Synthesis of biomorphic SiC and SiO2 ceramics

Coniferous wood (fir) was transformed by pyrolysis into carbon preforms, which were subsequently converted into biomorphic ceramics by the pressure infiltration technique with colloidal silica. An in situ reaction between the silica and the carbon template occurred in the cellular wall at a high sintering temperature. Depending on the employed atmosphere, non-oxide (SiC) or oxide (SiO2) ceramics were obtained. The morphology of the resulting porous ceramics and their phase composition were investigated by scanning electron microscopy (SEM/EDX) and X-ray diffraction (XRD). The experimental results showed that the biomorphic cellular morphology of the wood maintained in both the SiC and silica ceramics, which consisted of only the b-SiC phase and SiO2, respectively. .

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Synthesis of biomorphic Si-based ceramics

Processing and Application of Ceramics ◽

10.2298/pac0904197e ◽

2009 ◽

Vol 3 (4) ◽

pp. 197-201

Author(s):

Adela Egelja ◽

Aleksandar Devecerski ◽

Jelena Gulicovski ◽

Milena Rosic ◽

Biljana Babic ◽

...

Keyword(s):

Crystal Structure ◽

Mercury Porosimetry ◽

X Ray Diffraction ◽

X Ray ◽

Carbon Preform ◽

Carbon Template ◽

Cellular Wall ◽

Biomorphic Ceramics ◽

Scanning Electron

Tilia wood was transformed by pyrolysis into carbon preform. This porous carbon preform was infiltrated with TEOS (Si(OC2H5)4), as a source of silica. In situ reaction between the silica and the carbon template occurred in the cellular wall at a hight temperature. Depending on the applied atmosphere, non-oxide (SiC) or oxide (SiO2) ceramics were obtained. Scanning electron microscopy (SEM), X-ray diffraction (XRD), infrared (IR) spectroscopy, mercury porosimetry and BET measurements were employed to characterize the phases and crystal structure of biomorphic ceramics. The experimental results showed that the biomorphic cellular morphology of the wood maintained in both the SiC and SiO2 ceramics, wich consisted of ?-SiC with trace of ?-SiC and SiO2, respectively. .

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Study of Preforms of Quartzite for Production of Ceramic Matrix Composites

Materials Science Forum ◽

10.4028/www.scientific.net/msf.591-593.430 ◽

2008 ◽

Vol 591-593 ◽

pp. 430-435

Author(s):

Adriana Scoton Antonio Chinelatto ◽

R. Justus ◽

Adilson Luiz Chinelatto ◽

F.M.C.N. Nadal ◽

E.A.T. Berg

Keyword(s):

Squeeze Casting ◽

Ceramic Matrix Composites ◽

Ceramic Matrix ◽

Matrix Composites ◽

X Ray Diffraction ◽

Flexure Strength ◽

Pressure Infiltration ◽

X Ray ◽

Infiltration Technique ◽

Sufficient Strength

The ceramic matrix composites (CMCs) can be fabricated by the pressure infiltration technique. In this work it was studied porous preforms of quartzite that were infiltrated with aluminum liquid. For to produce the more resistant preforms of quartzite, it was additioned different quantities of bentonite (5 and 10%) and the preforms were firing at 1100°C and 1200°C. For the composites production, the melted aluminum was introduced into preforms under a pressure of 7 MPa. The characterizations of the composites were made by X-ray diffraction, scanning electron microscopy, and flexure strength. All the preforms studied presented sufficient strength for support the pressing during the process of squeeze casting. The results of X-ray diffraction of composites showed the presence of alumina, silicon and aluminum and fully interpenetration aluminum-siliconalumina composites were obtained by infiltration.

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Synthesis and Characterization of Magnesium Aluminate Spinel Porous Ceramics by Novel Molten Salt Method

Key Engineering Materials ◽

10.4028/www.scientific.net/kem.697.399 ◽

2016 ◽

Vol 697 ◽

pp. 399-403 ◽

Cited By ~ 3

Author(s):

Xian Gong Deng ◽

Jun Kai Wang ◽

Hai Jun Zhang ◽

Jiang Hao Liu ◽

Shao Wei Zhang

Keyword(s):

Molten Salt ◽

Porous Ceramics ◽

Magnesium Aluminate ◽

Molten Salt Method ◽

Magnesium Aluminate Spinel ◽

X Ray Diffraction ◽

Liquid Environment ◽

X Ray

Magnesium aluminate spinel (MgAl2O4) porous ceramics were in-situ synthesized by heating the mixture of Al2O3 and MgCO3 with MgCl2 salt at 1400~1600 °C for 3 h, and then characterized by X-ray diffraction (XRD) and scanning electron microscopy (SEM). The morphology of as-prepared MgAl2O4 porous ceramics was dependent on the addition of MgCl2, and it indicated that the MgCl2 molten salt not only acted as a template for pore formation of the porous ceramics, but also provided a liquid environment for the synthesis of MgAl2O4.

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In Situ Reaction Synthesis of Porous Silica-Matrix Ceramics

Key Engineering Materials ◽

10.4028/www.scientific.net/kem.280-283.1143 ◽

2007 ◽

Vol 280-283 ◽

pp. 1143-1146

Author(s):

Shu Qiang Ding ◽

Dong Liang Jiang ◽

Su Min Zhu

Keyword(s):

Porous Silica ◽

Porous Ceramics ◽

Silica Matrix ◽

X Ray Diffraction ◽

Pore Former ◽

Reaction Bonding ◽

X Ray ◽

Pine Sawdust ◽

Y2o3 Addition

A novel technique was developed to synthesize porous silica–matrix ceramics from silicon carbide and alumina with an Y2O3 addition, using pine sawdust as a pore former. The porous ceramics were fabricated at temperatures of 1300–1500 oC in air by a reaction–bonding process based on two reactions: (1)SiC+2O2→SiO2+CO2 (Oxidation) and (2)2SiO2+3Al2O3→3Al2O3·2SiO2 (Mullitization). Reaction–bonding behavior, mechanical property and open porosity were investigated as a function of Y2O3 content as well as sintering temperature and holding time. Moreover, phase composition and microstructure of the porous silica–matrix ceramics were studied by X–ray diffraction (XRD) and scanning electron microscopy (SEM).

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Effect of Sintering Process on Fabrication of Porous Si3N4/SiC Composites

Key Engineering Materials ◽

10.4028/www.scientific.net/kem.353-358.1572 ◽

2007 ◽

Vol 353-358 ◽

pp. 1572-1575 ◽

Cited By ~ 1

Author(s):

Cong Hoa Vu ◽

Quoc Thai Phan ◽

Do Won Seo ◽

Jae Kyoo Lim

Keyword(s):

Mechanical Performance ◽

Porous Ceramics ◽

Nitrogen Atmosphere ◽

Sintering Process ◽

X Ray Diffraction ◽

Compressive Test ◽

X Ray ◽

Sic Composites ◽

Porous Sic

Porous SiC/Si3N4 composites were fabricated by reaction between Si3N4 and C powder in 0.5 MPa nitrogen atmosphere at 1700oC, 1800oC and 1900oC for 0.5h, 1h and 2h, respectively. The characteristics of in situ porous Si3N4/SiC composites were further investigated by X-ray diffraction (XRD) and scanning electronic microscopy (SEM). Results show that the SiC particles are very fine. And the transformation from α-Si3N4 to β-Si3N4 is obvious at 1800oC for 2h and at 1900oC. Otherwise, at 1700oC, the formation of rod-like β-Si3N4 is inhibited. The compressive test was conducted at a cross-head speed of 0.5 mm/min to get the basic mechanical performance of the porous ceramics. The highest value of strength of these composites was obtained when sintered at 1800oC for 1h.

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The Use of Advanced Analytical Techniques for Characterization of the Chemical, Physical, and Crystallographic Nature of a Surface

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100071107 ◽

1973 ◽

Vol 31 ◽

pp. 132-133 ◽

Cited By ~ 1

Author(s):

R. E. Herfert

Keyword(s):

Surface Characterization ◽

Analytical Techniques ◽

X Ray Diffraction ◽

Depth Of Penetration ◽

X Ray ◽

The Past ◽

Transmission Electron ◽

Scanning Electron

Studies of the nature of a surface, either metallic or nonmetallic, in the past, have been limited to the instrumentation available for these measurements. In the past, optical microscopy, replica transmission electron microscopy, electron or X-ray diffraction and optical or X-ray spectroscopy have provided the means of surface characterization. Actually, some of these techniques are not purely surface; the depth of penetration may be a few thousands of an inch. Within the last five years, instrumentation has been made available which now makes it practical for use to study the outer few 100A of layers and characterize it completely from a chemical, physical, and crystallographic standpoint. The scanning electron microscope (SEM) provides a means of viewing the surface of a material in situ to magnifications as high as 250,000X.

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