scholarly journals Improvement in sinterability and high-temperature mechanical properties by grain boundary design for high purity mullite ceramics: Crystallization of grain-boundary glassy phase

2020 ◽  
Vol 128 (10) ◽  
pp. 685-692
Author(s):  
Takeshi KUMAZAWA ◽  
Hisao SUZUKI
Keyword(s):  
Mechanical Properties ◽  
High Temperature ◽  
Grain Boundary ◽  
High Purity ◽  
Glassy Phase ◽  
High Temperature Mechanical Properties ◽  
Mullite Ceramics

scholarly journals High-Temperature Mechanical Properties of a High-Purity Cr–Ni Alloy

2000 ◽  
Vol 41 (1) ◽  
pp. 178-183 ◽  
Author(s):  
Minoru Asahina ◽  
Nobuyuki Harima ◽  
Seiichi Takaki ◽  
Kenji Abiko
Keyword(s):  
Mechanical Properties ◽  
High Temperature ◽  
High Purity ◽  
High Temperature Mechanical Properties ◽  
Ni Alloy

Preparation of Density Ceramic and Fiber Joining Materials

2013 ◽  
Vol 753-755 ◽  
pp. 379-382
Author(s):  
Jiang Ren ◽  
Ying Na Zhao ◽  
Meng Zhang ◽  
Wen Li Zhang
Keyword(s):  
Mechanical Properties ◽  
High Temperature ◽  
Heating Method ◽  
Temperature Resistance ◽  
Potential Value ◽  
High Temperature Mechanical Properties ◽  
Microwave Hybrid Heating ◽  
Sealing Materials ◽  
Silica Ceramic ◽  
Mullite Ceramics

The joining materials of density ceramics and the fibre would be potential value as sealing materials for high-temperature seal field. Zirconia toughened mullite ceramics (ZTM) were chosen the density ceramics due to excellent high temperature mechanical properties. Aluminum silica ceramic fibre was attractive because of favorable elasticity properties. Combining the two materials, the high-temperature resistance elasticity seal materials would be prepared by microwave joining technique. Using the absorber-microwaves properties of Al-Si alloy, interlayer compositions of the joining materials were designed. The ZTM ceramics and fibers materials were joining by microwave hybrid heating method and the mechanism of microwave joining was discussed.

Characterization of grain boundary phases in Si3N4 sintered using Y-Si-Al-O-N additives

1990 ◽  
Vol 48 (4) ◽  
pp. 1070-1071
Author(s):  
C. Koehler ◽  
G. Thomas
Keyword(s):  
Mechanical Properties ◽  
High Temperature ◽  
Silicon Nitride ◽  
Grain Boundary ◽  
Grain Boundaries ◽  
Elevated Temperatures ◽  
Secondary Phases ◽  
Amorphous Phases ◽  
High Temperature Mechanical Properties

The usefulness of silicon nitride as a high temperature ceramic can be limited by the presence of amorphous phases at the grain boundaries. Dense silicon nitride ceramics are produced using pressureless sintering of Si3N4 with Y-Si-Al-O-N additives. When these additives are left as a glassy phase at the grain boundaries and triple grain junctions, the mechanical properties at elevated temperatures are weakened due to these low viscous glasses. Post-sintering heat treatments and close compositional control can be effective in transforming the glass into crystalline phases at the grain boundaries thereby increasing the refractoriness.To optimize high temperature mechanical properties, processing must be controlled not only to fully crystallize the grain boundaries but also to avoid certain unstable secondary phases whose oxidation leads to large molar volume changes which causes possible cracking. Transmisssion electron microscopy and x-ray microanalysis (EDS) are significant methods to characterize the amorphous grain boundary pockets and to identify the crystalline grain boundary phases.

scholarly journals High-Temperature Mechanical Properties of 4.5%Al δ-TRIP Steel

2019 ◽  
Vol 9 (23) ◽  
pp. 5094
Author(s):  
Dayu Chen ◽  
Heng Cui ◽  
Rudong Wang
Keyword(s):  
Mechanical Properties ◽  
Phase Transformation ◽  
High Temperature ◽  
Grain Boundary ◽  
Trip Steel ◽  
Scanning Calorimetry ◽  
The Third ◽  
High Temperature Mechanical Properties ◽  
Brittle Zone ◽  
Austenite Grain Boundary

The high-temperature mechanical properties of a 4.5% Al-containing δ-transformation-induced plasticity (TRIP) steel were studied by using the Gleeble 3500 thermomechanical simulator. The zero ductility temperature (ZDT) and the zero strength temperature (ZST) were measured, and the brittle zones were divided. The phase transformation zone was determined by differential scanning calorimetry (DSC). The temperature of the phase transformation and the proportion of the phase were calculated by the Thermo-Calc software. The ZDT and the ZST of the 4.5% Al-containing δ-TRIP steel are 1355 and 1405 °C, respectively. The first brittle zone and the third brittle zone of the steel are 1300–1350 °C and 800–975 °C, respectively. The reason for the embrittlement of the third brittle zone of the 4.5% Al-containing δ-TRIP steel is that the α-ferrite formed at the austenite grain boundary causes the sample to crack along the grain boundary under stress. The ductility of the 4.5% Al-containing δ-TRIP steel decreases first and then increases with the increase of the α-ferrite. When the proportion of the α-ferrite reaches 37%, the reduction of area (RA) of the 4.5% Al-containing δ-TRIP steel is reduced to 44%. The 4.5% Al-containing δ-TRIP steel has good resistance to the high-temperature cracking.

TEM Studies of Grain Boundary Films in Si3N4 Ceramics

1991 ◽  
Vol 49 ◽  
pp. 930-931
Author(s):  
H.-J. Kleebe ◽  
J.S. Vetrano ◽  
J. Bruley ◽  
M. Rühle
Keyword(s):  
Mechanical Properties ◽  
High Temperature ◽  
Silicon Nitride ◽  
Hot Isostatic Pressing ◽  
Amorphous Film ◽  
Liquid Phase Sintering ◽  
Second Phase ◽  
High Temperature Mechanical Properties ◽  
Triple Points ◽  
Boundary Films

It is expected that silicon nitride based ceramics will be used as high-temperature structural components. Though much progress has been made in both processing techniques and microstructural control, the mechanical properties required have not yet been achieved. It is thought that the high-temperature mechanical properties of Si3N4 are limited largely by the secondary glassy phases present at triple points. These are due to various oxide additives used to promote liquid-phase sintering. Therefore, many attempts have been performed to crystallize these second phase glassy pockets in order to improve high temperature properties. In addition to the glassy or crystallized second phases at triple points a thin amorphous film exists at two-grain junctions. This thin film is found even in silicon nitride formed by hot isostatic pressing (HIPing) without additives. It has been proposed by Clarke that an amorphous film can exist at two-grain junctions with an equilibrium thickness.

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