Elaboration of low shrinkage mullite by active filler controlled pyrolysis of siloxanes

Michalet, Thibaut; Parlier, M.; béclin, franck; Duclos, R.; Crampon, J.

doi:10.1016/s0955-2219(01)00251-5

Cited by 33 publications

(45 citation statements)

References 25 publications

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“…This method consists of the impregnation of a polymeric foam with a ceramic slurry followed by a burnout of the organic material and the sintering of the ceramic skeleton. The resulting material is a negative replica of the foam with fully open porosity 5,12,13 . The composite materials obtained by this technique have low shrinkage, good properties and homogeneous microstructure 6,7 .…”

Section: Introductionmentioning

confidence: 99%

Using lithium glass infiltration to enhance the properties of alumina bodies

Acchar

Queiroz

2008

Mat. Res.

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The use of an infiltration process to improve the properties of sintered materials has been widely investigated. This work describes the research carried out in the manufacturing of lithium glass-infiltrated alumina. The infiltration material consisted of a mixture of elements such as Li 2 O, ZrO 2 , SiO 2 Al 2 O 3, CaO and La 2 O 3 . Alumina specimens were sintered in air at 1400 °C for 2 hours. A number of samples were then submitted to the infiltration process at 1400 °C for 15 minutes. Sintered and infiltrated specimens were characterized by X ray diffraction, apparent density, open porosity, flexural strengths and scanning electron microscopy. The results showed that the infiltration process considerably improves the properties of alumina bodies.

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Section: Introductionmentioning

confidence: 99%

Using lithium glass infiltration to enhance the properties of alumina bodies

Acchar

Queiroz

2008

Mat. Res.

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“…By pyrolysis of preceramic precursors such as polysiloxanes, silicon oxycarbide (SiOC) glasses, that contain silicon atoms bonded to oxygen and carbon randomly, can be produced. 7,12,13 Polysiloxane-derived silicon oxycarbide glasses have random three dimensional arrangement of tetrahedral silicon atoms bonded to carbon and oxygen. Thermomechanical properties of the silica glasses can be improved with the replacement of divalent oxygen atoms by tetravalent carbon atoms in silica structure.…”

Section: Introductionmentioning

confidence: 99%

“…To compensate these effects and to control shrinkage, crack and pore formation, a relatively new concept, active filler controlled polymer pyrolysis process (AFCOP) has been developed by several researchers. [4][5][6][7][8][9]13 In this method, the polymer is partially filled with inert or active particles in order to reduce the shrinkage and to allow the fabrication of bulk, crack free ceramics. By incorporation of the active fillers, reactions between the active particles and the precursor occur, which typically result in a volume expansion of the reaction product, as compared to the starting compounds.…”

Section: Introductionmentioning

confidence: 99%

“…Suitable active fillers are elements or compounds such as Al, B, Si, Ti, CrSi 2 , and MoSi 2 to obtain carbide, nitride, or oxide reaction products. 4,6,7,13 In the present work, phenyl and methyl containing polysiloxanes were pyrolyzed by the addition of active Ti particles to develop SiOC-based CMCs. CMC composite monoliths were fabricated with the addition of 60-80 wt.% of Ti fillers by warm pressing under 15 MPa pressure and pyrolysis at elevated temperatures between 900 and 1500 • C under inert argon and reactive nitrogen atmospheres.…”

Section: Introductionmentioning

confidence: 99%

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Silicon oxycarbide-based composites produced from pyrolysis of polysiloxanes with active Ti filler

Akkaş

Öveçoğlu

Tanoğlu

2006

Journal of the European Ceramic Society

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Phenyl (PPS) and methyl (PMS) containing polysiloxanes were pyrolyzed at elevated temperatures (900-1500• C) under argon atmosphere to investigate the phase developments within the polymers. It was found that pyrolysis of the polymers under inert atmosphere up to 1300• C leads to amorphous silicon oxycarbide (SiO x C y ) ceramics. Conversions at higher temperatures results in the transformations into the crystalline ␤-SiC phases. Ceramic matrix composites (CMCs) were developed based on the active filler controlled pyrolysis (AFCOP) of polysiloxanes with active Ti filler additions. CMC monoliths were prepared with 60-80 wt.% of active Ti particulates blended into polymer precursors. Green bodies of the composites were made by warm pressing under 15 MPa pressure and ceramics were obtained by pyrolysis at elevated temperatures between 900 and 1500• C under argon atmosphere. The results showed that due to the incorporation of active Ti fillers, formation of crystalline phases such as TiC, TiSi, and TiO occured within the amorphous matrix due to the reactions between the Ti and the polymer decomposition products. The microstructural and mechanical characterization results of the composites are presented within the paper.

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“…[9][10][11][12] There are many examples, where a combination of a polysiloxane with a metal or a metal salt was used to prevent shrinkage, crack and pore formation of the resulting dense ceramic following the active filler controlled polymer pyrolysis concept (AFCOP). [2,13,14] Other groups used metal salts to introduce electrical conductivity or magnetic properties to SiOC materials [15] or investigated the Ni catalysed formation of carbon nanotubes in the resulting ceramics, which was observed applying temperatures beyond 800°C. [16] The size of Ni nanoparticles (< 1 wt.%) formed during pyrolysis from methylphenyl polysiloxanenickel acetate precursor came up with average diameters of 40-60 nm.…”

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Synthesis and Properties of Porous Hybrid Materials containing Metallic Nanoparticles

et al. 2008

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The pyrolysis of preceramic polymers like polysiloxanes provides the possibility of manufacturing ceramics at lower temperatures (500-1500°C) compared to the powder sintering route and of using versatile polymer shaping routes, what has attracted a growing attention in the last decade. [1] Ceramic products with different structures and functions (e.g. bulk materials, [2] composites, [3] coatings [4] and foams [5] ) were manufactured by this route and their properties (e.g. oxidation and thermal resistance, [6] electrical conductivity [7] ) can be altered by tailoring the molecular structure of the precursor and by loading the polymer with filler particles. [8] The transformation of polysiloxanes [RSiO 3/2 ] carrying hydrocarbon groups (R = methyl, phenyl, vinyl) in an inert atmosphere is well investigated and results in the formation of an amorphous silicon oxycarbide (SiOC, 800-1000°C), which decomposes to a ceramic consisting of SiC, SiO 2 and graphite at higher temperatures (1400-1500°C). [9][10][11][12] There are many examples, where a combination of a polysiloxane with a metal or a metal salt was used to prevent shrinkage, crack and pore formation of the resulting dense ceramic following the active filler controlled polymer pyrolysis concept (AFCOP). [2,13,14] Other groups used metal salts to introduce electrical conductivity or magnetic properties to SiOC materials [15] or investigated the Ni catalysed formation of carbon nanotubes in the resulting ceramics, which was observed applying temperatures beyond 800°C. [16] The size of Ni nanoparticles (< 1 wt.%) formed during pyrolysis from methylphenyl polysiloxanenickel acetate precursor came up with average diameters of 40-60 nm.A partial conversion of polysiloxane precursors below 800°C yields novel hybrid materials, which often exhibit high porosities and are therefore considered to be potential materials for adsorption and for catalyst supports. However, an adjusted design or functional testing of these hybrid materials in terms of sorption behaviour or catalytic activity has only been performed in far cases. [17] The current study focuses on the use of Ni and Pt containing polysiloxanes for preparation of highly porous hybrid materials (so called "ceramers") by inert gas pyrolysis (400-600°C) for use as adsorbent and as catalyst. In order to realize a homogeneous distribution of metallic particles at high metal contents 3-aminopropyltriethoxysilane was used for complexation of metal ions also in the combination with varying amounts of phenyltriethoxysilane. At the same time it was of interest how the different polarity of the siloxanes used for precursor preparation influenced the surface characteristic (hydrophilic/hydrophobic) of the resulting ceramers. These surface characteristics were examined in sorption experiments and first catalytic measurements revealed the catalytic activity of these ceramers. Experimental Synthesis of Polysiloxane Precursors and Processing of CeramersFor the synthesis of metal containing polysiloxane precursors 3-aminopropyltr...

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Elaboration of low shrinkage mullite by active filler controlled pyrolysis of siloxanes

Cited by 33 publications

References 25 publications

Using lithium glass infiltration to enhance the properties of alumina bodies

Using lithium glass infiltration to enhance the properties of alumina bodies

Silicon oxycarbide-based composites produced from pyrolysis of polysiloxanes with active Ti filler

Synthesis and Properties of Porous Hybrid Materials containing Metallic Nanoparticles

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