Aluminum titanate based composite porous ceramics with both high porosity and mechanical strength prepared by a special two-step sintering method

Highly porous ceramics are employed in a variety of engineering applications due to their unique mechanical, optical, and electrical characteristics. In order to achieve proper design and function, information about the pore structure must be obtained. Parameters of importance include pore size, pore volume, and size distribution, as well as pore texture and geometry. A quantitative determination of these features for high porosity materials by a microscopic technique is usually not done because artifacts introduced by either the sample preparation method or the image forming process of the microscope make interpretation difficult.Scanning electron microscopy for both fractured and polished surfaces has been utilized extensively for examining pore structures. However, there is uncertainty in distinguishing between topography and pores for the fractured specimen and sample pullout obscures the true morphology for samples that are polished. In addition, very small pores (nm range) cannot be resolved in the S.E.M. On the other hand, T.E.M. has better resolution but the specimen preparation methods involved such as powder dispersion, ion milling, and chemical etching may incur problems ranging from preferential widening of pores to partial or complete destruction of the pore network.

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One-pot foam-gelcasting/nitridation synthesis of high porosity nano-whiskers based 3D Si3N4 porous ceramics

Journal of the European Ceramic Society ◽

10.1016/j.jeurceramsoc.2021.05.016 ◽

2021 ◽

Author(s):

Lei Han ◽

Yu Chen ◽

Hong Chang ◽

Faliang Li ◽

Cheng Liu ◽

...

Keyword(s):

Porous Ceramics ◽

High Porosity ◽

One Pot

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Enhanced mechanical strength of SiC reticulated porous ceramics via addition of in-situ chopped carbon fibers

Journal of Alloys and Compounds ◽

10.1016/j.jallcom.2021.161638 ◽

2021 ◽

pp. 161638

Author(s):

Ruoyu Chen ◽

Xinxin Jin ◽

Daqian Hei ◽

Peng Lin ◽

Feng Liu ◽

...

Keyword(s):

Mechanical Strength ◽

Carbon Fibers ◽

Porous Ceramics

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Radial-Concentric Freeze Casting Inspired by Porcupine Fish Spines

Ceramics ◽

10.3390/ceramics2010015 ◽

2019 ◽

Vol 2 (1) ◽

pp. 161-179 ◽

Cited By ~ 9

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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Preparation of Porous Wollastonite Ceramics for Filtration

Key Engineering Materials ◽

10.4028/www.scientific.net/kem.336-338.1102 ◽

2007 ◽

Vol 336-338 ◽

pp. 1102-1104 ◽

Cited By ~ 1

Author(s):

Ming Sheng He ◽

Jian Bao Li ◽

Bo Wen Li ◽

Hong Lin ◽

Xiao Zhan Yang ◽

...

Keyword(s):

Specific Surface ◽

Pore Size ◽

Surface Area ◽

Specific Surface Area ◽

Sintering Temperature ◽

Porous Ceramics ◽

Holding Time ◽

Starting Material ◽

Sintering Method

Wollastonite powder was selected as a starting material with carbonate as pore-forming agent and binder added. The porous ceramics were prepared at different temperature by sintering method. The process includes batching, granulating, pressing molding, drying and sintering. It is discussed the influence of sintering temperature, dosage of binder, dosage of pore-forming agent, pressure of molding and holding time on the performance of porous ceramics. According to the principle of particles stack, the porous wollastonite ceramics for filtration with various diameters, shapes and porosity were fabricated by serial experiments. These products have 1 to 10 microns in pore size, 30.04 to 66.15% in porosity, 2.82 m2/g in specific surface area.

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Effect of Sintering Temperature on Properties of YAG Porous Ceramics via Atmospheric Sintering Method

Solid State Phenomena ◽

10.4028/www.scientific.net/ssp.281.224 ◽

2018 ◽

Vol 281 ◽

pp. 224-229 ◽

Cited By ~ 1

Author(s):

Fang Wang ◽

Ming Han Xu ◽

Ai Xia Chen ◽

Long Tao Liu ◽

Zhi Hui Li ◽

...

Keyword(s):

Sintering Temperature ◽

Raw Materials ◽

Porous Ceramics ◽

Soluble Starch ◽

Product Performance ◽

Effect Of Temperature ◽

Sintering Process ◽

Molding Process ◽

Sintering Aid ◽

Sintering Method

YAG materials have a number of unique properties, the application is very extensive, the burn is due to the temperature is too high or the residence time at high temperatures is caused. The undercurrent is the sintering temperature is too low or the holding time is not enough, resulting in product performance is too low or too small shrinkage. In this paper, the effect of sintering temperature on properties of YAG porous ceramics was investigated. The results showed that the firing temperature of the ingredients will be different and cause the same sintering process and sintering additives content of different samples burned. The increase in the content of SiO2 in the furnish with the sintering aid tends to occur. the effect of temperature on the mechanical properties of the samples after sintering was significant, so the raw materials include 60wt%YAG, 10wt% CaO, 10wt% SiO2 and 20wt% soluble starch, the molding process in 20MPa pressure 10min, the sintering at 1500°C for 2h, the sample porosity is 42.2%, the compressive strength is 5.8MPa, the outside shape is keep intact and the better pore microstructure is shown.

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Computational Design and Optimization of Nerve Guidance Conduits for Improved Mechanical Properties and Permeability

Journal of Biomechanical Engineering ◽

10.1115/1.4043036 ◽

2019 ◽

Vol 141 (5) ◽

Cited By ~ 6

Author(s):

Shuo Zhang ◽

Sanjairaj Vijayavenkataraman ◽

Geng Liang Chong ◽

Jerry Ying Hsi Fuh ◽

Wen Feng Lu

Keyword(s):

Mechanical Properties ◽

Tissue Engineering ◽

Mechanical Strength ◽

Tensile Modulus ◽

Computational Design ◽

Structural Features ◽

Nerve Tissue ◽

High Porosity ◽

Engineering Research ◽

Design And Optimization

Nerve guidance conduits (NGCs) are tubular tissue engineering scaffolds used for nerve regeneration. The poor mechanical properties and porosity have always compromised their performances for guiding and supporting axonal growth. Therefore, in order to improve the properties of NGCs, the computational design approach was adopted to investigate the effects of different NGC structural features on their various properties, and finally, design an ideal NGC with mechanical properties matching human nerves and high porosity and permeability. Three common NGC designs, namely hollow luminal, multichannel, and microgrooved, were chosen in this study. Simulations were conducted to study the mechanical properties and permeability. The results show that pore size is the most influential structural feature for NGC tensile modulus. Multichannel NGCs have higher mechanical strength but lower permeability compared to other designs. Square pores lead to higher permeability but lower mechanical strength than circular pores. The study finally selected an optimized hollow luminal NGC with a porosity of 71% and a tensile modulus of 8 MPa to achieve multiple design requirements. The use of computational design and optimization was shown to be promising in future NGC design and nerve tissue engineering research.

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High strength and low swelling composite hydrogels from gelatin and delignified wood

Scientific Reports ◽

10.1038/s41598-020-74860-w ◽

2020 ◽

Vol 10 (1) ◽

Author(s):

Shennan Wang ◽

Kai Li ◽

Qi Zhou

Keyword(s):

Mechanical Strength ◽

High Strength ◽

Honeycomb Structure ◽

Composite Hydrogel ◽

High Porosity ◽

High Mechanical Strength ◽

Composite Hydrogels ◽

Freeze Dried ◽

Strength And Stiffness ◽

Phosphate Buffered Saline

Abstract A delignified wood template with hydrophilic characteristics and high porosity was obtained by removal of lignin. Gelatin was infiltrated into the delignified wood and further crosslinked with a natural crosslinker genipin to form hydrogels. The composite hydrogels showed high mechanical strength under compression and low swelling in physiological condition. The effect of genipin concentrations (1, 50 and 100 mM) on structure and properties of the composite hydrogels were studied. A porous honeycomb structure with tunable pore size and porosity was observed in the freeze-dried composite hydrogels. High elastic modulus of 11.82 ± 1.51 MPa and high compressive yield stress of 689.3 ± 34.9 kPa were achieved for the composite hydrogel with a water content as high as 81%. The equilibrium water uptake of the freeze-dried hydrogel in phosphate buffered saline at 37 °C was as low as 407.5%. These enables the delignified wood structure an excellent template in composite hydrogel preparation by using infiltration and in-situ synthesis, particularly when high mechanical strength and stiffness are desired.

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Strength, Permeability, and Freeze-Thaw Durability of Pervious Concrete with Different Aggregate Sizes, Porosities, and Water-Binder Ratios

Applied Sciences ◽

10.3390/app8081217 ◽

2018 ◽

Vol 8 (8) ◽

pp. 1217 ◽

Cited By ~ 12

Author(s):

Hanbing Liu ◽

Guobao Luo ◽

Haibin Wei ◽

Han Yu

Keyword(s):

Compressive Strength ◽

Mechanical Strength ◽

Aggregate Size ◽

Pervious Concrete ◽

High Porosity ◽

Range Analysis ◽

Freeze Thaw ◽

Binder Ratio ◽

The Impact ◽

Water Binder Ratio

Pervious concrete (PC), as an environmental friendly material, can be very important in solving urban problems and mitigating the impact of climate change; i.e., flooding, urban heat island phenomena, and groundwater decline. The objective of this research is to evaluate the strength, permeability, and freeze-thaw durability of PC with different aggregate sizes, porosities, and water-binder ratios. The orthogonal experiment method is employed in the study and nine experiments are conducted. The compressive strength, flexural strength, permeability coefficient, porosity, density, and freeze-thaw durability of PC mixtures are tested. Range analysis and variance analysis are carried out to analyze the collected data and estimate the influence of aggregate size, porosity, and water-binder ratio on PC properties. The results indicate that porosity is the most important factor determining the properties of PC. High porosity results in better permeability, but negatively affects the mechanical strength and freeze-thaw durability. PC of 15% porosity can obtain high compressive strength in excess of 20 MPa and favorable freeze-thaw durability of 80 cycles without sacrificing excessive permeability. Aggregate size also has a significant effect on freeze-thaw durability and mechanical strength. Small aggregate size is advantageous for PC properties. PC with 4.75–9.5 mm coarse aggregate presents excellent freeze-thaw durability. The influence of the water-binder ratio on PC properties is not as significant as that of aggregate size and porosity. An optimal mix ratio is required to trade-off between permeability, mechanical strength, and freeze-thaw durability.

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