Synthesis of dense silicon-based ceramics at low temperatures

Riedel, Ralf; Passing, G.; Schönfelder, H.; Brook, R. J.

doi:10.1038/355714a0

Cited by 331 publications

(183 citation statements)

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“…As previously reported, the size and distribution of the pores of the PDCs depend on the precursor and the pyrolysis condition. 38 The volatilization of large organic molecules or oligomers causes the formation of defects such as pores and cracks, while the mass loss of the material caused by the thermal decomposition during pyrolysis is leading to shrinkage of the ceramic in comparison to the green body. The decomposition products from the SiBCN material during the main step in the mass loss from 400 to 650c C were relatively small molecules, methane and hydrogen, and the thin film was densified by the further pyrolysis up to 1100c C Fig.…”

mentioning

confidence: 99%

Polymer-Derived SiBCN Ceramic and their Potential Application for High Temperature Membranes Dedicated to Prof. Dr.-Ing. Dr.h.c. Hartmut Fuess on the occasion of his 65th birthday

Hauser

Nahar-Borchard

Riedel

et al. 2006

J. Ceram. Soc. Japan

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A novel preceramic polymer suitable to form a SiBCN ceramic was synthesized by hydroboration reaction of 1,3,5-trivinyl-1,3,5-trimethyl-cyclotrisilazane with borane dimethylsulphide. The obtained polymer denoted as polyborosilazane was characterised by FT-IR and NMR spectroscopy and its thermal stability was studied by thermal gravimetric analysis in combination with in situ mass spectrometry TGMS. The polymer-to-ceramic transformation was achieved at 1050c C in inert argon atmosphere yielding black and X-ray amorphous SiBCN ceramics thermally stable up to 1800c C. Using the dip-coating technique, a SiBCN ceramic thin film was formed on a porous alumina substrate. N 2 sorption isotherm analysis revealed that the thin film contained a small amount of micropores of about 0.6 nm in diameter, as well as mesopores between 2.7 and 6 nm in size. The total pore volume was found to be about three orders of magnitude smaller than that of a hydrogen permselective amorphous silica membrane derived from polysilazane. These results indicated potential application of the SiBCN thin film as a molecular sieve membrane suitable for high-temperature separation of small gas molecules like hydrogen below 0.3 nm in size.

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mentioning

confidence: 99%

Polymer-Derived SiBCN Ceramic and their Potential Application for High Temperature Membranes Dedicated to Prof. Dr.-Ing. Dr.h.c. Hartmut Fuess on the occasion of his 65th birthday

Hauser

Nahar-Borchard

Riedel

et al. 2006

J. Ceram. Soc. Japan

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“…The system of Si 3 B 3 C 3 N 4 corresponds to the one where a part of N atoms in Si 3 B 3 N 7 are replaced by carbon atoms. To create an initial structure for MD, a random mixture with a composition of Si 3 N 4 , Si 3 B 3 N 7 or Si 3 B 3 C 3 N 4 in a cubic simulation box was generated, where the density was 2.5 g/cm 3 . This is because several experimental studies of precursor-derived amorphous Si 3 N 4 -based materials showed a density of around 2.5 g/cm 3 .…”

Section: Computational Proceduresmentioning

confidence: 99%

“…To create an initial structure for MD, a random mixture with a composition of Si 3 N 4 , Si 3 B 3 N 7 or Si 3 B 3 C 3 N 4 in a cubic simulation box was generated, where the density was 2.5 g/cm 3 . This is because several experimental studies of precursor-derived amorphous Si 3 N 4 -based materials showed a density of around 2.5 g/cm 3 . The system of Si 3 N 4 contains 896 atoms, while those of Si 3 B 3 N 7 and Si 3 B 3 C 3 N 4 have 832 atoms.…”

Section: Computational Proceduresmentioning

confidence: 99%

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Atomic Structure and Diffusion in Amorphous Si-B-C-N by Molecular Dynamics Simulation

2002

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We carried out molecular dynamics simulation of amorphous silicon nitride containing boron and carbon, in order to investigate the short-range atomic arrangement and diffusion behavior. In amorphous Si-B-N, boron atoms are in a nearly threefold coordinated state with nitrogen atoms, while boron atoms in amorphous Si-B-C-N have bonding with both carbon and nitrogen atoms. Carbon atoms in Si-B-C-N are also bonded to silicon atoms. The self-diffusion constant of nitrogen in Si-B-N becomes much smaller than that in amorphous Si 3 N 4 . Also, amorphous Si-B-C-N exhibits smaller self-diffusion constants of constituent atoms, even compared to Si-B-N. Addition of boron and carbon is important in decreasing atomic mobility in amorphous Si-B-C-N. This may explain the increased thermal stability of the amorphous state observed experimentally.

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“…[4][5][6] Bulk amorphous ceramics such as Si-C-N and Si-B-C-N have been developed by pyrolyzing the isostatically pressed and warm pressed preceramic powders. [7][8][9][10][11] However, it is difficult to fabricate no porosity ceramic monoliths by these processes since porosity is necessary to remove the gas species during pyrolysis.…”

Section: Introductionmentioning

confidence: 99%

Compressive Deformation of Partially Crystallized Amorphous Si-B-C-N Ceramics at Elevated Temperatures

Ishihara¹,

Hirayama²,

Aldinger

et al. 2003

Mater. Trans.

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The deformation behavior of Si-B-C-N ceramics derived from a polymer precursor has been investigated by compression tests at high temperatures. The hot isostatic pressing of pyrolyzed powder compact was conducted at 1450 C and at 900 MPa in order to obtain a dense ceramic monolith. The material consisted of the amorphous matrix and the dispersed Si 3 N 4 particles with the diameter of about 20 nm. While only apparent elastic deformation was observed at the testing temperatures up to 1500 C, significant plastic deformation occurred at temperatures higher than 1650 C. The plastic deformation is considered to be caused by the viscous flow of the amorphous matrix. The flow stress at the testing temperatures in the range of 1650 to 1750 C increased with initial strain rate. The flow stress was not proportional to the strain rate. The shear viscosity at 0.02 strain was about 10 11 -10 13 Pa s and decreased proportionally to about À0:75 power of the strain rate. The decrease in shear viscosity is considered to show a strain localization behavior. Strain hardening was observed during the plastic deformation. As the reason of the strain hardening, the crystallization can be considered, in addition to the decrease in atomic site defects during the deformation.

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Synthesis of dense silicon-based ceramics at low temperatures

Cited by 331 publications

References 9 publications

Polymer-Derived SiBCN Ceramic and their Potential Application for High Temperature Membranes Dedicated to Prof. Dr.-Ing. Dr.h.c. Hartmut Fuess on the occasion of his 65th birthday

Polymer-Derived SiBCN Ceramic and their Potential Application for High Temperature Membranes Dedicated to Prof. Dr.-Ing. Dr.h.c. Hartmut Fuess on the occasion of his 65th birthday

Atomic Structure and Diffusion in Amorphous Si-B-C-N by Molecular Dynamics Simulation

Compressive Deformation of Partially Crystallized Amorphous Si-B-C-N Ceramics at Elevated Temperatures

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