Co-Catalyzed Si3N4/Sialon Nanofibers Reinforced SiC Refractories

2018 ◽  
Vol 281 ◽  
pp. 316-322
Author(s):  
Meng Zhang ◽  
Jun Tong Huang ◽  
Xi Bao Li ◽  
Zhi Hui Hu ◽  
Ming Qiang Liu ◽  
...  
Keyword(s):  
Bulk Density ◽  
Bending Strength ◽  
Apparent Porosity ◽  
Structure And Properties ◽  
Co Addition

SiCp matrix refractories reinforced by Si3N4/Sialon nanofibers in-situ catalytic formed were prepared at 1400 °C. The roles of catalyst Co on the structure and properties of as-prepared products were studied. We found that the catalyst Co enhanced the nitridation of Si and/or Al. With the increasing of Co addition (from 0-2.0 wt.%), the apparent porosity of the products decreased first and then increased, while the bending strength and the bulk density were exactly the opposite. The as-prepared Si3N4/Sialon bonded SiC refractories exhibited the highest strength of 61.1 MPa as the Co content was 1.0 wt.%. The addition of Co was beneficial to the formation of Si3N4/Sialon nanofibers and the sintering of Si3N4/Sialon bonded SiC matrix refractories, which effectively improved the strength of the samples.

scholarly journals Si3N4-SiCpComposites Reinforced byIn SituCo-Catalyzed Generated Si3N4Nanofibers

2014 ◽  
Vol 2014 ◽  
pp. 1-6 ◽  
Author(s):  
Juntong Huang ◽  
Zhaohui Huang ◽  
Shaowei Zhang ◽  
Minghao Fang ◽  
Yan’gai Liu
Keyword(s):  
Mechanical Properties ◽  
Bulk Density ◽  
Bending Strength ◽  
Sintering Temperature ◽  
Apparent Porosity ◽  
Network Connection ◽  
Opposite Trend ◽  
Low Sintering Temperature ◽  
Co Addition

Si3N4-SiCpcomposites reinforced byin situcatalytic formed nanofibers were prepared at a relatively low sintering temperature. The effects of catalyst Co on the phase compositions, microstructures, and physicochemical-mechanical properties of samples sintered at 1350°C–1450°C were investigated. The results showed that the catalyst Co enhanced the nitridation of Si. With the increase of Co addition (from 0 wt% to 2.0 wt.%), the apparent porosity of as-prepared refractories was initially decreased and subsequently increased, while the bulk density and the bending strength exhibited an opposite trend. TheSi3N4-SiCpcomposites sintered at 1400°C had the highest strength of 60.2 MPa when the Co content was 0.5 wt.%. The catalyst Co facilitated the sintering ofSi3N4-SiCpcomposites as well as the formation of Si3N4nanofibers which exhibited network connection and could improve their strength.

In Situ Formation of Mullite-Al2O3 Refractory Ceramic from Al-Matrix Mixtures

2014 ◽  
Vol 602-603 ◽  
pp. 628-631
Author(s):  
Xing Yong Gu ◽  
Ping Li ◽  
Wei Xia Dong ◽  
Ting Luo
Keyword(s):  
Thermal Expansion ◽  
Bulk Density ◽  
Thermal Expansion Coefficient ◽  
Expansion Coefficient ◽  
Bending Strength ◽  
Potential Effect ◽  
Apparent Porosity ◽  
Mullite Phase ◽  
Two Samples

Two types of mullite-Al2O3 composites were designed and sintered in situ from different composition containing Al composites e.g. kaolin, alumina hydroxide and calcined bauxite etc, and auxiliary additives. The phase composition and microstructure were studied using X-ray diffraction (XRD) and scanning electron microscope (SEM) techniques. Bulk density, apparent porosity, thermal expansion coefficient and bending strength were also measured. The two samples exhibited XRD reflections characteristic of alumina and mullite phases. The amount of these phases depended on starting batch compositions, and reaction of starting and auxiliary materials together to form mullite. Because of in-situ formation of mullite fiber, the bulk density and bending strength were improved and apparent porosity was decreased for the composites with uniform microstructure. The presence of high mullite phase was found to decrease the thermal expansion coefficient. The potential effect of these morphologies and phase on properties was discussed. These mullite-Al2O3 composite was expected to have major applications in the areas of refractory material.

Effect of Z Values on the Microstructure and Mechanical Properties of Post-sintered Reaction Bonded β-SiAlON

2017 ◽  
Vol 36 (5) ◽  
pp. 453-458 ◽  
Author(s):  
Yanjun Li ◽  
Donghua Liu ◽  
Han Jin ◽  
Donghai Ding ◽  
Guoqing Xiao ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Phase Composition ◽  
Bulk Density ◽  
Grain Growth ◽  
Bending Strength ◽  
Raw Materials ◽  
Apparent Porosity ◽  
Reaction Bonding ◽  
Microstructure And Mechanical Properties ◽  
Before And After

Abstractβ-SiAlON materials with different Z values (Z=0.5–3) were fabricated by a reaction bonding combining post-sintering route using raw materials of Si, Al2O3, AlN, etc. The reaction bonded β-SiAlON (RB-β-SiAlON) were post-sintered at 1,750 °C for 6 h. Apparent porosity, bulk density, bending strength and Vicker’s hardness of the samples before and after post-sintering were tested. XRD results showed that the phase composition of both RB-β-SiAlON and post-sintered RB-β-SiAlON (PSRB-β-SiAlON) were β-SiAlON. For RB-β-SiAlON, the apparent porosity was decreased with the increase of Z values, while the strength and hardness was increased accordingly. After the post-sintering procedure, nearly full densified PSRB-β-SiAlON was obtained and the mechanical properties were significantly improved. The bending strength and Vicker’s hardness of the PSRB-β-SiAlON (Z=0.5) achieved 510 MPa and 16.5 GPa, respectively, which were as 2.7 and 6.7 times high as those of the corresponding RB-β-SiAlON. However, the strength and hardness of PSRB-β-SiAlON decreased with the increase of Z value due to the grain growth.

The Optimal Ratio of Mixed Talc Silica and Narathiwat Clay for Cordierite-Mullite Refractories

2018 ◽  
Vol 766 ◽  
pp. 223-227
Author(s):  
Nattawut Ariyajinno ◽  
Sakdipown Thiansem
Keyword(s):  
Mechanical Properties ◽  
Optimum Condition ◽  
Water Absorption ◽  
Bulk Density ◽  
Bending Strength ◽  
Raw Materials ◽  
Apparent Porosity ◽  
Kiln Furniture ◽  
Firing Shrinkage ◽  
Xrd Patterns

In this paper, effects of incorporation of Narathiwat clay (NT), talc and silica on the mechanical properties of cordierite-mullite refractories were investigated. The starting raw materials were mixed in different ratios and fired at 1300 °C for 2 hours. XRD patterns of fired refectories indicated cordierite and mullite phases. The fired samples were studied the firing shrinkage, water absorption, bulk density, apparent porosity and bending strength of the cordierite-mullite refractories. The optimum condition was achieved for the composition of 20% Talc that had shrinkage: 11.78%, water absorption: 4.16%, bulk density: 2.28 g/cm3, apparent porosity: 9.2% and bending strength: 330.82 kg/cm2. The results thus showed that Narathiwat clay, talc and silica was a potential materials for use kiln furniture cordierite-mullite refractories.

Effects of Sintering Temperature on Phases, Microstructures and Properties of Fused Silica Ceramics

2017 ◽  
Vol 726 ◽  
pp. 399-403 ◽  
Author(s):  
Shi Hua Liu ◽  
Peng Chen ◽  
Dan Hua Xu ◽  
Qing Dan Yuan
Keyword(s):  
Bulk Density ◽  
Bending Strength ◽  
Sintering Temperature ◽  
Fused Silica ◽  
High Density ◽  
Apparent Porosity

Fused silica ceramics, named fused silica articles by means of ceramics fabrication processes, had been widely used in metallurgy, refractory, aviation and many other areas. How to get fused silica ceramics with high density and less cristobalite is on the focus. In this paper, effects of sintering temperature (1150°C, 1200°C, 1250°C, 1300°C, 1350°C) on phases, microstructures and properties of fused silica ceramics were investigated. The results showed that the bulk density of samples increased and the apparent porosity of samples minished gradually, with the increase of sintering temperature. However, the bending strength increased to maximum firstly and then decreased because the emergency of cristobalite at 1300°C. When the sintering temperature was 1250°C, the bulk density, apparent porosity and bending strength was 1.71g·cm-3, 17.6% and 38.87MPa, respectively.

scholarly journals Preparation, Microstructure, and Mechanical Properties of Spinel-Corundum-Sialon Composite Materials from Waste Fly Ash and Aluminum Dross

2014 ◽  
Vol 2014 ◽  
pp. 1-10 ◽  
Author(s):  
Juntong Huang ◽  
Minghao Fang ◽  
Zhaohui Huang ◽  
Yan’gai Liu ◽  
Jingzhou Yang ◽  
...  
Keyword(s):  
Fly Ash ◽  
Bulk Density ◽  
Bending Strength ◽  
Low Cost ◽  
Apparent Porosity ◽  
Raw Material ◽  
Added Value ◽  
Ni Doping ◽  
Aluminum Dross ◽  
Al Content

The solid wastes fly ash and aluminum dross were used to prepare the low cost, high added-value product spinel-corundum-Sialon with anin situaluminothermic reduction-nitridation reaction. The effects of varying raw material components and heating temperatures on the phase compositions, microstructure, bulk density, apparent porosity, and bending strength of products were investigated. The presence of hazardous or impure elements in the products was also evaluated. The sintered materials mainly consisted of micro-/nanosized plate corundum, octahedral spinel, and hexagonal columnarβ-Sialon. The bulk density and bending strength of product samples initially increased and then decreased as Al content increased. Product samples with an Al content exceeding 10 mass% that were sintered at 1450°C exhibited the highest bending strength (288 MPa), the lowest apparent porosity (1.24%), and extremely low linear shrinkage (0.67%). The main impurity present was Fe5Si3with hazardous elements P, Cr, Mn, and Ni doping. This work could provide a new method to reduce environmental pollution and manufacture low cost high performance refractory materials using the abundant waste materials fly ash and aluminum dross.

Fabrication and Properties of Al2O3-SiC/Sialon Composite Refractories

2012 ◽  
Vol 512-515 ◽  
pp. 908-911
Author(s):  
Ding Yun Ye ◽  
Yan Gai Liu ◽  
Zhao Hui Huang ◽  
Ming Hao Fang ◽  
Yang Yang Liu
Keyword(s):  
Water Absorption ◽  
Bulk Density ◽  
Carbothermal Reduction ◽  
Room Temperature ◽  
Bending Strength ◽  
Raw Materials ◽  
Apparent Porosity ◽  
Low Grade ◽  
Sialon Powder ◽  
Aluminate Cement

Sialon powder was synthesized using low grade bauxite as raw materials by carbothermal reduction-nitridation reaction. The influence of synthesizing temperatures (1300°C, 1350°C, 1400°C, 1450°C, 1500°C and 1550°C) on the phases of the final products was studied by XRD technique. β-Sialon (Z=3) formed at 1350°C and decreased when the temperature was higher than 1450°C. The optimizing reaction temperature for preparing Sialon was 1450°C. The Al2O3-SiC/Sialon composite refractories were prepared at 200°C, 400°C and 600°C for 24h with white corundum, brown corundum, SiC, Sialon powders prepared at 1450°C and calcium aluminate cement. The bulk density, apparent porosity, water absorption and bending strength of the Al2O3-SiC/Sialon composite refractories at room temperature were studied. The results show that the bulk density decreased and then increased with the enhancing of the temperature and reached the highest value of 2.43g/cm3 at 200°C. The apparent porosity and water absorption reached the lowest values of 26.68% and 10.99% at 200°C respectively. The bending strength decreased as the temperature increased, reached the highest value of 0.73MPa at 200°C.

Fabrication and Properties of CaAl12O19-Al2O3 Composite Ceramics

2012 ◽  
Vol 512-515 ◽  
pp. 539-542 ◽  
Author(s):  
Xue Yin Liu ◽  
Yan Gai Liu ◽  
De Xin Yang ◽  
Ding Yun Ye ◽  
Zhao Hui Huang ◽  
...  
Keyword(s):  
Solid State ◽  
Bulk Density ◽  
Solid State Reaction ◽  
Bending Strength ◽  
Sintering Temperature ◽  
Apparent Porosity ◽  
Composite Ceramics ◽  
Final Composite

CaAl12O19-Al2O3 composite ceramics were synthesized by in situ solid state reaction using CaCO3 and industrial α-Al2O3 powders. The effects of sintering temperature and ratio of CA6 (CaAl12O19) content on phases and microstructure of the final composite ceramics were studied by XRD and SEM. The result showed that sheet-like CA6 appeared in the materials when sintering temperature was higher than 1400°C and grew up with the increased of the sintering temperature. The optimum sintering temperature was 1600°C, when the sample containing 20wt% CA6 was sintered at 1600°C, the bulk density was 3.21g/cm3, the apparent porosity achieved 9.94% and the bending strength gained 149.88MPa. With the increasing of CA6 content in the final composite ceramics, the bulk density and the bending strength increased firstly and then decreased. The lowest apparent porosity 1.42%, a density of 3.60g/cm3 and the highest bending strength of 265.10MPa were achieved for the sample containing 10wt% CA6 sintered at 1600°C.

Structure and properties of compact articles from high-alloyed iron powder with adding of boron nitride

2020 ◽  
pp. 39-48
Author(s):  
B. O. Bolshakov ◽  
◽  
R. F. Galiakbarov ◽  
A. M. Smyslov ◽  
◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Boron Nitride ◽  
Grain Boundary ◽  
Bending Strength ◽  
Physical And Mechanical Properties ◽  
Operating Conditions ◽  
Structure And Properties ◽  
Steam Turbines ◽  
Friction Forces ◽  
Wide Range

The results of the research of structure and properties of a composite compact from 13 Cr – 2 Мо and BN powders depending on the concentration of boron nitride are provided. It is shown that adding boron nitride in an amount of more than 2% by weight of the charge mixture leads to the formation of extended grain boundary porosity and finely dispersed BN layers in the structure, which provides a high level of wearing properties of the material. The effect of boron nitride concentration on physical and mechanical properties is determined. It was found that the introduction of a small amount of BN (up to 2 % by weight) into the compacts leads to an increase in plasticity, bending strength, and toughness by reducing the friction forces between the metal powder particles during pressing and a more complete grain boundary diffusion process during sintering. The formation of a regulated structure-phase composition of powder compacts of 13 Cr – 2 Mо – BN when the content of boron nitride changes in them allows us to provide the specified physical and mechanical properties in a wide range. The obtained results of studies of the physical and mechanical characteristics of the developed material allow us to reasonably choose the necessary composition of the powder compact for sealing structures of the flow part of steam turbines, depending on their operating conditions.

Mechanical Properties and Thermal Conductivity of Lightweight Clay Bricks Fabricated with a Powdered Marble Dust Additive

2018 ◽  
Vol 777 ◽  
pp. 465-470
Author(s):  
Sutas Janbuala ◽  
Mana Eambua ◽  
Arpapan Satayavibul ◽  
Watcharakhon Nethan
Keyword(s):  
Mechanical Properties ◽  
Thermal Conductivity ◽  
Compressive Strength ◽  
Water Absorption ◽  
Bulk Density ◽  
Firing Temperature ◽  
Apparent Porosity ◽  
Clay Brick ◽  
Clay Bricks ◽  
Marble Dust

The objective of this study was to recycle powdered marble dust to improve mechanical properties and thermal conductivity of lightweight clay bricks. Varying amounts of powdered marble dust (10, 20, 30, and 40 vol.%) were added to a lightweight clay brick at the firing temperatures of 900, 1000, and 1100 °C. When higher quantities of powdered marble dust were added, the values of porosity and water absorption increased while those of thermal conductivity and bulk density decreased. The decrease in apparent porosity and water absorption were also affected by the increase in firing temperature. The most desirable properties of the clay bricks were obtained for the powdered marble dust content of 40 vol.% and firing temperature 900 °C: bulk density of 1.20 g/cm3, compressive strength 9.2 MPa, thermal conductivity 0.32 W/m.K, and water absorption 22.5%.

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