Pore structure and thermal oxidation curing behavior of porous polymer derived ceramics with superhigh porosity fabricated by freeze casting

Li, Fuping; Zhao, Linna; Dang, Wei; Xu, Zhuoli; Zhao, Kang; Min-biao, Xue; Tang, Yufei

doi:10.1016/j.ceramint.2021.07.285

Cited by 9 publications

(6 citation statements)

References 44 publications

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“…The SEM images show the formation of a dendritic pore morphology which typically occurs when cyclohexane is used as a solvent during freeze-casting [ 33 , 37 ]. The lateral view of the pores shows an aligned pore structure with primary dendritic arms (bigger pore size) and secondary dendritic arms (smaller pore size) parallel and perpendicular to the mass transport direction, respectively.…”

Section: Resultsmentioning

confidence: 99%

SiOC Screens with Aligned and Adjustable Pore Structure for Screen Channel Liquid Acquisition Device

et al. 2023

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The development of porous ceramic screens with high chemical stability, low density, and thermal conductivity can lead to promising screen channel liquid acquisition devices (SC-LADs) for propellant management under microgravity conditions in the future. Therefore, SiOC screens with aligned pores were fabricated via freeze-casting and applied as a SC-LAD. The pore window sizes and open porosity varied from 6 µm to 43 µm and 65 % or 79 %, depending on the freezing temperature or the solid loading, respectively. The pore window size distributions and bubble point tests indicate crack-free screens. On the one hand, SC-LADs with an open porosity of 79 % removed gas-free liquid up to a volumetric flow rate of 4 mL s−1. On the other hand, SC-LADs with an open porosity of 65 % were limited to 2 mL s−1 as the pressure drop across these screens was relatively higher. SC-LADs with the same open porosity but smaller pore window sizes showed a higher pressure drop across the screen and bubble ingestion at higher values of effective screen area when increasing the applied removal volumetric flow rate. The removed liquid from the SC-LADs was particle-free, thus representing a potential for applications in a harsh chemical environment or broad-range temperatures.

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Section: Resultsmentioning

confidence: 99%

SiOC Screens with Aligned and Adjustable Pore Structure for Screen Channel Liquid Acquisition Device

et al. 2023

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“…Organic matter in pectin was repelled and concentrated by the growing solidification front and separated between ice crystals. After the ice crystals sublimated, the pore structure was obtained, 25 as shown in Figure 7A.…”

Section: Resultsmentioning

confidence: 99%

“…In recent years, the preparation of porous ceramics by sol gel method, 9 freeze casting method, [10][11][12][13][14][15] and gel freezing [16][17][18][19][20][21] method has recently been reported by many researchers. However, among these methods tert-butanol, cyclohexane, camphene, diphenyl methane, and dioxane are often used as solvents, [22][23][24][25][26] and N, N'methylene-bisacrylamide, acrylamide, divinylbenzene, and triethanolamine lauryl sulfate are often used as monomers, cross-linking agents and foaming agents. [27][28][29] Most of these chemical reagents are toxic or expensive, contrary to economic, and green environmental protection requirements.…”

Section: Introductionmentioning

confidence: 99%

High gas permeability and directional channels of mullite porous ceramics prepared by pectin‐based freeze‐drying method

Liu

Yuan

Tian

et al. 2023

Int J Applied Ceramic Tech

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New gel system for preparing mullite porous ceramics by gel‐casting freeze‐drying was proposed, using pectin as gel source and alumina and silica as raw materials. Directional channels were formed due to sublimation of water during freeze‐drying and decomposition of pectin during high temperature sintering to prepare porous mullite ceramic membranes. Effects of solid content on the properties of mullite ceramics in terms of phase composition, microstructure, apparent porosity, bulk density, pore size distribution, compressive strength, thermal conductivity, pressure drop, and gas permeability were investigated. It was found that prepared porous mullite possessed high apparent porosity (56.04%–75.34%), low bulk density (.77–1.37 g/cm3), uniform pore size distribution, relatively high compressive strength (.61–3.03 MPa), low thermal conductivity (.224–.329 W/(m·K)), high gas permeability coefficient (1.11 × 10−10–4.73 × 10−11 m2), and gas permeance (2.18 × 10−2–9.32 × 10−3 mol⋅m−2⋅s−1⋅Pa−1). These properties make prepared lightweight mullite ceramic membranes promising for application in high temperature flue gas filtration. Proposed gel system is expected to provide a new route to prepare porous ceramics with high porosity and directional channels.

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“…34 Typical technologies for producing porous ceramics mainly involve direct foaming method, freeze casting method, sacrificial template method, additive manufacturing technique, reaction sintering, and so forth. [35][36][37][38][39] Direct foaming method can be used to prepare porous ceramics with both high strength and high porosity, and there is no discharge of hazardous waste during the preparation process. 40 Generally, mechanical agitation or chemical reaction are utilized during direct foaming method, thus physical foaming agents involving amphiphiles, surfactants, proteins, modified colloidal particles used to tune surface tension as well as chemical foaming agents are contained.…”

Section: Introductionmentioning

confidence: 99%

“…Open pores have the functions of filtering and adsorption, whereas closed pores have the characteristics of heat insulation and blocking sound 34 . Typical technologies for producing porous ceramics mainly involve direct foaming method, freeze casting method, sacrificial template method, additive manufacturing technique, reaction sintering, and so forth 35–39 . Direct foaming method can be used to prepare porous ceramics with both high strength and high porosity, and there is no discharge of hazardous waste during the preparation process 40 .…”

Section: Introductionmentioning

confidence: 99%

Porous ceramics with near‐zero shrinkage and low thermal conductivity from hazardous secondary aluminum dross

Zhang

Shen

et al. 2022

J Am Ceram Soc

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Herein, a simple, versatile, and low-cost approach has been proposed to realize the green utilization of secondary aluminum dross, the hazardous solid waste, namely directly sintering dry-pressed green bodies from secondary aluminum dross to fabricate porous ceramics according to high-temperature foaming process spontaneously without adding spare foaming agents. Aluminum nitride (AlN) in secondary aluminum dross was employed to realize high-temperature foaming due to its oxidation, which makes traditional AlN and salts removal process needless. Moreover, near-zero shrinkage or even expansion during sintering of porous ceramics have occurred because in-situ foaming process together with the oxidation of Al particles well offset the sintering shrinkage. After sintering at 1400 • C for 2 h, porous ceramics composed of α-Al 2 O 3 and spinel phases with open porosity of 37.91%, sintering expansion rate of 1.13%, flexural strength of 45.67 MPa, and thermal conductivity of 0.97 W/(m⋅K) have been prepared. Cenospheres as pore-forming agents have been added to further improve the porosity, and alumina-based porous ceramics with open porosity of 28.39%-43.20% and flexural strength of 15.80-52.48 MPa have been obtained. This effective solution for recycling secondary aluminum dross could supply high-performance porous ceramics, which is expected to be applied in the fields of light-weight structural components and thermal insulations.

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Pore structure and thermal oxidation curing behavior of porous polymer derived ceramics with superhigh porosity fabricated by freeze casting

Cited by 9 publications

References 44 publications

SiOC Screens with Aligned and Adjustable Pore Structure for Screen Channel Liquid Acquisition Device

SiOC Screens with Aligned and Adjustable Pore Structure for Screen Channel Liquid Acquisition Device

High gas permeability and directional channels of mullite porous ceramics prepared by pectin‐based freeze‐drying method

Porous ceramics with near‐zero shrinkage and low thermal conductivity from hazardous secondary aluminum dross

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