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Freeze Casting (freeze + casting)

Distribution by Scientific Domains
Polymers and Materials Science100%

Selected Abstracts

Hydroxyapatite/SiO2 Composites via Freeze Casting for Bone Tissue Engineering,

ADVANCED ENGINEERING MATERIALS, Issue 11 2009
Silke Blindow
Freeze casting is a fabrication method that allows producing near-net-shaped ceramics with variable porosity. Hydroxyapatite (HA) was modified by the addition of different amounts of SiO2 nanoparticles during freeze cast preparation. The addition of SiO2 introduced a partial phase transformation of HA to , -tricalcium phosphate and improved the form stability due to less shrinkage after sintering. The impact of surface roughness of pure HA ceramics and the influence of SiO2 introduction during freeze casting on adhesion, proliferation, and differentiation of human osteoblast-like cells (MG-63) was investigated. While both cell attachment and proliferation of smooth pressed HA was significantly enhanced compared to rough freeze cast HA, the addition of SiO2 improved the cell numbers of the latter. The expression of cell differentiation markers osteocalcin and collagen I was found to be supported by rough surfaces (Ra,=,5,6,µm) in particular on ceramics containing SiO2 [source]

Fabrication of a Porous Bioactive Glass,Ceramic Using Room-Temperature Freeze Casting

JOURNAL OF THE AMERICAN CERAMIC SOCIETY, Issue 8 2006
Ju-Ha Song
The room-temperature freeze-casting method was used to fabricate porous bioactive glass,ceramics. In this method, a glass/camphene slurry prepared at 60°C was cast into a mold at 20°C, resulting in the production of a rigid green body that was comprised of three-dimensional dendritic camphene networks surrounded by highly concentrated glass powder walls. After the sublimation of camphene, the samples were sintered for 3 h at elevated temperatures ranging from 700° to 1100°C. As the sintering temperature was increased to 1000°C, the densification of the glass,ceramic wall was remarkably enhanced, while its highly porous structure was preserved. The sample sintered at 1000°C showed a high porosity of 53% and pore channels with a size of several tens of micrometers, as well as dense glass,ceramic walls. In addition, the fabricated samples effectively induced the deposition of apatite on their surfaces when immersed in simulated body fluid, implying that they are very bioactive. [source]

Room-Temperature Freeze Casting for Ceramics with Nonaqueous Sublimable Vehicles in the Naphthalene,Camphor Eutectic System

JOURNAL OF THE AMERICAN CERAMIC SOCIETY, Issue 11 2004
Kiyoshi Araki
Freeze casting for Al2O3 was accomplished at room temperature with nonaqueous sublimable vehicles in the naphthalene,camphor eutectic system with a eutectic temperature of 31°C. A fully dense sintered body (>99.5% of theoretical density (T.D.)) was obtained with a eutectic composition vehicle, whereas at most 90% T.D. was obtained with an off-eutectic (i.e., hypo- or hypereutectic) composition vehicle due to formation of large uniquely shaped voids. Microstructural observation suggested that growing pro-eutectic crystals rejected the suspended Al2O3 particles to form large voids during the solidification process. At the eutectic composition, formation of fine lamellar microstructure in a solidified vehicle is considered to inhibit particle rejection resulting in large voids. [source]

Hydroxyapatite/SiO2 Composites via Freeze Casting for Bone Tissue Engineering,

ADVANCED ENGINEERING MATERIALS, Issue 11 2009
Silke Blindow
Freeze casting is a fabrication method that allows producing near-net-shaped ceramics with variable porosity. Hydroxyapatite (HA) was modified by the addition of different amounts of SiO2 nanoparticles during freeze cast preparation. The addition of SiO2 introduced a partial phase transformation of HA to , -tricalcium phosphate and improved the form stability due to less shrinkage after sintering. The impact of surface roughness of pure HA ceramics and the influence of SiO2 introduction during freeze casting on adhesion, proliferation, and differentiation of human osteoblast-like cells (MG-63) was investigated. While both cell attachment and proliferation of smooth pressed HA was significantly enhanced compared to rough freeze cast HA, the addition of SiO2 improved the cell numbers of the latter. The expression of cell differentiation markers osteocalcin and collagen I was found to be supported by rough surfaces (Ra,=,5,6,µm) in particular on ceramics containing SiO2 [source]

In situ Study of Internal Load Transfer in a Novel Metal/Ceramic Composite Exhibiting Lamellar Microstructure Using Energy Dispersive Synchrotron X-ray Diffraction,

ADVANCED ENGINEERING MATERIALS, Issue 6 2009
Siddhartha Roy
Freeze casting offers a new technique to fabricate ceramic preforms for metal/ceramic composites. Internal load transfer under external compressive loading in such composites has been studied for the first time using energy dispersive synchrotron X-ray diffraction. The results show that load transfer takes place from the soft metallic alloy to the hard ceramic which has been explained in the light of generalized Hooke's law and classical laminate theory. [source]

Room-Temperature Freeze Casting for Ceramics with Nonaqueous Sublimable Vehicles in the Naphthalene,Camphor Eutectic System

JOURNAL OF THE AMERICAN CERAMIC SOCIETY, Issue 11 2004
Kiyoshi Araki
Freeze casting for Al2O3 was accomplished at room temperature with nonaqueous sublimable vehicles in the naphthalene,camphor eutectic system with a eutectic temperature of 31°C. A fully dense sintered body (>99.5% of theoretical density (T.D.)) was obtained with a eutectic composition vehicle, whereas at most 90% T.D. was obtained with an off-eutectic (i.e., hypo- or hypereutectic) composition vehicle due to formation of large uniquely shaped voids. Microstructural observation suggested that growing pro-eutectic crystals rejected the suspended Al2O3 particles to form large voids during the solidification process. At the eutectic composition, formation of fine lamellar microstructure in a solidified vehicle is considered to inhibit particle rejection resulting in large voids. [source]

Hydroxyapatite/SiO2 Composites via Freeze Casting for Bone Tissue Engineering,

ADVANCED ENGINEERING MATERIALS, Issue 11 2009
Silke Blindow
Freeze casting is a fabrication method that allows producing near-net-shaped ceramics with variable porosity. Hydroxyapatite (HA) was modified by the addition of different amounts of SiO2 nanoparticles during freeze cast preparation. The addition of SiO2 introduced a partial phase transformation of HA to , -tricalcium phosphate and improved the form stability due to less shrinkage after sintering. The impact of surface roughness of pure HA ceramics and the influence of SiO2 introduction during freeze casting on adhesion, proliferation, and differentiation of human osteoblast-like cells (MG-63) was investigated. While both cell attachment and proliferation of smooth pressed HA was significantly enhanced compared to rough freeze cast HA, the addition of SiO2 improved the cell numbers of the latter. The expression of cell differentiation markers osteocalcin and collagen I was found to be supported by rough surfaces (Ra,=,5,6,µm) in particular on ceramics containing SiO2 [source]

Fabrication of Graphene,Polymer Nanocomposites With Higher-Order Three-Dimensional Architectures

ADVANCED MATERIALS, Issue 21 2009
Jemma L. Vickery
The use of aqueous dispersions of polystyrene sulfonate-stabilized graphene sheets for the fabrication of nanocomposites with higher-order 3D architectures is demonstrated using two examples of template-directed assembly. Macroscopic sponge-like polymer,graphene scaffolds are readily produced by directional freeze casting, while hollow graphene microspheres are prepared by electrostatically induced assembly on positively charged polymer beads. [source]