Porous Ceramic Pellets Research Articles

Electronically conductive metal oxide incorporation in electrode to enable high energy density all active material electrodes

Lithium-ion batteries are ubiquitous in our modern society, and research continues to further improve their energy and power density. Thicker electrodes lead to energy density improvements at the cell level due to relative reductions in inactive component volume, but conventional composite electrodes have mechanical challenges in achieving high electrode thicknesses. All active material (AAM) electrodes achieve high thicknesses via processing active material via compression and mild thermal treatment to produce porous ceramic pellets. In AAM electrodes, matrix electronic conductivity must proceed through the electroactive material itself, thus low electronic conductivity materials have limited rate capability. In this work, a high energy density but low electronic conductivity material, LiNi0.80Co0.15Al0.05O2 (NCA), was evaluated in AAM electrodes. To enable improved utilization and rate capability of NCA, this report will describe coating of high electronic conductivity LiCoO2 within the NCA electrode. Rate capabilities and stability were drastically improved with 5 wt% LiCoO2 incorporation. The AAM cathode had high areal capacity of 26 mAh cm−2 and areal energy of 56 mWh cm−2, and delivered 5.5 mAh cm−2 at areal current of 6.0 mA cm−2.

W-doped Lanthanum Molybdenum Oxide/Lithium-Sodium-Potassium Carbonate Composite Membranes for Carbon Dioxide Permeation.

Single-phase tungsten-doped lanthanum molybdenum oxide (La2MoWO9) ceramic powders were synthesized using the complex polymerization technique. Porous ceramic pellets were obtained by thermally removing graphite, which served as a pore former. The porous pellets were then impregnated with molten eutectic lithium-sodium-potassium carbonates. The energy dispersive X-ray analysis and scanning electron microscopy (FEG-SEM) images of the external and fracture surfaces of the La2MoWO9-(Li,Na,K)2CO3 composite dual-phase membrane revealed the percolation of the carbonate mixture through the pores. Electrochemical impedance spectroscopy measurements conducted at temperatures below and above the melting point of the eutectic carbonate composition demonstrated the contributions of oxygen and carbonate ions to the ionic conductivity of the dual membrane. The electrical conductivity of the carbonate ions within the membrane was continuously monitored for over 1300 h with negligible degradation, implying that the membrane could be used for long-term monitoring of CO2 without aging effects. A comparison of FEG-SEM images taken before and after this endurance test suggested minimal fouling, indicating that the membrane could potentially replace similar zirconia- and ceria-based composite membranes.

Development of Mesoporous Geo-Adsorbent Pellets from Low Fire Clay and Cellulose for Removal of Methylene Blue in Aquaculture

Porous ceramic pellets have been prepared using low fire clay and cellulose as a pore forming agent. The pore size and BET analysis, water absorption capacity and compressive strength of the pellets have been determined. The methylene blue uptake of pellets increased on increasing the percentage of initial cellulose content. Batch mode studies showed that the methylene blue adsorption decreased with increasing dose of pellets, increased with increasing initial dye concentration, while solution pH and presence of co-ions had negligible effect on removal of methylene blue, making them suitable for dye removal over a wide range of pH. The adsorption process followed both the Freundlich and Langmuir adsorption isotherms, whereas the adsorption kinetics followed the pseudo-second-order kinetic model. An inexpensive and simple device consisting of the mesoporous pellets enclosed in a tea ball wire mesh, which can be conveniently dipped and taken out of water in an aquarium and can remove methylene blue, has been developed.

Corrosion resistance and thermal-mechanical properties of ceramic pellets to molten calcium-magnesium-alumina-silicate (CMAS)

Because gas turbine engines must operate under increasingly harsh conditions, the degradation of thermal barrier coatings (TBCs) by calcium-magnesium-alumina-silicate (CMAS) is becoming an urgent issue. Mullite (3Al 2 O 3 ·2SiO 2 ) is considered a potential material for CMAS resistance; however, the performance of mullite in the presence of CMAS is still unclear. In this study, mullite and Al 2 O 3 –SiO 2 were premixed with yttria stabilized zirconia (YSZ) in different proportions, respectively. Porous ceramic pellets were used to conduct CMAS hot corrosion tests, and the penetration of molten CMAS and its mechanism were investigated. The thermal and mechanical properties of the samples were also characterized. It was found that the introduction of mullite and Al 2 O 3 –SiO 2 mitigated the penetration of molten CMAS into the pellets owing to the formation of anorthite, especially at 45 wt% mullite/55 wt% YSZ. Compared with Al 2 O 3 –SiO 2 , mullite possesses a higher chemical activity and undergoes a faster reaction with CMAS, thus forming a sealing layer in a short time. Additionally, the thermal expansion coefficient, thermal conductivity, and fracture toughness of different samples were considered to guide the architectural design. Considering the CMAS corrosion resistance, thermal and mechanical performance of TBCs systematically, a TBC system with a multilayer architecture is proposed to provide a theoretical and practical basis for the design and optimization of the TBC microstructure.

The synthesis, characterisation and in vivo study of a bioceramic for potential tissue regeneration applications.

Hydroxyapatite (HAP) is a biocompatible ceramic that is currently used in a number of current biomedical applications. Recently, nanometre scale forms of HAP have attracted considerable interest due to their close similarity to the inorganic mineral component of the bone matrix found in humans. In this study ultrafine nanometre scale HAP powders were prepared via a wet precipitation method under the influence of ultrasonic irradiation. The resulting powders were compacted and sintered to form a series of ceramic pellets with a sponge-like structure with varying density and porosity. The crystalline structure, size and morphology of the powders and the porous ceramic pellets were investigated using advanced characterization techniques. The pellets demonstrated good biocompatibility, including mixed cell colonisation and matrix deposition, in vivo following surgical implantation into sheep M. latissimus dorsi.

Influence of thermal treatment and combustible additives on properties of Latvian clay ceramics pellets

Porous ceramic pellets for possible environmental application were produced from different Latvian clays by sintering at different temperatures. Their characteristics and influence of additives were analysed using X-ray diffraction, mercury porosimetry and BET tests. The obtained ceramic pellets from calcareous clays after immersion in distilled water change its pH value, which affects their capability to adsorb ions or molecules on the surface. The sorption capabilities are dependent on the pH level of water solution, composition of clays, and used adsorbate. Porosity of the produced pellets is mostly within range from 15 to 25 % throughout all sintering temperatures with a slight decrease at 1050 ?C. The specific surface area has a wide range up to 30 m2/g. The highest surface area has pellets sintered at lower temperatures. The adsorption capability of pellets was evaluated using water solutions with different ions. The most promising results were obtained with iodine sorption. For most pellets the sorption capacity was 12.7 mg/g, although for the pellets sintered at 1050 ?C it was lower.

Composition effects of thermal barrier coating ceramics on their interaction with molten Ca–Mg–Al–silicate (CMAS) glass

Systematic studies have been performed to investigate the composition effects of ZrO2-based thermal barrier coating (TBC) ceramics on their interactions with molten Ca–Mg–Al–silicate (CMAS) glass. Porous ceramic pellets (∼15% porosity), instead of actual TBCs, are used in these model studies, where the penetration of molten CMAS into the pellets is investigated. This study involves a total of six compositions of ZrO2-based ceramics: two containing low solute (Y3+ or Gd3+) concentration, three with high concentration of solute (Y3+, Gd3+ or Yb3+), and one containing a combined intermediate concentration of Y3++Al3++Ti4+ solutes. While both the type of the solute and its concentration in the ZrO2-based TBC ceramics have been found to influence the extent of molten CMAS penetration into the pellets, the solute concentration has the most dramatic effect. In particular, molten CMAS penetration is almost completely suppressed in porous TBC ceramic pellets containing a high concentration of Y3+ solute (Y2Zr2O7). Possible mechanisms governing these effects are presented, together with a discussion of guidelines for the chemical design of CMAS-resistant zirconate TBC ceramics. Generally, for a TBC ceramic to be highly effective against CMAS attack it must interact vigorously with the molten CMAS, which must result in the rapid crystallization of the refractory oxide phase(s) that form a sealing layer, arresting further penetration of the molten CMAS. The porous ceramic pellets approach used here could be developed into rapid-screening methodologies for the discovery of CMAS-resistant TBC ceramic compositions, and to study the effect of composition of CMAS glasses on their interactions with TBC ceramics of specific compositions.

Microstructure evolution of nanostructured and submicrometric porous refractory ceramics induced by a continuous high-energy proton beam

The production of radioactive ion beams by the isotope mass separation online (ISOL) method requires a fast diffusion and effusion of nuclear products from thick refractory target materials under high-energy particle beam irradiation. A new generation of ISOL nanostructured and submicrometric porous materials have been developed, exhibiting enhanced release of exotic isotopes, compared to previously used conventional micrometric materials. A programme was developed at PSI within the framework sof the Design Study of EURISOL, the next generation European ISOL-type facility to study aging under irradiation on porous ceramic pellets and dense thin metal foils at high temperatures. Ceramic oxides and carbide samples underwent proton damage with fluence up to 3.0 × 10 20 and 1.3 × 10 21 cm −2 respectively. The post-irradiation examination on Al 2O 3, Y 2O 3 and SiC – C nanotube composite matrices show a proton-induced densification region in which a moderate grain growth occurred. The microstructural evolution effects were associated to the combination of radiation-enhanced diffusion and thermal diffusion. The irradiated Al 2O 3 shows higher sintering rates than in similar non-irradiation isothermal conditions, in particular at the lowest irradiation temperature, subjected to a proton fluence inferior to 1.1 × 10 15 cm −2. The apparent activation energy for its sintering controlling mechanism was found to be between 44 and 88 kJ mol −1. However, despite the enhanced sintering, shrinkage and increased grain growth, the selected nanostructured and submicrometric TARPIPE materials did not display an average grain diameter above 2 μm, which confirms that these materials are suited as production targets for present and next generation ISOL facilities.

Antibacterial properties of TiO2 ceramic pellets prepared using nano TiO2 powder

Titanium dioxide (TiO2) porous ceramic pellets with three dimension nano-structure were prepared using nano TiO2 powder. The TiO2 porous ceramic pellets were composed of TiO2 nanoparticles with 14–16 nm in diameter and had porosity of 74.85%. The mean pore size of the TiO2 porous ceramic pellets was 20.73 nm and the main pore size ranged from 3 to 16 nm. The mass loss of the TiO2 ceramic pellets was less than 5% after 20 d immersion in water. The antibacterial properties of the TiO2 pellets were studied. The sterilization rate of Colibacillus (hospital polluted water with bacterium) can reach 99% after 3 h photocatalytic process and these TiO2 pellets are easy to be re-activated and cyclically be used. The shaping mechanism and photocatalysis sterilization mechanism of the TiO2 pellets were discussed.

Preparation and characterization of porous cordierite pellets and use as a diesel particulate filter

This paper discusses the preparation and characterization of porous pellet filters for a diesel particulate filter (DPF). The process for creating the porous ceramic pellets was developed using simple gelcasting and a bubble-in-water-in-oil type of pseudo-double-emulsion. The pellets, consisting of a foamed cordierite suspension, were dispersed and consolidated in spherical shapes in liquid paraffin as gelation progressed, and were prepared by a conventional mechanical foaming method combined with gelcasting. In comparison with a wall-flow filter, the pellet filter has the advantages of being free of cracks during regeneration and having a flexible shape. Experiments were conducted in a test simulation of diesel engine exhaust conditions. Pressure drop and particle loading rate were compared using two pellet filters having porosities of 70% and 0%, respectively. Regeneration capability was also tested. The filter which mixed 1 and 2 mm pellets demonstrated feasibility as a DPF.