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Bao, Xujin; Nangrejo, M.; Edirisinghe, Mohan

doi:10.1023/a:1004666326039

Cited by 35 publications

(6 citation statements)

References 18 publications

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“…The specimens possessed a quite complex morphology, as was the case for samples obtained using a similar fabrication procedure which were investigated in previous studies. [9,10] In addition to large cells of a few hundred microns in size (up to about 600 lm), a large amount of smaller, micron sized pores (∼ 5 lm) and cavities were present. Interestingly, the increase in the PDMS amount in the blends did not seem to significantly affect the mean pore size for both systems (PMS and PMPS).…”

Section: Resultsmentioning

confidence: 99%

“…[8] In recent years, it has been shown that blending preceramic polymers with different characteristics (molecular weight, molecular architecture, ceramic yield) allows to produce cellular ceramics. [9,10] This paper further explores this possibility, with the specific aim of directly developing a large amount of porosity within the resulting ceramic body during a one-step pyrolysis treatment.…”

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confidence: 99%

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A Direct Method for the Fabrication of Macro‐Porous SiOC Ceramics from Preceramic Polymers

Vakifahmetoğlu

Colombo

2008

Adv Eng Mater

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Cellular ceramics, possessing both open or closed porosity, find use in several demanding engineering applications because of their favorable set of properties.[1] Several processing methods have been proposed for their fabrication, including the replication of the structure of polymeric foams, direct blowing, the use of sacrificial fillers, extrusion through special dies (for honeycombs), solid freeform techniques, the mimicking of natural templates (e.g. wood) or the assemblage of fibers or hollow bodies.[2,3] Preceramic polymers, in particular silicones, have been successfully used for obtaining ceramic components (such as foams and membranes) possessing a large amount of porosity, in the micro-, meso- and macro-size scale.[4, and references therein] However, some of the fabrication methods have some limitations: for instance, direct foaming techniques often lead to a gradient in the porosity amount and pore size along the main expansion axis;[5,6] the infiltration of a silicone resin within organic sacrificial fillers requires a burn out step that has to be carried out in a very controlled fashion in order to produce components without defects (besides often requiring warm pressing – depending on the rheological characteristics of the preceramic polymer – to obtain a well controlled morphology), thus limiting the size and shape of the component that can be produced;[7] the use of supercritical CO2 is regulated by the diffusion within the solid polymer, and works well only for components of limited thickness.[8] In recent years, it has been shown that blending preceramic polymers with different characteristics (molecular weight, molecular architecture, ceramic yield) allows to produce cellular ceramics.[9,10] This paper further explores this possibility, with the specific aim of directly developing a large amount of porosity within the resulting ceramic body during a one-step pyrolysis treatment

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Section: Resultsmentioning

confidence: 99%

mentioning

confidence: 99%

A Direct Method for the Fabrication of Macro‐Porous SiOC Ceramics from Preceramic Polymers

Vakifahmetoğlu

Colombo

2008

Adv Eng Mater

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“…6(a) [148]. Bao et al [149] processed SiC foams by using volatiles, as a pore former, which were generated by the decomposition of the polymeric precursors. It was possible to control the porosity of the SiC ceramics by controlling the gas evaporation by tailoring the composition and structure of the polymeric precursors.…”

Section: Direct Foaming Methodsmentioning

confidence: 99%

Processing and properties of macroporous silicon carbide ceramics: A review

Eom

Kim

Raju

2013

Journal of Asian Ceramic Societies

321

162

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Macroporous silicon carbide is widely used in various industrial applications including filtration for gas and water, absorption, catalyst supports, concentrated solar power, thermoelectric conversion, etc. During the past several years, many researchers have found diverse routes to fabricate macroporous SiC with porosity ranging from 9% to 95%. This review presents a detailed discussion on processing techniques such as partial sintering, replica, sacrificial template, direct foaming, and bonding techniques, as well as the mechanical and thermal properties of macroporous SiC ceramics fabricated using these methods. The full potential of these materials can only be achieved when properties are tailored for a specific application, whereas the control over these properties is highly dependent on the processing route. From the collected data, we have found that the porosity ranges from 9% to 91% with flexural strength of 1-205 MPa, compressive strength of 1-600 MPa, fracture toughness of 0.3-4.3 MPa m 1/2 , and thermal conductivity of 2-82 W/(m•K). This review will enlighten future investigations on processing of porous SiC and its usage in various applications.

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“…It was demonstrated that the features of the produced ceramic foams were dependent on the composition and the structure of the pyrolyzed precursors. The polymers with higher functionalities gave higher pyrolytic yields due to cross-linking or branched structures formed during polymerization and pyrolysis [17,76,79]. The higher microbead content in the polycarbosilane precursor led to a larger number of cells, lower bulk density, and higher porosity, while enhanced densification of strut at high-temperature pyrolysis resulted in flexural strength as high as ∼30 MPa at 70% porosity [66,78].…”

Section: Sacrificial Templatementioning

confidence: 99%

“…The processing of porous ceramics using preceramic polymers offers many advantages compared to ceramic powders. These include (i) low processing temperatures or low energy consumption for the synthesis compared to high temperatures required for sintering of ceramic powders [13][14][15][16][17], (ii) no additives required for densification [1,4], (iii) a variety of low-cost plastic-forming techniques can be applied with easy control over rheological properties by modified molecular architecture; important plastic-forming techniques include injection molding, extrusion, resin transfer molding, melt spinning [4,9,15], (iv) machining before ceramization can be avoided, thereby reducing tool wear and brittle fracture [1,5,10], (v) easy handling before heat treatment, because preceramic polymers can effectively bind the parts at low temperatures [10], (vi) utilization of unique polymeric properties that cannot be found in ceramic powders, such as appreciable plasticity, in situ gas evolution ability, appreciable CO 2 solubility, and appreciable solubility of preceramic polymers in organic solvents [9,10,18,19], (vii) nanostructures (wires, belts, tubes, etc) can be created directly during the pyrolysis of catalyst-containing preceramic polymers [10,11], and (viii) ceramic products containing unique combination of polymer-like nanostructures with ceramic-like properties (hardness, creep resistance and oxidation resistance) can be obtained [6,9,10]. Hence, several polymers with different substituents were synthesized, blended and used as precursors for fabricating a variety of porous ceramics such as zirconia, alumina, silica, silicon carbide, silicon oxycarbide, mullite, cordierite, etc.…”

Section: Introductionmentioning

confidence: 99%

Processing of polysiloxane-derived porous ceramics: a review

Kumar

Kim

2010

Science and Technology of Advanced Materials

109

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Because of the unique combination of their attractive properties, porous ceramics are considered as candidate materials for several engineering applications. The production of porous ceramics from polysiloxane precursors offers advantages in terms of simple processing methodology, low processing cost, and easy control over porosity and other properties of the resultant ceramics. Therefore, considerable research has been conducted to produce various Si(O)C-based ceramics from polysiloxane precursors by employing different processing strategies. The complete potential of these materials can only be achieved when properties are tailored for a specific application, whereas the control over these properties is highly dependent on the processing route. This review deals with processing strategies of polysiloxane-derived porous ceramics. The essential features of processing strategies-replica, sacrificial template, direct foaming and reaction techniques-are explained and the available literature reports are thoroughly reviewed with particular regard to the critical issues that affect pore characteristics. A short note on the cross-linking methods of polysiloxanes is also provided. The potential of each processing strategy on porosity and strength of the resultant SiC or SiOC ceramics is outlined.

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Cited by 35 publications

References 18 publications

A Direct Method for the Fabrication of Macro‐Porous SiOC Ceramics from Preceramic Polymers

A Direct Method for the Fabrication of Macro‐Porous SiOC Ceramics from Preceramic Polymers

Processing and properties of macroporous silicon carbide ceramics: A review

Processing of polysiloxane-derived porous ceramics: a review

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