scholarly journals Effects of oxidation of SiC aggregates on the sintering behaviour and microstructures of SiC-CaAl12O19 composite refractories

2021 ◽  
Vol 15 (1) ◽  
pp. 11-18
Author(s):  
Yaochen Si ◽  
Miao Xia ◽  
Hongxia Li ◽  
Honggang Sun ◽  
Ang Guo ◽  
...  
Keyword(s):  
Firing Temperature ◽  
Sintering Temperature ◽  
Raw Materials ◽  
Coal Slurry ◽  
Refractory Materials ◽  
Sintering Process ◽  
Active Oxidation ◽  
Passive Oxidation ◽  
Different Temperatures ◽  
Sintering Behaviour

In order to develop chrome-free refractory materials applicable in coal slurry gasification, SiC-CaAl12O19 (SiC-CA6) composite refractories were developed and prepared by using SiC aggregates and CA6 powders as main raw materials. The sintering behaviour of the composites was investigated. After firing at different temperatures under CO atmosphere, the effects of oxidation of SiC aggregates on the sintering behaviour and microstructures of SiC-CA6 composite refractorieswere investigated. SiC-CA6 composites could not be sintered when firing temperature was lower than 1500?C. SiC had a passive oxidation and the oxidation components were able to react with CA6 to form CaAl2Si2O8. The CaAl2Si2O8 melted into liquid when sintering temperature was in the range of 1500-1600?C, which promoted the sintering process of the SiC-CA6 composites. At temperatures above 1600 ?C, an active oxidation of SiC occurred. Simultaneously, SiC could also reacted with the SiO2(s,l) to form SiO, leading to the precipitation of Al2O3 and CaO in the liquid to generate plate-like CA6. Above this temperature, the sintering of the SiC-CA6 composite refractories was affected by the growth of CA6 and oxidation of SiC. This work demonstrates that the optimal sintering temperature for the SiC-CA6 composite refractories was 1600?C.

scholarly journals Pressureless Sintering of YIG Ceramics from Coprecipitated Nanopowders

2021 ◽  
Vol 7 (5) ◽  
pp. 56
Author(s):  
Yimin Yang ◽  
Xiaoying Li ◽  
Ziyu Liu ◽  
Dianjun Hu ◽  
Xin Liu ◽  
...  
Keyword(s):  
High Temperature ◽  
Calcination Temperature ◽  
Sintering Temperature ◽  
Raw Materials ◽  
Secondary Phase ◽  
Coprecipitation Method ◽  
Pressureless Sintering ◽  
Densification Behavior ◽  
Sintering Process

Nanoparticles prepared by the coprecipitation method were used as raw materials to fabricate Y3Fe5O12 (YIG) ceramics by air pressureless sintering. The synthesized YIG precursor was calcinated at 900–1100 °C for 4 h in air. The influences of the calcination temperature on the phase and morphology of the nanopowders were investigated in detail. The powders calcined at 1000–1100 °C retained the pure YIG phase. YIG ceramics were fabricated by sintering at 1200–1400 °C for 10 h, and its densification behavior was studied. YIG ceramics prepared by air sintering at 1250 °C from powders calcinated at 1000 °C have the highest in-line transmittance in the range of 1000-3000 nm. When the sintering temperature exceeds 1300 °C, the secondary phase appears in the YIG ceramics, which may be due to the loss of oxygen during the high-temperature sintering process, resulting in the conversion of Fe3+ into Fe2+.

Barium Strontium Titanate Ceramics Prepared by a Reaction-Sintering Process

2004 ◽  
Vol 848 ◽  
Author(s):  
Yi-Cheng Liou ◽  
Jen-Hsien Chen ◽  
Chi-Ting Wu
Keyword(s):  
Strontium Titanate ◽  
Barium Strontium Titanate ◽  
Sintering Temperature ◽  
Raw Materials ◽  
Reaction Sintering ◽  
Sintering Process ◽  
Barium Strontium ◽  
Bst Ceramics ◽  
Titanate Ceramics

ABSTRACTBarium strontium titanate (Ba0.7Sr0.3TiO3, BST) ceramics prepared by a reaction-sintering process were investigated. The mixture of raw materials of stoichiometric Ba0.7Sr0.3TiO3 was pressed and sintered into ceramics without any calcination stage involved. Perovskite BST ceramics were obtained after sintered at 1330–1370°C for 2–6 h. For 6 h soak time, a density value 5.68g/cm3 (99.8% of the theoretic value) was obtained at 1350°C sintering. Grains of sizes between 2μm and 15μm were formed after 1330–1370°C sintering for 2–6 h. A diffused ferroelectric-paraelectric transition was observed in pellets sintered at 1330°C for 2 h and disappeared at a longer soak time or a higher sintering temperature.

Effect of Sintering Temperature on Properties of YAG Porous Ceramics via Atmospheric Sintering Method

2018 ◽  
Vol 281 ◽  
pp. 224-229 ◽  
Author(s):  
Fang Wang ◽  
Ming Han Xu ◽  
Ai Xia Chen ◽  
Long Tao Liu ◽  
Zhi Hui Li ◽  
...  
Keyword(s):  
Sintering Temperature ◽  
Raw Materials ◽  
Porous Ceramics ◽  
Soluble Starch ◽  
Product Performance ◽  
Effect Of Temperature ◽  
Sintering Process ◽  
Molding Process ◽  
Sintering Aid ◽  
Sintering Method

YAG materials have a number of unique properties, the application is very extensive, the burn is due to the temperature is too high or the residence time at high temperatures is caused. The undercurrent is the sintering temperature is too low or the holding time is not enough, resulting in product performance is too low or too small shrinkage. In this paper, the effect of sintering temperature on properties of YAG porous ceramics was investigated. The results showed that the firing temperature of the ingredients will be different and cause the same sintering process and sintering additives content of different samples burned. The increase in the content of SiO2 in the furnish with the sintering aid tends to occur. the effect of temperature on the mechanical properties of the samples after sintering was significant, so the raw materials include 60wt%YAG, 10wt% CaO, 10wt% SiO2 and 20wt% soluble starch, the molding process in 20MPa pressure 10min, the sintering at 1500°C for 2h, the sample porosity is 42.2%, the compressive strength is 5.8MPa, the outside shape is keep intact and the better pore microstructure is shown.

A Process for Sintering of Diopside Prepared from Dolomite

2005 ◽  
Vol 492-493 ◽  
pp. 235-240 ◽  
Author(s):  
S. Zouai ◽  
F.Z. Mezahi ◽  
S. Achour ◽  
Abdelhamid Harabi
Keyword(s):  
Sintering Temperature ◽  
Raw Materials ◽  
Egg White ◽  
Different Temperatures ◽  
Pure Sio2

Diopside CaMgSi2O6 is an attractive material because of its multi applications. It was prepared by sintering the mixture at different temperatures (900°C-1300°C). Starting materials were pure SiO2 and dolomite raw materials. In order to improve the properties of sintered samples, such as the density egg white (ovalbemin) has been added into diopside. Furthermore, the effect of P2O5 addition on the sintering of the prepared diopside in the range of 0.5 to 5.0 wt% was studied as a function of the sintering temperature. A density of 96.5% of theoretical has been achieved when 5.0 wt% P2O5 was added, at a sintering temperature of 1225°C, whereas the density of diopside samples, without P2O5 addition was lower than 83.0% of theoretical.

Preparation and characterization of low-cost high-performance mullite-quartz ceramic proppants for coal bed methane wells

2018 ◽  
Vol 25 (5) ◽  
pp. 957-961 ◽  
Author(s):  
Kaiyue Wang ◽  
Huijun Wang ◽  
Yi Zhou ◽  
Guomin Li ◽  
Yaqiao Wu ◽  
...  
Keyword(s):  
High Performance ◽  
Sintering Temperature ◽  
Raw Materials ◽  
Low Cost ◽  
Quartz Ceramic ◽  
Coal Bed ◽  
Coal Bed Methane ◽  
Sintering Process ◽  
Flow Mechanism

AbstractIn this study, the mullite-quartz-based proppants were successfully prepared by using the coal gangue as the raw materials. Then, the effects of the additive and the sintering temperature on the composition, microstructure, and properties of the proppants were investigated. Results showed that the proppants sintered at 1250°C with the 10 wt% bauxite additive presented the best performance, which was very close to that of the quartz-proppant, and met the operational requirements of the 52 MPa coal bed methane wells. The viscous flow mechanism of the liquid phase formed during the sintering process also promoted the arrangement of the grains, thus benefiting the densification and the strength of the proppants.

Porous SiO2/SiC Fiber Via Carbothermal-Reduction of Hybrid Fiber in Air Flows

2011 ◽  
Vol 236-238 ◽  
pp. 1492-1496
Author(s):  
Qiu Sheng Song ◽  
Kai Zhang ◽  
Shun Xu ◽  
Zhen Biao Zhong ◽  
Meng Li
Keyword(s):  
Sintering Temperature ◽  
Raw Materials ◽  
Sol Gel ◽  
Drawing Process ◽  
Hybrid Fiber ◽  
Hybrid Fibers ◽  
Air Atmosphere ◽  
Sic Fiber ◽  
Different Temperatures ◽  
Ft Ir

Using tetraethoxysilane (TEOS) and novolac-PF as raw materials, SiO2/PF hybrid fibers were prepared via sol-gel associated with drawing process, and then sintered at different temperatures (500-1300 °C) under air atmosphere. The microstructure variation and reaction mechanism of the fiber were investigated by FT-IR, XRD, and SEM measurements. The results showed that the microstructure variation of the hybrid fiber was influenced greatly by sintering temperatures. When the sintering temperature was below 900 °C, the fibers were amorphous, and converted into porous SiO2/SiC fibers after being sintered at 1300 °C.

Preparation and Characterization of Al2TiO5- Si3N4 Composites by Reaction Sintering Process

2011 ◽  
Vol 284-286 ◽  
pp. 201-204
Author(s):  
Rui Sheng Wang ◽  
Jun Hong Zhao ◽  
Heng Yong Wei ◽  
Shao Wei Yao
Keyword(s):  
Mechanical Strength ◽  
Sintering Temperature ◽  
Raw Materials ◽  
Reaction Sintering ◽  
Sintering Process ◽  
Soaking Time ◽  
Sintering Properties ◽  
The One

Al2TiO5-Si3N4 composites were prepared by reaction sintering process using Al2TiO5 and α-Si3N4 powders as raw materials. The effect ofsintering temperature, soaking time and Si3N4 content on the sintering properties of the composites was studied. The results showed that the best sintering temperature and soaking time were 1550 °C and 2 h, respectively. The samples with 15 wt% of Si3N4 addition had good sintering properties, and its mechanical strength was 28.96 MPa, which was 2 times of the one of the samples without Si3N4 addition.

scholarly journals Microstructural evolution of h-BN matrix composite ceramics with La-Al-Si-O glass phase during hot-pressed sintering

2020 ◽  
Author(s):  
Baofu Qiu ◽  
Xiaoming Duan ◽  
Zhuo Zhang ◽  
Chen Zhao ◽  
Bo Niu ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Fracture Toughness ◽  
Elastic Modulus ◽  
Microstructural Evolution ◽  
Glass Phase ◽  
Sintering Temperature ◽  
Raw Materials ◽  
Sintering Process ◽  
Composite Ceramics ◽  
Phase Precipitation

Abstract BN/La-Al-Si-O composite ceramics were fabricated by hot-pressed sintering using h-BN, La2O3, Al2O3 and amorphous SiO2 as the raw materials. The effects of sintering temperature on the microstructural evolution, bulk density, apparent porosity, and mechanical properties of h-BN composite ceramics were investigated. The results indicated that La-Al-Si-O liquid phase was formed during sintering process, which provided an environment for the growth of h-BN grains. With increasing sintering temperature, the cristobalite phase precipitation and h-BN grain growth occurred at the same time, which had the significant influence on the densification and mechanical properties of h-BN composite ceramics. The best mechanical properties of BN/La-Al-Si-O composite ceramics were obtained under sintering temperature of 1700 °C, and the elastic modulus, flexural strength, and fracture toughness were 80.5 GPa, 266.4 MPa and 3.25 MPa·m1/2, respectively.

scholarly journals Study on Sintering of Artificially Oxidized Steel Compacts

2019 ◽  
Vol 19 (1) ◽  
pp. 12-22
Author(s):  
C. Gierl-Mayer ◽  
T. Stepan ◽  
J. Sun ◽  
H. Danninger
Keyword(s):  
Thermal Analysis ◽  
Iron Oxides ◽  
Steel Powder ◽  
Microstructural Development ◽  
Sintering Process ◽  
Low Oxygen ◽  
Iron And Steel ◽  
Reducing Conditions ◽  
Different Temperatures ◽  
Sintering Behaviour

AbstractSintering of Cr-prealloyed PM steels requires atmospheres with good quality – low oxygen potential – to achieve satisfactory sintering results. But during heating even the best atmospheres may be oxidizing, the system turns to reducing conditions only at high temperatures, which can be monitored by thermal analysis. During the dewaxing process, oxidizing conditions are favourable for effective dewaxing without sooting and blistering. However, this may result in some oxygen pickup during heating, and then the final properties of the produced parts may be strongly influenced by this intermediate oxidation. This study demonstrates the behaviour of artificially oxidized steels (Fe-C and Fe3Cr-0.5Mo-C) during the sintering process by stepwise sintering. Iron and steel powder were slightly oxidized and then pressed and sintered at different temperatures. In parallel, as a second approach, pressed samples were oxidized and then sintered. Density, hardness and impact energy were measured and dilatometry/MS was used for online monitoring of the sintering process. The starting oxygen content of 0.20 to 0.30 wt% is high enough to change the sintering behaviour of the materials, but still leads to rather good properties. Thermal analysis showed that most of the oxygen picked up was present as iron oxides on the surface which were reduced by hydrogen at rather low temperatures, confirming that these were iron oxides, which also holds for the Cr-prealloyed variant. The biggest influence on the final performance was exerted by the final carbon content and the microstructural development of the material.

scholarly journals Effect of Sintering Temperature on the Properties of Aluminium-Aluminium Oxide Composite Materials

2016 ◽  
Vol 1 (2) ◽  
pp. 59-64 ◽  
Author(s):  
Dewan Muhammad Nuruzzaman ◽  
Farah Fazira Kamaruzaman ◽  
Nasrah Mohd Azmi
Keyword(s):  
Composite Materials ◽  
Powder Metallurgy ◽  
Metal Matrix ◽  
Sintering Temperature ◽  
Aluminium Oxide ◽  
Weight Fraction ◽  
Matrix Composites ◽  
Sintering Process ◽  
Weight Percentage ◽  
Different Temperatures

In this study, aluminium-aluminium oxide (Al-Al2O3) metal matrix composites of different weight percentage reinforcements of aluminium oxide were processed at different sintering temperatures. In order to prepare these composite specimens, conventional powder metallurgy (PM) method was used. Three types specimens of different compositions such as 95%Al+5%Al2O3, 90%Al+10%Al2O3 and 85%Al+15%Al2O3 were prepared under 20 Ton compaction load. Then, all the specimens were sintered in a furnace at two different temperatures 550oC and 580oC. In each sintering process, two different heating cycles were used. After the sintering process, it was observed that undistorted flat specimens were successfully prepared for all the compositions. The effects of sintering temperature and weight fraction of aluminium oxide particulates on the density, hardness and microstructure of Al-Al2O3 composites were observed. It was found that density and hardness of the composite specimens were significantly influenced by sintering temperature and percentage aluminium oxide reinforcement. Furthermore, optical microscopy revealed that almost uniform distribution of aluminium oxide reinforcement within the aluminium matrix was achieved.

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