Preparation of porous YB4 ceramics using a combination of in-situ borothermal reaction and high temperature partial sintering

Guo, Qi; Xiang, Huimin; Sun, Xiaohua; Wang, Xiaohui; Zhou, Yanchun

doi:10.1016/j.jeurceramsoc.2015.05.023

Cited by 27 publications

(9 citation statements)

References 30 publications

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“…However, high thermal conductivity is the main obstacle for ultrahigh temperature insulating application. In order to reduce the thermal conductivity, low thermal conductivity high-entropy carbides and borides were selected as backbone materials and a novel in-situ reaction/partial sintering method was developed to fabricate highly porous bulk materials [146][147][148]. This process is based on the fact that highentropy carbides and borides can be synthesized through carbothermal reduction, borothermal reduction, and boro/carbothermal reduction.…”

Section: Dense and Porous Bulksmentioning

confidence: 99%

High-entropy ceramics: Present status, challenges, and a look forward

et al. 2021

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High-entropy ceramics (HECs) are solid solutions of inorganic compounds with one or more Wyckoff sites shared by equal or near-equal atomic ratios of multi-principal elements. Although in the infant stage, the emerging of this new family of materials has brought new opportunities for material design and property tailoring. Distinct from metals, the diversity in crystal structure and electronic structure of ceramics provides huge space for properties tuning through band structure engineering and phonon engineering. Aside from strengthening, hardening, and low thermal conductivity that have already been found in high-entropy alloys, new properties like colossal dielectric constant, super ionic conductivity, severe anisotropic thermal expansion coefficient, strong electromagnetic wave absorption, etc., have been discovered in HECs. As a response to the rapid development in this nascent field, this article gives a comprehensive review on the structure features, theoretical methods for stability and property prediction, processing routes, novel properties, and prospective applications of HECs. The challenges on processing, characterization, and property predictions are also emphasized. Finally, future directions for new material exploration, novel processing, fundamental understanding, in-depth characterization, and database assessments are given.

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Section: Dense and Porous Bulksmentioning

confidence: 99%

High-entropy ceramics: Present status, challenges, and a look forward

et al. 2021

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“…Porous ceramics are widely used in high temperature gas filtration [ 1 , 2 ], sewage purification [ 3 , 4 ], energy absorption [ 5 , 6 ], thermal insulation materials [ 7 , 8 ], ultrahigh temperature structural materials [ 9 ], electrolyte isolation [ 10 ], electromagnetic interference (EMI) shielding [ 11 ] and other energy and environmental technology fields. The key technology for producing novel porous ceramics with improved functions is to realize the interconnectivity and controllable preparation of complex microstructure units, which is also a challenge for the development of preparation technology of porous ceramics [ 12 ].…”

Section: Introductionmentioning

confidence: 99%

Effects of Filling Rate and Resin Concentration on Pore Characteristics and Properties of Carbon Based Wood Ceramics

Guo

Gao

et al. 2021

Materials

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As a kind of novel porous ceramics, wood ceramics can be used for filtration, friction, energy storage and electrode materials, etc. In current work, the carbon based wood ceramics (C WCMs) was prepared using pine wood powder and phenolic resin as starting materials. The effects of filling rate of wood powder and resin concentration on pore characteristics and properties of C WCMs were characterized and analyzed with different techniques. Furthermore, the association among porosity of C WCMs, filling rate of wood powder and resin concentration was explored with multiple regression model. The results showed that: increasing the resin concentration and the filling rate of wood powder can improve the mechanical properties of C WCMs, but reduce the porosity and air permeability; when resin concentration is more than 50%, a large amount of caking will appear in the C WCMs, causing internal defects; changing the filling rate under a certain resin concentration can obtain the C WCMs with better pore structure; the porosity of C WCMs has a good linear relationship with resin concentration and filling rate, under the condition that sintering process and the size of wood powder are determined.

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“…Among those methods, partial sintering is the most simple, considerable, and efficient method, which has been successfully employed to produce porous oxide ceramics (e.g., Al 2 O 3 ) and non-oxide ceramics (e.g., Si 3 N 4 , YbB 6 , YB 4 ). [16][17][18][19] The products generated by using this method have homogeneous pore structure with narrow pore size distributions without impurities introduced, 20,21 and the porosity can be controlled by simply adjusting the processing parameters. 15,22 Boron-mullite Al 5 BO 9 possesses a unique combination of wide band gap, low density, low thermal conductivity and high strength, which is prospective as ceramic wafer seal structure and porous high-temperature wavetransparent material of hypersonic vehicles.…”

Section: Introductionmentioning

confidence: 99%

“…Porous materials can be prepared by several processes including partial sintering, sacrificial fugitives, replica templates, and direct foaming, 13–15 and so forth. Among those methods, partial sintering is the most simple, considerable, and efficient method, which has been successfully employed to produce porous oxide ceramics (e.g., Al 2 O 3 ) and non‐oxide ceramics (e.g., Si 3 N 4 , YbB 6 , YB 4 ) 16–19 . The products generated by using this method have homogeneous pore structure with narrow pore size distributions without impurities introduced, 20,21 and the porosity can be controlled by simply adjusting the processing parameters 15,22 …”

Section: Introductionmentioning

confidence: 99%

Preparation and properties of porous Al₅BO₉ for high‐temperature wave‐transparent and thermal insulating applications

Ren

Dai

Xiang

et al. 2021

Int J Applied Ceramic Tech

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Porous Al 5 BO 9 is a promising high-temperature wave-transparent material. However, method for the preparation of this material is not readily available.Herein, porous Al 5 BO 9 ceramics with controlled porosity and small volume shrinkage are successfully prepared by using Al 2 O 3 and B 2 O 3 as starting materials without pore formers. The SEM and pore size distribution studies show that the as-prepared porous Al 5 BO 9 ceramics exhibit a uniform pore structure and a narrow pore size distribution. Intriguingly, simply adjusting the densities of the green bodies, the density and porosity of the porous Al 5 BO 9 ceramics can be controlled. The pore-forming mechanism is presumed to be a combination of boron oxide volatilization during the high-temperature synthesis and lap of elongated grains. Porous Al 5 BO 9 ceramics have good high-temperature stability, which can maintain dimensional and composition stability up to 1673 K. The compressive strength can reach 211 MPa at 32.4% porosity and the dielectric constant can be as low as 3.02 at 43.2% porosity. In addition, the dielectric constant and loss tangent keep almost unchanged with temperature.

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Preparation of porous YB4 ceramics using a combination of in-situ borothermal reaction and high temperature partial sintering

Cited by 27 publications

References 30 publications

High-entropy ceramics: Present status, challenges, and a look forward

High-entropy ceramics: Present status, challenges, and a look forward

Effects of Filling Rate and Resin Concentration on Pore Characteristics and Properties of Carbon Based Wood Ceramics

Preparation and properties of porous Al₅BO₉ for high‐temperature wave‐transparent and thermal insulating applications

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Preparation of porous YB4 ceramics using a combination of in-situ borothermal reaction and high temperature partial sintering

Cited by 27 publications

References 30 publications

High-entropy ceramics: Present status, challenges, and a look forward

High-entropy ceramics: Present status, challenges, and a look forward

Effects of Filling Rate and Resin Concentration on Pore Characteristics and Properties of Carbon Based Wood Ceramics

Preparation and properties of porous Al5BO9 for high‐temperature wave‐transparent and thermal insulating applications

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Preparation and properties of porous Al₅BO₉ for high‐temperature wave‐transparent and thermal insulating applications