Phase Inversion Tape Casting Method Research Articles

Superior Heat and Mass Transfer Performance of Bionic Wick with Finger-like Pores Inspired by the Stomatal Array of Natural Leaf.

The thermal management of electronics has gained significant attention, with loop heat pipes (LHPs) emerging as an attractive solution for heat dissipation. The heat transfer performance of LHPs is influenced by the heat and mass transfer processes within the wick. However, designing the pore diameter of the wick is challenging due to the different requirements of flow resistance and capillary force. Specifically, the working fluid needs large pores to reduce resistance, while the liquid suction requires small pores to provide a large capillary force. To address this issue, we drew inspiration from the stomatal array of natural leaves used for transpiration and developed an alumina ceramic bionic wick with finger-like pores using the phase-inversion tape casting method. The finger-like pores in the wick resemble the straight hole structure of stomata, which increases the gas-liquid interface area within the wick. This design allows for timely discharge of water vapor generated by boiling, thereby reducing mass transfer resistance. Additionally, numerous micrometer-sized small pores surrounding the finger-like pores provide sufficient capillary force to replenish liquid for the gas-liquid evaporation interface. Experimental results demonstrate that the introduction of finger-like pores in the wick increases gas and water permeabilities by 2.4 and 5.2 times, respectively. Furthermore, the superior heat and mass transfer performance of the bionic wick was demonstrated with an LHP. This work effectively addresses the conflicting demands of capillary force and flow resistance, enhancing the heat transfer performance of LHPs, which holds great promise for addressing heat dissipation challenges in high power density electronic chips and has potential applications in aviation, aerospace, and microelectronics for efficient thermal management.

Engineering the wetting behavior of ceramic membrane by carbon nanotubes via a chemical vapor deposition technique

Hydrophobic membrane is widely applied for various applications due to its water repellent and self-cleaning properties. In this work, novel alumina/carbon nanotubes (Al2O3/CNTs) composite hydrophobic membranes are prepared in two steps: first, the membranes are fabricated via the phase inversion tape casting method, and then post-treated in a chemical vapor deposition (CVD) process to include CNTs into their structure. The addition of CNTs allows for controlling the contact angle of the membrane from 0 to 136°, creating highly hydrophobic. Moreover, a nitrogen permeability of 0.74±0.01 × 106 L m−2 h−1 bar−1 is achieved of the composite membrane, while its pure water flux is effectively decreased to 0, further indicating the good hydrophobicity. In addition, the hydrophobicity of the membrane can be maintained in the temperature range of 25–200 °C. It is demonstrated that the Al2O3/CNTs composite membrane is a promising hydrophobic membrane candidate for membrane separation application because of its good hydrophobicity, high thermal stability and considerable gas permeability, moreover, the wetting properties of ceramic membrane can be effectively engineered by adding CNTs into the membrane skeleton via the CVD technique.

Effect of MgO on the microstructure and properties of mullite membranes made by phase-inversion tape casting

ABSTRACT Flat microfiltration mullite (3Al2O32SiO2) membranes were prepared via phase-inversion tape casting method. The sintering temperature has been reduced from 1700°C to 1450°C by adding 3 wt.% of magnesium oxide (MgO) as a sintering aid. The effect of this compound on the membrane properties was systematically investigated. The presence of MgO promoted at the same time a change in membrane morphology resulting in a symmetric structure, which is opposite to the asymmetrical structure obtained for mullite membranes prepared without this sintering aid. Porosity of 38.9% and average pore size of 2.33 μm was achieved. Water and n-heptane vapor adsorption analysis showed an increment in hydrophilic behavior due to MgO. The reduction of sintering temperature from 1700°C (MgO free) to 1450°C (MgO added) produced mechanical stable samples with flexural strength about 15.3 MPa. The membrane was resistant enough to withstand the water flux permeation test up to 3 bar. Compared to the pure mullite membranes, the MgO containing sample displayed higher water permeation fluxes, which might be related to both the larger superficial pore size and its hydrophilicity.

Asymmetric porous cordierite ceramic membranes prepared by phase inversion tape casting and their desalination performance

Asymmetric porous cordierite ceramic membranes were fabricated by phase inversion tape casting method. It is shown that the membranes consist of a relatively dense skin layer on the top, a sponge layer at the bottom and a finger-like layer in the middle. The membranes have a hierarchical pore structure, where macrovoids (denoted as dozens-micron-sized (DMS) pores) are present in the finger-like layer and micron-sized (MS) pores are located in the skin layer, sponge layer and the wall of macrovoids. After surface silylation by post-grafting with 1H,1H,2H,2H-perfluorodecyltriethoxysilane (FAS), the sample with a starting powder/polyethersulfone (PESf) weight ratio of 9 (M − 4) becomes hydrophobic, with a water contact angle of 150°. At a NaCl concentration of 3.5 wt%, a feed rate of 18L/h and a feed temperature of 80 °C, the hydrophobic M − 4 membrane exhibits a water permeate flux of 22.33 kg/m2h, which is considerably larger than that of the membranes prepared by dry pressing method previously, and a salt rejection of 99.9%. The higher water permeate flux is attributed to the much lower transport resistance of water vapor in the membranes of the present work.

Direct electrolysis of CO2 in solid oxide cells supported on ceramic fuel electrodes with straight open pores and coated catalysts

This study was to investigate direct electrolysis of CO2via solid oxide cells with thin Y0.16Zr0.84O1.92 (YSZ) electrolytes and (La0.8Sr0.2)0.95MnO3−δ (LSM)-YSZ air electrodes supported on La0.8Sr0.2Cr0.5Fe0.5O3−δ (LSCrF)-YSZ fuel electrodes. The fuel electrode with straight open pores was prepared using the phase-inversion tape casting method, modified with nano-scaled Sr2Fe1.5Mo0.5O6−δ (SFM) catalysts using the impregnation method. Substantially larger maximum power densities were observed in the fuel cell mode for single cells with the SFM catalysts than without, e.g., 423 vs. 51 mW·cm−2 at 800 °C. Impedance analysis showed an order magnitude drop in the pure ohmic resistances and the interfacial polarization resistances in the presence of electronically conductive and catalytically active SFM nanoparticulates. Electrolysis measurements indicated that these nano-scaled SFM catalysts also helped to promote CO2 reduction reactions. The electrolysis current densities at 1.5 V were 0.48, 0.64 and 1.02 A·cm−2 for the SFM-infiltrated cells at 700, 750, 800 °C, respectively. In contrast, the blank cells displayed much smaller current densities of 0.22, 0.35 and 0.41 A·cm−2 under the similar conditions. Apparently, the modification of the LSCrF-YSZ electrode with SFM nanoparticulates provided extended electrochemically active sites with sufficient interconnected paths to transfer electrons and oxygen ions, which led to a significant increase in the electrochemical performance. The reduced polarization resistance and high current density show that the nano-scaled SFM-modified LSCrF-YSZ fuel electrode is highly effective for pure CO2 electrolysis without using the safe gas.

The effect of anode structure on the performance of NiO-BaZr0.1Ce0.7Y0.2O3-δ supported ceria-based solid oxide fuel cells

In this work, two asymmetric NiO-BaZr0.1Ce0.7Y0.2O3-δ (NiO-BZCY) anode substrates were prepared via the phase-inversion tape casting method for Ce0.8Sm0.2O2-δ (SDC)-based solid oxide fuel cells. The results showed that the anode support structure significantly influenced the electrochemical properties of the cells. The cell supported on the anode substrate consisted of a finger-like layer and a sponge-like layer outputs highest electrochemical performance with a maximum power density of 823 mW cm−2 at 650 °C and shows great superiority over the cell fabricated by a typical dry-pressing method. The excellent performances demonstrate that the phase-inversion tape casting technique is a good strategy in fabricating anode supports for SOFCs, and the anode structure with the relatively dense sponge-like layer as top surface is optimal to construct the complete cell.

A 3D Cu current collector with a biporous structure derived by a phase inversion tape casting method for stable Li metal anodes

A 3D biporous and bicontinuous Cu current collector derived by a phase inversion method stabilizes high-loading Li metal anodes.

Preparation of high-efficiency ceramic planar membrane and its application for water desalination

Highly efficient Si3N4 ceramic planar membrane for water desalination process using membrane distillation was prepared by the dual-layer phase inversion tape casting and sintering method. In comparison with typical phase inversion tape casting method, the green tape was formed using Si3N4 slurry on the top and graphite slurry on the bottom. After consuming away the graphite structure, a ceramic membrane consisting of a two-layered structure (skin and finger-like layers) was obtained. The skin layer was relatively tight, and thus could act as a functional layer for separation, while the finger-like layer contained straight open pores with a diameter of 100 μm, acting as a support with low transport resistance. For comparison, typical Si3N4 ceramic membrane was fabricated by phase inversion technique without graphite substrate, resulting in a three-layered structure (skin, finger-like, and sponge layers). After membrane modification from hydrophilic to hydrophobic with polymer derived nanoparticle method, the water desalination performance of the membranes was tested using the sweeping gas membrane distillation (SGMD) with different NaCl feed solutions. With the increase of salt content from 4 to 12 wt%, the water flux decreased slightly while rejection rate maintained over 99.99%. Comparing with typical three-layered Si3N4 membrane, an excellent water flux enhancement of over 83% was resulted and the rejection rate remained over 99.99%.

Symmetrical solid oxide fuel cells fabricated by phase inversion tape casting with impregnated SrFe0.75Mo0.25O3-δ (SFMO) electrodes

The new phase inversion tape casting method is explored to fabricate the “porous|dense|porous” La0.9Sr0.1Ga0.8Mg0.2O3 (LSGM) with aligned straight pores. Symmetrical fuel cells are obtained by impregnating nano-scale SrFe0.75Mo0.25O3-δ (SFMO) catalysts into both porous LSGM scaffolds. Operation on hydrogen and air oxidants produces 401, 521, 602 and 703 mW cm−2 at 650, 700, 750 and 800 °C, respectively. Impedance measurements show that the overall interfacial polarization resistances are 0.17, 0.20, 0.25 and 0.36 Ω cm2 for such symmetrical fuel cells at 800, 750, 700 and 650 °C, respectively. Impedance analysis under varied oxygen partial pressures indicates that the symmetrical SFMO-LSGM electrodes exhibit lower polarization resistances for phase-inversion casted LSGM scaffolds than for the traditionally casted LSGM scaffolds.

Asymmetric La0.6Sr0.4Co0.2Fe0.8O3-δ membrane with reduced concentration polarization prepared by phase-inversion tape casting and warm pressing

A three-layered La0.6Sr0.4Co0.2Fe0.8O3-δ membrane was prepared via a modified phase-inversion tape casting method combined with warm pressing and screen-printing. The membrane comprised a thick porous support with straight and large open finger-like pores, a dense separation layer with reduced thickness of 40µm, and a thin catalytic layer. Oxygen permeation performance was studied under various conditions, and compared with that for a similar membrane, the support of which was fabricated by conventional tape casting and associated with a distinctly different pore structure. Under an air/He gradient, an oxygen flux as high as 1.54ml (STP) cm−2 min−1 was achieved at 900°C for the former membrane, about 2.5 times higher than that for the latter. When pure oxygen was used instead of air as the feed gas, their oxygen permeation fluxes were only slightly differed. The obtained results clearly indicated serious presence of concentration polarization in air feed gas in the membrane made by conventional tape casting, which was markedly reduced in the phase-inversion derived membrane. The significantly improved oxygen permeation performance of the latter membrane could be ascribed to its unique pore structure, which allowed fast gas transport through the porous support.

Improving the water splitting performance of nickel electrodes by optimizing their pore structure using a phase inversion method

Porous nickel electrodes were fabricated by the phase inversion tape casting method for OER and HER, which showed a cell voltage of 1.65 V to reach 10 mA cm−2 for overall water splitting.

Phase inversion tape casting and oxygen permeation properties of supported planar Zr0.84Y0.16O1.92–La0.8Sr0.2Cr0.5Fe0.5O3 − δ composite membrane

The Zr0.84Y0.16O1.92 (YSZ)–La0.8Sr0.2Cr0.5Fe0.5O3−δ (LSCrF) composite membrane was prepared using the phase inversion tape casting method. Two slurries, one composed of YSZ and LSCrF powder, and the other composed also graphite, were used for preparation of the membrane. They were co-tape cast onto a Mylar sheet, and then immersed in a water bath for solidification into a green tape through phase inversion mechanism. After sintering at 1450°C in the air, the green tape was converted into a ceramic membrane. The sintered membrane possessed an asymmetric structure: a dense layer of thickness ~30μm and a finger-like porous support of thickness ~1mm. The membrane was further modified by applying a porous YSZ–LSCrF layer on its surfaces at the dense layer side and depositing Sm0.2Ce0.8O2 nano-particles on the inner surfaces of the support. The oxygen permeability of the as-prepared membrane was measured by exposing its dense layer side to air and the support side to CO at elevated temperatures. The membrane exhibited desired oxygen permeability under the given measurement conditions. An oxygen permeation flux as large as 2.4ml·cm−2·min−1 (STP) was observed at 900°C, which is comparable to the hollow fiber membrane of the same composition. Owing to its desired oxygen permeability and good stability, the supported planar YSZ–LSCrF membrane developed in the present study holds promise for applications in chemical reactors integrating oxygen separation and oxygen-consuming chemical reactions such as partial oxidation of methane (POM). The phase inversion tape casting method explored in the present study can be applied to the preparation of other ceramic membranes.

Preparation and characterization of supported planar Zr0.84Y0.16O1.92–La0.8Sr0.2Cr0.5Fe0.5O3−δ composite membrane

The Zr0.84Y0.16O1.92 (YSZ)−La0.8Sr0.2Cr0.5Fe0.5O3−δ (LSCrF) supported membrane was formed by a new variant of phase inversion tape casting method. A slurry composed of YSZ and LSCrF was co-tape cast with a slurry of graphite, and solidified into a green tape by immersion in the water bath. The as-formed green tape comprised a relatively dense layer at the top derived from the graphite slurry, a finger-like porous layer in the middle and a sponge-like layer at the bottom both derived from the YSZ–LSCrF slurry. After firing at 1420°C in the air, the graphite layer was eliminated, and the other two layers were converted into ceramics. The resulting membrane consisted of a dense layer of thickness ~150μm providing the oxygen separation function and a finger-like porous layer of thickness ~850μm providing mechanical strength. Due to the use of graphite sacrificing layer, the finger-like pores in the support was fully opened up to the outer surface, allowing fast mass transport. The oxygen permeability of the membrane was measured by exposing its dense separation layer to the ambient air and the porous support to flowing CO at elevated temperatures. An oxygen permeation flux as large as 6.82×10−7molcm−2s−1, equivalent to 1.0ml (STP) cm−2min−1, was obtained at 850°C. And no significant changes to the microstructure and phase composition of the membrane were observed after the oxygen permeation test. The reasonably high oxygen permeability together with the satisfactory stability makes the supported planar YSZ–LSCrF composite suitable for practical applications.

Steam electrolysis in a solid oxide electrolysis cell fabricated by the phase-inversion tape casting method

In this study, an asymmetric NiO–yttria-stabilized zirconia (YSZ) cathode substrate has been successfully fabricated by the phase-inversion tape casting method. 3-dimensional X-ray microscopy and subsequent analysis demonstrate that the NiO–YSZ substrates exhibit dual-layer structure: a thin sponge-like pore layer is supported on a thick finger-like macro-void layer. The electrochemical performance of the Ni–YSZ/YSZ/YSZ–LSM electrolyzer with this novel dual-layer cathode has been significantly enhanced. The electrolyzer exhibits an excellent current density of 2.3Acm−2 and a high H2 production rate of 958mLcm−2h−1 at 800°C and 1.5V, and a polarization resistance of 0.25Ωcm2 at the open circuit voltage when the cathode and anode are exposed to 33vol.% H2O–67vol.% H2 and ambient air, respectively, demonstrating that the thin sponge-like pore layer in the dual-layer cathode can provide sufficient electrochemical reaction sites for H2O reduction, while the thick finger-like macro-void layer can serve as the support for the electrolyzer and facilitate H2/H2O transport in the cathode, reducing the cathode polarization resistance and enhancing the cell performance.

Facile one-step forming of NiO and yttrium-stabilized zirconia composite anodes with straight open pores for planar solid oxide fuel cell using phase-inversion tape casting method

The anode of NiO and yttria-stabilized zirconia (YSZ) with straight open pores is prepared by phase-inversion tape casting method. In the as-prepared green tape, its top and middle layers are derived from a slurry of NiO and YSZ, while the bottom layer from a slurry of graphite. The graphite layer is eliminated by calcination at elevated temperatures, leaving the finger-like porous layer exposed to the gas phase. A cell supported on the as-prepared anode substrate exhibits satisfactory electrochemical performances with a maximum power density of 780 mW cm−2 at 800 °C. The cell dose not show a convex-up curvature in I–V plots at high current density as often observed for most anode-supported cells, indicating the absence of concentration polarization which is in turn attributed to the open pore structure of the phase-inversion derived anode. The phase inversion tape casting technique explored in the present study involves almost the same equipments as and similar procedures to the conventional tape casting, and after further optimization it may become a simple and effective technique for mass production of anodes for SOFCs.

Preparation and characterization of hydrophobic alumina planar membranes for water desalination

A planar alumina membrane was prepared by a one-step phase-inversion tape casting method. The membrane consisted of a thick support layer with finger-like large pores and a thin separation layer containing small pores with an average diameter of ∼0.76 μm. The overall porosity of the membrane was ∼59%, as determined with the Archimedes method, and the porosity associated with the large, finger-like pores in the support layer was ∼34% as derived from image analysis. The surface of this alumina membrane was converted from hydrophilic to hydrophobic via grafting with a fluoroalkylsilane. The water desalination performance was tested by exposing the hydrophobic separation layer to an aqueous solution of 2 wt.% NaCl at 80 °C, while a sweep of distilled water at 20 °C was used, resulting in a water flux of 19.1 L m−2 h−1 and a salt rejection over 99.5%. Due to the excellent water desalination performance, the hydrophobic porous ceramic membrane holds promise for practical applications.

Phase-inversion tape-casting preparation and significant performance enhancement of Ce0.9Gd0.1O1.95–La0.6Sr0.4Co0.2Fe0.8O3−δ dual-phase asymmetric membrane for oxygen separation

The dual-phase Ce0.9Gd0.1O1.95–La0.6Sr0.4Co0.2Fe0.8O3−δ asymmetric membrane was prepared via a phase-inversion tape-casting method. The membrane consisted of a thicker porous support layer and a thinner dense layer. When the dense side of the membrane was coated with a La0.6Sr0.4CoO3−δ catalytic activation layer, the oxygen permeation flux was markedly increased by a factor of 4.1–5.6, reaching 0.45mLcm−2min−1 at 900°C. The flux increase can be attributed to enhanced surface oxygen exhange kinetics.