Al2O3-ZrO2 Ceramics with Submicron Microstructures Obtained through Microwave Sintering, Plasma Sintering and Shock Compaction

1992 ◽  
Vol 274 ◽  
Author(s):  
J. McKittrick ◽  
B. Tunaboylu ◽  
J. D. Katz ◽  
W. Nellis
Keyword(s):  
Liquid Phase ◽  
Eutectic Composition ◽  
Microwave Sintering ◽  
Liquid Phase Sintering ◽  
Fine Grained ◽  
Grain Sizes ◽  
Final Density ◽  
Plasma Sintering ◽  
Shock Compaction ◽  
Rapidly Solidified

ABSTRACTSubmicron and nanocrystalline grain sizes were achieved in the Al2O3-ZrO2 eutectic composition through conventional, microwave and plasma sintering of rapidly solidified starting powders and through shock compaction of commercial powders. Post sintering studies revealed nanocrystalline intragranular ZrO2 in the 1–2 μm Al2O3 grains, which is thought to be a result of the solidification synthesis. Additions of B2O3 greatly increased the final density through liquid phase sintering. Shock compression of commercial powders produced dense, crack-free, fine grained ceramics with loading pressures up to 9.1 GPa and a metastable ZrO2 phase under higher pressures.

The Influence of Processing Parameters on Mechanical Properties of Spark Plasma Sintered Chromium Carbide Based Cermets

2017 ◽  
Vol 267 ◽  
pp. 162-166
Author(s):  
Kristjan Juhani ◽  
Jüri Pirso ◽  
Marek Tarraste ◽  
Mart Viljus ◽  
Sergei Letunovitš
Keyword(s):  
Mechanical Properties ◽  
Fracture Toughness ◽  
Liquid Phase ◽  
Chromium Carbide ◽  
Processing Parameters ◽  
Liquid Phase Sintering ◽  
Fine Grained ◽  
Plasma Sintering ◽  
Spark Plasma ◽  
Sintered Chromium

Present paper discusses the influence of spark plasma sintering (SPS) on the microstructure and perfomances of chromium carbide based cermets. The effect of SPS parameters (temperature, pressure) is discussed. It is shown that SPS enables to produce more fine grained chromium carbide based cermets compared to conventional liquid phase sintering. Hardness and fracture toughness are exhibited.

scholarly journals Effect of Doped CeO with Si3N4 Powders on the Densification Mechanism During

2021 ◽  
Author(s):  
Yao Liu
Keyword(s):  
Liquid Phase ◽  
Relative Density ◽  
Stress Exponent ◽  
Spark Plasma Sintering ◽  
Liquid Phase Sintering ◽  
Creep Model ◽  
Stress Regime ◽  
Densification Mechanism ◽  
Plasma Sintering ◽  
Spark Plasma

Abstract The densification mechanism of doped CeO with Si3N4 powder during Spark Plasma Sintering (SPS) was investigated under temperatures ranging from 1500 to 1750 °C at soaking pressures of 30, 40, 50 MPa. Results showed that the relative density of Si3N4 ceramics sintered at 1650 °C and 30 MPa was 97.9%. A creep model was employed to determine the mechanism, which can be interpreted on the basis of the stress exponent (n). The results showed that the mechanism was controlled by liquid phase sintering at low effective stress regime (n=1).

Liquid Phase Sintering of α-Si3N4 by Spark Plasma Sintering

2007 ◽  
Vol 336-338 ◽  
pp. 1062-1064 ◽  
Author(s):  
Fa Qiang Yan ◽  
Fei Chen ◽  
Qiang Shen ◽  
Lian Meng Zhang
Keyword(s):  
Liquid Phase ◽  
Spark Plasma Sintering ◽  
Sintering Temperature ◽  
Liquid Phase Sintering ◽  
Sintering Behavior ◽  
Sintering Aids ◽  
Factors Influencing ◽  
Plasma Sintering ◽  
Spark Plasma ◽  
Si3n4 Ceramics

In this study, spark plasma sintering (SPS) was applied to prepare α-Si3N4 ceramics of different densities with magnesia, silicon dioxide, alumina as the sintering aids. The sintering behavior and liquid phase sintering (LPS) mechanism were discussed and the factors influencing the density of the prepared samples were analyzed. Microstructures of sintered samples were observed and the phase compositions were analyzed. The results showed that α-Si3N4 ceramics can be sintered by SPS based on the reaction among α-Si3N4 and sintering additives which lead to the liquid phase and the density can be well controlled from 2.48 to 3.09 g/cm3 while the content of the sintering aids changes from 10% to 28.5% and sintering temperature from 1400°C to 1500°C.

Effect of Rare-Earth Oxides Additive on Liquid Phase Sintered SiC

2014 ◽  
Vol 602-603 ◽  
pp. 407-411 ◽  
Author(s):  
Yu Hong Chen ◽  
Liang Jiang ◽  
Li Li Zhang ◽  
Zhen Kun Huang ◽  
Lan Er Wu
Keyword(s):  
Fracture Toughness ◽  
Rare Earth ◽  
Liquid Phase ◽  
Bending Strength ◽  
Sintered Sample ◽  
Linear Shrinkage ◽  
Rare Earth Oxides ◽  
Liquid Phase Sintering ◽  
Fine Grained ◽  
Cationic Radius

The densification of α-SiC occurred by liquid-phase sintering mechanism with AlN-RE2O3(RE=Nd, Gd, Y, Lu) was studied. The total additive content was fixed at 15 wt%. Cold isostatically pressed samples were sintered at 1800-1950 °C under N2atmosphere for 1 h. The linear shrinkage and weight loss of the samples were about 17-20% and 2-5%, respectively. The mechanical properties and microstructure of sintered samples were investigated. The experimental results showed that the fracture toughness of samples was 6-8 MPa·m1/2, the hardness was in the range of 18-21 GPa and the bending strength was in the range of 400-500 MPa. It was found that a decrease in the cationic radius of the rare-earth oxides was accompanied by an increase in hardness and flexural strength of the SiC ceramics, whereas the fracture toughness was improved by incorporating rare-earth oxides of larger cationic radius. The morphology (SEM) of sintered sample showed a fine grained microstructure with equiaxed grains. Fracture mode was intergranular fracture.

Fast Fabrication and Wear Behavior of Alumina–Nickel Composites

2012 ◽  
Vol 624 ◽  
pp. 94-97
Author(s):  
Fan Cheng Meng ◽  
Xiao Lei Zhang ◽  
Ying Zhang ◽  
Cheng Liu ◽  
Ya Bo Dong ◽  
...  
Keyword(s):  
Sintering Temperature ◽  
Wear Behavior ◽  
Testing Machine ◽  
Matrix Composites ◽  
Fine Grained ◽  
Grain Sizes ◽  
Plasma Sintering ◽  
Fine Grained Structure ◽  
Spark Plasma ◽  
Nickel Composites

Alumina matrix composites containing 20 wt % of Ni was sintered by spark plasma sintering (SPS) process. The influence of sintering temperature (1400-1550 °C) on densification and grain size of the composites were investigated (heating rate: 200 °C /min, sintering time: 5 min). Wear behavior of samples obtained by SPS were evaluated in a dry condition with reciprocate ball-on-disk testing machine. The results show that the relative density and alumina grain sizes increase with the increasing sintering temperature, and the fine-grained structure (alumina size controlled in 1–2 µm) are obtained at a temperature lower than 1400 °C; the alumina grain sizes increase to 5 µm at a temperature higher than 1500 °C. The fine-grained structure samples exhibits higher wear resistance.

Liquid Phase Sintering of SiC-Ceramics

2009 ◽  
Vol 624 ◽  
pp. 91-108 ◽  
Author(s):  
Koushik Biswas
Keyword(s):  
Mechanical Properties ◽  
Liquid Phase ◽  
Grain Boundary ◽  
Secondary Phase ◽  
Phase Evolution ◽  
Liquid Phase Sintering ◽  
Secondary Phases ◽  
Plasma Sintering ◽  
Carbide Ceramics ◽  
Silicon Carbide Ceramics

In view of considerable attention in the development of liquid phase sintered SiC, a comprehensive study of the data on processing, structure and properties seems highly relevant. This article provides a detailed and critical overview of liquid phase sintered silicon carbide ceramics with primary emphasis of grain-boundary/secondary phase evolution, their structure, distribution on the final properties of the sintered materials. The roles of individual additives in developing boundary microstructures will be identified and demonstrated to be critical in optimizing the mechanical properties, including fracture toughness, flexural strength and creep resistance. Numerous methods of structure-properties modification, like in-situ-toughening, -SiC phase transformation, volume of liquid phase, partial/full crystallization of grain-boundary and/or secondary phases are conclusively discussed. Apart from conventional pressureless sintering of SiC, enhanced spark plasma sintering with different oxide and non-oxide sintering additives are also discussed in terms of phase evolution, microstructure and their structure mechanical properties are correlated.

Microwave Sintering BaTiO3 Ceramics Using Liquid Phase Sintering

2006 ◽  
Vol 317-318 ◽  
pp. 131-134 ◽  
Author(s):  
Yutsuki Nishimura ◽  
Masaki Yasuoka ◽  
Takaaki Nagaoka ◽  
Yoshiaki Kinemuchi ◽  
Koji Watari
Keyword(s):  
Dielectric Properties ◽  
Liquid Phase ◽  
Sintering Temperature ◽  
Microwave Sintering ◽  
Microwave Energy ◽  
Liquid Phase Sintering ◽  
Electrical Characteristics ◽  
Electronic Components ◽  
Semiconducting Properties ◽  
Material Energy

Microwave sintering is a process in which target materials absorb microwaves and heat themselves from the inside. When microwave energy is effectively absorbed by the material, energy consumption for the sintering can be reduced. Our study is focused on the microwave sintering of BaTiO3 to more rapidly obtain dense ceramics with specific characteristics. For BaTiO3-based electronic components, the sintering temperature is too high for manufacture, so various additives are used to decrease the sintering temperature without undue worsening of the electrical characteristics. In this work, during microwave sintering, BaCO3, H3BO3, BaB2O4 and LiF were added to form a liquid. The effects of the amount of liquid phase on density and dielectric properties were investigated. BaTiO3 sintered with BaCO3 and H3BO3 showed dielectric properties, whereas BaTiO3 sintered with BaB2O4 had semiconducting properties with PTCR characteristics. Also, LiF-added BaTiO3 indicated a dielectric constant in which the peak shifts to lower temperatures with higher LiF concentrations.

Energy-loss studies of carbon content in yttrium barium cuprate

1989 ◽  
Vol 47 ◽  
pp. 196-197
Author(s):  
P.E. Batson ◽  
M.E. Chisholm ◽  
D.R. Clarke ◽  
D. Dimos ◽  
T. Shaw
Keyword(s):  
Carbon Dioxide ◽  
High Temperature ◽  
Liquid Phase ◽  
Boundary Diffusion ◽  
Liquid Phase Sintering ◽  
Superconducting Properties ◽  
Superconducting Cuprates ◽  
Final Density ◽  
Yttrium Barium Cuprate ◽  
Yttrium Barium

In spite of early reports of the simplicity of preparation of the high temperature superconducting cuprates, it has been found that reproducibly good mechanical and bulk superconducting properties are difficult to obtain. This occurs partly because the densification mechanisms in this system are poorly understood. Since the good superconducting properties are dependent on proper oxygen content, and since oxygen movement appears to occur mainly by surface and grain boundary diffusion, the final density, and the rapidity of densification, are important. In practice, it has been found that rapid densification occurs in the presence of a couple of conditions — 1) the initial mixing is done in air, or 2) that BaCO3 is in the initial mix. In both cases, carbon is found in the final material, and it has been suggested that carbon may aid densification by participating in a low melting temperature peritectic material, promoting liquid phase sintering. In some cases, carbon can be picked up from carbon dioxide in the air.

Liquid-Phase Sintered Silicon Carbide with Aluminum Nitride and Rare-Earth Oxide Additives

2006 ◽  
Vol 317-318 ◽  
pp. 111-114 ◽  
Author(s):  
Mikinori Hotta ◽  
Naoya Enomoto ◽  
Junichi Hojo
Keyword(s):  
Liquid Phase ◽  
Sintered Density ◽  
Secondary Phase ◽  
Rare Earth Oxide ◽  
Liquid Phase Sintering ◽  
Α Phase ◽  
Maximum Value ◽  
Plasma Sintering ◽  
Spark Plasma ◽  
Sintered Silicon

SiC was sintered with AlN and Y2O3 as sintering additives by spark plasma sintering (SPS). Using nano-sized β-SiC powder as the starting material, the sintered density reached about 95% of theoretical at 1800-2000oC for 10min. The β to α phase transformation of SiC was not found by XRD. The secondary phase such as Y2O3 decreased as the firing temperature was elevated, and β-SiC monophase was identified at 2000oC. It seems that the residual intergranular glassy phase is present between the SiC grains. Significant SiC grain growth was observed at 1800-1900oC by SEM. The grain size decreased with increasing amount of AlN additive. The maximum value of flexural strength of the sample reached approximately 800MPa. These results are discussed on the basis of the liquid-phase sintering mechanism in AlN-Y2O3 and Al2O3-Y2O3 systems.

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