scholarly journals Freeze casting process for the generation of graded porosity in Al2O3 ceramics

Cerâmica ◽  
2020 ◽  
Vol 66 (377) ◽  
pp. 65-73
Author(s):  
E. Pagano ◽  
A. S. A. Chinelatto ◽  
A. L. Chinelatto
Keyword(s):  
Fracture Mode ◽  
Pore Formation ◽  
Mechanical Response ◽  
Casting Process ◽  
Ceramic Materials ◽  
Processing Route ◽  
Uniaxial Compression Test ◽  
Freeze Casting ◽  
Casting Method ◽  
Pore Characteristics

Abstract Alumina ceramic materials with graded functional porosity were prepared by the freeze casting method and characterized. The effects of processing route parameters on the pore formation were studied. Pore characteristics were investigated concerning morphology and distribution in the ceramic matrix. The mercury intrusion method was used to evaluate the porosity. Mechanical properties, as well as the fracture mode, were investigated by the uniaxial compression test. Scanning electron microscopy was used to analyze and correlate the created interface between the layers with the mechanical response. The results suggested that the porosity obtained in all samples was similar, even with varying parameters (different suspension solidification configurations). When evaluating the mechanical behavior, these distinct parameters showed drastic differences in compressive strength and failure mode. This was due to the formation of interfaces between the layers of different porosities, according to the solidification configuration. The interfaces modified the fracture mode, changing from a longitudinal-directed to an interface-directed fracture. The pore microstructure and morphology indicated highly connected pore channels.

scholarly journals Microstructure and Thermoelectric Properties of (Bi0.48Sb1.52)Te3 Thick Films Prepared with Tape Casting Method

Electronics ◽  
2021 ◽  
Vol 10 (2) ◽  
pp. 140
Author(s):  
Lichen Liu ◽  
Ziping Cao ◽  
Min Chen ◽  
Jun Jiang
Keyword(s):  
Thermoelectric Properties ◽  
Low Cost ◽  
Thick Films ◽  
Tape Casting ◽  
Casting Process ◽  
Casting Method ◽  
Glass Substrates ◽  
Conductive Films ◽  
Casting Technology

This paper reports the fabrication and characterization of (Bi0.48Sb1.52)Te3 thick films using a tape casting process on glass substrates. A slurry of thermoelectric (Bi0.48Sb1.52)Te3 was developed and cured thick films were annealed in a vacuum chamber at 500–600 °C. The microstructure of these films was analyzed, and the Seebeck coefficient and electric conductivity were tested. It was found that the subsequent annealing process must be carefully designed to achieve good thermoelectric properties of these samples. Conductive films were obtained after annealing and led to acceptable thermoelectric performance. While the properties of these initial materials are not at the level of bulk materials, this work demonstrates that the low-cost tape casting technology is promising for fabricating thermoelectric modules for energy conversion.

scholarly journals Nanostructured ZnFe2O4: An Exotic Energy Material

Nanomaterials ◽  
2021 ◽  
Vol 11 (5) ◽  
pp. 1286
Author(s):  
Murtaza Bohra ◽  
Vidya Alman ◽  
Rémi Arras
Keyword(s):  
Data Storage ◽  
Smart Materials ◽  
Energy Demand ◽  
Ceramic Materials ◽  
Magnetic Data ◽  
Processing Route ◽  
Energy Storage Devices ◽  
Storage Devices ◽  
Reduced Toxicity ◽  
Cation Arrangement

More people, more cities; the energy demand increases in consequence and much of that will rely on next-generation smart materials. Zn-ferrites (ZnFe2O4) are nonconventional ceramic materials on account of their unique properties, such as chemical and thermal stability and the reduced toxicity of Zn over other metals. Furthermore, the remarkable cation inversion behavior in nanostructured ZnFe2O4 extensively cast-off in the high-density magnetic data storage, 5G mobile communication, energy storage devices like Li-ion batteries, supercapacitors, and water splitting for hydrogen production, among others. Here, we review how aforesaid properties can be easily tuned in various ZnFe2O4 nanostructures depending on the choice, amount, and oxidation state of metal ions, the specific features of cation arrangement in the crystal lattice and the processing route used for the fabrication.

Slip Casting Used as a Forming Technique for Hydroxyapatite Processing

2016 ◽  
Vol 720 ◽  
pp. 219-222 ◽  
Author(s):  
Rubens Lincoln Santana Blazutti Marçal ◽  
Daniel Navarro da Rocha ◽  
Marcelo Henrique Prado da Silva
Keyword(s):  
Slip Casting ◽  
Ceramic Materials ◽  
Processing Route ◽  
Ceramic Suspension ◽  
Polyethylene Glycol 400 ◽  
Density Measurements ◽  
Hydroxyapatite Powder ◽  
Heat Treated ◽  
Thermal Phase ◽  
Before And After

Ceramic materials have particular properties when compared to other classes of materials, exhibiting poor ductility as an example. Slip casting is a widely used ceramic forming technique, and already established in the literature and in the ceramic industry. This study aims to present slip casting as a processing route for producing hydroxyapatite (HA) struts, and show the thermal phase stability. The ceramic suspension was produced and stabilized with hydroxyapatite powder, deionized water and polyethylene glycol 400. The slip was poured into gypsum mold. The green bodies were heat treated at 900 and 1100°C. Hydroxyapatite was the only phase present in all samples, before and after heat treatments. Density measurements showed that the densification was higher for the ceramic bodies sintered at 1100°C, when compared to the ones calcined at 900°C.

Fabrication and characterization of collagen–hydroxyapatite-based composite scaffolds containing doxycycline via freeze-casting method for bone tissue engineering

2018 ◽  
Vol 33 (4) ◽  
pp. 501-513 ◽  
Author(s):  
Hossein Semyari ◽  
Majid Salehi ◽  
Ferial Taleghani ◽  
Arian Ehterami ◽  
Farshid Bastami ◽  
...  
Keyword(s):  
Cellular Response ◽  
Composite Scaffold ◽  
Precipitation Method ◽  
Structural Isomer ◽  
Freeze Casting ◽  
Hydroxyapatite Nanoparticles ◽  
Casting Method ◽  
Defect Model ◽  
Co Precipitation

In this study, hydroxyapatite nanoparticles containing 10% doxycycline, a structural isomer of tetracycline, was prepared by the co-precipitation method. It was added to collagen solution for the preparation of the scaffold with freeze-casting method in order to develop a composite scaffold with both antibacterial and osteoinductive properties for repairing bone defects. The scaffolds were evaluated regarding their morphology, porosity, degradation and cellular response. The scaffolds for further investigation were added in a rat calvaria defect model. The study showed that after eight weeks, the bone formation was relatively higher in the collagen/nano-hydroxyapatite/doxycycline group with completely filled defect when compared with other groups. Histopathological evaluation showed that the defect in the collagen/nano-hydroxyapatite/doxycycline group was fully replaced by the new bone and connective tissue. Our results provide evidence supporting the possible applicability of doxycycline-containing scaffolds for successful bone regeneration.

scholarly journals Heat transfer in the mold during vertical continuous casting of steel

2018 ◽  
pp. 26-30
Author(s):  
E. I. Marukovich ◽  
E. B. Demchenko
Keyword(s):  
Heat Transfer ◽  
Temperature Regime ◽  
Thermal State ◽  
Effective Means ◽  
Experimental Studies ◽  
Casting Process ◽  
Continuous Casting Of Steel ◽  
Technological Parameters ◽  
Casting Method ◽  
Calculation Technique

The analysis of the performed researches has shown that the offered calculation technique is an effective means of management of formation process in casting. The found dependences and experimental data allow to calculate the specific value of the exactм heat flux in a given range of technological parameters obtained during a series of successful experiments for a particular casting method.Having the results of studies of the temperature regime of the mold during casting of a certain size and profile, it is possible to calculate the thermal state of the mold for the same casting process, but for the production of castings of any other size and profile.Having a certain amount of information on the temperature regime of the mold at different casting methods, you can use the solutions obtained to become the owner of a database containing the necessary information for solving the problems of solidification of the casting. In the subsequent design of equipment and equipment there is no need for additional experimental studies and analysis of the results.

Properties and CA4GE-Engine Test of TiAl-Based Alloy Valves by Permanent Mold Casting

2010 ◽  
Vol 139-141 ◽  
pp. 557-560
Author(s):  
Wen Bin Sheng ◽  
Chun Xue Ma ◽  
Wan Li Gu
Keyword(s):  
Tial Alloy ◽  
Centrifugal Casting ◽  
Casting Process ◽  
Vacuum Arc ◽  
Permanent Mold ◽  
Casting Method ◽  
Arc Melting ◽  
Vacuum Arc Melting ◽  
Mold Casting ◽  
Induction Skull Melting

TiAl-based alloy valves were manufactured by combining charges compressed /vacuum arc melting (VA)/ induction skull melting (ISM) procedure with permanent mold centrifugal casting method. Microstructures, compositions and mechanical properties of as-cast and hot isostatical pressed (HIPed) valves are detected. Results show that the permanent mold centrifugal casting process obviously refines the size of grain in TiAl alloy and the tensile strength of as-cast and HIPed valves are 550MPa and 580MPa at 20°C, 370MPa and 470MPa at 815°C, respectively. As-cast specimens show ~0% elongation at 20°C and 1~2% at 815°C, while HIPed ones show an elongation of 1~2% at room temperature and about 10% at 815°C. Furthermore, a 200-hour test was carried out with CA4GE-engine, which demonstrated the possibility of as-cast TiAl alloy valves for the substitution of present steel ones.

scholarly journals Radial-Concentric Freeze Casting Inspired by Porcupine Fish Spines

Ceramics ◽  
2019 ◽  
Vol 2 (1) ◽  
pp. 161-179 ◽  
Author(s):  
Frances Su ◽  
Joyce Mok ◽  
Joanna McKittrick
Keyword(s):  
Mechanical Properties ◽  
Tensile Strength ◽  
Axial Compression ◽  
Porous Ceramics ◽  
Compressive Modulus ◽  
Splitting Tensile Strength ◽  
High Porosity ◽  
Freeze Casting ◽  
Casting Method ◽  
Multiphase Materials

Freeze casting is a technique used to manufacture porous ceramics with aligned microstructures. In conventional freeze casting, these microstructures are aligned along a single direction of freezing. However, a caveat to these ceramics has been their ensuing lack of strength and toughness due to their high porosity, especially in the direction orthogonal to the direction of alignment. In this work, a novel freezing casting method referred to as “radial-concentric freeze casting” is presented, which takes its inspiration from the radially and concentrically aligned structure of the defensive spines of the porcupine fish. The method builds off the radial freeze casting method, in which the microstructure is aligned radially, and imposes a concentric alignment. Axial compression and Brazilian tests were performed to obtain axial compressive strengths, axial compressive moduli, and splitting tensile strengths of freeze cast samples with and without epoxy infiltration. Notably, radial-concentric freeze cast samples had the greatest improvements in axial compressive modulus and splitting tensile strength with infiltration, when compared against the changes in mechanical properties of conventional and radial freeze cast ceramics with infiltration. These results provide further evidence for the importance of structure in multiphase materials and the possibility of enhancing mechanical properties through the controlled alignment of microstructures.

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