode functional layer (AFL), and electrolyte films of SOFC. The iso-static pressure of 300 MPa exhibits a firm attachment of the green films of SOFC with the metal mesh. Subsequently, the metal mesh-supported planar SOFC exhibits 3.3 times higher flexural strength compared to the conventional commercial anode-supported planar SOFC. The nano-CuO is added to constituent layers as a sintering aid to attain the maximum density at a lower sintering temperature of 1100 °C. The result shows that the practical application of the metal mesh-supported cell technology has a great potential to overwhelm the mechanical durability of SOFCs. [ABSTRACT FROM AUTHOR]

The electrolytic cell is the main equipment for electrolytic aluminum production. The visual electrolytic cell can observe and study the production process and mechanism of aluminum electrolysis. The effects of Y2O3 addition and sample thickness on the densification behavior and transmittance of Magnesium-aluminate spinel (MAS) were studied. The relative density, porosity, phase composition, microstructure, Vickers hardness, and transmittance of the sintered samples were characterized using the Archimedes method, x-ray diffraction analysis, scanning electron microscopy, Vickers hardness tester, and UV-visible near-infrared diffuse reflection. The results show that the appropriate amount of Y2O3 can enhance the transmittance of MgAl2O4 and the optimum Y2O3 content is 2 wt.%. At this time, the relative density of Magnesium-aluminate spinel (MAS), the maximum hardness, and the maximum transmittance are 96.19%, 18.18 GPa, and 36.3%, respectively. Under the optimum conditions, when the mass of the sample is 0.2 g, the relative density and maximum hardness of the Magnesium-aluminate spinel (MAS) sample are 97.28% and 18.18 GPa, respectively. Although the transmittance is not the highest, it is only lower than the transmittance of 0.15 g sample. The optimum sintering additive content and sample thickness jointly promote the densification, hardness, and transmittance of Magnesium-aluminate spinel (MAS). [ABSTRACT FROM AUTHOR]

This work investigated the influence of microwave sintering on the BaCe 0.2 Zr 0.7 Y 0.1 O 3-δ phase, incorporating 2 mol% or 4 mol% NiO as sintering aid. X-ray diffraction analysis of perovskite phase detected a rhombohedral structure under both sintering heating rates (280 and 500 °C/min), also exhibiting the presence of a second phase deficient in Ba with Ni incorporated into the structure, replacing part of the Zr. Raman analysis indicated no distortions in the perovskite structure, independent of the rates and NiO concentrations. The efficacy of NiO addition as a sintering aid was demonstrated by high densification of the samples, exceeding 97 % relative density. Detailed analysis of structural, microstructural, and conductivity properties revealed that microwave sintering, particularly using a heating rate of 500 °C/min, yielded superior results compared to conventional sintering. The enhanced electrical response was attributed to a higher concentration of structural defects, oxygen vacancies, in the microwave-sintered samples, evidenced by the band at 630 cm−1 in the Raman spectrum. Among these, the BCZY sample with 2 mol% NiO, sintered under these conditions, stood out as the most promising, showcasing not only high density but also a uniform microstructure and appreciable electrical conductivity. [ABSTRACT FROM AUTHOR]

Proton-conducting solid-state electrolytes, including perovskite-type materials, hold promise for hydrogen sensor development. These sensors leverage the proton conductivity of such materials to detect hydrogen gas presence. However, achieving both high density for gas tightness and good protonic conductivity in these refractory materials can be challenging. In this study, we propose the preparation of dense pellets of BaCe 0.6 Zr 0.3 Y 0.1 O 3-δ using ZnO as a sintering aid (BCZY-Zn). These pellets were extensively characterized using X-ray diffraction and electrochemical impedance spectroscopy and compared with pellets sintered without sintering aid (BCZY). Subsequently, BCZY-Zn electrolyte was utilized to fabricate amperometric sensors for hydrogen monitoring. Finally, amperometric measurements were conducted at 500 °C while maintaining a voltage of 150 mV between electrodes. The sensors' performance was evaluated for hydrogen partial pressures ranging from 12 to 100 Pa within an argon atmosphere. Additionally, response and recovery times were calculated. [Display omitted] • XRD showed smaller lattice parameters for BCZY-Zn (4.3410 Å) than for BCZY (4.3450 Å). • Bulk, grain boundary and three electrode processes were identified in EIS. • Bulk conductivity's activation energy was mostly unaffected by ZnO. • ZnO enhanced pellet densification, reducing the activation energy. • BCZY-Zn had good sensitivity and response and recovery times from 12 to 100 Pa. [ABSTRACT FROM AUTHOR]

Ceramic proton conductors have the potential to lower the operating temperature of solid oxide cells (SOCs) to the intermediate temperature range of 400–600 °C. This is attributed to their superior ionic conductivity compared to oxide ion conductors under these conditions. However, prominent proton-conducting materials, such as yttrium-doped barium cerates and zirconates with specified compositions like BaCe1−xYxO3−δ (BCY), BaZr1−xYxO3−δ (BZY), and Ba(Ce,Zr)1−yYyO3−δ (BCZY), face significant challenges in achieving dense electrolyte membranes. It is suggested that the incorporation of transition and alkali metal oxides as sintering additives can induce liquid phase sintering (LPS), offering an efficient method to facilitate the densification of these proton-conducting ceramics. However, current research underscores that incorporating these sintering additives may lead to adverse secondary effects on the ionic transport properties of these materials since the concentration and mobility of protonic defects in a perovskite are highly sensitive to symmetry change. Such a drop in ionic conductivity, specifically proton transference, can adversely affect the overall performance of cells. The extent of variation in the proton conductivity of the perovskite BCZY depends on the type and concentration of the sintering aid, the nature of the sintering aid precursors used, the incorporation technique, and the sintering profile. This review provides a synopsis of various potential sintering techniques, explores the influence of diverse sintering additives, and evaluates their effects on the densification, ionic transport, and electrochemical properties of BCZY. We also report the performance of most of these combinations in an actual test environment (fuel cell or electrolysis mode) and comparison with BCZY. [ABSTRACT FROM AUTHOR]

Al2O3 ceramics are the most widely used structural ceramics because of excellent mechanical properties, acid and alkali corrosion resistance and high quality-price-ratio. Due to serious agglomeration and high content of sodium and potassium impurities in domestic calcined Al2O3 powder, the preparation of Al2O3 ceramics with high performance relies heavily on imported powder. In this work, the Al2O3 powder produced by a domestic company was firstly disaggregated using ball milling, and the median particle size D50 of the powder was reduced from 1. 88 μm to 0. 90 μm. Afterwards, the impurity content in the powder was reduced by washing with water, and the Na content was reduced from 140 x 10-6 to 60 x 10-6, which was close to the level of the same grade powder abroad. Finally, Al2O3 ceramic green bodies were prepared by spontaneous coagulation casting using MgO and MgAl2O4 as sintering aids. It is found that the addition of MgO increases the slurry viscosity, while MgAl2O4 does not affect that, and both can effectively reduce the sintering temperature and inhibit the grain growth. And the average grain size is reduced from 41. 10 μm to 10. 64 μm, which improves the mechanical properties of Al2O3 ceramics. Through disaggregation and purification, the domestic Al2O3 powder can reach the same level as the Japanese Sumitomo Al2O3 powder with the best performance in the same grade. [ABSTRACT FROM AUTHOR]

Featured Application: The findings of the research study have implications for the development of high-temperature electrochemical devices based on solid electrolytes with symmetrical electrodes. R&D in the area of high-temperature symmetrical electrochemical devices is needed to meet the challenges of hydrogen energy. In the present study, the effect of Fe2O3 and CuO sintering aids on the electrochemical properties of the highly conductive solid electrolyte La0.8Sr0.2Ga0.8Mg0.2O3−δ and La0.6Sr0.4FeO3−δ electrodes for symmetrical solid oxide fuel cells was investigated. It is shown that the use of sintering aids leads to an improvement in grain boundary conductivity and allows us to reduce the sintering temperature to obtain a dense electrolyte with the same level of conductivity. It is shown for the first time that the nature of the sintering aids and the sintering temperature affect the La0.6Sr0.4FeO3−δ electrode activity differently depending on the gas environment (air or hydrogen). On the basis of the analysis of the impedance spectra by the distribution of relaxation times, assumptions were made about the nature of the rate-determining steps of hydrogen oxidation and oxygen reduction. It is shown that the nature of the rate-determining steps can change depending on the electrode sintering temperature. It was found that among the studied electrodes, La0.6Sr0.4FeO3−δ with 3 wt.% Fe2O3 sintered at 1050 °C is optimal in terms of activity in oxidizing and reducing atmospheres. [ABSTRACT FROM AUTHOR]

Improving the density of Na3Zr2Si2PO12 (NZSP) solid electrolyte is crucial for its application in solid-state sodium batteries. Here, bismuth oxide with low melting point has been evaluated as a sintering aid for NZSP solid electrolytes. Research has found that NZSP doped with 5 mass% Bi2O3 increases grain boundary mobility by 3.1 times and has an ionic conductivity of 4.78 × 10−3 S cm−1, with a minimum activation energy of 0.30 eV, approximately 5 times that of undoped Bi2O3. This is because the electrolyte density increased from 77.3 to 93.7%. Compared with the region III process of NZSP without Bi2O3, Bi2O3 promotes the densification process of Bi2O3 dopant coarsening in region III. The constant current cycle of Na | NZSP-5 mass% Bi2O3 | Na symmetric battery indicates that no short circuit will occur within 1200 h. The discharge capacity of solid-state batteries at 0.2 C is 98.5 mAh g−1. This indicates that NZSP doped with 5% Bi2O3 is a good electrolyte choice for sodium-ion batteries. [ABSTRACT FROM AUTHOR]

Alumina‐based porous ceramics were fabricated via the starch consolidation casting route, using titanium oxide as a sintering additive. Alumina‐titania‐starch slurries with starch contents of 2.5, 5, 7.5, and 10 wt% relative to the alumina‐titania system were prepared. Titania was added to the slurries in proportions of 0, 1, 3, and 5 wt%, relative to alumina. The effects of starch and titania contents in the green bodies on the linear and volumetric shrinkage, as well as the total and open porosities of the sintered alumina product, were investigated. The effect of titania addition on mechanical, electrical, and thermal properties of the obtained porous alumina ceramics was studied. Microstructure and pores morphology were characterized by SEM. The alumina‐based ceramics obtained had external porosities that varied between 54 and 76 vol%. Thermal conductivities as low as 0.06–0.1 W/m.K were achieved and the volume electrical resistivity ranged from 3.6 to 600 GΩ·m, while compressive strengths up to 2.8 MPa for a titania ratio of 1 wt% were attained. [ABSTRACT FROM AUTHOR]

For the first time, Ni 25 Co 20 Cu 10 Fe 25 Mn 20 high entropy alloy (HEA) was employed as a sintering aid for fabrication of ZrB 2 -based ceramics using spark plasma sintering (SPS) process. The mechanical properties, phase evolution, microstructural changes, and the densification mechanisms of ZrB 2 -5 wt% HEA ceramics during the SPS step were scrutinized. The ZrB 2 -5 wt% HEA ceramic, manufactured at 1900 °C, yielded interesting combination of properties, counting a relative density of 96%, a fracture toughness of 6.4 MPa m1/2, and a hardness of 12.6 GPa. According to XRD patterns, there were ZrC and ZrO 2 phases with ZrB 2 matrix in the sintered samples. An unknown phase was also observed in the XRD patterns. Based on the history of the NiCoCuFeMn alloy and separation of Cu within the temperature range of 650–850 °C, that phase was related to CuB. [ABSTRACT FROM AUTHOR]

Via composition designing and sintering condition tailoring, high-density pure perovskite structure xBi(Ni0.50Ti0.50)O3–0.05BiFeO3–(0.95−x)Pb(Zr0.50Ti0.50)O3 [xBNT–0.05BF–(0.95−x)PZT, x = 0.19, 0.20, 0.21, 0.22, 0.23] ceramics were prepared by solid-state sintering method with adding additional 0.5 wt% LiBO2 sintering aid, whose sintering temperature was lower than that reported in literature. The xBNT–0.05BF–(0.95−x)PZT ceramics have mainly tetragonal structure confirmed by X-ray diffraction measurement and Raman spectroscopy, which is affected by composition and sintering condition. Broad dielectric peaks appear in all samples, and diffusive phase transition and dielectric frequency dispersion are obvious as well. The 0.20BNT–0.05BF–0.75PZT ceramics exhibit large piezoelectricity d33 = 386 pC/N combined with rather high dielectric constant maximum temperature Tm = 264°C, presenting enormous application potential in the high-temperature piezoelectric-related field. [ABSTRACT FROM AUTHOR]

Yttria-stabilised zirconia (YSZ) materials are of great interest due to their mechanical properties, chemical inertness, low thermal conductivity and high ionic conductivity. However, a high temperature is required to consolidate the YSZ, while homogeneity problems may arise. This study proposes a modified wet chemical method for commercial YSZ sintering started from a scalable colloidal solution containing yttrium and lithium in an aqueous medium. This homogeneous mixture, adjusted by pH and Li/Y content, transforms into intermediate phases that play a key role as "cement" linking YSZ particles at low sintering temperatures. The originality consists of the use of the citric acid enabling the formation of either porous or dense microstructure depending on processing conditions. A complete follow-up of the transformation of compounds throughout the process, from liquid phase to cement, is proposed and enables us to propose the consolidation mechanism that will be useful for further optimization. [ABSTRACT FROM AUTHOR]

To achieve the low temperature synthesis of cordierite, according to its theoretical ratio, porous cordierite ceramics were prepared using calcined kaolin (≤0.044 mm), sintered magnesia (≤0.074 mm) and silica micropowder (d50 =2.6 µm) as main raw materials, analytically pure zirconia and lanthana as sintering aids, and polyvinyl alcohol (PVA) solution as the binder, pressing to samples of Φ30 mm x30 mm at 60 MPa, drying and calcining. The effects of the extra additions of zirconia (0 and 8%, by mass) and lanthana (0, 0.2%, 0.4%, 0.6% and 0.8%, by mass) and calcination temperatures (1 200, 1 250 and 1 300 °C) on the cold physical properties, phase composition and microstructure of the porous cordierite ceramics were studied. The results show that: (1) the sample fired at 1 300 °C and introduced with 8% zirconia and 0.6% lanthana shows good physical properties; (2) the co-doping of zirconia and lanthana can improve the mechanical properties of the sample while maintaining the apparent porosity, and promote the formation of cordierite; (3) the co-doping of zirconia and lanthana can reduce the synthesis temperature of cordierite and improve the comprehensive performance of the sample. [ABSTRACT FROM AUTHOR]

In this study, ceramic samples of Bi2Sr2Co2Oy + v wt% B2O3 (v = 0.0, 0.1, 0.2, 0.3, 0.4) were synthesized using the solid state reaction method, and the influence of B2O3 additive on their microstructure and thermoelectric properties were investigated. On one hand, the B2O3 additive acted as a sintering aid, enhancing carrier mobility. On the other hand, B2O3 dispersion served as a nano-second-phase, increasing hetero-interfaces and strengthen phonon scattering, thereby effectively suppressing lattice thermal conductivity. By dual optimization of both electric and thermal transport performance, the Bi2Sr2Co2Oy + 0.3 wt% B2O3 sample achieved a high ZT value (thermoelectric figure of merit) of 0.31 at 923 K, which was improved by approximately 33% compared with the pristine Bi2Sr2Co2Oy sample. [ABSTRACT FROM AUTHOR]

Copyright of Bulletin of the Chinese Ceramic Society is the property of Bulletin of the Chinese Ceramic Society Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Abstract Alumina‐based porous ceramics were fabricated via the starch consolidation casting route, using titanium oxide as a sintering additive. Alumina‐titania‐starch slurries with starch contents of 2.5, 5, 7.5, and 10 wt% relative to the alumina‐titania system were prepared. Titania was added to the slurries in proportions of 0, 1, 3, and 5 wt%, relative to alumina. The effects of starch and titania contents in the green bodies on the linear and volumetric shrinkage, as well as the total and open porosities of the sintered alumina product, were investigated. The effect of titania addition on mechanical, electrical, and thermal properties of the obtained porous alumina ceramics was studied. Microstructure and pores morphology were characterized by SEM. The alumina‐based ceramics obtained had external porosities that varied between 54 and 76 vol%. Thermal conductivities as low as 0.06–0.1 W/m.K were achieved and the volume electrical resistivity ranged from 3.6 to 600 GΩ·m, while compressive strengths up to 2.8 MPa for a titania ratio of 1 wt% were attained.

R&D in the area of high-temperature symmetrical electrochemical devices is needed to meet the challenges of hydrogen energy. In the present study, the effect of Fe2O3 and CuO sintering aids on the electrochemical properties of the highly conductive solid electrolyte La0.8Sr0.2Ga0.8Mg0.2O3−δ and La0.6Sr0.4FeO3−δ electrodes for symmetrical solid oxide fuel cells was investigated. It is shown that the use of sintering aids leads to an improvement in grain boundary conductivity and allows us to reduce the sintering temperature to obtain a dense electrolyte with the same level of conductivity. It is shown for the first time that the nature of the sintering aids and the sintering temperature affect the La0.6Sr0.4FeO3−δ electrode activity differently depending on the gas environment (air or hydrogen). On the basis of the analysis of the impedance spectra by the distribution of relaxation times, assumptions were made about the nature of the rate-determining steps of hydrogen oxidation and oxygen reduction. It is shown that the nature of the rate-determining steps can change depending on the electrode sintering temperature. It was found that among the studied electrodes, La0.6Sr0.4FeO3−δ with 3 wt.% Fe2O3 sintered at 1050 °C is optimal in terms of activity in oxidizing and reducing atmospheres.

Sintering aids are commonly used to improve the sinterability of proton-conducting oxides, whereas the sintering aid elements are being used alone in previous research. In this study, a high-entropy design method for the BaCe 0.4 Zr 0.4 Y 0.2 O 3 (BCZY) proton-conducting oxides sintering aid is proposed. In contrast to the use of sintering aids such as Ni, Fe, Cu, Co, and Zn alone, the high-entropy design allows for the simultaneous use of all five elements, resulting in the new composition BaCe 0.4 Zr 0.4 Y 0.15 Ni 0.01 Cu 0.01 Co 0.01 Fe 0.01 Zn 0.01 O 3 (HE-BCZY). Compared to conventional BaCe 0.4 Zr 0.4 Y 0.15 M 0.05 O 3 (BCZYM, M = Ni, Cu, Co, Fe, Zn) materials, the sinterability of the new HE-BCZY material is significantly greater than that of BCZYM, despite the fact that the concentration of sintering aids is the same. Following sintering at 1300 °C, the HE-BCZY electrolyte membrane is completely dense. In addition, the HE-BCZY electrolyte has a higher conductivity than BCZYM. The low sintering temperature allows the successful preparation of proton ceramic fuel cells (PCFCs) with the HE-BCZY electrolyte, and the fuel cell reaches a high peak power density of 1218 mW cm−2 at 700 °C, which is much higher than that of PCFCs using BCZY-based electrolytes. In addition, the excellent chemical stability of HE-BCZY is maintained under both H 2 O and CO 2 conditions. Consequently, a fuel cell employing the HE-BCZY electrolyte operates without detectable degradation for 200 h. This study demonstrates that although the high-entropy design is seldom used for sintering aids of proton-conducting oxides, it is an intriguing and promising strategy for creating high-performance electrolyte materials with good sinterability, high conductivity, and excellent stability. [ABSTRACT FROM AUTHOR]

The effects of calcite (CaCO3) as sintering aid on the preparation of local aluminum silicate microfiltration membranes were characterized in terms of morphology, thermal shrinkage behavior, porosity, permeation performance, and pure water permeate flux for the membrane. Material selection is based on availability and formability. In order to create a suspension, an organic solvent (N-methyl-2-pyrrolidone) and a polymer binder were added to a mixture of aluminum silicate and calcium carbonate. The coagulant bath consisted of water, and the suspension was extruded into a hollow fiber using a spinneret. The membrane precursor is subjected to high temperatures up to 1250 °C and this process called the sintering process gets strong hollow fiber with high mechanical stability. The addition of the CaCO3) to the dispersion altered the structure of the resulting sintered membranes. The obtained finding demonstrates that carbon calcium addition to aluminum silicate has an affirmative on overall porosity in contrast to those made from purely natural aluminum silicate, as a result the aluminum silicate calcite ceramic microfiltration membrane, which had a high porosity of above 50%, shows the highest permeability of 35.8 ml m-2 s-1 and above 97% oil rejection when operating at 0.15 MPa trans-membrane pressure in oil-in-water separation experiments. The results show that low-cost aluminum silicate-calcite component of ceramic membranes and the manufactured ceramic microfiltration membrane can handle emulsified oily wastewater.

Ceramic membranes with high porosity and excellent separation efficiency are necessary for the efficient treatment of large‐scale wastewaters. However, the conventional ceramic membranes are usually prepared by particles‐packing, which inhibits the advances of separation efficiency because of the low porosity and connectivity. Here, a fibrous ceramic membrane with mullite whiskers‐interlocked structure was prepared by gas‐solid reaction. The effects of aluminum fluoride (AlF3) on the formation and growth of mullite whiskers, and then the permeability and selectivity of the ceramic membranes were investigated. With the increase of AlF3 contents, the mullite phase evolved from needle‐like, rod‐like to flake‐like structure, thus the catalyst accelerated the growth of mullite whiskers in the diameter direction. For the ceramic membrane sintered at 1400°C, the porosity increased from 58% to 76% while the average pore sizes increased from 0.65 to 3.93 μm because of the whisker‐constructed structures. For the ceramic membrane sintered at 1450°C, the emulsion flux increased stably from 295 L/(m2·h) to 992 L/(m2·h) with the increase of trans‐membrane pressure, and the oil rejection exceeded 98%. Thus, this study provides a feasible strategy for the preparation of ceramic membranes with high porosity and excellent separation performances. [ABSTRACT FROM AUTHOR]

In the past decades, Zirconia (ZrO 2) has emerged as a promising technical ceramic, both as high temperature structural material and electrolyte for fuel cells, etc. The traditional synthesis of ZrO 2 with spark plasma sintering (SPS) usually requires a sintering temperature as high as 1200 °C. General interest in lowering the sintering temperature to reduce energy consumption and thermal stresses has led to research on two promising routes – cold sintering via temperature-dependent chemical reactivity and sintering aids, which facilitates mass transport and improves densification. Here we combine both by developing a single-step sintering process benefitting from both water vapor through the in-situ conversion of Zr(OH) 4 to ZrO 2 and liquid phase Bi 2 O 3 as a sintering aid. The resultant ZrO 2 has a relative density above 80% with a sintering temperature as low as 900 °C, significantly higher than that of ZrO 2 without sintering aids, which had a relative density of 54%, both sintered at 50 MPa. The dependence of porosity of sintered samples as a function of sintering pressure (range: 50 MPa–300 MPa) and temperature (range 400 °C–1200 °C) is mapped out as guidance for further material property design. A linear relationship between hardness and relative density was found, with a maximal hardness of 6.6 GPa achieved in samples with 30% porosity. In addition to sintered density, phase stabilization of tetragonal ZrO 2 is enhanced at sintering temperature of 900 °C with water vapor and Bi 2 O 3 , respectively. [ABSTRACT FROM AUTHOR]

The effects of Y 2 O 3 and ZnO co-doping on the densification and properties of magnesium aluminum spinel were investigated. The physical phase composition, microstructure, elemental distribution, densification, apparent porosity, particle size distribution and average corrosion depth of the specimens were investigated by XRD, SEM-EDS, Archimedes drainage method, Nano Measurer 1.2 software, and molten salt corrosion tests. The results showed that after co-doping with Y 2 O 3 and ZnO, the cations in the sintering aids could dissolve into the spinel structure, forming solid solution ZnAl 2 O 4 , second phase Y 3 Al 5 O 12 and Al 2 Y 4 O 9 , which inhibited the abnormal grain growth and made the grain distribution more uniform, thus promoting the densification of the samples. The best co-doping amount of Y 2 O 3 and ZnO was 1 wt% Y 2 O 3 -3 wt.% ZnO, the relative density of the sample was 99.3%, the apparent porosity was 0.021%, and the grain size was the most uniform (6.52 μm). After the sample was placed into the aluminum electrolytic molten salt electrolyte for 1 h, and it was found that the sample doped with 1 wt% Y 2 O 3 -3 wt.% ZnO had the minimum average corrosion depth (131.9 μm) and the best corrosion resistance. [ABSTRACT FROM AUTHOR]

Copyright of Journal of Ordnance Equipment Engineering is the property of Chongqing University of Technology and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

We have studied the effect of sodium fluoride as a sintering aid for β-sialons on the phase composition and physicomechanical properties of Si5AlON7 and Si4Al2O2N6. Two-step high-temperature firing of the β-sialons in the presence of NaF under a nitrogen atmosphere has been shown to cause no significant changes in the phase composition of the materials. The density and microhardness of the materials prepared using 0.5 and 5.0 wt % NaF are lower than those of the materials prepared without sintering aids, but the bending strength is higher by up to 14.3% in the case of Si5AlON7 prepared using 0.5 wt % NaF and by 4.9% in the case of Si4Al2O2N6 prepared using 5.0 wt % NaF. [ABSTRACT FROM AUTHOR]

Partial oxidation of methane (POM) is a prominent pathway for syngas production, wherein the hydrogen in syngas product can be recovered directly from the reaction system using a hydrogen (H2)-permeable membrane. Enhancing the efficiency of this H2 separation process is a current major challenge. In this study, Ce0.8Y0.2O2-δ-BaCe0.8Y0.2O3-δ (YDC-BCY) hollow fiber (HF) membranes were developed and characterized for their H2 permeation fluxes. Firstly, YDC and BCY ceramic powders were synthesized using the sol-gel method, followed by the fabrication of YDC-BCY dual-phase ceramic HF membranes using a combined phase inversion–sintering process. Characterization using SEM, powder XRD, EDS, and electrical conductivity tests confirmed the phases of the prepared powders and HF membranes. Well-structured YDC and BCY powders with uniform particle sizes were obtained after calcination at 900 °C. With the addition of 1 wt.% Co2O3 as a sintering aid, the YDC-BCY dual-phase HF membrane achieved densification after sintering at 1500 °C. Subsequently, the influences of sweep gas composition and temperature on the hydrogen permeation of the YDC-BCY HF membranes with YDC/BCY molar ratios of 2:1, 3:1, and 4:1 were investigated. At 1000 °C and a sweep-gas flow rate of 120 mL·min−1, the YDC-BCY HF membrane with a YDC/BCY molar ratio of 4:1 exhibited a peak hydrogen flux of 0.30 mL·min−1 cm−2. There is significant potential for improving the hydrogen permeation of dual-phase ceramic membranes, with future efforts aimed at reducing dense layer thickness and enhancing the membrane material's electronic and proton conductivities. [ABSTRACT FROM AUTHOR]

This research aims to investigate the effect of different amounts of doping elements (magnesium and yttrium ions) on the hardness, elastic modulus, flexural strength, and transparency of alumina ceramics. For this purpose, different amounts of Mg2+ and Y3+ doped α-Al2O3 nanoparticles were synthesized via the co-precipitation method. The results revealed that the majority of Mg2+ and Y3+ doped α-Al2O3 nanoparticles have a particle size of 300–400 nm. Furthermore, the density and transparency (60% in-line transmittance at a wavelength of 5 μm, with a sample thickness of 2.4 mm) of the bulk materials prepared with doping of 100 ppm Mg2+and 400 ppm Y3+ (100M400Y) presented the best performance compared with other samples. Furthermore, the hardness and Young modulus of this sample were 28 GPa and 349 GPa, respectively. The flexural strength of the 100M400Y sample reached the highest value, 193 MPa, due to the smaller grain size and minimal porosity.

Silicon carbide ceramic membranes have been widely used in the treatment of various corrosive and high temperature wastewaters. However, SiC is a compound with strong covalent bond, thus the sintering temperature and then the energy consumption during sintering of SiC ceramics is high, which inhibits the scale-up manufacturing of SiC ceramic membranes. Here, a silicon carbide ceramic membrane support was prepared at 800 °C with a low melting-point glaze as the sintering aid. The glaze infiltrated the SiC skeleton during sintering, and gave rise to high fracture strength of the porous ceramics. With the content increase of sintering aid from 10 wt% to 30 wt%, the pore-formation mechanism of the ceramic membrane support transformed from SiC particles packing to SiC aggregations packing, leading to the increase in pore size and decrease in porosity. The permeance and selectivity of the support was investigated via pure-water and oil-in-water emulsion tests. Due to the high hydrophilicity, the pure-water flux increased from 32 L/(m2·h) to 87 L/(m2·h) while the oil rejection decreased from 99.0% to 93.1% with the increase of trans -membrane pressure. This work provides a feasible route for the preparation of SiC porous ceramics with low energy consumption. [ABSTRACT FROM AUTHOR]

In this study, it is executed to obtain Zr 2 - x Ti x WP 2 O 12 (x = 0. 0 5 , 0.10, 0.15, 0.20) ceramics with high relative density, 0–0.9 wt% MgO was added as a sintering aid. The influence of MgO amount and relative density on the coefficient of thermal expansion for Zr 2 - x Ti x WP 2 O 12 was also investigated. Pure and monophase of Zr 1. 8 Ti 0. 2 WP2O 1 2 with MgO has been obtained and MgO used sintering aid was doped in the crystal. The coefficients of thermal expansion of the 0.9 wt% MgO-doped sample and MgO-free sample were − 2. 2 4 ppm/K and − 2. 2 5 ppm/K, respectively. This result suggests that doping of MgO does not have an influence on the coefficient of thermal expansion. In other words, adding MgO increases sintering properties without change in the coefficient of thermal expansion. [ABSTRACT FROM AUTHOR]

Solid oxide fuel cells (SOFCs) with the Gd 0.1 Ce 0.9 O 1.95 (GDC) diffusion barrier layer require the densification of GDC to improve the performance of the cells. In this work, the addition of 0.5 mol% Fe 2 O 3 in GDC diffusion barrier layer as sintering aid is studied. The symmetrical cell and the fuel cell are fabricated by hot-pressing, co-sintering and screen-printing technologies. It is found that the addition of Fe 2 O 3 can make GDC barrier layer denser at a reduced sintering temperature of 1250 °C and prevent diffusion of Sr to form ionic insulating interface between YSZ (Y 2 O 3 stabilized ZrO 2) and La 0.6 Sr 0.4 Co 0.8 Fe 0.2 O 3-δ (LSCF). The fuel cell based on the GDC-Fe 2 O 3 barrier layer achieves better maximum power density of 0.89 W cm−2 at 800 °C than that of 0.68 W cm−2 without Fe 2 O 3 addition. No obvious degradation was observed on fuel cell based on the GDC-Fe 2 O 3 diffusion barrier layer after a stability test at 750 °C for 100 h under 0.75 V and the thermal cycling between 750 and 400 °C. The results indicate that the addition of Fe 2 O 3 sintering aid in GDC diffusion barrier layer can promote the densification of GDC and exhibit good long-term stability and thermal cycle stability. [Display omitted] • Anode support SOFC was successfully fabricated by tape casting, hot-pressing and co-sintering technology. • A dense Gd 0.1 Ce 0.9 O 1.95 (GDC) layer was obtained at 1250 °C with Fe 2 O 3 sintering aid. • The maximum power density at 800 °C of the cell is improved by 24% through addition of Fe 2 O 3 to the GDC layer. • The fuel cell based on the GDC-Fe 2 O 3 barrier layer is demonstrated to have good durability and thermal cycling stability. [ABSTRACT FROM AUTHOR]

This study investigates the sintering behaviour and properties of WC-based composites in which WC was mixed with W5vol%Ni in concentrations of 10vol% and 20vol%. Colloidal processing in water and spark plasma sintering were employed to disperse the WC particles and facilitate sintering. The addition of W5vol%Ni improved the sintering process, as evident from a lower onset temperature of shrinkage determined through dilatometric studies. All samples exhibited the formation of tungsten monocarbide (W2C), with a more pronounced presence in the WC/20(W5vol%Ni) composite. Sintering reached its maximum rate at 1550 °C and was completed at 1600 °C, resulting in a final density exceeding 99.8%. X-ray diffraction analysis confirmed the detection of WC and W2C phases after sintering. The observed WC content was higher than expected, which may be attributed to carbon diffusion during the process. Macro-scale mechanical characterisations revealed that the WC/10(W5vol%Ni) composite exhibited a hardness of 18.9 GPa, while the WC/20(W5vol%Ni) composite demonstrated a hardness of 18.3 GPa. Increasing the W5vol%Ni binder content caused a decrease in mechanical properties due to the formation of W2C phases. This study provides valuable insights into the sintering behavior and properties of WC/W5vol%Ni composites, offering potential applications in extreme environments. [ABSTRACT FROM AUTHOR]

The effects of calcite (CaCO3) as sintering aid on the preparation of local aluminum silicate microfiltration membranes were characterized in terms of morphology, thermal shrinkage behavior, porosity, permeation performance, and pure water permeate flux for the membrane. Material selection is based on availability and formability. In order to create a suspension, an organic solvent (N-methyl-2-pyrrolidone) and a polymer binder were added to a mixture of aluminum silicate and calcium carbonate. The coagulant bath consisted of water, and the suspension was extruded into a hollow fiber using a spinneret. The membrane precursor is subjected to high temperatures up to 1250 °C and this process called the sintering process gets strong hollow fiber with high mechanical stability. The addition of the CaCO3) to the dispersion altered the structure of the resulting sintered membranes. The obtained finding demonstrates that carbon calcium addition to aluminum silicate has an affirmative on overall porosity in contrast to those made from purely natural aluminum silicate, as a result the aluminum silicate calcite ceramic microfiltration membrane, which had a high porosity of above 50%, shows the highest permeability of 35.8 ml m-2·s-1 and above 97% oil rejection when operating at 0.15 MPa trans-membrane pressure in oil-in-water separation experiments. The results show that low-cost aluminum silicate-calcite component of ceramic membranes and the manufactured ceramic microfiltration membrane can handle emulsified oily wastewater. [ABSTRACT FROM AUTHOR]

Herein, we report an in-situ reaction-bonded SiC membrane sintered at low temperature using a solid waste (i.e. coal gangue) as the sintering aid to form strong neck connections. The effects of sintering temperature and coal gangue proportion on their properties regarding pore size, open porosity, bending strength and pure water permeability were investigated. The single-channel tubular SiC membrane sintered at 1300 °C with a coal gangue proportion of 12 wt% was optimal, exhibiting an average pore size of 2.78 μm, a open porosity of 47.08%, a bending strength of 34.01 ± 1.3 MPa and a high water permeability of 83967 L m−2 h−1 bar−1. The membrane could completely reject D 50 = 0.87 μm SiC solids and presented a steady-state water permeability of 458 L m−2 h−1·bar−1. The SiC membrane could be regenerated through ultrasonication and its steady-state water permeability was almost unchanged for 3 cycles, proving its mechanical robustness. This work may appeal to the practical low-cost production of high-performance SiC membranes. [ABSTRACT FROM AUTHOR]

The reduction of sintering time and temperature using an unconventional route and sintering aid for the densification of BaCe 0.2 Zr 0.7 Y 0.1 O 3-δ were investigated. The effects of ZnO addition and microwave sintering were explored on the structure, sinterability, microstructure, and electrical conductivity. BaCe 0.2 Zr 0.7 Y 0.1 O 3-δ powders were synthesized by solid-state reaction. The addition of 2 and 4 mol% ZnO was beneficial to obtain a single perovskite structure and improved sinterability producing dense samples. Relative densities of 99% at 1300 °C by conventional sintering and 98% at 1400 °C by microwave sintering were reached. A total conductivity of 1.20 mS cm−1 for the sample with 2 mol% ZnO by conventional sintering (relative density 99%) was obtained at 550 °C in a wet nitrogen atmosphere. Additionally, a high conductivity was also obtained for this compound produced by microwave sintering (relative density 98%) even with its microstructure exhibiting the smallest average grain size. In conventional sintering, the presence of the eutectic liquid phase responsible for the densification, was prejudicial to the total conductivity, being more evident in the samples with 4 mol% ZnO addition. The results indicate that microwave sintering was a rapid alternative for sintering, capable of reducing or inhibiting the appearance of the liquid phase producing dense, uniform samples, and with high conductivity. [ABSTRACT FROM AUTHOR]

The BaCe 0 · 4 Zr 0 · 4 Y 0 · 2 O 3 (BCZY) was modified with the NiO sintering aid and prepared by a microwave sintering (MVS) method as the electrolyte for proton-conducting solid oxide fuel cells (H–SOFCs). The incorporation of NiO into the BCZY lattice improves the sinterability of the material, leading to the increase of the shrinkage from 3% to 26% after the high-temperature sintering. The dense BaCe 0 · 4 Zr 0 · 4 Y 0 · 15 Ni 0 · 05 O 3 (BCZYN) pellet can be obtained after sintering at 1500 °C, whereas the Ni-free BCZY is porous after sintering at the same condition. By further using the MVS method, the BCZYN can be densified at 1300 °C, which is 200 °C lower than conventional sintering. Furthermore, the microwave-sintered BCZYN has a higher conductivity than the conventionally sintered one due to the larger grain size. Using the MVS method in the H–SOFCs fabrication, the high porosity of the anode substrate can be retained. In contrast, the cell prepared by the conventional sintering (CS) method has a relatively dense anode, which is detrimental to gas fuel transportation. As a result, the microwave sintered cell exhibits an output of 1010 mW cm−2 at 700 °C, which is significantly larger than that for the conventionally sintered cell, being 535 mW cm−2 at the same testing condition, suggesting the advantage of using the MVS method for the fuel cell fabrication. [ABSTRACT FROM AUTHOR]

Al2O3 corundum precursor was synthesized by sol-gel technology, and microcrystalline ceramic corundum (SG) abrasive was prepared by traditional sintering technology with SiO2-MgO-CaO as sintering aids and α-Al2O3 nano-powder as crystal seed. The characteristics of seed and thermal properties of gel precursor were analyzed by means of transmission electron microscopy (TEM), X-ray diffraction (XRD) and thermogravimetric-calorimetric scanning (TG-DSC). The effects of sintering temperature and holding time on microstructure and mechanical properties of SG abrasive were studied. The results show that αAl2O3 nano-seed makes the transition temperature of θ-Al2O3 → α-Al2O3 decrease by 250 °C. With increasing sintering temperature and holding time, the single particle compressive strength and density increase first and then decrease, and the grain morphology changes from equiaxed crystal to platelike crystal. Sintering at 1320 °C for 45 min, the single particle compressive strength and density of SG abrasives reach 40.2 N and 3.88 g/ cm³, respectively, and the average particle size is 0.56 µm, which is superior to micron seed abrasive samples prepared by traditional sintering technology. [ABSTRACT FROM AUTHOR]

C f -SiC air brake discs are being developed due to their high-temperature oxidation resistance compared to conventional C f /C discs. The C f -SiC air brake discs should have a coefficient of friction (COF) close to 0.4, a low wear rate, a density higher than 95% of the theoretical density, and flexural strength of more than 200 MPa. To reach the properties of C f -SiC composite to the required characteristics of the air brake disc, different amounts of alumina-based sintering aid were used. For this purpose, first silicon carbide nanoparticles, sintering aids Al 2 O 3 –MgO, MgAl 2 O 4 , Al 2 O 3 –Y 2 O 3 , Al 2 O 3 –SiO 2 –MgO, and carbon fiber (20 wt%) with a 5-mm length were prepared. Next, the final composite bulk was created via the SPS method at 1900 °C under a pressure of 50 MPa. The density of the sample sintered with the Al 2 O 3 –SiO 2 –MgO sintering aid was higher than that of other sintering aids. The density value was obtained at 98% and 100% at 8 wt% and 4 wt% respectively. It was also found that the use of 4 wt% of Al 2 O 3 –SiO 2 –MgO offered better mechanical properties compared to 8 wt%, due to the absence of Al 8 Si 4 O 20 phase at 4 wt%. The examination of mechanical properties showed that the hardness (3564 Vickers) and flexural strength (479 MPa) of the sample with the Al 2 O 3 –SiO 2 –MgO sintering aid were higher than those of other sintering aids. The samples with the Al 2 O 3 –SiO 2 –MgO sintering aid with 4 wt% revealed a COF of 0.41, showing the closest feature to the desired indices of aircraft brake discs. [ABSTRACT FROM AUTHOR]

A low-temperature sintering strategy was realized for preparing 0.21Bi(Ni0.5Ti0.5)O3-0.05BiFeO3-0.74Pb(Zr0.5Ti0.5)O3 (0.21BNT-0.05BF-0.74PZT) ceramics by conventional ceramic processing by adding low melting point BiFeO3 and additional sintering aid LiBO2. Pure perovskite 0.21BNT-0.05BF-0.74PZT ceramics are prepared at relatively low sintering temperatures, and their structure presents tetragonal distortion that is affected slightly by the sintering temperature. The 1030 °C sintered samples have high densification accompanied by relatively large grains. All ceramics have excellent dielectric performance with a relatively high temperature of dielectric constant maximum, and present an apparent relaxation characteristic. A narrow sintering temperature range exists in the 0.21BNT-0.05BF-0.74PZT system, and the 1030 °C sintered 0.21BNT-0.05BF-0.74PZT ceramics exhibit overall excellent electrical performance. The high-temperature conductivity can be attributed to the oxygen vacancies' conduction produced by the evaporation of Pb and Bi during sintering revealed by energy dispersive X-ray measurement. [ABSTRACT FROM AUTHOR]

In this work, MgAl 2 O 4 : Cr3+ transparent ceramics have been synthesized by the hot press sintering techniques, and the effect of the sintering aid Gd 2 O 3 and its content on the densification, microstructure, and optical, photoluminescence was studied and discussed. The relative density reached 99.29% with 0.8 wt% Gd 2 O 3 as a sintering aid, and the optical transmittance at 686 nm and 1446 nm were approximately 76%. As Gd 2 O 3 content continued to increase, the grain size of the ceramics became smaller and uniform, accompanied by some pores with the size of ～1 μm. The ceramics with 4.0 wt% Gd 2 O 3 showed a higher transmittance, of 82% at 1446 nm. Additionally, Gd 2 O 3 was helpful for Cr3+ in the sites of octahedral symmetry, which increased the quantum yield. The quantum yield of MgAl 2 O 4 : Cr3+ with 0.8 wt% Gd 2 O 3 was about 0.175, which was 36% higher than that of ceramic without Gd 2 O 3. In short, the sintering aid Gd 2 O 3 not only contributed to improving the densification, homogenizing the grain size, and heightening the optical transmittance but also enhanced the quantum yield of Cr3+. [ABSTRACT FROM AUTHOR]

Lead lanthanum zirconate titanate (PLZT) ceramics exhibit excellent dielectric, ferroelectric and piezoelectric properties, and they can be used in many applications, including actuators. In this review, the processing and properties of PLZT-based ceramics will be the main focus of the first part. An introduction to PLZT ceramics is given and the methods to improve processing of PLZT-based ceramics are explained in terms of the addition of sintering aids, fabrication in the form of composites, and the application of dopants. The second part will be related to strain measurement to investigate converse piezoelectric properties (actuating effect). Strain measurement techniques by Michelson interferometry and case studies in PLZT-based ceramics (aging effect, temperature dependence and magnetic field effect) are included. [ABSTRACT FROM AUTHOR]

Ceramic slurry of 78 mass% solid loading was prepared using photosensitive acrylic resin and dispersant SP-710 as the liquid phase, Al2O3 powder (d50=2.38 pm) and TiO2 powder additive as the solid phase. Alumina ceramics were prepared by DLP, sintering for 4 h at 1 450, 1 500, 1 550 or 1 600 °, respectively. The effects of the TiO2 addition (0, 1%, 2%, 3% and 5%, by mass) on the properties of the ceramics were studied. The results show that the addition of TiO2 can improve the sintering of Al2O3 ceramics, significantly improve the densification, and reduce the sintering temperature. With the optimum TiO2 addition of 3% and the optimum sintering temperature of 1 600 °C, the obtained Al2O3 ceramics have shrinkage of 15.7%, 15.8% and 23.8% at the x axis, the y axis, and the z axis, respectively, the porosity of 2.4%, the bulk density of 3.74 g • cm-3 and the threepoint bending strength of 251.1 MPa. Compared with the undoped alumina ceramics, the doped alumina ceramic has increased bulk density by 0.56 g • cm-3, decreased apparent porosity from 20.2% to 2.4%, and the three-point bending strength increases by 2.5 times. Therefore, the density and the strength of DLP prepared ceramics can be improved effectively by adding an appropriate amount of TiO2, and the performance of the DLP prepared ceramics is close to that of the pressed samples. Thus, it is hopeful to apply DLP in refractories field. [ABSTRACT FROM AUTHOR]

Four-channel dual-layer Al 2 O 3 hollow fiber with ultra-high permeability and mechanical strength was prepared by co-extrusion and co-sintering technique for the first time and used as support for NaA zeolite membranes fabrication. The macroporous inner layer of the Al 2 O 3 hollow fiber, composed by large Al 2 O 3 particle, gives supports the high permeability and mechanical strength, while the thin out layer, composed by small particles, provides an even and smooth surface for zeolite membrane growth. By using SiO 2 as the sintering aid, the sintering temperature of the inner layer was reduced and match with that of the outer layer. The effects of SiO 2 adding amount, sintering temperature, Al 2 O 3 particle size and their content on the structure and properties of the prepared hollow fiber were investigated systematically. At a sintering temperature of 1520 °C, a dual-layer hollow fiber with surface pore size of 0.38 μm and fracture load of 24.52 N, exhibits pure water flux as high as 22.23 m3 m 2 h−1 bar−1. The NaA membrane prepared on this support achieved a flux of 14.14 kg m−2 h−1 and a separation factor >10,000 in pervaporation separation of EtOH/H 2 O solution (90 wt%, 75 °C). This work provides an efficient and low-cost way to prepare ceramic hollow fiber support for high-performance zeolite membrane fabrication. [Display omitted] • Dual-layer Al 2 O 3 hollow fiber was prepared by co-extrusion and co-sintering technique. • Larger particle Al 2 O 3 and sintering aid SiO 2 were used to form macroporous inner layer. • Small particle Al 2 O 3 was used to form a thin outer layer with reduced surface pore size. • Dual-layer Al 2 O 3 hollow fiber with ultra-high permeability and mechanical strength can be obtained. • High performance NaA zeolite membrane was prepared on the Dual-layer Al 2 O 3 hollow fiber. [ABSTRACT FROM AUTHOR]

Partial oxidation of methane (POM) is a prominent pathway for syngas production, wherein the hydrogen in syngas product can be recovered directly from the reaction system using a hydrogen (H2)-permeable membrane. Enhancing the efficiency of this H2 separation process is a current major challenge. In this study, Ce0.8Y0.2O2-δ-BaCe0.8Y0.2O3-δ (YDC-BCY) hollow fiber (HF) membranes were developed and characterized for their H2 permeation fluxes. Firstly, YDC and BCY ceramic powders were synthesized using the sol-gel method, followed by the fabrication of YDC-BCY dual-phase ceramic HF membranes using a combined phase inversion–sintering process. Characterization using SEM, powder XRD, EDS, and electrical conductivity tests confirmed the phases of the prepared powders and HF membranes. Well-structured YDC and BCY powders with uniform particle sizes were obtained after calcination at 900 °C. With the addition of 1 wt.% Co2O3 as a sintering aid, the YDC-BCY dual-phase HF membrane achieved densification after sintering at 1500 °C. Subsequently, the influences of sweep gas composition and temperature on the hydrogen permeation of the YDC-BCY HF membranes with YDC/BCY molar ratios of 2:1, 3:1, and 4:1 were investigated. At 1000 °C and a sweep-gas flow rate of 120 mL·min−1, the YDC-BCY HF membrane with a YDC/BCY molar ratio of 4:1 exhibited a peak hydrogen flux of 0.30 mL·min−1 cm−2. There is significant potential for improving the hydrogen permeation of dual-phase ceramic membranes, with future efforts aimed at reducing dense layer thickness and enhancing the membrane material’s electronic and proton conductivities.

Sintering aid was very crucial to influence the microstructure and thus the optical property of the sintered optical ceramics. The purpose of this work was to explain the difference between the sintering aids of Li+ and Y3+ on Al23O27N5 (AlON) ceramic via reaction sintering method. The effects of LiAl5O8 (LA) and Y2O3 on the sintering of Al2O3–AlN system were carefully compared, in terms of X-ray diffraction (XRD), microstructure, density, X-ray photoelectron spectroscopy (XPS) and optical transmittance. According to the XPS and XRD lattice analysis, the chemical structure of the materials was not obviously affected by different dopants. We firstly reported that, there was obvious volume expansion in the Y3+ dopped AlON ceramics, which was responsible for the low transparency of the ceramics. Obvious enhancements were achieved using Li+ aids from the results that Li: AlONs showing a higher transparency and less optical defects. A higher LA content (20 wt%) was effective to remove pores and thus obtain a higher transmittance (~86.8% at ~3.5 μm). Thus, pores were the main contributions to the property difference between the dopant samples. The importance of sintering aids should be carefully realized for the reaction sintering fabrication of AlON based ceramics towards high transparency. [ABSTRACT FROM AUTHOR]

Garnet-type Li7La3Zr2O12 (LLZO) is considered as a promising solid electrolyte. However, the synthesis of LLZO often requires a high temperature, which may lead to the evaporation of the lithium and result in a decrease in ionic conductivity. Therefore, it is an important issue how to reduce the synthesis temperature of LLZO and simultaneously increase its ionic conductivity. Herein, we synthesized garnet-type solid electrolytes of Li6.1Ga0.3La3Zr2O12 (LLZO-Ga) with x wt% CuO (x = 0, 0.2, 0.5, 1, 2) by the traditional solid-state reaction method, in which CuO was introduced as a sintering aid to reduce the sintering temperature of LLZO-Ga and increase its Li-ion conductivity. It is found that adding a small amount of CuO as an additive can reduce the sintering temperature from 1100 ℃ to about 1000 ℃. As a result, when the amount of CuO is 0.5 wt%, LLZO-Ga shows the highest room-temperature ionic conductivity and the lowest activation energy, which are 1.111 mS/cm and 0.27 eV, respectively. [ABSTRACT FROM AUTHOR]