scholarly journals Synthesis of TiN-Si3N4 composites from rutile and quartz by carbothermal reduction nitridation

2012 ◽  
Vol 44 (1) ◽  
pp. 57-64 ◽  
Author(s):  
Kai Chen ◽  
Zhaohui Huang ◽  
Minghao Fang ◽  
Yan-Gai Liu
Keyword(s):  
Carbothermal Reduction ◽  
Raw Materials ◽  
Average Particle Size ◽  
Equilibrium Phase ◽  
Phase Evolution ◽  
Equilibrium Phase Diagram ◽  
Nitrogen Pressure ◽  
Average Particle ◽  
Carbon Addition ◽  
Composite Powders

TiN-Si3N4 composite powders were prepared by carbothermal reduction nitridation using rutile and quartz as raw materials. The influence of temperature and carbon addition on the phase evolution and microstructure of the products were investigated. The equilibrium phase diagram of Si-C-N-O and Ti-C-N-O system at different temperatures under 0.2 MPa nitrogen pressure was drew. The results show that the optimum parameters for synthesizing TiN-Si3N4 by carbothermal reduction nitridation process are carbon addition of stoichiometric content, temperature of 1873 K for 4 h and nitrogen pressure of 0.2 MPa. The produced TiN-Si3N4 in this experiment exist in granular and hexagonal columnar shape, and the average particle size of the synthesized powders is 2 ~ 10 ?m.

Novel synthesis of a NiMoP phosphide catalyst via carbothermal reduction for dry reforming of methane

2021 ◽  
Author(s):  
Xinyu Chen ◽  
Wei Ding ◽  
Zhiwei Yao ◽  
Na Sun ◽  
Zhimeng Wang ◽  
...  
Keyword(s):  
Particle Size ◽  
Carbon Content ◽  
Carbothermal Reduction ◽  
Average Particle Size ◽  
Dry Reforming ◽  
Dry Reforming Of Methane ◽  
Average Particle ◽  
Novel Synthesis ◽  
Highly Dispersed

A Highly dispersed NiMoP phosphide catalyst with an average particle size of 9.1 nm and a carbon content of 53.5 wt% was firstly synthesized by carbothermal route using glucose as...

Minimum Particle Diameter of the Vanadium/Iron Co-Doped Nano TiO2 Transparent Hydrosol at Room Temperature

2014 ◽  
Vol 989-994 ◽  
pp. 611-614
Author(s):  
Ling Li ◽  
Wen Ming Zhang ◽  
Hua Yan Zhang ◽  
Zi Hao Xu ◽  
Sen Wang ◽  
...  
Keyword(s):  
Particle Size ◽  
Room Temperature ◽  
Raw Materials ◽  
Average Particle Size ◽  
Particle Diameter ◽  
Ferric Nitrate ◽  
Average Particle ◽  
Hydrolysis Method ◽  
Vanadium Iron ◽  
Co Doped

Vanadium/iron co-doped nanoTiO2 transparent hydrosol with an average particle size of 3.8 nm was synthesized by a novel complexation-controlled hydrolysis method at room temperature and atmospheric pressure by using TiCl4, ferric nitrate, ammonium metavanadate, etc. as raw materials. The composition, phase structure, particle size, absorbance spectrum, and photocatalytic performance of samples were characterized by XRD, EDS, nanolaser particle size analyzer, and UV-Vis spectrophotometer. The photocatalytic properties of V/Fe doped TiO2 were studied through degrading acid 3R dye, and the results show that when the content of V/Fe was 0.5%, the degradation rate reached more than 96% under irridation for 60 min.

Heterophase ceramics in the Hf–Si–Mo–B system obtained by a combination of SHS and hot pressing methods

2019 ◽  
pp. 36-46
Author(s):  
Yu. S. Pogozhev ◽  
M. V. Lemesheva ◽  
A. Yu. Potanin ◽  
S. I. Rupasov ◽  
V. I. Vershinnikov ◽  
...  
Keyword(s):  
Hot Pressing ◽  
Raw Materials ◽  
Average Particle Size ◽  
High Hardness ◽  
Maximum Size ◽  
Composite Ceramic ◽  
Thermal Reduction ◽  
High Mass ◽  
Average Particle ◽  
Chemical Homogeneity

The paper focuses on obtaining heterophase powder ceramics and consolidated ceramics based on borides and silicides of hafnium and molybdenum by combining the methods of self-propagating high-temperature synthesis (SHS) and hot pressing (HP). Composite ceramic SHS powders HfB2–HfSi2–MoSi2 were obtained according to the scheme of magnesium-thermal reduction from oxide raw materials where the combustion wave is characterized by temperatures of 1750–2119 K and high mass combustion rates of 8,4– 9,3 g/s. The structure of synthesized SHS powders consists of relatively large MoSi2 grains up to 10 μm in size and submicron elongated HfB2 grains located mainly inside the MoSi2 grains and rounded Si precipitates. The composition with a lower concentration of boron contains a large number of polyhedral HfSi2 grains with a size of less than 10 μm. The resulting powders are characterized by an average particle size of ~6 μm with a maximum size up to 26 μm. Phase compositions of ceramics consolidated by the HP method and SHS synthesized powders are identical. The microstructure of compact samples consists of faceted HfB2 elongated grains 0,5– 10,0 μm in size, polyhedral HfSi2 and MoSi2 grains up to 8–10 μm in size and silicon interlayers. Consolidated ceramics has a high structural and chemical homogeneity, low residual porosity of 1,1–1,7 %, high hardness of 11,7–12,6 GPa and thermal conductivity of 62–87 W/(m·K).

Rheological, Structural and Mechanical Characterization of Monolithic Zircon-Alumina Bodies

2014 ◽  
Vol 793 ◽  
pp. 151-158 ◽  
Author(s):  
M. León-Carriedo ◽  
C.A. Gutiérrez Chavarría ◽  
J.L. Rodríguez Galicia ◽  
Jorge López-Cuevas ◽  
M.I. Pech Canul
Keyword(s):  
Particle Size ◽  
Raw Materials ◽  
Mechanical Test ◽  
Average Particle Size ◽  
Young Modulus ◽  
Particle Morphology ◽  
Ceramic Materials ◽  
Transgranular Fracture ◽  
Average Particle

In the present work, the characterization of monolithic materials formulated at different weight concentrations was conducted; employing two of the ceramic materials most used in the refractory industry, zircon and alumina. These monolithic materials were fabricated using colloidal techniques, specifically plaster casting mold, in order to obtain pieces with a higher particle consolidation and density, reducing porosity to lower values than the obtained using traditional shaping process of these materials. The monoliths were obtained employing two ceramic powders with different average particle size and morphology to achieve better packing in the green body. This characterization was carried out, firstly, determining the particle size of the raw materials by laser diffraction and the evaluation of particle morphology by scanning electron microscopy. Aqueous suspensions were formulated by containing both ceramic materials, which were dispersed with Tamol 963, and analyzed by rheometric techniques. Subsequently, bars were manufactured having the following dimensions; 4 mm wide, 3 mm thick and 45 mm in length, according to ASTM C1161-02cc, to be characterized microstructural and mechanically, also was observed the fracture habit after the mechanical test. As a final result, the materials formulated at higher alumina content showed higher density values, reaching 94.95% of the theoretical density, also showed a higher thermal expansion coefficient and high rupture modulus, reaching up to 600 MPa and Young modulus of 230 GPa. From the microstructure characterization it was observed that alumina matrix shows a transgranular fracture across the grains and zircon particles exhibited intergranular fracture among the grain boundaries.

Effect of Concentration of Iron Oxide on Crystallization Behavior in Leadless Iron Oxide Crystalline Glaze

2012 ◽  
Vol 554-556 ◽  
pp. 18-22
Author(s):  
Supakorn Silakate ◽  
Anucha Wannagon ◽  
Apinon Nuntiya
Keyword(s):  
Iron Oxide ◽  
Nepheline Syenite ◽  
Crystallization Behavior ◽  
Raw Materials ◽  
Average Particle Size ◽  
Average Particle ◽  
Oxide Content ◽  
Iron Oxide Content ◽  
X Ray Diffraction ◽  
X Ray

The objectives of this study were to prepare leadless crystalline glazes from iron oxide by using low temperature firing (1,100°C) and to study the effect of concentration of iron oxide on the phase composition of the glaze raw materials on phase transformation in leadless iron oxide crystalline glaze. The crystalline phases were investigated by using the DTA, X-ray diffraction (XRD) and scanning electron microscopy (SEM) techniques. The composition of the glaze raw materials compose of nepheline syenite, colemanite, pottery stone, bentonite, ZnO, Li2CO3, SiOSubscript text2 and 10, 15 and 20%(w/w) iron oxide (Fe2O3). The glaze raw materials were ground for homogeneous mixtures by ball milling for 24h. The average particle size of the mixture was 3.86 µm. The glaze bodies were carried to firing at 1,100°C at the heating rate of 2°C/min and soaking for 0.5h. Then, the glaze bodies were cooled at the cooling rate of 1°C/min and maintained at 1,080°C for 3h and then maintained at 980°C for 1h, respectively. From the experiment results, it was found that the crystallization temperatures (Tc) of franklinite (ZnFe2O4) and anorthite (CaAl2Si2O8) depend on the concentration of iron oxide content.

Synthesis and Electromagnetic Properties of Hollow Ceramic Microspheres

2011 ◽  
Vol 492 ◽  
pp. 260-263 ◽  
Author(s):  
Bao Cai Xu ◽  
Jian Jiang Wang ◽  
Rong Xia Duan ◽  
Xing Jian Huo
Keyword(s):  
Reflection Loss ◽  
Structural Characteristics ◽  
Average Particle Size ◽  
Coaxial Line ◽  
Electromagnetic Properties ◽  
Flame Spraying ◽  
Average Particle ◽  
Composite Powders ◽  
Composite Microspheres

The hollow ceramic microspheres were prepared by Self-reactive flame spraying method. The structural characteristics and morphology properties of the composite powders were obtained by XRD and SEM. The results show that the obtained particles are hollow ceramic microspheres. The average particle size is about 30μm. An analytical method for the determination of electromagnetic parameters (ε, μ) of materials under test is presented by the analysis of normalized general matrix of equivalent network of coaxial line filled with samples. The analysis of vector network analyzer show that reflectance of hollow composite microspheres could well absorb microwaves in 2-18 GHz. The reflection loss is less than -l0dB in the range of 12.4 to15.2GHz while the minimum reflection loss is -18.5dB at 13.6GHz.

scholarly journals Influence of Glass Powder Size Sorting on Properties of Composite Systems

2016 ◽  
Vol 47 (1) ◽  
pp. 25-31
Author(s):  
K. Dědičová ◽  
P. Valášek
Keyword(s):  
Glass Powder ◽  
Adhesive Bonding ◽  
Raw Materials ◽  
Average Particle Size ◽  
Polymeric Materials ◽  
Average Particle ◽  
Powder Size ◽  
Size Sorting ◽  
Powder Particles ◽  
Size Of Particles

Abstract Glass powder ranks among the secondary raw materials, which can be used in the interaction with polymeric materials. In the present experiment the polymeric/epoxy particle composite with different sizes of glass powder particles is described. Such utilization of recyclable materials is environmental-friendly and should be preferred. The size of particles forming the filler of the described composites is one of the key characteristics affecting the mechanical properties. Due to the properties of the systems filled with glass powder, these materials can potentially be used in agriculture (renovations, adhesive bonding, cementing, etc.). In the experiment, glass powder was dimensionally sorted through sieves. Three fractions of glass powder with particles size of 0−30, 30−50, and 50−90 μm were created and utilized, the average particle size being 18.7, 38.7, and 72.6 μm, respectively. The interaction of the 18.7 μm particles did not lead to a statistically significant decrease of shear strength values in the interval 0−20 vol.%. The presence of glass powder, however, in all cases decreased tensile strength.

scholarly journals Effect of Heat Exposure on Grain Growth and Oxidation Behavior of Cobalt Based Composite Powders by Facile Suspension Synthesis

2019 ◽  
Vol 8 (4) ◽  
pp. 6195-6197
Keyword(s):  
Grain Growth ◽  
Matrix Composite ◽  
Exposure Time ◽  
Average Particle Size ◽  
Heat Exposure ◽  
Average Particle ◽  
Composite Powders ◽  
X Ray ◽  
Intermetallic Matrix ◽  
Intermetallic Matrix Composite

In this study the intermetallic-matrix composite powders CoNiCrAlY-2wt. %Al2O3 were characterized in order to investigate the effect of heat exposure time on morphologies, grain growth and phases formed by facile suspension route synthesis. The as-synthesized powders were examined by Scanning Electron Microscopy (SEM), Energy Dispersive X-ray (EDX) and X-ray diffraction (XRD). The formation of NiAl phase was noticed after 1 hour of heat treatment. The average particle size of intermetallic-matrix composite powders CoNiCrAlY-2wt.%Al2O3 increased as the heat exposure time increased. It is found that the reinforcement of alumina allowed the particles to uniformly distributed when the sample was heated for 10 hours. The formation of NiAl started when the sample was heated at 1 hour and NiAl continued to form when heated at 10 hours.

Synthesis of Dispersed Y2O3 Nanopowder from Yttrium Stearate

2013 ◽  
Vol 544 ◽  
pp. 3-7 ◽  
Author(s):  
Jin Sheng Li ◽  
Xu Dong Sun ◽  
Shao Hong Liu ◽  
Di Huo ◽  
Xiao Dong Li ◽  
...  
Keyword(s):  
Particle Size ◽  
Raw Materials ◽  
Average Particle Size ◽  
Ceramic Materials ◽  
Average Particle ◽  
Water Medium ◽  
Nitrate Hexahydrate ◽  
Yttrium Nitrate ◽  
Ft Ir ◽  
Yttrium Nitrate Hexahydrate

Fine yttrium stearate powder was produced at a relatively low temperature using yttrium nitrate hexahydrate, ammonia and stearic acid as the raw materials. Dispersed Y2O3 nanopowder was synthesized by calcining the yttrium stearate. The formation mechanism of the precursor and the Y2O3 nanopowder was studied by means of XRD, TG-DTA, FT-IR, BET, FE-SEM and HR-TEM. Pure and dispersed Y2O3 nanopowder with an average particle size of 30 nm was produced by calcining the precursor at 600 °C. The particle size increases to about 60 nm with the increase of the calcination temperature to 1000 °C. In the preparation of Y2O3 from yttrium stearate, no water medium is involved, thus capillarity force and bridging of adjacent particles by hydrogen bonds can be avoided, resulting in good dispersion of the particles. The dispersed Y2O3 nanopowder prepared in this work has potential application in phosphors and transparent ceramic materials.

scholarly journals In situ controlled rapid growth of novel high activity TiB2/(TiB2–TiN) hierarchical/heterostructured nanocomposites

2017 ◽  
Vol 8 ◽  
pp. 2116-2125 ◽  
Author(s):  
Jilin Wang ◽  
Hejie Liao ◽  
Yuchun Ji ◽  
Fei Long ◽  
Yunle Gu ◽  
...  
Keyword(s):  
High Activity ◽  
Raw Materials ◽  
Average Particle Size ◽  
Particle Surface ◽  
Average Particle ◽  
Scanning Calorimetry ◽  
X Ray ◽  
Transition Electron Microscopy ◽  
Reaction Coupling

In this work, a reaction coupling self-propagating high-temperature synthesis (RC-SHS) method was developed for the in situ controlled synthesis of novel, high activity TiB2/(TiB2–TiN) hierarchical/heterostructured nanocomposites using TiO2, Mg, B2O3, KBH4 and NH4NO3 as raw materials. The as-synthesized samples were characterized using X-ray diffraction (XRD), scanning electron microscope (SEM), X-ray energy dispersive spectroscopy (EDX), transition electron microscopy (TEM), high-resolution TEM (HRTEM) and selected-area electron diffraction (SAED). The obtained TiB2/TiN hierarchical/heterostructured nanocomposites demonstrated an average particle size of 100–500 nm, and every particle surface was covered by many multibranched, tapered nanorods with diameters in the range of 10–40 nm and lengths of 50–200 nm. In addition, the tapered nanorod presents a rough surface with abundant exposed atoms. The internal and external components of the nanorods were TiB2 and TiN, respectively. Additionally, a thermogravimetric and differential scanning calorimetry analyzer (TG-DSC) comparison analysis indicated that the as-synthesized samples presented better chemical activity than that of commercial TiB2 powders. Finally, the possible chemical reactions as well as the proposed growth mechanism of the TiB2/(TiB2–TiN) hierarchical/heterostructured nanocomposites were further discussed.

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