Development of ethylene glycol-based gelcasting for the preparation of highly porous SiC ceramics

Jin, Yicheng; Zhang, Biao; Ye, Feng; Zhang, Haoqian; Zhong, Zhaoxin; Liu, Qiang; Zhang, Zhiguo

doi:10.1016/j.ceramint.2019.12.009

Cited by 23 publications

(23 citation statements)

References 23 publications

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“…Various methods can be used to prepare porous ceramics, such as gelcasting, polymeric sponge impregnation, freeze-drying, pore-forming method. [10][11][12][13][14][15][16] Compared with the above methods, particle-stabilized foaming method is a simple way to prepare porous ceramics (to be precise, ceramic foams) with a high porosity (more than 90%). [17][18][19] Air is introduced into slurry by mechanical stirring, and then the stable foam comes into being because of the presence of particle stabilizer which can make particles hydrophobic at the air-water interface.…”

Section: Introductionmentioning

confidence: 99%

“…Various methods can be used to prepare porous ceramics, such as gelcasting, polymeric sponge impregnation, freeze‐drying, pore‐forming method 10‐16 . Compared with the above methods, particle‐stabilized foaming method is a simple way to prepare porous ceramics (to be precise, ceramic foams) with a high porosity (more than 90%) 17‐19 .…”

Section: Introductionmentioning

confidence: 99%

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Hierarchically porous lanthanum zirconate foams with low thermal conductivity from particle‐stabilized foams

et al. 2020

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Lanthanum zirconate (LZO) ceramic foams with hierarchical pore structure were fabricated by particle‐stabilized foaming method for the first time, and the as‐prepared ceramics have high porosity of 90.7%‐94.9%, low thermal conductivity, and relatively high compressive strength. The LZO powder was synthesized by solid‐state method. The porosity of the ceramic foams was tailored by suspensions with different solid loadings (20‐40 wt%). The sample with porosity of 94.9% has thermal conductivity of 0.073 W/(m·K) and compressive strength of 1.19 MPa, which exhibits outstanding property of thermal insulation and mechanical performance, indicating that LZO ceramic foam is a promising thermal insulation material in high temperature applications.

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Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Hierarchically porous lanthanum zirconate foams with low thermal conductivity from particle‐stabilized foams

et al. 2020

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“…It is clear that a large amount of heat was emitted during the reaction process. This result implies that porous YbB 2 C 2 ceramics possess individual chemical activity in wet environments, which is different from the chemical inertness of other porous ceramics 37,38 . It was also found that the reaction between porous YbB 2 C 2 ceramic and water became slow and non-obvious with decreasing porosity.…”

Section: Microstructure Of the Ybbmentioning

confidence: 85%

“…Porous YbB 2 C 2 ceramics. Advanced porous ceramics (also called ceramic foams) usually have low density, high porosity, large specific surface area, thermal shock resistance, corrosion and wear resistance, and high chemical stability [36][37][38] . SEM images of the as-prepared porous YbB 2 C 2 samples with porosities of 69.89%, 61.58% and 58.11% are shown in Fig.…”

Section: Microstructure Of the Ybbmentioning

confidence: 99%

Unique chemical activity in porous YbB2C2 ceramics with high porosity and high compressive strength

Chen

Zhang

et al. 2020

Sci Rep

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High purity layered YbB2C2 powder is synthesized by a boro/carbothermic reduction method using YbBO3, B4C and graphite powders as raw materials. Its X-ray diffraction data are presented, and the space group P4/mbm (No. 127) is confirmed. The lattice parameters are a = b = 5.3389 Å and c = 3.5683 Å, and the atom positions are Yb (0.0000, 0.0000, 0.0000), B (0.3621, 0.8621, 0.5000), and C (0.1606, 0.6606, 0.5000). Porous YbB2C2 ceramics have a high porosity in the range of 69.89–58.11% and a high compressive strength in the range of 19.49–63.44 MPa. Furthermore, the as-produced porous YbB2C2 ceramics show unique chemical activity. Porous YbB2C2 ceramic with a porosity of 69.89% emits so much heat that it can burn a piece of paper when this ceramic is wetted by water. The rate of reaction between the porous YbB2C2 ceramic and water can be simply controlled by adjusting the porosity. The solid reaction products are YbB6, C and an unknown amorphous phase.

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“…Tian et al [ 24 ] successfully prepared the SiC ceramics using the gel-casting process and proposed a pretreatment and surface modification method to avoid the problem that Isobam is difficult to crosslink and gelling with non-oxide ceramics. Jin et al [ 25 ] developed a novel ethylene glycol-based gel cast to prepare highly porous SiC ceramics, and the strength of green bodies was effectively increased. However, it is worth noting that the gel-casting technologies cannot completely eliminate the defects caused by the thermal non-uniformity.…”

Section: Introductionmentioning

confidence: 99%

A Finite Element Analysis for Improvement of Shaping Process of Complex-Shaped Large-Size Silicon Carbide Mirrors

et al. 2021

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In the gel-casting process, the proper selection of technological parameters is crucial for the final quality of a green body. In this work, the finite element method is used to investigate the mold characteristics in the gel-casting process, and the typical flow behaviors under different conditions are presented. Based on the distribution characteristics of temperature, pressure and flow field of gel polymer, the simulated results provide some possible reasons for the generation mechanisms of defects. Then, a series of simulations were performed to investigate the effect of process parameters on the molding quality of green gel-cast bodies. The results show that the decreasing loading speed can effectively reduce the number of defects and improve the molding quality. In addition, this paper presents a new technique by applying the exhaust hole to decrease the number of defects and, hence, improve structural integrity. The influence of the loading speed on the mold characteristics is well understood for the gating system with an exhaust hole, which suggests to us appropriate parameters for optimizing the molding design. This work provides a theoretical basis to explicate the generating mechanism of defects involved in the gel-casting process and acquires an optimized technique to produce a silicon carbide green body.

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Development of ethylene glycol-based gelcasting for the preparation of highly porous SiC ceramics

Cited by 23 publications

References 23 publications

Hierarchically porous lanthanum zirconate foams with low thermal conductivity from particle‐stabilized foams

Hierarchically porous lanthanum zirconate foams with low thermal conductivity from particle‐stabilized foams

Unique chemical activity in porous YbB2C2 ceramics with high porosity and high compressive strength

A Finite Element Analysis for Improvement of Shaping Process of Complex-Shaped Large-Size Silicon Carbide Mirrors

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