Synthesis of silicon carbide powders from fumed silica powder and phenolic resin

Satoru Ishihara; Hidehiko Tanaka; Toshiyuki Nishimura

doi:10.1557/jmr.2006.0138

Synthesis of silicon carbide powders from fumed silica powder and phenolic resin

Journal of Materials Research ◽

10.1557/jmr.2006.0138 ◽

2006 ◽

Vol 21 (5) ◽

pp. 1167-1174 ◽

Cited By ~ 18

Author(s):

Satoru Ishihara ◽

Hidehiko Tanaka ◽

Toshiyuki Nishimura

Keyword(s):

Silicon Carbide ◽

Fumed Silica ◽

Single Phase ◽

Phenolic Resin ◽

Sol Gel ◽

Molar Ratio ◽

Homogeneous Distribution ◽

Mixing Ratio ◽

Silica Powder ◽

Gel Processing

Silicon carbide powders were synthesized by application of sol-gel processing. Fumed silica powder was used as the starting material for the silicon source, and phenolic resin was used for the carbon source. The effects of mixing ratio and difference between hydrophilic and hydrophobic types of fumed silica powders were investigated. The stirred mixtures of fumed silica powders and phenolic resin became apparent sol states owing to homogeneous distribution. SiC powders were formed derived from both the types of fumed silica powders after the gelation and pyrolysis up to 1800 °C. The hydrophilic silica powder was effective to synthesize more homogeneous SiC powders than the hydrophobic type. Single-phase SiC was obtained in the C/Si (molar ratio after pyrolysis at 1000 °C) range between 1.0 and 2.5, while free carbon was contained in the obtained powders of C/Si > 2.5. In contrast, formation of SiC was insufficient, and SiO2 was retained at ratios of C/Si < 1.0.

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Sol-gel processing of cordierite: Effect of seeding and optimization of heat treatment

Journal of Materials Research ◽

10.1557/jmr.1990.1095 ◽

1990 ◽

Vol 5 (5) ◽

pp. 1095-1103 ◽

Cited By ~ 44

Author(s):

Ann M. Kazakos ◽

Sridhar Komarneni ◽

Rustum Roy

Keyword(s):

Heat Treatment ◽

Single Phase ◽

Excess Free Energy ◽

Sol Gel ◽

Nucleating Agents ◽

Optimum Conditions ◽

Nanosized Powders ◽

Nanocomposite Gels ◽

Powder Compacts ◽

Gel Processing

Three series of cordierite powders were prepared by the sol-gel route: a single phase (monophasic) gel prepared from alkoxides, a nominally triphasic nanocomposite gel made with two nanosized powders and one solution phase, and a truly compositionally triphasic nanocomposite gel prepared from three nanosized powders. Crystalline α-cordierite seeds were also incorporated with the gels and their effectiveness as nucleating agents was investigated and found to lower the crystallization temperature of α-cordierite by 125–150°C. The densification behavior of powder compacts was examined and alterations made to the heat treatment until optimum conditions were found. The truly triphasic compact sintered at 1300°C for 2 h resulted in 100% of theoretical density whereas the nominally triphasic and monophasis pellets densified to 96% and 80%, respectively. The enhanced densification achieved with powder compacct prepared for triphasic nanocomposite gels is due to part to the excess free energy of the three components.

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Small-angle scattering investigation of silica xerogels and sonogels prepared with ionic liquid pyridinium tetrafluoroborate

Processing and Application of Ceramics ◽

10.2298/pac1703229a ◽

2017 ◽

Vol 11 (3) ◽

pp. 229-233 ◽

Cited By ~ 2

Author(s):

László Almásy ◽

Ana-Maria Putz ◽

Adél Len ◽

Josef Plestil ◽

Cecilia Savii

Keyword(s):

Ionic Liquid ◽

Small Angle ◽

Sol Gel ◽

Molar Ratio ◽

Strong Increase ◽

Silica Xerogels ◽

X Ray Scattering ◽

Angle Scattering ◽

Gel Processing ◽

Functionalized Alkoxide

Silica matrices were prepared via acid catalysed sol-gel processing augmented with sonocatalysis. As silica precursors, a mixture of tetra-functionalized alkoxide (TMOS) and three-functionalized alkoxide methyl-trimethoxysilane (MTMS) were employed. Ionic liquid N-butyl-3-methylpyridinium tetrafluoroborate ([bmPy][BF4]), was used in various proportions, aiming to catalyse the sol-gel reactions, and to influence the mesoporous silica materials properties, serving as pore template. Small-angle neutron (SANS) and small-angle X-ray scattering (SAXS) techniques were used to explore the xerogels and sonogels microstructure evolution as a function of the IL/Si molar ratio. The results show a strong increase of the primary particle size under the influence of the ionic liquid. Ultrasonic agitation leads to further size increase by ca. 10%.

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Low temperature synthesis of ultrafine Pb(Zr, Ti)O3 powder by sol-gel combustion

Journal of Materials Research ◽

10.1557/jmr.1997.0333 ◽

1997 ◽

Vol 12 (10) ◽

pp. 2518-2521 ◽

Cited By ~ 88

Author(s):

J. Schäfer ◽

W. Sigmund ◽

S. Roy ◽

F. Aldinger

Keyword(s):

Lead Zirconate Titanate ◽

Single Phase ◽

Sol Gel ◽

Combustion Process ◽

Lead Zirconate ◽

Homogeneous Distribution ◽

Low Temperature Synthesis ◽

Metal Nitrates ◽

Gel Combustion ◽

Diffusion Paths

Lead zirconate titanate powders are derived from a novel aqueous-based citrate-nitrate/oxynitrate sol-gel combustion process. Aqueous solutions of metal nitrates or oxynitrates are transformed into gels with citric acid under heating. The received gels undergo a self-propagating combustion reaction on heating to 180 °C and subsequently yield voluminous ashes. These ashes form single phase perovskite Pb(Zr0.53Ti0.47)O3 powder with a specific surface area of 8 m2/g upon calcination at 550 °C. The ashes show a homogeneous distribution of lead, zirconium, and titanium ions which guarantees short diffusion paths in solid state formation of PZT perovskite. The redox behavior of the gels was studied with the help of DTA experiments. Powders are characterized in terms of XRD, SEM, and EDX analysis.

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Sol-Gel Precursors and the Oxygen Storage Capacity of PrOy-ZrO2 Materials

MRS Proceedings ◽

10.1557/proc-497-15 ◽

1997 ◽

Vol 497 ◽

Cited By ~ 2

Author(s):

C. K. Narula ◽

K. L. Taylor ◽

L. P. Haack ◽

L. F. Allard ◽

A. Datye ◽

...

Keyword(s):

Single Phase ◽

High Surface ◽

Sol Gel ◽

High Surface Area ◽

Fluorite Structure ◽

Oxygen Storage Capacity ◽

Oxygen Storage ◽

Molar Ratio ◽

Metal Nitrates ◽

Temperature Programmed

ABSTRACTThe gels derived from mixtures of Pr(OiC3H7)3 and Zr(OiC3H7)4•iC3H7OH, upon hydrolysis and pyrolysis, furnish single-phase PrOy-ZrO2 materials crystallized in the fluorite structure. These materials can be coated onto high-surface-area γ-alumina powders or deposited onto dense α-alumina coupons in the form of thin films from a solution of parent alkoxides modified with 2,4-pentanedione in THF. The fluorite structure of the PrOy-ZrO2 in the films appears to be thermally stable in air up to 1200°C. Temperature-programmed-reduction (TPR) measurements show that the bulk PrOy-ZrO2 material with a Pr. Zr molar ratio of 1:1 can store and release oxygen while that with a molar ratio of 1:3 cannot.The precursors play an important role in determining phase composition of the resulting PrOy-ZrO2 material. A mixture of monoclinic and cubic or tetragonal phases was found in PrOy-ZrO2 prepared from a new single-source heterometallic alkoxide, Pr2Zr6(μ4-O)2(μ-OAc)6(μ-OiPr)10(OiPr)10, whereas a mixture of cubic and tetragonal phases was present in PrOy-ZrO2 made previously by coprecipitation from aqueous solutions of the metal nitrates.

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The Influences of Different Precursors on Morphology of Bi3TiNbO9 Powders Prepared by a Sol-Gel Method

Advanced Materials Research ◽

10.4028/www.scientific.net/amr.815.765 ◽

2013 ◽

Vol 815 ◽

pp. 765-772 ◽

Cited By ~ 1

Author(s):

Zuo Dong Li ◽

Dan Liu

Keyword(s):

Ethylene Glycol ◽

Chemical Method ◽

Single Phase ◽

Perovskite Phase ◽

Sol Gel ◽

Particle Morphology ◽

Deionized Water ◽

Molar Ratio ◽

Molar Ratios ◽

Baking Process

Bi3NbTiO9 (BNTO) powders were synthesized by a sol-gel chemical method using niobium oxalates, bismuth nitrate and tetra-n-butyl-titanate as starting materials. In order to determine the influence of the molar ratio of the deionized water to ethylene glycol on the particle morphology and crystallization, different molar ratios, the deionized water/ethylene glycol, were chosen to prepare BNTO powders. Single phase BNTO powders could be obtained at a calcinations temperature of 600°C. Moreover, the possible formation mechanism of BNTO powders was also proposed in this paper. In the baking process, perovskite phase BNTO was formed via a reaction between oxides and bismuth niobium.

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HIGHLY HOMOGENEOUS NITROGEN DOPED TITANIA NANOMATERIALS: SYNTHESIS AND CHARACTERIZATION

Jurnal Teknologi ◽

10.11113/jt.v78.9241 ◽

2016 ◽

Vol 78 (6-12) ◽

Author(s):

Nurul Diyana Zainal ◽

Hadi Nur ◽

Siew Ling Lee

Keyword(s):

Single Phase ◽

Sol Gel ◽

Ammonium Hydroxide ◽

Homogeneous Distribution ◽

X Ray Diffraction ◽

Nitrogen Doped ◽

Mapping Analysis ◽

N Doping ◽

Nanomaterials Synthesis ◽

Doped Titania

A series of nitrogen doped titania nanomaterials were synthesized via sol-gel method by using tetraethyl ammonium hydroxide as N source. Doping of N into TiO2 was confirmed via X-ray diffraction (XRD) and fourier transform infrared spectroscopy (FTIR) analyses. Mixture of anatase and rutile phases appeared in the unmodified TiO2 which was calcined at 773 K. The addition of N to TiO2 matrix led to formation of single phase of anatase. It has been demonstrated thatTiO2 and all the N-doped TiO2 materials were in nanoscale ranging 15.91 – 20.82 nm. Change in surface morphology after N doping was detected by field emission scanning electron microscope (FESEM). Results of EDX mapping analysis indicated homogeneous distribution of N dopants.

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Production of SrAl2O4:Eu2+, Dy3+ green-emitting phosphor nano-pigment powders via microwave processing route

Pigment & Resin Technology ◽

10.1108/prt-07-2015-0064 ◽

2017 ◽

Vol 46 (2) ◽

pp. 85-91 ◽

Cited By ~ 3

Author(s):

Mohammadreza Johari ◽

Masoud Rajabi ◽

Vahid Mohammadi

Keyword(s):

Sol Gel ◽

Research Work ◽

Precursor Solution ◽

Heating System ◽

Molar Ratio ◽

Processing Route ◽

X Ray Diffraction ◽

Content Type ◽

Microwave Assisted ◽

Gel Processing

Purpose The present paper aims to synthesize SrAl2O4:Eu2+, Dy3+ green-emitting phosphor nano-pigment powder using a combination of citrate – gel processing and microwave-assisted heating route. Design/methodology/approach Microwave-assisted citrate – gel processing of SrAl2O4:Eu2+, Dy3+ green-emitting phosphor nano-pigment powder has been carried out by varying the pH and the molar ratio of H3Cit/Al3+ + Sr2+ +Eu2++Dy3+ (f/o). X-ray diffraction analysis showed that the produced powders were nearly pure SrAl2O4 phase, in which the SrAl2O4 host phase has the maximum fraction of green-emitting monoclinic SrAl2O4 phase. Findings Spectrophotometer results revealed that two excitation peaks appeared at 238 and 339 nm and an emission peak at 515 nm. The crystallite size of the green-emitting phosphor nano-pigment powder was about 37 nm as determined by Scherrer’s formula. The best conditions for formation of monoclinic SrAl2O4 phase with high purity were achieved at pH of precursor solution equal to 7 and the molar ratio of f/o equal to 3. Originality/value The present research work for the first time (to the best of the authors’ knowledge) has used microwave and sol–gel combination techniques to produce green-emitting phosphor nano-pigment powder (without using any other heating system).

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Sol-gel processing of varistor powders

Journal of Materials Research ◽

10.1557/jmr.1992.0546 ◽

1992 ◽

Vol 7 (3) ◽

pp. 546-548 ◽

Cited By ~ 30

Author(s):

Gert Hohenberger ◽

Gerhard Tomandl

Keyword(s):

Grain Boundaries ◽

Mixed Oxide ◽

Sol Gel ◽

Homogeneous Distribution ◽

Electrical Behavior ◽

Gel Method ◽

Sol Gel Method ◽

Zno Varistor ◽

Gel Processing ◽

Source Materials

A new sol-gel method for the preparation of ZnO varistor powders, using inexpensive source materials such as acetates and nitrates, is described. It yields powders with a more homogeneous distribution of dopants compared to the commercially used mixed oxide technique. Varistor ceramics made from sol-gel powders can be sintered at lower temperatures and show improved electrical behavior. This is a consequence of formation of more varistor-active grain boundaries within the ceramics.

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Morphology-Controlled Synthesis of Nanostructured Silicon Carbide

MRS Proceedings ◽

10.1557/proc-815-j5.3 ◽

2004 ◽

Vol 815 ◽

Cited By ~ 1

Author(s):

Xiang-Yun Guo ◽

Guo-Qiang Jin ◽

Ya-Juan Hao

Keyword(s):

Silicon Carbide ◽

Chemical Composition ◽

Carbothermal Reduction ◽

Phenolic Resin ◽

Preparation Method ◽

Sol Gel ◽

Controlled Synthesis ◽

Nanostructured Silicon ◽

Sol Gel Process

AbstractPhenolic resin and tetraethoxysilane were used to prepare a binary carbonaceous silicon xerogel, the precursor of silicon carbide (SiC). By employing different additives in the sol-gel process, a series of xerogel precursors with differently chemical composition were obtained. Heating these xerogels to 1250°C, nanostructured β-SiC with various morphologies including nanowires, nanofibers, nanoparticles and mesoporous SiC were produced via carbothermal reduction. The preparation method of the xerogels was presented and the influences of different additives on the sol-gel process and the SiC formation were discussed in this paper.

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