scholarly journals Mechanical Investigation of a Novel Ceramic Composite Consisting of the YAG Matrix With Alumina Nanoparticles Fabricated by Slip Casting and the Conventional Sintering Process

2020 ◽  
Author(s):  
Mohammad Torki ◽  
behrooz movahedi ◽  
S S. ghazanfari ◽  
M. Milani
Keyword(s):  
Relative Density ◽  
Slip Casting ◽  
Ceramic Composites ◽  
Alumina Nanoparticles ◽  
Solid Loading ◽  
Sintering Process ◽  
The Matrix ◽  
Conventional Sintering ◽  
Mechanical Investigation ◽  
Composite Hardness

Abstract The aim of this study was to fabricate YAG/Al2O3 ceramic composites with different alumina nanoparticles using slip casting and the atmospheric sintering process. In addition, some mechanical properties such as hardness and elastic modules of this novel ceramics were evaluated using the nanoindention technique. The results showed that the rheological behavior of the slurry was optimized to the solid loading of 55 wt% and the relative density of the green body was enhanced up to 65%. Relative density was increased after sintering at 1700 °C for 12 h to 99.5% and the pore size (150 nm) was reduced to half of that of powder particles. It should be noted that the optimum amount of alumina nanoparticles as a reinforcing agent in the matrix was less than 5%wt and the composite hardness was increased to 7.3%, as compared to the pure YAG ceramic.

scholarly journals Influence of molybdenum content on the microstructure of spark plasma sintered titanium alloys

2021 ◽  
Vol 1 (1) ◽  
pp. 41-47
Author(s):  
M. Saravana Kumar ◽  
S. Rashia Begum ◽  
M. Vasumathi ◽  
Chinh Chien Nguyen ◽  
Quyet Van Le
Keyword(s):  
Relative Density ◽  
Phase Evolution ◽  
Microstructural Development ◽  
Sintered Titanium ◽  
Sintering Process ◽  
Plasma Sintering ◽  
The Matrix ◽  
Molybdenum Addition ◽  
Spark Plasma ◽  
Mo Content

Five titanium-based alloys containing 4, 8, 12, 16, and 20 wt% molybdenum additive were fabricated by spark plasma sintering process at 1200 ˚C. The samples were scrutinized in terms of relative density, phase evolution, and microstructural development. The relative density reached 99.9% with the molybdenum addition up to 16 wt% but slightly dropped in the sample with 20 wt% additive. In the specimens with 4 wt% Mo, molybdenum solved completely in the matrix and three different phase morphologies were observed, namely continuous α-Ti, laminar α-Ti, and very thin laminar β-Ti. With increasing Mo content to 20 wt%, widespread single β-Ti appeared alongside remained Mo and α-Ti. Ductile fracture mode was dominant in the samples with low Mo contents whilst it changed to brittle in the specimens with higher content of molybdenum.

Study on ZrB2-SiC Prepared by Field Assisted Sintering

2012 ◽  
Vol 512-515 ◽  
pp. 729-734
Author(s):  
Wei Jun Wang ◽  
Shi Zhen Zhu ◽  
Zhen Yu Yan ◽  
Qiang Xu
Keyword(s):  
Relative Density ◽  
Sintering Temperature ◽  
Ceramic Composites ◽  
Holding Time ◽  
Sintering Process ◽  
Covalent Bonds ◽  
Current Voltage ◽  
Sic Ceramic ◽  
Higher Temperature ◽  
Field Assisted Sintering

Zirconium diboride and silicon carbide are thought to have a low intrinsic sinterability due to their strong covalent bonds, low bulk and grain boundary diffusivities. ZrB2-SiC ceramic composites were prepared by a field assisted pressureless sintering process in the present work. The densification behavior and the effect of sintering temperature on microstructure and properties of sintered samples were studied. Pellets were in-situ formed by dry uniaxial pressing in the graphite die at a pressure of 50MPa for 3min and then sintered at a sintering temperature ranged from 1650 °C to 1950 °C with fixed heating rate and holding time. The current, voltage, temperature and displacement data were all collected by the real-time acquisition system. The bulk densities were determined by Archimedes method and the microstructure of samples was characterized by SEM. The onset of some measurable shrinkage of the green body was recorded at around 1400 °C regardless of the sintering temperature and significant shrinkage took place at higher temperature of around 1600 °C. For the sample sintered at 1950 °C, no shrinkage occurred after ~2min holding time. The relative density increased significantly with increasing temperatures and samples could be densified to a relative density of more than 99% at 1950 °C by the field assisted sintering process without obvious grain growth.

scholarly journals Fabrication and Enhanced Thermoelectric Properties of Alumina Nanoparticle-Dispersed Bi0.5Sb1.5Te3Matrix Composites

2013 ◽  
Vol 2013 ◽  
pp. 1-6 ◽  
Author(s):  
Kyung Tae Kim ◽  
Gook Hyun Ha
Keyword(s):  
Milling Process ◽  
Alumina Nanoparticles ◽  
Sintering Process ◽  
Composite Powders ◽  
Alumina Nanoparticle ◽  
Plasma Sintering ◽  
The Matrix ◽  
High Resolution Tem ◽  
Spark Plasma ◽  
P Type

Alumina nanoparticle-dispersed bismuth-antimony-tellurium matrix (Al2O3/BST) composite powders were fabricated by using ball milling process of alumina nanoparticle about 10 nm and p-type bismuth telluride nanopowders prepared from the mechanochemical process (MCP). The fabricated Al2O3/BST composite powders were a few hundreds of nanometer in size, with a clear Bi0.5Sb1.5Te3phase. The composite powders were consolidated into p-type bulk composite by spark plasma sintering process. High-resolution TEM images reveal that alumina nanoparticles were dispersed among the grain boundary or in the matrix grain. The sintered 0.3 vol.% Al2O3/BST composite exhibited significantly improved power factor and reduced thermal conductivity in the temperature ranging from 293 to 473 K compared to those of pure BST. From these results, the highly increased ZT value of 1.5 was obtained from 0.3 vol.% Al2O3/BST composite at 323 K.

Interfacial Particle Bonding Via an Ultrathin Polymer Film on Al2O3 Nanoparticles by Plasma Polymerization

2002 ◽  
Vol 17 (5) ◽  
pp. 981-990 ◽  
Author(s):  
Donglu Shi ◽  
Peng He ◽  
S. X. Wang ◽  
Wim J. van Ooij ◽  
L. M. Wang ◽  
...  
Keyword(s):  
Plasma Polymerization ◽  
Treatment Time ◽  
Hardness Test ◽  
Alumina Nanoparticles ◽  
Al2o3 Nanoparticles ◽  
Particle Bonding ◽  
Transmission Electron ◽  
The Matrix ◽  
Conventional Sintering ◽  
Plasma Treatment Time

To study interfacial particle-to-particle bonding mechanisms, an ultrathin film of pyrrole was deposited on alumina nanoparticles using a plasma polymerization treatment. High resolution transmission electron microscopy experiments showed that an extremely thin film of the pyrrole layer (2 nm) was uniformly deposited on the surfaces of the nanoparticles. In particular, the particles of all sizes (10–150 nm) exhibited equally uniform ultrathin films indicating well-dispersed nanoparticles in the fluidized bed during the plasma treatment. Time-of-flight secondary ion mass spectroscopy experiments confirmed the nano-surface deposition of the pyrrole films on the nanoparticles. The pyrrole-coated nanoparticles were consolidated at a temperature range (approximately 250 °C) much lower than the conventional sintering temperature. The density of consolidated bulk alumina has reached about 95% of the theoretical density of alumina with only a few percent of polymer in the matrix. After low-temperature consolidation, the micro-hardness test was performed on the bulk samples to study the strength that was related to particle-particle adhesion. The underlying adhesion mechanism for bonding of the nanoparticles is discussed.

Addition of Nano-ZrO2 Effects on Microstructures and Properties of WC-8Co Hard Alloys

2012 ◽  
Vol 496 ◽  
pp. 302-305 ◽  
Author(s):  
Lan Sun
Keyword(s):  
Mechanical Properties ◽  
Phase Transition ◽  
Fracture Toughness ◽  
Relative Density ◽  
Hard Alloys ◽  
Densification Behavior ◽  
Sintering Process ◽  
Toughening Mechanism ◽  
Hard Metals ◽  
Conventional Sintering

This paper carries out the research on using the toughening mechanism of phase transition of ZrO2 to inhibit the WC grain and improve the toughness of the hard alloys. WC–ZrO2–8wt%Co hard metals was mixed with 0-2 wt% nano-ZrO2 and prepared by conventional sintering (CS) for 2 h at 1440oC to see whether the addition of ZrO2 could improve densification behavior, the microstructure and mechanical properties of the samples. Experimental results showed that the use of ZrO2 nanoparticles could decrease the relative density because of the worse wetting effects; it could also inhibit the growth of the grains of WC-Co hardmetal to enhance the hardness of the alloy. The fracture toughness of sample has an increasing tendency as a whole because of the phase transition during the sintering process.

Multilayered Ceramic Composites – A Review

2015 ◽  
Vol 820 ◽  
pp. 393-398 ◽  
Author(s):  
Flávia Dagostim Minatto ◽  
Pâmela Milak ◽  
Edivelton S. Gislon ◽  
Kétlin Coelho ◽  
Agenor de Noni Jr. ◽  
...  
Keyword(s):  
Tape Casting ◽  
Slip Casting ◽  
Crack Arrest ◽  
Ceramic Materials ◽  
Ceramic Composites ◽  
Crack Deflection ◽  
Sintering Process ◽  
General Aspects ◽  
Toughness Enhancement ◽  
Thermal Expansion Coefficient Mismatch

Fracture toughness enhancement of ceramic materials through multilayered ceramic composites has been developed since 1990. Toughening mechanisms are based mainly on delamination, deflection, bifurcation or crack arrest effect. Delamination and crack deflection occur by means of weak interfaces. Bifurcation (and deflection as well) and crack arrest effects are result of residual stresses arising from the thermal expansion coefficient mismatch or phase transformation on alternating layers. The main manufacturing methods of these composites are slip casting of two ceramic materials, and stacking and pressing of ceramic tapes obtained by tape casting or rolling technics, followed by suitable sintering process. This review aims to present general aspects of research performed around the theme so far. It is verified that occurs the enhancement of ceramic toughness and reliability with this technic, so it is possible to enlarge its range of application in engineering.

scholarly journals Processing of MMC through conventional sintering and spark plasma sintering process: A review

2020 ◽  
Vol 988 ◽  
pp. 012092
Author(s):  
B Stalin ◽  
M Ravichandran ◽  
M Balasubramanian ◽  
C Anand Chairman ◽  
D Pritima ◽  
...  
Keyword(s):  
Spark Plasma Sintering ◽  
Sintering Process ◽  
Plasma Sintering ◽  
Conventional Sintering ◽  
Spark Plasma

scholarly journals Improvement of mechanical properties of HfB2-based composites by incorporating in situ SiC reinforcement through pressureless sintering

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
S. Ghadami ◽  
E. Taheri-Nassaj ◽  
H. R. Baharvandi ◽  
F. Ghadami
Keyword(s):  
Mechanical Properties ◽  
Thermal Conductivity ◽  
Relative Density ◽  
Pressureless Sintering ◽  
Sintering Process ◽  
Vacuum Atmosphere ◽  
Sic Reinforcement ◽  
Microstructural Studies ◽  
Composite Samples

AbstractHfB2, Si, and activated carbon powders were selected to fabricate 0–30 vol% SiC reinforced HfB2-based composite. Pressureless sintering process was performed at 2050 °C for 4 h under a vacuum atmosphere. Microstructural studies revealed that in situ SiC reinforcement was formed and distributed in the composite according to the following reaction: Si + C = SiC. A maximum relative density of 98% was measured for the 20 vol% SiC containing HfB2 composite. Mechanical investigations showed that the hardness and the fracture toughness of these composites were increased and reached up to 21.2 GPa for HfB2-30 vol% SiC and 4.9 MPa.m1/2 for HfB2-20 vol% SiC, respectively. Results showed that alpha-SiC reinforcements were created jagged, irregular, and elongated in shape which were in situ formed between HfB2 grains and filled the porosities. Formation of alpha-SiC contributed to improving the relative density and mechanical properties of the composite samples. By increasing SiC content, an enhanced trend of thermal conductivity was observed as well as a reduced trend for electrical conductivity.

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