Synthesis of Ti(C,N) ultrafine powders by carbothermal reduction of TiO2 derived from sol–gel process

2000 ◽  
Vol 20 (7) ◽  
pp. 933-938 ◽  
Author(s):  
Junhui Xiang ◽  
Zhipeng Xie ◽  
Yong Huang ◽  
Hanning Xiao
Keyword(s):  
Carbothermal Reduction ◽  
Sol Gel ◽  
Ultrafine Powders ◽  
Sol Gel Process

Oxidation Behavior of β-Sialon Ultrafine Powders Prepared by the Combined Sol-Gel and Microwave Carbothermal Reduction Nitridation Method

2018 ◽  
Vol 281 ◽  
pp. 34-39
Author(s):  
Fa Liang Li ◽  
Fang Fu ◽  
Li Lin Lu ◽  
Hai Jun Zhang ◽  
Shao Wei Zhang
Keyword(s):  
Activation Energy ◽  
Carbothermal Reduction ◽  
Oxidation Behavior ◽  
Oxidation Process ◽  
Sol Gel ◽  
Probable Mechanism ◽  
Ultrafine Powders ◽  
Isothermal Thermogravimetry ◽  
Temperature Range ◽  
Mechanism Function

Ultrafine powders of β-Sialon were prepared by the combined sol-gel and microwave carbothermal reduction nitridation method, and their oxidation process was studied by a non-isothermal thermogravimetry method. The results indicated that two different mechanism functions respectively corresponded to the initial and final oxidation stages. The reverse Jander equation with activation energy of 240.5 kJ/mol and the Avrami-Erofeev equation with activation energy of 410.7 kJ/mol were respectively identified as the most probable mechanism function for the initial and final oxidation stages in the temperature range of 1423-1623 K.

scholarly journals A novel sol–gel route to synthesize (Sr0.5Ba0.5)Nb2O6 ceramics with enhanced electrocaloric effect

2017 ◽  
Vol 07 (02) ◽  
pp. 1750012 ◽  
Author(s):  
Ting Chen ◽  
Shu Ya Wu ◽  
Xiao Qiang Liu ◽  
Xiang Ming Chen
Keyword(s):  
Sol Gel ◽  
Synthesis Temperature ◽  
Ultrafine Powders ◽  
X Ray Diffraction ◽  
Electrocaloric Effect ◽  
X Ray ◽  
Fine Powders ◽  
Sol Gel Process ◽  
Size And Morphology ◽  
Mechanism Of The Reaction

(Sr[Formula: see text]Ba[Formula: see text])Nb2O6 ultra-fine powders were synthesized by a novel sol–gel route, and the mechanism of the reaction was discussed. SrCO3, BaCO3, oxalate niobium and citric acid were used to initiate the sol–gel process, and ethylene glycol (EG) was added to further polymerize the cross-linking structure. The evolution of the (Sr[Formula: see text]Ba[Formula: see text])Nb2O6 phase, the reaction process and the microstructures were investigated by X-ray diffraction (XRD), Raman spectroscopy, Fourier transform infrared spectroscopy, DSC-TG and scanning electron microscopy. The synthesis temperature of the (Sr[Formula: see text]Ba[Formula: see text])Nb2O6 powders reached as low as 1200[Formula: see text]C, and the size and morphology of the powders were controlled by temperature. By adjusting the calcination temperature, we obtained (Sr[Formula: see text]Ba[Formula: see text])Nb2O6 powders with uniform sizes of 20[Formula: see text]nm to 500[Formula: see text]nm. Then, dense (Sr[Formula: see text]Ba[Formula: see text])Nb2O6 ceramics were successfully prepared using these ultrafine powders. Finally, an enhanced electrocaloric effect (ECE) value of 0.35[Formula: see text]C was obtained at 100[Formula: see text]kV/cm.

ChemInform Abstract: Sol-Gel Process Synthesis of High-Temperature Non-Oxide Ultrafine Powders

ChemInform ◽  
2014 ◽  
Vol 45 (17) ◽  
pp. no-no
Author(s):  
Haijun Zhang ◽  
Fang Fu ◽  
Yingnan Cao ◽  
Shuang Du ◽  
Lilin Lu ◽  
...  
Keyword(s):  
High Temperature ◽  
Sol Gel ◽  
Process Synthesis ◽  
Ultrafine Powders ◽  
Sol Gel Process

Morphology-Controlled Synthesis of Nanostructured Silicon Carbide

2004 ◽  
Vol 815 ◽  
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.

Synthesis of Heterogeneous β-SiC Nano-Particles and Nano-Whisker from TEOS/SiO2 Bead/PMMA Ternary Xerogel

2005 ◽  
Vol 486-487 ◽  
pp. 522-525 ◽  
Author(s):  
Jae Won Kim ◽  
Seoung Soo Lee ◽  
Sung Kang Hur ◽  
Yeon Gil Jung ◽  
Chang Yong Jo
Keyword(s):  
Carbothermal Reduction ◽  
Sol Gel ◽  
Argon Atmosphere ◽  
Nano Particles ◽  
Residual Carbon ◽  
Carbon Precursor ◽  
Growth Mechanisms ◽  
Subsequent Growth ◽  
Initial Nucleation ◽  
Sol Gel Process

A modified sol-gel method is proposed for the preparation of silicon carbide nano-particles and nano-whisker. Tetraethoxysilane (TEOS), SiO2 bead, and PMMA as precursor of carbon source were used for preparing a ternary carbonaceous silicon xerogel, and morpholine is employed in the sol-gel process as a catalyst reagent. SiC nano-particles and nano-whisker were obtained from carbothermal reduction and vapor-solid (VS) reaction of the ternary xerogel at 1300°C for 9h in a dynamic argon atmosphere (flow rate; 600 cm3/min), and then purified by removing excess silica, residual carbon, and other impurities. The purified SiC sample was characterized by TG/DTA, XRD, SEM, and HRTEM. The nano-particles and the nano-whisker were synthesized by different growth mechanisms, with an initial nucleation via a VS reaction between SiO vapor and carbon precursor (PMMA) and a partially subsequent growth via a vapor-vapor (VV) reaction between SiO and CO, respectively.

Fabrication and Properties of 3D-Cf/Mullite Composites with SiC Interfacial Coatings

2013 ◽  
Vol 833 ◽  
pp. 150-153 ◽  
Author(s):  
Ke Wei Dai ◽  
Chen Chen Zhang ◽  
Qing Song Ma ◽  
Hai Tao Liu
Keyword(s):  
Carbon Fiber ◽  
Flexural Strength ◽  
Great Improvement ◽  
Carbothermal Reduction ◽  
Raw Materials ◽  
Sol Gel ◽  
Three Dimensional ◽  
Retention Rates ◽  
Sol Gel Process ◽  
Sic Coatings

Three-dimensional carbon fiber reinforced mullite composites (3D-Cf/mullite) were fabricated by sol-gel method with diphasic mullite sol as raw materials. SiC interfacial coatings were deposited by polycarbosilane infiltration and pyrolysis before sol-gel process. The as-fabricated composites showed 285.7MPa in flexural strength, relatively close to 277.6MPa of those without coatings. After treated at 1300°C and 1500°C in Ar atmosphere for 1h, the retention rates of flexural strength were 80.0% and 69.9%, respectively, which showed a great improvement compared to the composites without coatings. This was attributed to the prevention of carbothermal reduction between carbon fiber and matrix by SiC coatings.

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