Preparation and Performance of AlN-ZrO2 Multiphase Material

2008 ◽  
Vol 368-372 ◽  
pp. 778-780
Author(s):  
Rong Lin Wang ◽  
Zhi Fa Wang ◽  
Jing Long Bu ◽  
Li Fang Zhang
Keyword(s):  
Thermal Expansion ◽  
Thermal Expansion Coefficient ◽  
Expansion Coefficient ◽  
Bending Strength ◽  
Raw Materials ◽  
Diffusion Reaction ◽  
Al Content ◽  
N2 Atmosphere ◽  
And Performance ◽  
And Diffusion

AlN-ZrO2 composites were prepared by solid state reaction in N2 atmosphere at 1500°C for 4h with PSZ and Al powders as raw materials. Effects of Al content on performance of the composites and the process of nitriding reaction were investigated. The results showed that surface layer reaction of samples happened between 450°C and 765°C, and diffusion reaction happened between 765°C and 1500°C. With increasing of Al content, thermal expansion coefficient decreased, bending strength increased, thermal shock resistance and oxidization resistance were improved. Finally, bending strength of 73.61 MPa and thermal expansion coefficient of 6.06×10-6 /°C were realized for AlN-ZrO2 composites.

Crystallization Behavior and Performance of MgO-Al2O3-SiO2 Glass-Ceramics by Sintering

2010 ◽  
Vol 92 ◽  
pp. 65-71 ◽  
Author(s):  
Pei Xin Zhang ◽  
Li Gao ◽  
Qiu Hua Yuan ◽  
Hai Lin Peng ◽  
Xiang Zhong Ren ◽  
...  
Keyword(s):  
Thermal Expansion ◽  
Flexural Strength ◽  
Thermal Expansion Coefficient ◽  
Expansion Coefficient ◽  
Crystallization Process ◽  
Glass Ceramics ◽  
X Ray Diffraction ◽  
Low Thermal Expansion ◽  
Main Crystalline Phase ◽  
And Performance

The glass-ceramics of MgO-Al2O3-SiO2 system were prepared by sintering technology. The crystallization process of MgO-Al2O3-SiO2 glass-ceramics was investigated with X-ray diffraction (XRD), scanning electron microscopy (SEM), and other techniques; the discussion of breaking strength, thermal expansion coefficient and relevant properties at different sintering temperatures was also presented. The results show that: (1) The main crystalline phase isα-cordierite at different sintering temperatures, and the samples show high flexural strength and low thermal expansion coefficient; (2) with the increase of sintering temperature, the content of crystal phase increases, while the thermal expansion coefficient decreases evidently, the flexural strength and tightness density rise up first, then go down.

Effects of Heat-Treatment Temperature on the Properties of Negative CTE Eucryptite Ceramics

2010 ◽  
Vol 105-106 ◽  
pp. 123-125 ◽  
Author(s):  
Yong Li ◽  
Qi Hong Wei ◽  
Ling Li ◽  
Chong Hai Wang ◽  
Xiao Li Zhang ◽  
...  
Keyword(s):  
Heat Treatment ◽  
Thermal Expansion ◽  
Thermal Expansion Coefficient ◽  
Expansion Coefficient ◽  
Heat Treatment Temperature ◽  
Bending Strength ◽  
Sol Gel ◽  
Negative Thermal Expansion ◽  
Treatment Temperature ◽  
Heat Treated

In this paper, negative thermal expansion coefficient eucryptite powders were prepared by sol-gel method using silica-sol as starting material. The raw blocks were obtained by dry pressing process after the powder was synthesized, and then the raw blocks were heat-treated at 600º, 1150º, 1280º, 1380º, 1420º and 1450°C, respectively. Variations of density, porosity and thermal expansion coefficient at different heat treatment temperatures were investigated. Phase transformation and fracture surface morphology of eucryptite heat-treated at different temperatures, respectively, were observed by XRD and SEM. The results indicate that, with the increasing heat- treatment temperature, the grain size and the bending strength increased, porosity decreased, thermal expansion coefficient decreased continuously. Negative thermal expansion coefficient of -5.3162×10-6~-7.4413×10-6 (0~800°C) was obtained. But when the heat-treatment temperature was more than 1420°C, porosity began to increase, bending strength began to decrease, which were the symbols of over-burning, while the main crystal phase didn’t change.

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.

Synthesis and Characteristics of Porous Silicon Carbide Ceramic Reinforced by Silicon Carbide Whiskers

2014 ◽  
Vol 602-603 ◽  
pp. 397-402 ◽  
Author(s):  
Xiao Xue Liu ◽  
Hong Sheng Zhao ◽  
Hui Yang ◽  
Kai Hong Zhang ◽  
Zi Qiang Li
Keyword(s):  
Silicon Carbide ◽  
Thermal Expansion ◽  
Porous Silicon ◽  
Thermal Expansion Coefficient ◽  
Expansion Coefficient ◽  
Bending Strength ◽  
Silicon Powder ◽  
Fluid Filtration ◽  
Porous Silicon Carbide ◽  
Silicon Carbide Ceramics

Silicon powder and phenolic resin were used as raw materials to produce porous silicon carbide (SiC) ceramics, with SiC whiskers (SiCw) as reinforcement additionally. Starting with the preparation of core-shell structure precursor powder through coat-mix method, and then by carrying out molding, carbonization and sintering processes, SiCw/SiC ceramic examples were produced. The phase composite, fracture surface morphology, pore size and porosity, bending strength and thermal expansion coefficient of the final product were measured. Results show that the addition of SiCw apparently improved the intensive property of the products and the changing pattern were quantitatively analyzed; while little influence was observed on some other properties such as phase composition and thermal expansion coefficient. It means that SiCw can strengthen porous silicon carbide ceramics without weakening their thermal properties, which is particularly important because of its application in the field of high temperature fluid filtration. Incorporated SiCw is supposed to work in accordance with some toughening mechanism such as load transferring and matrix prestressing. Microstructure, pore evaluation and weight loss rate during carbonation and sintering were also noted to describe the procedure better.

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).

scholarly journals Characterization of Zirconia- Hydroxyapatite Nanocomposites for Orthopedic and Dental Applications

2018 ◽  
Vol 7 (4.19) ◽  
pp. 926
Author(s):  
Israa Khahtan Sabree ◽  
Ola Saleh Mahdi
Keyword(s):  
Thermal Expansion ◽  
Thermal Expansion Coefficient ◽  
Expansion Coefficient ◽  
Bending Strength ◽  
Oxide Ceramic ◽  
Knee Prostheses ◽  
Aesthetic Property ◽  
Expansion Test ◽  
The Aesthetic ◽  
Composite Samples

Zirconium oxide ceramic was proposed for different biomedical applications. It is used in orthopedic as hip and knee prostheses and in dentistry due to the good mechanical, biological high corrosion and wear resistance properties, addition to the aesthetic property owing to tooth like color. Zirconia stabilized with Y2O3 has the best properties for these applications. The present work aims to study the effect of (5 and 10)Wt.% hydroxyapatite (HA) as additives to 3 mol% yttria stabilized zirconia (3YSZ) nano powder matrix. The green body samples were shaped by powder technology using cold pressing then sintering at (1300 and 1400)ᵒC. The 3YSZ/ HA nanocomposites samples were characterized by XRD to investigate phase stability with varying percent's of HA and different sintering temperatures, the mechanical properties  (maximum bending strength and hardness) were investigated as a function of the HA content, the changes of the thermal expansion coefficient for composite samples were investigated using Dilatometer. The experimental results proved that additions of (5 and 10)Wt.% HA to 3YSZ matrix reduce both hardness and max. bending strength, while increasing sintering temperature from 1300ᵒC to 1400ᵒC leading to an increase in the hardness and bending strength for all composite samples. The results of thermal expansion test showed a reduction in the thermal expansion coefficient with presence of HA%, however the coefficient of 3YSZ/ 10%HA is closer to 3YSZ from 3YSZ/ 5%HA. EDS analysis shows improvement in the bioactivity of inert 3YSZ with HA% additions represented by increasing Ca and P ions on the composite samples after immersing in SBF for 6 days.                                                                                   

Effect of B2O3 and P2O5 Addition on the Phase Separation and Crystallization of Li2O-MgO-Al2O3-SiO2 Glass-Ceramics

2016 ◽  
Vol 848 ◽  
pp. 243-248 ◽  
Author(s):  
Zhen Hong Bao ◽  
Li Feng Miao ◽  
Wei Hui Jiang ◽  
Jian Min Liu ◽  
Jian Liang ◽  
...  
Keyword(s):  
Thermal Expansion ◽  
Phase Separation ◽  
Thermal Expansion Coefficient ◽  
Expansion Coefficient ◽  
Crystalline Phase ◽  
Raw Materials ◽  
Glass Ceramics ◽  
Lithium Silicate ◽  
Solid State Method ◽  
Main Crystalline Phase

B2O3- or P2O5-doped Li2O-MgO-Al2O3-SiO2 (LMAS) glass-ceramics were prepared by solid state method using Li2CO3, MgO, Al2O3 and SiO2 as the raw materials, B2O3 or P2O5 as the additives. The effects of adding B2O3 and P2O5 on the phase separation, crystallization and thermal expansion coefficient were investigated by means of X-ray diffraction (XRD), differential thermal analysis (DTA), scanning electron microscopy (SEM) and thermal dilatometer, respectively. The results showed that B2O3 or P2O5 addition could promoted phase separation of glass and increased the size of spherical phase separation droplet. With the addition of B2O3 or P2O5, the crystallization temperatures (Tc) of LMAS system decreased from 764 oC to 726 oC and 764 oC to 750 oC, respectively. However, the crystalline phase compositions did not changed, and β-quartz solid solution (s.s) (Li2Al2Si3O10) was still the main crystalline phase, and lithium silicate (Li2SiO3) and forsterite (Mg2SiO4) were the minor phases. The thermal expansion coefficient (α) of B2O3-doped and P2O5-doped LMAS glass-ceramics in the temperature range 20-600 oC were 5.215×10-6/ oC and 5.008×10-6/ oC, respectively, which were higher than that of LMAS glass-ceramics (α=3.790×10-6/ oC).

Preparation of High Thermal Expansion Coefficient Glass-Ceramics in Li2O-ZnO-SiO2 System

2011 ◽  
Vol 412 ◽  
pp. 348-351 ◽  
Author(s):  
Zhuo Hao Xiao ◽  
Li Gang Zhu ◽  
Sheng Long Wang
Keyword(s):  
Thermal Expansion ◽  
Thermal Expansion Coefficient ◽  
Expansion Coefficient ◽  
Crystallization Temperature ◽  
Performance Test ◽  
Raw Materials ◽  
Glass Ceramics ◽  
Lithium Carbonate ◽  
Nucleating Agent ◽  
Potassium Oxide

Lithium carbonate, zinc oxide and silica as the main raw materials, potassium oxide and sodium as flux, phosphorus pentoxide as nucleating agent, the glass in Li2O-ZnO-SiO2 was synthesized by conventional melt cooling method and then converted to glass-ceramics. The crystallization behavior, microstructure and thermal expansion coefficient of the resulting glass-ceramics were investigated by XRD, SEM and thermal performance test. The results show that the Tg of the matrix glass is about 508°C, initial crystallization temperature is about 620°C. When the crystallization temperature ranges from 650°C to 750°C, the main crystal phase is Li2ZnSiO4. Increasing crystallization temperature to 850°C, much cristobalite crystals is formed. Owing to the high TEC of the cristobalite, the glass-ceramics with TEC of 12.27×10-6°C-1 were obtained, which is matched with the TEC of stainless steel SAE 1010.

Effect of Al2O3 Addition on Microstructure, Thermal Expansion and Mechanical Properties of Ta2O5 Ceramics

2012 ◽  
Vol 512-515 ◽  
pp. 631-634 ◽  
Author(s):  
Jian Er Zhou ◽  
Jing Zhang ◽  
Xiao Zhen Zhang ◽  
Xue Bing Hu
Keyword(s):  
Mechanical Properties ◽  
Thermal Expansion ◽  
Phase Transformation ◽  
Mechanical Strength ◽  
Thermal Expansion Coefficient ◽  
Expansion Coefficient ◽  
Bending Strength ◽  
Minor Phase ◽  
Α Phase ◽  
Dry Pressing

The Ta2O5-based ceramics were prepared by dry pressing/sintering technique using Ta2O5and Al2O3as the starting materials. The present work investigated the effect of alumina (Al2O3) additions on the composition, microstructure, thermal expansion coefficient (TEC) and bending strength of Ta2O5ceramics. The thermal expansion of the samples was measured by the dilatometry method. It was found that Al2O3additions can effectively inhibit the β to α phase transformation in Ta2O5ceramics. Orthorhombic AlTaO4as the minor phase formed when 2.5 and 7.0 wt% Al2O3was added. The addition of Al2O3results in obvious change of TEC and an increase of bending strength. This work demonstrated that the addition of Al2O3is an effective way to modify the TEC and mechanical strength of Ta2O5ceramics.

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.

Sign in / Sign up

Export Citation Format

Share Document