Preparation and Characterization of Nb2O5-Al2O3 System Ceramics with Different Al2O3 Additions

2013 ◽  
Vol 544 ◽  
pp. 60-63 ◽  
Author(s):  
Xiao Zhen Zhang ◽  
Jian Er Zhou ◽  
Yu Hua Jiang ◽  
Chun Rong Wu ◽  
Chuan Ying Lin
Keyword(s):  
Thermal Expansion ◽  
Phase Composition ◽  
Binary System ◽  
Monoclinic Phase ◽  
Bending Strength ◽  
Raw Materials ◽  
Reaction Sintering ◽  
Strength Measurement ◽  
Low Thermal Expansion

The Nb2O5-Al2O3 binary system ceramics were prepared by high temperature solid state reaction sintering, using Nb2O5 and Al2O3 micro powder as the raw materials. The samples were characterized by XRD, SEM, thermodilatometric analysis and mechanical strength measurement. The influences of Al2O3 content on the phase composition, microstructure, thermal expansion properties and bending strength were investigated. Results show the samples shows obvious changes in phase composition and microstructure with the addition of Al2O3 from 2.5% to 15%. The pure Nb2O5 ceramic is composed of monoclinic phase Nb2O5, while different monoclinic aluminum niobates were formed with different Al2O3 additions. Obvious microcracking can be observed for the samples without and with 2.5% and 7.5% Al2O3 additions. The addition of Al2O3 leads to significant increase of bending strength, and all the samples keep relatively low thermal expansion coefficient (TEC). The Nb2O5-Al2O3 binary system ceramics with ultra low TEC (0.55~0.86×10-6°C-1) and improved bending strength (50.4~70.6MPa) could be obtained with the addition of 7.5~15% Al2O3 when sintered at 1390°C for 2h.

Effect of WO3 on the Performances of Cordierite Ceramics Synthesized by Using Kyanite as Raw Materials

2018 ◽  
Vol 281 ◽  
pp. 99-104
Author(s):  
Meng Li Qin ◽  
Xi Tang Wang ◽  
Zhou Fu Wang ◽  
Yan Ma ◽  
Hao Liu
Keyword(s):  
Thermal Expansion ◽  
Phase Composition ◽  
Thermal Expansion Coefficient ◽  
Expansion Coefficient ◽  
Intermediate Phase ◽  
Raw Materials ◽  
Low Thermal Expansion ◽  
Cordierite Ceramics ◽  
The Right

In order to synthesize cordierite ceramics with low thermal expansion coefficient and good properties, in our work, the cordierite ceramics were prepared by using talc, natural containing zirconium kyanite, common kyanite and industrial Al2O3 as raw materials, introducing the right amount of WO3 (introducing tungsten acid) as catalyst. The effects of the introduced WO3 on the phase composition, sintering characters, microstructure and thermal expansion coefficient of the cordierite ceramics were investigated. The results show that the introduction of WO3 can eliminate the intermediate phase magnesia-alumina spinel and promote the formation of cordierite; the as-prepared cordierite ceramics synthesized by using natural containing zirconium kyanite as raw materials have high densification degree and low thermal expansion coefficient (1.53×10-6/°C, Rt~1000 °C).

Fabrication of Pressureless Sintered β-Sialon-ZrO2 Composites

2011 ◽  
Vol 284-286 ◽  
pp. 335-338
Author(s):  
Jian Zhang ◽  
Jing Long Bu ◽  
Rong Lin Wang ◽  
Zhi Fa Wang
Keyword(s):  
Thermal Expansion ◽  
Phase Composition ◽  
Thermal Expansion Coefficient ◽  
Bending Strength ◽  
Raw Materials ◽  
Pressureless Sintering ◽  
Lower Thermal Expansion ◽  
Z Value ◽  
Bonding Phase

β-sialon-ZrO2composites with Si5AlON7 or Si4Al2O2N6 bonding phase were prapared in N2 atmosphere at 1550°C with Si, Al2O3, AlN and ZrO2 (Ca) as raw materials by reaction in situ pressureless sintering. Effect of Z value and content of β-sialon batch on its sintering performance, phase composition, microstructure, and thermal expansion character were investigated. Results showed that the phase of Si5AlON7 was formed in samples with β-sialon designing Z=1, and phases of Si5AlON7 and Si4Al2O2N6 were formed in samples with β-sialon designed Z=2 and β-sialon designed Z=3, respectively and Bending strength of samples increase with content of β-sialon batch. When content of β-sialon batch equals 10wt%, 15wt% and 15% respectively, the samples with β-sialon designed Z=1, Z=2, and Z=3 have lower apparent porosity, microstructure of homogeneous and compact and lower thermal expansion coefficient, respectively.

Some recent developments in high-strength glasses and ceramics

1964 ◽  
Vol 282 (1388) ◽  
pp. 52-56
Keyword(s):  
Thermal Expansion ◽  
Bending Strength ◽  
Glass Ceramics ◽  
High Strength ◽  
Fine Grained ◽  
Thermal Expansion Coefficients ◽  
Low Thermal Expansion ◽  
Recent Developments ◽  
Expansion Coefficients ◽  
Mechanical Strengths

Two areas of development in the field of glasses and ceramics have produced new materials with unusual combinations of properties. Glass-ceramics are melted and formed as glasses by conventional glass-forming techniques, but by a subsequent heat treatment, they are converted to fine-grained crystalline structures with new and useful combinations of properties. Products with thermal expansion coefficients approaching zero and flexural strengths ranging from 10 000 to 50 000 Lb./in. 2 have been made though not all combinations of low thermal expansion coefficients and high mechanical strengths are possible. The second area of development is in so-called Chemcor glasses. Such glass products can be preferentially pre-stressed by chemical means so as to produce an outer layer with high compressive stress and a bending strength in the finished product up to 100 000 Lb/in. 2 .

Preparation and Properties of MgAl2O4-CaAl12O19 High Temperature Composite

2012 ◽  
Vol 512-515 ◽  
pp. 617-620
Author(s):  
Yong Hong Wang ◽  
Yan Gai Liu ◽  
Tao Yang ◽  
Zhao Hui Huang ◽  
Ming Hao Fang
Keyword(s):  
Phase Composition ◽  
High Temperature ◽  
Reaction Temperature ◽  
Bending Strength ◽  
Raw Materials ◽  
Weight Ratio ◽  
Raw Material ◽  
Reaction Conditions ◽  
Optimum Reaction ◽  
Industrial Alumina

The utilization of lightweight refractories plays an important role in reducing the energy consumption of industrial furnaces. In this paper, MgAl2O4-CaA112O19 high temperature composite was synthesized via solid state reaction using magnesite, dolomite and industrial alumina as raw materials. The influences of raw materials and reaction temperature on phase compositions and microstructure of the composite were investigated by XRD and SEM，respectively. The parameters to prepare MgAl2O4-CaA112O19 high temperature composite were optimized. The results show that the optimum reaction conditions for synthesizing MgAl2O4-CaA112O19 composite is the CA6/MA weight ratio of 2:3, and the reaction temperature of 1500°C for 4h. The CaA112O19 crystals showed laminated or plate-like structure, and the MgAl2O4 showed spherical morphology. The reaction temperature had little effect on the phase compositions of MA-CA6 composite in this experiment. The content of Al2O3 in the raw material affected the phase composition of MA-CA6 composite.With the increase of the CaA112O19 amount, the bending strength of the composite decreased.

Preparation and Characterization of Fused Silica Micro-Powders and Ceramics

2011 ◽  
Vol 412 ◽  
pp. 129-132 ◽  
Author(s):  
Jin Ye Niu ◽  
Zhi Wei Chen ◽  
Liu Feng ◽  
Zheng Min Li ◽  
Min Tan
Keyword(s):  
Particle Size ◽  
Thermal Expansion ◽  
Lactic Acid ◽  
Milling Time ◽  
Bending Strength ◽  
Slip Casting ◽  
Volume Density ◽  
Fused Silica ◽  
Lactic Acid Content

Fused silica micro-powders with D50of 1.8μm were firstly prepared by ball milling. Effects of milling time on particle size distribution and microstructures of the powders were discussed. Then, the green compacts with volume density of 1.86g/cm3was obtained by slip casting with lactic acid as dispersant. Effects of lactic acid content on apparent viscosity of the slurry, thickness and density of the green compacts were investigated. Finally, fused silica ceramics with thermal expansion coefficient of 0.56∙10-6/°C, bending strength of 64MPa and volume density of 1.94g/cm3were prepared.

Preparation and Characterization of 3Y-ZrO2 Composite Ceramics

2018 ◽  
Vol 281 ◽  
pp. 189-194
Author(s):  
Yin Yan Ju ◽  
Xue Xian Gan ◽  
Jie Guang Song ◽  
Fang Wang ◽  
Qun Huang ◽  
...  
Keyword(s):  
Ball Milling ◽  
Bending Strength ◽  
Raw Materials ◽  
Microwave Sintering ◽  
Linear Shrinkage ◽  
Organic Substrate ◽  
Mass Ratio ◽  
Composite Ceramics ◽  
Surface Morphologies

Dense 3Y-ZrO2composite ceramics were prepared by using 3Y-ZrO2nanopowders as the raw materials, via the process of ball milling, granulating, molding and calcination.We investigated the microstructure, surface morphologies, the mechanical property, the density and linear shrinkage rate of the sintered ceramics and the effect of the ball milling technics and the sintering technics on the above properties of the3Y-ZrO2composite ceramics via SEM and testing. The results show that the most excellent technics in all was explored as follows: the ultrafine ball milling by adding zirconium balls of 2 mm at the speed of 35 r/min for 10 h, with the mass ratio of zirconium ball, water and mixed powders of 6:1:1, the granulaing with 1.5% PVA, the CIP, the pre-sintering to remove the organic substrate to 500°C and the microwave sintering from 20°C to 1450 °Cin 80 min in which the duration at 1450°C was 20 min and the natural cooling time of the samples was 90 min. And the 3Y-ZrO2composite ceramics obtained by this process have a relative density of 99.2%, bending strength of 1098 MPa, and a fracture toughness of 7.8 MPa·m1/2.

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.

Influence of Ceramic Aggregate on the Microstructure of Filtration Materials

2008 ◽  
Vol 575-578 ◽  
pp. 1025-1030
Author(s):  
Xiao E Ma ◽  
Hui Guo ◽  
You Guo Li
Keyword(s):  
Bending Strength ◽  
Sintering Temperature ◽  
Raw Materials ◽  
Xrd Analysis ◽  
Chemical Durability ◽  
Strength Measurement ◽  
Industry Waste ◽  
Aggregate Content ◽  
Filtration Effect ◽  
Aperture Distribution

In this paper, by some technological process, the reusable filtration materials has been made by using the main waste residue of ceramic industry—waste ceramics as the aggregate and mixing with proper binder and pore-forming agent. The production process of filtration materials and the character of light CaCO3 as pore-forming agent were described; For the selected raw materials, changed the ratio and aggregate granularity, the influence of ceramic aggregate content on the aperture, aperture distribution, porosity and bending strength of filtration materials and the influence of aperture distribution of aggregate on sample’s capability have been revealed based on the XRD analysis, SEM observation and bending strength measurement of filtration materials; at the same time, the influence of sintering temperature on the porosity and bending strength of filtration materials was also studied. The results show that the better filtration effect and better chemical durability, the higher bending strength (15MPa) of the synthetical filtration materials can be obtained when the content of aggregate, the particle size and the sintering temperature are respectively 50~55wt%, 150~1804m and 1205°C.

Comparison of Porous Ceramic Materials with Low Thermal Expansion Coefficient Prepared with SiC and Black-Al2O3

2008 ◽  
Vol 569 ◽  
pp. 321-324
Author(s):  
Isaías Juárez-Ramírez ◽  
Koji Matsumaru ◽  
Kozo Ishizaki ◽  
Leticia M. Torres-Martínez
Keyword(s):  
Thermal Expansion ◽  
Room Temperature ◽  
Raw Materials ◽  
Porous Ceramic ◽  
Ceramic Materials ◽  
X Ray Diffraction ◽  
Low Thermal Expansion ◽  
New Phase ◽  
Porous Ceramic Materials ◽  
Made In

Porous ceramic materials with low thermal expansion (LTE) at room temperature were prepared by heating a mixture of SiC or black-Al2O3, vitrified bonding material (VBM) and LiAlSiO4 at temperatures from 850°C to 1100°C. The mixture was prepared in adequate proportions to obtain a material with LTE according to previous works made in our laboratory. It was observed that a change in temperature provoked the formation of a new phase, LiAlSi3O8, which appears above 900°C. The presence of this new phase did not affect the thermal expansion value, keeping LTE at room temperature. All compounds showed around 40% of porosity, and Young’s modulus values of 30 GPa using black-Al2O3 or SiC. X-ray diffraction analysis (XRD) revealed that above 900°C the phase LiAlSi3O8 starts to appear as a consequence of the melting of VBM, which is reacting with the raw materials. SEM micrographs showed the presence of SiC or black-Al2O3 grains joined by VBM, which is acting as a bridge between them.

Sign in / Sign up

Export Citation Format

Share Document