Preparation of Transparent AlON Ceramics Using Single-Phase Powder Obtained from Carbothermal Reduction

2008 ◽  
Vol 368-372 ◽  
pp. 444-446
Author(s):  
Wei Pang ◽  
Deng Xue Wu ◽  
Hai Ping Wang ◽  
Jian Qi Qi ◽  
Ji Cheng Zhou ◽  
...  
Keyword(s):  
Carbothermal Reduction ◽  
Single Phase ◽  
Raw Materials ◽  
Nitrogen Atmosphere ◽  
Holding Time ◽  
Carbon Powder ◽  
Ceramic Samples ◽  
Increasing Temperature

Single-phase AlON powder was prepared by carbothermal reduction in flowing nitrogen atmosphere, using nano-sized alumina and carbon powder as raw materials. Transparent AlON ceramic samples using the single-phase powder were prepared by sintering at the temperature of 1880°C for 10h, 20h and 40h in flowing nitrogen atmosphere, respectively. It showed that the transparency and the density of the ceramic samples increased with increasing temperature holding-time. And the microstructures of the obtained samples were observed.

Fabrication of Porous SiC/SiAlON Composites Using Semi Coke and Fly Ash as Raw Material

2012 ◽  
Vol 724 ◽  
pp. 347-350 ◽  
Author(s):  
Qing Wen Duan ◽  
Rong Zhen Liu ◽  
Hai Yun Jin ◽  
Jian Feng Yang ◽  
Zhi Hao Jin
Keyword(s):  
Fly Ash ◽  
Carbothermal Reduction ◽  
Pore Diameter ◽  
Reduction Method ◽  
Raw Materials ◽  
Nitrogen Atmosphere ◽  
Raw Material ◽  
Coke Content ◽  
Porous Sic ◽  
Median Pore

Porous SiC/SiAlON ceramics were fabricated by carbothermal reduction method from raw materials of fly ash and semi coke in nitrogen atmosphere. The results showed that composites were composed by multi-structure of SiC, Ca-SiAlON and AlN phases. With the increase of semi coke contents, the contents of Ca-Sialon increased. The fracture mode of this material was intergranular. The results also showed that micro area hereditary of semi coke particles was observed in the morphology of this material. The morphology of this material was composed by nanosized SiC and plate like Ca-SiAlON. The median pore diameter was affected by the contents of semi coke and increased with the increase of semi coke content.

Preparation of β-Sialon from Fly Ash by Carbothermal Reduction-Nitridation Reaction

2008 ◽  
Vol 368-372 ◽  
pp. 910-912 ◽  
Author(s):  
Jun Tong Huang ◽  
Ming Hao Fang ◽  
Yan Gai Liu ◽  
Zhao Hui Huang
Keyword(s):  
Fly Ash ◽  
Carbon Black ◽  
Carbon Content ◽  
Carbothermal Reduction ◽  
Single Phase ◽  
Raw Materials ◽  
Synthesis Mechanism ◽  
Nitridation Reaction

Single phase Sialon was synthesized successfully from fly ash by carbothermal reductionnitridation reaction in this paper. The effects of synthesizing temperature (1200°C, 1300°C, 1400°C and 1450°C) and carbon content (stoichiometric content, exceeding 10%, 50% and 100%) on the final production were studied by XRD and SEM. Synthesis mechanism of β-Sialon was also analysized. The results indicated that single phase β-Sialon with z=3 was obtained using fly ash as raw materials and carbon black of stoichiometric content as reducer by carbothermal reduction- nitridation reaction in flow nitrogen at 1450°C for 3h. Temperature and content of carbon had significant effect on the synthesis of β-Sialon.

Growth and Morphology of β-Si3N4 Nano-Belts by Carbothermal Reduction Nitridation of Used Silica Refractory Brick

2012 ◽  
Vol 624 ◽  
pp. 1-4 ◽  
Author(s):  
Wen Juan Li ◽  
Zi He Pan ◽  
Zhao Hui Huang ◽  
Yan Gai Liu ◽  
Ming Hao Fang
Keyword(s):  
Cross Section ◽  
Carbothermal Reduction ◽  
Raw Materials ◽  
Carbon Powder ◽  
X Ray Diffraction ◽  
Refractory Brick ◽  
X Ray ◽  
Vs Mechanism ◽  
Energy Disperse Spectrum ◽  
Silica Refractory

Silicon nitride (β-Si3N4) nano-belts had been synthesized by used silica bricks and carbon powder as raw materials through carbothermal reduction nitridation. The morphology and microstructure of β-Si3N4 nano-belts were characterized by scanning electron microscopy (SEM/HRSEM), energy disperse spectrum (EDS) and X-ray diffraction (XRD). Results showed that the well-crystallized β-Si3N4 nano-beltes were grown with thinness of 50-150nm and width of 3-5μm. The relatively purer β-Si3N4 were prone to be thin films with thinness of 150nm, while the as-grown SiCN (impurityβ-Si3N4with C elements) were presented as nanorods with cross section length of 150*150nm. Orientation growth mechanism by grain dislocation and vapor-solid (VS) mechanism were both involved in the growth of nanostructures of β-Si3N4 nano-beltes and SiCN nanorods.

Preparation of TiB2 Ultrafine Powders by Carbothermal Reduction

2016 ◽  
Vol 697 ◽  
pp. 58-61
Author(s):  
Jin Cheng Yu ◽  
Li Ma ◽  
Yu Jun Zhang ◽  
Hong Yu Gong ◽  
Li Wei Zhou
Keyword(s):  
Carbon Black ◽  
Carbothermal Reduction ◽  
Reduction Method ◽  
Raw Materials ◽  
Structural Evolution ◽  
Holding Time ◽  
X Ray Diffraction ◽  
X Ray ◽  
Boron Source ◽  
Different Content

TiO2, B2O3, H3BO3, B4C and carbon black were used as the raw materials to prepare TiB2 powders by carbothermal reduction method. The influence of different content of carbon black (13.6~14.8 wt%) on products was discussed. The effects of different boron sources and holding time (10~50 min) on the microstructure of TiB2 powders were also investigated. X-ray diffraction (XRD) and scanning electron microscope (SEM) were used to study the phase composition and structural evolution of the powder. The final results showed that hexagonal TiB2 crystal grain could be successfully synthesized without impurities when heated at 1700°C for 30 min in Ar atmosphere with the addition of 14.1 wt% carbon black. Submicrometric TiB2 powders range from 0.5 to 1.0 μm could be obtained when B4C was used as the boron source. The increase in holding time contributed to the grain growth and completion of chemical reactions, but could also result in oversintering.

Synthesis of Fiber-Like SiС by Carbothermal Reduction of Used Silica Bricks

2012 ◽  
Vol 512-515 ◽  
pp. 7-10 ◽  
Author(s):  
Zi He Pan ◽  
Zhao Hui Huang ◽  
Wen Juan Li ◽  
Yan Gai Liu ◽  
Ming Hao Fang
Keyword(s):  
Carbothermal Reduction ◽  
Raw Materials ◽  
Ceramic Composites ◽  
Crack Deflection ◽  
Carbon Powder ◽  
Vapor Liquid Solid ◽  
Sic Fibers ◽  
Pull Out ◽  
The Matrix ◽  
Vs Mechanism

Fiber-like SiC had been synthesized using used silica bricks and carbon powder as raw materials by carbothermal reduction. A new kind of beaded SiC also had been found in the specimen. The result showed that well-crystallized β-SiC fibers began to appear at 1550 °C with excessive of 100 wt% content of carbon. While at 1600 °C for 6 h with excessive of 100 wt% content of carbon, the as-synthesized SiC fibers were grown with some beads in the fiber strings. The beaded SiC consisted of strings with diameters of less than 0.5 μm (or even 0.1μm) and periodic beads with diameters of 0.5-1.0 μm. Vapor-solid (VS) mechanism and vapor-liquid-solid (VLS) mechanism were also discussed in the synthesizing process of fiber-like SiC. This kind of fiber-like SiC may used as reinforce materials in ceramic composites, the fracture toughness of brittle ceramics can be effectively improved via the incorporation of strong SiC fibers into the matrix due to crack deflection, bridging and fiber pull-out. Moreover, these toughening mechanisms do not diminish as temperature increases.

Phase Behavior of Silica Brick Used in Carbothermal Reduction

2011 ◽  
Vol 492 ◽  
pp. 472-475 ◽  
Author(s):  
Zi He Pan ◽  
Zhao Hui Huang ◽  
Wen Juan Li ◽  
Yan Gai Liu ◽  
Ming Hao Fang
Keyword(s):  
Phase Composition ◽  
Carbon Content ◽  
Phase Behavior ◽  
Carbothermal Reduction ◽  
Reduction Method ◽  
Raw Materials ◽  
Holding Time ◽  
Silica Brick ◽  
Many Particles ◽  
Sem Analyses

In this study we observed the phase behavior of silica brick used in the process of carbothermal reduction. At 1550°C, there are liner β-SiC in clumps huddled together; At 1550°C, short line clumps changed into filamentous, mixed together. There are many particles and some β-SiC lines and few filamentous β-SiC at 1600°C . Different ratio of carbon coke also effect the phase behavior. From the results we obtained SiC powders. SiC refractory powders were prepared via carbothermal reduction method using used silica bricks as raw materials. The effects of carbon content, temperature and holding time on the phase composition and microstructure were analyzed. XRD and SEM analyses show that: β-SiC refractory powders were synthesized at 1600°C for 6 h with100 wt% excessive of carbon content. With the increase of carbon content, the reaction temperature and holding time, content of β-SiC gradually increased while that of cristobalite decreased.

Microstructural Study of Reduced Malaysian Ilmenite by Carbothermal Reduction and Nitridation in Nitrogen Atmosphere

2013 ◽  
Vol 858 ◽  
pp. 265-271 ◽  
Author(s):  
Aishah Syed Salim Sharifah ◽  
Hanizam Shah Saidin ◽  
Norlia Baharun ◽  
S.A. Rezan ◽  
Hussin Hashim
Keyword(s):  
Carbothermal Reduction ◽  
Raw Materials ◽  
Horizontal Tube ◽  
Nitrogen Atmosphere ◽  
Sem Analysis ◽  
Iron Chloride ◽  
Boudouard Reaction ◽  
Tube Reactor ◽  
Coal Mixtures

The reduction of Malaysia Ilmenite (FeTiO3) with coal by carbothermal reduction under N2 atmosphere was studied. Characterization of raw materials was done by XRD, XRF, Optical Microscopy (OM) and SEM analysis. Isothermal experiments were carried out using the pellets in a horizontal tube reactor with continuously flowing gas. From the experiments, 0-10 wt. % of FeCl3 was added in the ilmenite-coal mixtures before reduction. The mixture was reduced at 1100°C for 60, 120 and 180 minutes. The addition of FeCl3 acted as a catalyst and increased the rate of reduction. The microstructures of the reduced sample were porous with the addition of FeCl3. Furthermore, defects were observed due to increase release of Cl2 and CO during reduction. FeCl3 acted as catalyst in the gasification of coal by the Boudouard reaction. SEM analysis indicates that the microstructure of the particles was coarsened due to the addition of catalyst. Besides that, there was less agglomeration of metallic iron particles at higher addition of FeCl3. The effect of FeCl3 on the morphology iron was the nucleation of microscopic iron rich zones in the reduced sample. Keywords: Carbothermal Reduction, Iron Chloride, Malaysian Ilmenite, Nitridation, Titanium Oxycarbonitride.

Preparation of Transparent AlON Ceramics Using Powder Synthesized from Nano-Sized Al2O3 and AlN

2008 ◽  
Vol 368-372 ◽  
pp. 447-449 ◽  
Author(s):  
Jian Qi Qi ◽  
Tie Cheng Lu ◽  
Ji Cheng Zhou ◽  
Wei Pang ◽  
Jin Song Wen ◽  
...  
Keyword(s):  
Solid State ◽  
Polyvinyl Alcohol ◽  
High Purity ◽  
Solid State Reaction ◽  
Single Phase ◽  
Holding Time ◽  
Transparent Ceramics ◽  
Ceramic Samples ◽  
H 20

The single-phase AlON powder used to prepare transparent ceramics was synthesized from solid-state-reaction using nano-sized Al2O3 and AlN powders with high purity. An appropriate amount of the powder was molded into pellets and isostatically pressed using polyvinyl alcohol as the binder. The AlON ceramic samples were obtained by sintering the pellets at 1880°C for 10 h, 20 h and 40 h, respectively. The transparency of the samples increased as the temperature holding time was prolonged. The density, phase compositions and microstructures of the sintered samples were discussed in detail.

The Synthesis of TiC Powders by Carbothermal Reduction Method in Vacuum

2014 ◽  
Vol 1064 ◽  
pp. 62-65
Author(s):  
Xue Tan Ren ◽  
Yan Chun Liu ◽  
Shui Hui Chen ◽  
Lai Guang Hou ◽  
Guo Long Wang ◽  
...  
Keyword(s):  
Carbon Black ◽  
Crystalline Phase ◽  
Carbothermal Reduction ◽  
Single Phase ◽  
Reduction Method ◽  
Raw Materials ◽  
Molar Ratio ◽  
Carbothermal Reduction Method ◽  
System Pressure

The TiC powders were synthesized by carbothermal reduction of TiO2in vacuum using the titania and carbon black as raw materials. The molar ratio of C to TiO2was 3:1. The crystalline phase, microstructure and morphology of the obtained samples were investigated by XRD and SEM. The results show that single-phase and well-crystallized TiC powders were obtained at 1300°C for 1h when the system pressure was 20 Pa. The particle morphologies are composed of fine grains about 200 nm.

Phase Behavior Analysis of Low-Grade Bauxite and Rutile by Carbothermal Reduction-Nitridation

2012 ◽  
Vol 624 ◽  
pp. 239-243
Author(s):  
Tao Yang ◽  
Yan Gai Liu ◽  
Ding Yun Ye ◽  
Qi Wang ◽  
Zhao Hui Huang ◽  
...  
Keyword(s):  
Phase Composition ◽  
Phase Transitions ◽  
Phase Behavior ◽  
Carbothermal Reduction ◽  
Raw Materials ◽  
Nitrogen Atmosphere ◽  
Low Grade ◽  
Reaction Parameters ◽  
Nitridation Process ◽  
Nitridation Reaction

In this study, β-Sialon/Al2O3/TiN diphase powder was synthesized using low-grade bauxite and rutile via carbothermal reduction-nitridation. The phase transitions of low-grade bauxite and rutile in the carbothermal reduction and nitridation process were analyzed by XRD, SEM and EDS. The effects of different reaction parameters such as reaction temperature, rutile addition on the phase composition and microstructure of products were analyzed. The results showed that β-Sialon/Al2O3/TiN powder was prepared using low-grade bauxite and rutile as raw materials and coke as reducing agent by carbothermal reduction-nitridation reaction in flowing nitrogen atmosphere of 0.03 MPa at 1350-1375 °C, for 4 h.

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