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Tape Casting (tape + casting)

Distribution by Scientific Domains

Polymers and Materials Science	80%
Chemistry	20%

Selected Abstracts

Tape Casting of Graphite Material: A New Electrochemical Sensor

ELECTROANALYSIS, Issue 16 2006
M. Chicharro
Abstract Tape casting is a feasible method for preparing ceramic tapes with different electrical and magnetic properties for multilayer ceramic devices. This paper describes the tape casting process for the preparation of a new kind of self-standing carbon electrodes (SSCE) using different ratios of graphite and the organic additives generally used in the non-aqueous tape casting process. [source]

Tape Casting and Dielectric Properties of Zn2Te3O8 -Based Ceramics with an Ultra-Low Sintering Temperature

INTERNATIONAL JOURNAL OF APPLIED CERAMIC TECHNOLOGY, Issue 4 2009
Johanna Honkamo
The suitability of dielectric ceramics made of zinc tellurate (Zn2Te3O8) and titanium dioxide (TiO2) with an ultra-low sintering temperature (650°C) for tape casting and thus for the multimodule technique with Al electrodes was investigated. The properties of the tape before and after sintering as well as the amount of organic additives for the casting process and a thermal analysis of the tape up to 1000°C are reported. In addition, electrodes on a multilayer module made on stacked tapes were prepared using Al paste and postfiring, followed by relative permittivity and loss tangent measurements to verify the electrical performance of the whole structure. The dielectric properties of the stacked module without any electrodes were also measured. The results show that the composition is well suited for the tape process but extra care should be taken especially with the proper sintering temperature for optimized electrical performance. [source]

Comparison of Water-Based and Solvent-Based Tape Casting for Preparing Multilayer ZnO Varistors

JOURNAL OF THE AMERICAN CERAMIC SOCIETY, Issue 11 2008
Lanyi Wang
Water-soluble acrylic was used as the binder of the water-based (aqueous) slurry while polyvinyl butyral was the binder of the solvent-based (nonaqueous) slurry. Both types of slurry exhibited shear thinning properties suitable for tape casting. The casting parameters for them were different when the same thick green sheets were cast. Thermogravimetric analysis was used to find the binder burnout temperatures of the aqueous and nonaqueous green tape. Scanning electron microscopy (SEM) studies revealed that both types of green tapes have smooth defect-free surfaces but the aqueous green tape is denser than the nonaqueous one. The multilayer ZnO varistors prepared by aqueous tape casting display comparable good electrical properties to those prepared by nonaqueous tape casting because both types of ceramic have a uniform, fine grain microstructure with a homogeneous dopant distribution indicated using SEM and transmission electron microscopy. [source]

Tape Casting of Graphite Material: A New Electrochemical Sensor

Oxidation Resistance of Multilayer SiC for Space Vehicle Thermal Protection Systems,

ADVANCED ENGINEERING MATERIALS, Issue 7 2010
Claudia Milena Vega Bolivar
The oxidation resistances of different kinds of SiC-based laminates are compared. The materials under investigation are produced by tape casting of green ceramic sheets, followed by stacking of the sheets in a multilayer structure and laminate consolidation by de-binding and sintering. Three kinds of specimens are tested: multilayer SiC with fully dense layers, multilayer SiC integrating porous layers and multilayer composites made by stacking SiC/Cf composite layers. Two kinds of chopped carbon fibres (polyamide coated and uncoated) are used for the manufacture of the composite sheets. The oxidation behaviour is investigated by simultaneous TGA,DTA,MS analysis. Specimens are also submitted to a long-term oxidation treatment (30,h at 1,600,°C in flowing air) and their microstructure and mechanical behaviour compared before and after oxidation. This assessment shows that the integration of porous or composite layers in the multilayer architecture does not worsen the oxidation resistance. In every case the formation of a surface passivating layer prevents major degradation phenomena, so that only small changes in the mechanical features are found after oxidation. [source]

Processing of Carbon Nanofiber Reinforced ZrB2 Matrix Composites for Aerospace Applications,

ADVANCED ENGINEERING MATERIALS, Issue 7 2010
Jorge Barcena
Ceramic matrix composites (CMCs) based on zirconium diboride (ZrB2) reinforced by vapor grown carbon nanofibers are a potential constituent of reusable thermal protection systems. A manufacturing procedure was devised that involved the fabrication of thin films by tape casting to obtain a layer that could be integrated into a more complex system. Higher thermal conductivities and improved toughness can be expected for nanofiber additions, as compared to the matrix alone. Consolidation by hot-pressing was more effective than pressureless sintering, in terms of the final relative density and flatness of specimens. Examination of microstructures showed that few carbon nanofibers were present in the matrix after consolidation by sintering, which was attributed to a reaction between the nanofibers and zirconium oxide present on the surface of the ZrB2 powder. As a solution, oxygen impurities from the boride powders were removed by reduction with carbon coatings derived from phenolic resin. The deleterious reaction was avoided, but residual carbon remained at the grain boundaries, likely from decomposition of the binder. The use of an alternative binder (PMMA vs. PVB) will be used in future studies to reduce the residual carbon content. Further, consolidation by Spark Plasma Sintering (SPS) will be explored to further reduce the reaction of surface oxides with the nanofibers. Finally, characterization of the microstructure at the nanometric level and further determination of the mechanical and thermal properties will be conducted as part of future studies. [source]

Tape Casting and Dielectric Properties of Zn2Te3O8 -Based Ceramics with an Ultra-Low Sintering Temperature

Fabrication of Thin-Film SrCe0.9Eu0.1O3,, Hydrogen Separation Membranes on Ni,SrCeO3 Porous Tubular Supports

JOURNAL OF THE AMERICAN CERAMIC SOCIETY, Issue 8 2009
Heesung Yoon
SrCe0.9Eu0.1O3,, thin-film (,30 ,m) tubular hydrogen separation membranes were developed in order to obtain high hydrogen fluxes. Fifteen centimeters long, one end closed, NiO,SrCeO3 tubular supports were fabricated by tape casting, followed by rolling the green tape on a circular rod. SrCe0.9Eu0.1O3,, powders were prepared by the citrate process and coated on partially sintered NiO,SrCeO3 tubular supports. Leakage-free hydrogen membrane cells were obtained by adjusting the presintering and final sintering temperatures to reduce the difference of linear shrinkage rates between SrCe0.9Eu0.1O3,, thin films and NiO,SrCeO3 supports. A hydrogen flux of 2.2 cm3/min was obtained for the SrCe0.9Eu0.1O3,, on Ni,SrCeO3 tubular hydrogen separation membranes at 900°C using 25% H2 balanced with Ar and 3% H2O as the feed gas and He as the sweep gas. Thus, a 40% single pass yield of pure H2 was achieved with this membrane. [source]

Comparison of Water-Based and Solvent-Based Tape Casting for Preparing Multilayer ZnO Varistors

Fabrication of Gradient Pore TiO2 Sheets by a Novel Freeze,Tape-Casting Process

JOURNAL OF THE AMERICAN CERAMIC SOCIETY, Issue 9 2007
Linlin Ren
Gradient pore structure TiO2 sheets were fabricated by a novel freeze,tape-casting process. Aqueous TiO2 ceramic slurries were prepared by the traditional tape-casting processing and were then cast onto an aluminum foil carrier. The slurries were immediately frozen on the substrate, whose temperature was about ,18°C. After freezing completely, the green sheets were then dried in a lyophilizer. Freeze,tape casting led to formation of a gradient pore microstructure of the TiO2 sheet. The results showed that the solid loading of slurry considerably affected the pore microstructure, pore morphology, and the porosity. Solid loadings of 10, 20, 30, 40, and 50 wt% slurries were used, respectively, and the gradient pore structure TiO2 sheets with different porosities of 75%,88% were obtained. [source]

Direct Laser Sintering of Al2O3,SiO2 Dental Ceramic Components by Layer-Wise Slurry Deposition

JOURNAL OF THE AMERICAN CERAMIC SOCIETY, Issue 10 2006
André Gahler
This publication presents a solid freeform fabrication technique for ceramics in the alumina,silica system by layering binder-free, high-loaded ceramic slurries, followed by selective laser sintering. The low melting silica phase and the reaction sintering between silica and alumina favor the rapid prototyping of pure ceramic parts. On the basis of electroacoustic and viscosity measurements, stable slurries from Al2O3/SiO2 powder mixtures and water with a high fluidity have been prepared for the layer deposition with a doctor blade like in tape casting. Layers with a thickness of about 100 ,m were processed. It was found in laser parameter studies that ceramic parts can only be obtained using special alumina contents and laser parameters. But the biphasic approach may allow greater flexibility in the processing regime than is afforded by the use of just one material. The microstructure of these parts depends mainly on the temperature gradient induced by the laser absorption and thermal conduction. The wet shaping facilitates laser-sintered parts with a relatively high density, which could be increased by a thermal post-treatment. [source]

Microwave Bandgap in Multilayer Ceramic Structures

JOURNAL OF THE AMERICAN CERAMIC SOCIETY, Issue 3 2006
Bo Li
A multilayer ceramic structure with a photonic bandgap (MC-PBG) was fabricated by a method of tape casting combined with screen printing. The MC-PBG structure is a two-dimensional array with either rectangular or hexagonal metal coils in a ceramic matrix. The metal coils are connected to the base metal layer in the ceramic substrate to form a monolithic body. The surface-wave dispersion properties of these MC-PBG structures were measured. A stop band, which is significantly influenced by the symmetrical characteristics of the inductor,capacitor (LC) arrays, was found in both the structures in the frequency range of 2.0,3.5 GHz. Because of their effective surface-wave suppression, MC-PBG structures can be used as high-performance antenna substrates to enhance the broadside gain of patch antenna devices. [source]

Phase Stability and Ferroelectric Properties of Lead Strontium Zirconate Titanate Ceramics

JOURNAL OF THE AMERICAN CERAMIC SOCIETY, Issue 2 2001
Yongjian Yu
The effect of compositional modifications on the field-induced phase-transition behavior and dielectric properties of strontium-doped lead zirconate titanate (PZT) ceramics was studied. PZT compositions with different strontium and titanium contents, within the general formula Pb1,xSrx(Zr1,yTiy)O3 and located in the tetragonal antiferroelectric (AFE) and rhombohedral ferroelectric (FE) phase fields were prepared by tape casting and sintering. X-ray diffraction and polarization measurements were used to locate compositions suitable for investigation of the field-induced AFE,FE phase transition. The results indicated that a higher Sr2+ content decreased the polarization and hysteresis and increased the switching field; a lower Ti4+ content decreased the polarization and increased the switching field and hysteresis. A high room-temperature dielectric constant was obtained for compositions near the phase boundary. These results suggest that a combination of both A -site and B -site modifications can be used to tailor ferroelectric properties, such as the switching field and hysteresis, of these strontium-doped PZTs displaying a field-induced AFE,FE phase transition. [source]

Further Improvement in Mechanical Properties of Highly Anisotropic Silicon Nitride Ceramics

JOURNAL OF THE AMERICAN CERAMIC SOCIETY, Issue 3 2000
Hisayuki Imamura
Si3N4ceramics were fabricated by tape casting of a raw-powder slurry seeded with three types of rodlike ,-Si3N4particles. The effects of seed size on the microstructure and mechanical properties of the sintered specimens were investigated. All the seeded and tape-cast silicon nitrides presented an anisotropic microstructure, where the elongated grains grown from seeds were preferentially oriented parallel to the casting direction. The orientation degree of these grains, f0, was affected by seed size, and small-seed addition led to the highest f0value. This material exhibited high bending strength (,1.4 GPa) and high fracture toughness (,12 MPa.m1/2) in the direction normal to the grain alignment, which were attributed to the highly anisotropic and fine microstructure. [source]

Direct utilization of ethanol on ceria-based anodes for solid oxide fuel cells

ASIA-PACIFIC JOURNAL OF CHEMICAL ENGINEERING, Issue 1 2009
Massimiliano Cimenti
Abstract The direct utilization of ethanol was investigated in CuCeO2, CuZr0.35Ce0.65O2 (ZDC) and Cu/RuZr0.35Ce0.65O2 anodes for solid oxide fuel cells (SOFC). The anodes were prepared by impregnation with nitrate precursors on a porous layer of yttria-stabilized zirconia (YSZ) obtained by tape casting, while (La0.8Sr0.2MnO3,,) LSM cathodes were screen-printed. The cells were tested in both hydrogen and ethanol. The outlet gas composition was monitored with a gas chromatograph, which showed that almost all the ethanol was decomposed, mainly to H2, CH4, CO, H2O and C2H4. The maximum power outputs obtained in ethanol were 0.075 and 0.400 W/cm2 on CuCeO2|YSZ|LSM and CuZDC|YSZ|LSM, respectively. All cells were more active in alcohol than in hydrogen with the peak performance occurring after approximately 4 h. That is, the power density initially increased, peaked and then decreased. This behavior was likely a consequence of carbon deposition that initially results in an improvement of the electronic conductivity in the anode but later results in the blocking of the active sites. Zirconia doping (in the ZDC anodes) resulted in better stability and, in addition, the initial activity of the ZDC anodes could be recovered after approximately 1 h of exposure to humidified hydrogen, whereas the initial activity of the ceria anodes could not be recovered. The addition of ruthenium (<0.5 wt%) further improved the stability by delaying the onset of carbon formation. Copyright © 2008 Curtin University of Technology and John Wiley & Sons, Ltd. [source]