Dry-pressing Method Research Articles

Effect of Starch Content on Morphology, Mechanical Properties, and Thermal Properties of Mullite-Based Porous Ceramic as a Candidate Filter in Aluminum Casting

Research on ceramic filters, needed in the aluminum casting industry because of their ability to filter inclusions, has been done. This study's primary material to make ceramic or local filters is kaolin. The manufacture of local filters in this study uses the dry press method. In this study, potato starch with a composition of 5%, 10%, and 15% acted as a pore-former in the local filter. The local filter burned to a temperature of about 1200°C to obtain the mullite phase. Local filter characterization used SEM, XRD, XRF, and DTA. Several tests were carried out in this study, including Permanent Linear Change (PLC) test, thermal expansion test, flexural strength test, and porosity test. The results obtained in this study show that pores on the local filter are not open, have a prolate shape, and have an average pore size of 10 to 55 m. Burning kaolin up to 1200°C proved successful in obtaining the mullite phase. Another result of this study, the more starch content added to the material, the greater the shrinkage and expansion of the material; the highest shrinkage value on the material is 0.17%, and the highest expansion value of the material is 0,29%, the 15% values owned by potato starch. It is different in the flexural strength value, which has the highest value with 0% potato starch at 14.14 MPa and the lowest value with 15% potato starch at 5.39 MPa.

Effect of Wood Sawdust Addition on the Morphology, Mechanical Properties, and Thermal Properties of Mullite-Based Porous Ceramic Filter Candidates for Aluminum Casting Process

Porous ceramic is a heat-resistant porous material with extensive applications, especially for filtering inclusions in aluminum casting industry. To meet local need for these filters, ceramic foam is fabricated by mixing raw materials including kaolin and chamotte as base material, wood sawdust (WSD) as pore-forming agent (PFA), and carboxymethyl cellulose (CMC) with water as binder. WSD content variable: 0%, 5%, 10%, and 15% was used for this research. The mixture was then formed with dry-press method and sintered at 1200°C to form mullite-based local filters. Characterization of samples morphology, composition, and phase were done using SEM-EDS, XRD, and XRF, while its mechanical and thermal properties were characterized by conducting STA, porosity, coefficient thermal expansion (CTE), permanent linear change (PLC), and flexural strength testing. Results showed an increase of WSD addition on the local filter increased the formation number of open-type pores in fiber form on the ceramic microstructure, no significant heat exchanges from decomposition were detected, increased CTE value from 0,0071 to 0,0371%, PLC from 0,0025 to 0,0345%, apparent porosity from 33,29 to 47,95%, and water infiltration from 18,27 to 33,05%, as well as decreased flexural strength from 13,48 to 6,33 MPa and density from 1.82 to 1.43 g/cm3.

High Areal Capacity and Sustainable High Energy in Ferroelectric Doped Holey Graphene/Sulfur Composite Cathode for Lithium-Sulfur Batteries

In this study, we are reporting the impact of the incorporation of ferroelectric nanoparticles (FNPs), such as BaTiO3 (BTO), BiFeO3 (BFO), Bi4NdTi3Fe0.7Ni0.3O15 (BNTFN), and Bi4NdTi3Fe0.5Co0.5O15 (BNTFC), as well as the mass loading of sulfur to fabricated solvent-free sulfur/holey graphene-carbon black/polyvinylidene fluoride (S/FNPs/CBhG/PVDF) composite electrodes to achieve high areal capacity for lithium-sulfur (Li-S) batteries. The dry-press method was adopted to fabricate composite cathodes. The hG, a conductive and lightweight scaffold derived from graphene, served as a matrix to host sulfur and FNPs for the fabrication of solvent-free composites. Raman spectra confirmed the dominant hG framework for all the composites, with strong D, G, and 2D bands. The surface morphology of the fabricated cathode system showed a homogeneous distribution of FNPs throughout the composites, confirmed by the EDAX spectra. The observed Li+ ion diffusion coefficient for the composite cathode started at 2.17 × 10−16 cm2/s (S25(CBhG)65PVDF10) and reached up to the highest value (4.15 × 10−15 cm2/s) for S25BNTFC5(CBhG)60PVDF10. The best discharge capacity values for the S25(CBhG)65PVDF10 and S25BNTFC5(CBhG)60PVDF10 composites started at 1123 mAh/gs and 1509 mAh/gs and dropped to 612 mAh/gs and 572 mAh/gs, respectively, after 100 cycles; similar behavior was exhibited by the other composites that were among the best. These are better values than those previously reported in the literature. The incorporation of ferroelectric nanoparticles in the cathodes of Li-S batteries reduced the rapid formation of polysulfides due to their internal electric fields. The areal capacity for the S25(CBhG)65PVDF10 composites was 4.84 mAh/cm2 with a mass loading of 4.31 mgs/cm2, while that for the S25BNTFC5(CBhG)60PVDF10 composites was 6.74 mAh/cm2 with a mass loading of 4.46 mgs/cm2. It was confirmed that effective FNP incorporation within the S cathode improves the cycling response and stability of cathodes, enabling the high performance of Li-S batteries.

One step co-sintering synthesis of gradient ceramic microfiltration membrane with mullite/alumina whisker bi-layer for high permeability oil-in-water emulsion treatment

Developing a permeation property and reducing the cost for ceramic microfiltration membrane are significant challenges and target. In this study, a gradient structure ceramic microfiltration membrane with mullite/alumina whisker bi-layer was successfully prepared using the dry-pressing method and one-step co-sintering process. In addition, the co-sintering conditions of substrate and whisker layer, the pore size regulations of whisker layer and emulsified oily wastewater filtration performance of the ceramic microfiltration membranes were systematically investigated. The gradient structure ceramic microfiltration membranes with high bonding strength and flexural strength were obtained under a co-sintering temperature of 1300 °C, and the average pore size of ceramic membrane was approximated in 120 nm, through the coordinated adjustment of the gradient layer by mullite whisker and alumina whisker. The filter performance results showed that with the synergistic effect of high porosity and low tortuosity of the whisker stacking membrane structure, the obtained ceramic membrane exhibited high permeability performance and oil rejection efficiency. The separation fluxes of oil-in-water emulsion with 500 and 1000 mg/L were 901 and 547 L/(m2·h·bar), respectively, and the oil rejection efficiency was higher than 99%. Even after 10 filtration cycles, the separation flux was still steady at 415 L/(m2·h·bar) for the separation process of oil-in-water emulsion with 1000 mg/L. In conclusion, the excellent pore structure of ceramic membrane with whisker layer endowed the separation flux for the oil-in-water emulsion, and the one-step co-sintering indicated a promising practical application for reducing the cost of ceramic microfiltration membranes.

Statistical Analysis of Copper Doped Titanium Dioxide

In this research, titanium dioxide and Al nanoparticles were purchased from a Chinese company, then the copper materials were added in three ratios that are (0, 1, 2, 3, and 5) wt.%. The use of dry press method through a hydraulic press from one direction, using a mold of diameter of 10 mm to obtain a ceramic compressed dimension that was firing at a temperature of 900 °C. The thermal conductivity is studied for all samples that include pure with the copper added proportions and compared between them when adding the proportions for copper the ratio of 2 wt.% is the highest conductivity among the used ratios. For the mechanical properties, which included the hardness when adding percentage from copper toTiO2 2 wt.% ratio showed is the highest hardness value between other ratios, the samples surface, taking surface pictures of the samples through an optical microscope.

Manufacture and Characterization of Porous Ceramics Based On Clay Soil And Banana Frond Powder

This work reports the manufacture and characterization of porous ceramics synthesized using clay and banana frond powder by employing the dry-pressing method. The clay and banana frond powder was filtered with a grain size of 200 mesh. Production of printed ceramics was made with the proportion of the combination of clay and banana frond powder of 100%:0%; 95%:5%; 90%:10%; 85%:15%; 80%:20%; 75%:25%; 70%:30%; 65%:35%; 60%:40%; 55%:45%; 50%:50% and heated with a sintering temperature of 1000°C with a holding time of 3 hours. The resulting ceramics are described by determining their actual properties (thickness, porosity, and shrinkage), mechanical properties (compressive strength and hardness), surface morphology and pore size (SEM), and base material (EDX). The results show that the mixed varieties of 50%:50% clay and banana frond powder have a density value of 1.22 g/cm3, a porosity of 41.31%, and heat loss of 11.41 %, compressive strength of 1.36 MPa, and hardness of 99.15 MPa. The surface morphology results showed that the sample has evenly distributed pore sizes of 10.54 m, 10.77 m, and 12.15 m, which is called a macroporous ceramic with a pore size of > 50 nm.

Statistical Analysis of Aluminum Doped Titanium Dioxide

In the present research, titanium dioxide and Al nanoparticles were purchased from a Chinese company, then the aluminum materials were added in five ratios that are (0, 1, 2, 3, 5) wt.%. The dry press method was used through a hydraulic press from one direction, using a mold of diameter 10 mm to obtain a ceramic compressed dimension that was firing at a temperature of 900 °C. The thermal conductivity is studied for all samples that include pure with the added proportions and compared between them when adding the proportions for aluminum. The ratio of 2 wt.% is the highest conductivity among the used ratios. The mechanical properties included the hardness when adding percentage from aluminum toTiO2 2 wt. % ratio showed is the highest hardness value between other ratios, the samples surface, taking surface pictures of the samples through an optical microscope.

Statistical Analysis of Aluminum Doped Titanium Dioxide Using Solid State Method

In the present research, titanium dioxide nanoparticles were fabricated using the solid-state technique, then all of the aluminum materials were added in three ratios that are (0, 1, 2, and 3 (wt. %). The dry press method was used through a hydraulic press from one direction, using a mold of diameter (10 mm) to obtain a ceramic compressed dimension that was firing at a temperature of 900 °C. The thermal conductivity is studied for all samples that include pure with the added proportions and compared between them when adding the proportions for aluminum. The ratio of (2% wt.) is the highest conductivity among the used ratios. The mechanical properties included the hardness when adding percentage from aluminum toTiO2 (2% wt.) ratio showed is the highest hardness value between other ratios, the samples surface, taking surface pictures of the samples through an optical microscope.

Fabrication and characterization of ceramic membranes derived from inexpensive raw material fuller's earth clay

The present work discusses the fabrication of novel porous ceramic membranes from inexpensive, abundant, and locally available fuller's earth clay. The raw material and fabricated membranes were comprehensively characterized and discussed their results rationally. The low-cost and flat-shaped membranes were fabricated by the uniaxial dry-pressing method followed by sintering at different temperatures (650–950 °C). The raw material was characterized by XRD, XRF, FESEM-EDX, FTIR, and TG-DTA. Also, the fabricated membranes were subjected to characterization using shrinkage, porosity, chemical stability, flexural strength, FE-SEM, permeate flux, permeability, and pore size. As a result, the average porosity of 39% with a pore size of 0.176 µm was determined for the membrane sintered at 850 °C, which was identified as the most appropriate membrane for microfiltration applications. The chosen sintering temperature 850 °C was relatively much lower than the temperature required for the preparation of commercial ceramic membranes. Furthermore, the membrane's hydraulic permeability was found to be 175 L/m2 h bar. In addition, it has shown excellent chemical resistance with an average weight loss of less than 2% in acidic and basic media. Finally, the manufacturing cost of the prepared ceramic membrane was estimated to be 100 $/m2, which is much lower than the cost of commercial ceramic membranes.

Facile and Scalable Fabrication of Conductive Ceramic Composite for Energy Conversion and Electromagnetic Interference Shielding

A conductive ceramic composite (CCC) based on carbonized phenolic resin is fabricated via a facile and scalable dry-pressing method. A conductive carbonaceous precursor solution is homogeneously mixed with a ceramic precursor. Subsequently, carbonization and ceramicization are achieved simultaneously in a single heating process. The carbonized materials endow the composites with excellent electrical conductivity and reliable cyclic heating properties. The temperature of the obtained composites is approximately 386 °C at 12 V after 10 min and 400 °C at 20 V after 48 s, and their energy consumption is low. Thermal images show that an even heat distribution is achieved on the composite surface, and that the electro-thermal performance can be adjusted by changing the electrical circuit arrangement (series or parallel circuits). In addition, the ceramic composites exhibit favorable electromagnetic interference (EMI) shielding performance of 26.2 dB at 8.2 GHz and improved photothermal conversion effect compared with the pristine ceramic. More importantly, this single-step heating provides a convenient and cost-effective approach for producing CCCs, thereby enabling the scalable production of conductive ceramics for electro-thermal applications. The excellent electrical performance facilitates the application of ceramic composites in Joule heating (e.g., deicing, boiling water, and cooking) and EMI shielding.

Direct ammonia low-temperature symmetrical solid oxide fuel cells with composite semiconductor electrolyte

In this work, a low-temperature symmetrical solid oxide fuel cell with Ni-NCAL|SDC/NCAL|Ni-NCAL (70 SDC:30 NCAL) configuration was successfully constructed by a simple dry press method. At 500 and 550 °C, the peak power densities of the cell in ammonia were 501 and 755 mW cm−2, and in hydrogen were 670 and 895 mW cm−2, respectively. EIS data showed that the Rp values of the cell in ammonia and hydrogen at 550 °C were 0.250 and 0.246 Ω cm−2, respectively, indicating the excellent catalytic activity of the Ni-NCAL electrode toward ammonia decomposition and hydrogen oxidation. The different cell output can be ascribed to additional ammonia decomposition steps compared to hydrogen. The noticeable reaction product on the surface of the Ni foam was detrimental to ammonia decomposition. In summary, a symmetrical cell with SDC/NCAL semiconductor electrolyte and Ni-NCAL electrodes exhibited higher electrochemical performance at low temperature than the results reported to date. Therefore, higher electrochemical performance can be expected from this cell configuration with more efficient ammonia decomposition catalysts.

Fabrication of Compositionally Gradient Anode Functional Layer for Proton Conducting Fuel Cell at Intermediate Temperatures: A Preliminary Study

In this work, an anode-supported button cell was fabricated with compositionally gradient (CG) NiO-BaCe0.54Zr0.36Y0.1O2.95 (NiO-BCZY) anode functional layer (AFL). The button cell has a configuration of NiO-BCZY (50:50) | NiO-BCZY (30:70) | NiO-BCZY (10:90) | BCZY | LSCF. All powder materials were synthesized using a sol-gel method. Firstly, NiO-BCZY anode substrate was fabricated using dry-pressing method. Next, NiO-BCZY CG-AFL and BCZY electrolyte thin film were spin-coated on the anode substrate and lastly the La0.6Sr0.4Co0.2Fe0.8O3-δ (LSCF) cathode was spin-coated on the electrolyte thin film. The microstructure of the fabricated button cell with good adhesion between all the layers, thin and dense electrolyte layer, and gradient increase in density of materials from anode substrate to electrolyte were observed using Scanning Electron Microscopy (SEM). Cell’s performance in terms of resistivity was evaluated using Electrochemical Impedance Spectroscopy (EIS) and conductivity meter using four-point probe method. Values of ohmic (Ro) and polarization resistance (Rp) of the cell are 7.3 and 2.4 Ωcm2 at 700 °C, respectively. The lower resistance values obtained compared to our previous work on a conventional 3-layers BCZY-based single button cell (Ro = 9.6 and Rp = 7.8 Ωcm2 at 700 °C) confirmed the functionality of GC-AFL in enhancing the cell’s performance. This preliminary result shows that simple deposition technique of CG-AFL plays a significant role in the optimization of PCFC button cell designs and electrochemical performance.

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 novel BaCe0.5Fe0.3Bi0.2O3–δ perovskite-type cathode for proton-conducting solid oxide fuel cells

A perovskite-type BaCe0.5Fe0.3Bi0.2O3-δ (BCFB) was employed as a novel cathode material for proton-conducting solid oxide fuel cells (SOFCs). The single cells with the structure of NiO-BaZr0.1Ce0.7Y0.2O3-δ (BZCY7) anode substrate|NiO-BZCY7 anode functional layer|BZCY7 electrolyte membrane|BCFB cathode layer were fabricated by a dry-pressing method and investigated from 550 to 700°C with humidified hydrogen (~3% H2O) as the fuel and the static air as the oxidant. The low interfacial polarization resistance of 0.098Ωcm2 and the maximum power density of 736mWcm−2 are achieved at 700°C. The excellent electrochemical performance indicates that BCFB may be a promising cathode material for proton-conducting SOFCs.

Highly compressible, binderless and ultrathick holey graphene-based electrode architectures

Graphene is a renowned material due to its unique structural characteristics and chemical properties. By heating graphene powder in an open-ended tube furnace, a highly compressible carbon material, holey graphene (hG), can be created with controlled porosity and be further decorated with nanosized catalysts using a solvent-free procedure to impart functionality and electrocatalytic activity. For the first time, we demonstrate an additive-free, dry press method to compression mold hG-based materials into ultrathick, binderless and high mass loading architectures using a hydraulic press at room temperature. The compressibility and structure of the hG allows for fabrication of unique ultrathick electrode architectures (mixed, sandwich, and double-decker) using both hG and catalyst/hG nanohybrid materials. These high mass loading, mixed and stacked hG electrode architectures are the first of their kind and are successfully demonstrated as lithium-oxygen (Li-O2) cathodes. The scalable, binderless, and solventless dry press method and novel additive-free electrode architectures presented here greatly advance both electrode fabrication options, and open up new electrode designs for potential energy storage advancements.

Proton-conducting solid oxide fuel cells with yttrium-doped barium zirconate electrolyte films sintered at reduced temperatures

Barium zirconate-based high-temperature proton conductors have not been widely used as electrolytes for solid oxide fuel cells (SOFCs) due to the poor sintering activity and the difficulty in preparing dense and highly conductive electrolyte films. In this work, thin BaZr0.8Y0.2O3-δ (BZY) proton-conducting electrolyte films were prepared by a conventional dry-pressing method followed by sintering in flowing oxygen. BZY films got fully dense after sintered at a low temperature of 1350 °C for 5 h. Single cells with BZY electrolyte films prepared at various temperatures were assembled and tested. The influence of sintering temperature on the morphology of BZY films and electrochemical performances of single cells was investigated. Besides, the open circuit voltages of the single cells as well as those previously reported BZY-based SOFCs were also discussed.

Chemically stable and easily sintered high-temperature proton conductor BaZr0.8In0.2O3−δ for solid oxide fuel cells

Barium zirconate-based high-temperature proton conductors (HTPCs) exhibit excellent chemical stability in atmospheres containing CO2 or water vapor. However, such HPTCs haven't been widely used as electrolyte materials for solid oxide fuel cells (SOFCs) due to their poor sintering activity. In this work, indium is selected as a dopant to improve the sintering activity of barium zirconate. BaZr0.8In0.2O3−δ (BZI) powders with a pure cubic perovskite structure are synthesized via a typical citric acid–nitrate gel combustion process. The SEM results show that BZI exhibits improved sintering activity compared to the state-of-the-art proton conductor BaZr0.8Y0.2O3−δ (BZY), and fully dense BZI pellets with increased grain size are obtained after sintered at 1600 °C in air. Moreover, BZI also keeps sufficiently high chemical stability as BZY. The electrical conductivity of BZI under various atmospheres is investigated by electrochemical impedance spectroscopy (EIS) in detail. The total conductivity achieves 1.0 × 10−3 S cm−1 at 700 °C in wet H2 (3% H2O). Dense BZI electrolyte films are successfully fabricated on the anode substrates by a dry-pressing method after sintered at 1400 °C for 5 h in air. Single cells with dense BZI electrolyte films are also assembled and tested to further evaluate the feasibility of BZI as an electrolyte material for proton-conducting SOFCs.

The Effect of Sintering Temperature on the Physical Properties and Bending Strength of Zirconia Toughened Ceramic

This research investigated the effect of sintering temperature on the physical properties and bending strength of zirconia toughened ceramic (ZTC). 3mol% yttria-stabilized zirconia compacts were prepared by dry press method and then sintered with different final sintering temperature: 1490°C, 1530°C, 1570°C and 1610°C respectively. The physical properties and three-point bending strength were measured. The results of the test indicated that the density and shrinkage of ZTC increased along with the rise of sintering temperature, while the surface porosity of the samples decreased. The curve of flexural strength is indicated the variolation tendency of falling after rising, being the maximum at 1570°C. The results of this experiment showed that the best sintering temperature of yttria-stabilized zirconia was showed at 1570°C in terms of physical properties and bending strength among the selected temperature range.

Oxygen permeation study and improvement of Ba 0.5Sr 0.5Co 0.8Fe 0.2O x perovskite ceramic membranes

Ba 0.5Sr 0.5Co 0.8Fe 0.2O x (BSCF) is a promising mixed conducting material with high oxygen permeability, and has proven to be a good candidate for membrane reactors in air separation and catalytic conversion of CH 4. To determine the factors impacting the oxygen permeation through the BSCF membrane, Pt, Ag catalysts were coated on the membrane surface using photolithography and electron beam evaporation methods. The results showed that the coated catalysts did not increase the oxygen flux of BSCF within the studied thickness range. However, the oxygen flux increased as the thickness of the membrane decreased. To further enhance the oxygen flux, a BSCF membrane with asymmetric geometry was prepared using a dry-pressing method. The effects of the porous substrate and the dense thin layer on the performance of the BSCF asymmetric membrane were studied. The results showed that the oxygen flux increased as the thickness of thin dense layer decreased. Further analysis indicated that the porous substrate still appears to exert a resistance on the oxygen permeation through the membrane.

A symmetrical solid oxide fuel cell prepared by dry-pressing and impregnating methods

In this study, a simple and cost-effective dry-pressing method has been used to fabricate a symmetrical solid oxide fuel cell (SOFC) where the dense yttria-stabilized zirconia (YSZ) electrolyte film is sandwiched between two symmetrical porous YSZ layers in which La 0.75Sr 0.25Cr 0.5Mn 0.5O 3− δ (LSCM) based anode and cathode are incorporated using wet impregnation techniques. The maximum power densities ( P max) of a single cell with 32 wt.% LSCM impregnated YSZ anode and cathode reach 333 and 265 mW cm −2 at 900 °C in dry H 2 and CH 4, respectively. The cell performance is further improved with additional impregnation of a small amount of Sm-doped CeO 2 (SDC) or Ni. When 6 wt.% Ni as catalyst is added to both the anode and cathode, P max values of 559 and 547 mW cm −2 can be achieved, which are better than with SDC. The effect of Ni on the cathode performance is also investigated by impedance spectra analysis.