Fabrication of α-Sialon Nano-Ceramics

2006 ◽  
Vol 317-318 ◽  
pp. 629-632 ◽  
Author(s):  
Xin Xu ◽  
Toshiyuki Nishimura ◽  
Naoto Hirosaki ◽  
Rong Jun Xie ◽  
Yoshinobu Yamamoto ◽  
...  
Keyword(s):  
Grain Size ◽  
Phase Transformation ◽  
Liquid Phase ◽  
Superplastic Deformation ◽  
Transient Liquid Phase ◽  
Milled Powder ◽  
High Energy ◽  
Liquid Phase Sintering ◽  
Plasma Sintering ◽  
Spark Plasma

Y- α-sialon (m=1.35, n=0.675) ceramics were prepared by high-energy mechanical milling followed by spark plasma sintering. The milling promoted not only liquid-phase sintering, but also phase transformation from β-Si3N4 to α-sialon. Under the same holding time of 5 min, milled powder could be completely densified at 1500oC, which is about 250oC lower than that required for as-received powder. The temperature where the phase transformation finished was 1600oC and 1750oC for milled and as-received powder, respectively. The grain size of obtained dense ceramics from milled powder was significantly decreased. Nano-sized dense ceramics have been obtained by sintering the milled powder at 1500oC for 5 min. Although 100 % α-sialon has not been achieved, the nano-sized ceramics can be used for superplastic deformation, taking advantage of small grain size and large amount of transient liquid phase.

Superplastic Deformation of Nano-Sized α-Sialon Ceramics

2007 ◽  
Vol 336-338 ◽  
pp. 1001-1004 ◽  
Author(s):  
Xin Xu ◽  
Toshiyuki Nishimura ◽  
Naoto Hirosaki ◽  
Rong Jun Xie ◽  
Yoshinobu Yamamoto ◽  
...  
Keyword(s):  
Liquid Phase ◽  
Spark Plasma Sintering ◽  
Microstructural Evolution ◽  
Mechanical Milling ◽  
Superplastic Deformation ◽  
Transient Liquid Phase ◽  
High Energy ◽  
Post Annealing ◽  
Plasma Sintering ◽  
Spark Plasma

In previous report, we succeeded in preparing dense nano-sized ceramics with the composition of Y- α-sialon (m=1.35, n=0.675) by high-energy mechanical milling followed by spark plasma sintering. The superplastic deformation of the obtained nano-ceramics was studied in this report. A good ductility of the nano-sized ceramics has been confirmed, which arised from the nano-sized grains and large amount of transient liquid phase. The effects of deformation on the phase and microstructural evolution were also studied. The nano-sized grains promoted the formation of elongated α-sialon grains during post-annealing at 1850oC for 3 h, which would strengthen and toughen the deformed ceramics.

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.

Microstructural Development of SiC Ceramics by Liquid-Phase Sintering with Spark Plasma Sintering Technique

2006 ◽  
Vol 510-511 ◽  
pp. 1022-1025 ◽  
Author(s):  
Mikinori Hotta ◽  
Junichi Hojo
Keyword(s):  
Grain Size ◽  
Spark Plasma Sintering ◽  
Liquid Phase Sintering ◽  
Molar Ratio ◽  
Microstructural Development ◽  
Sic Ceramics ◽  
Plasma Sintering ◽  
N2 Atmosphere ◽  
Average Grain Size ◽  
Spark Plasma

Sub-micron and nano-sized β-SiC powders were sintered with AlN and Y2O3 as sintering additives by spark plasma sintering (SPS). The sintered densities reached >95% of theoretical with a different molar ratio of AlN to Y2O3 at total amount of 10vol% and temperature of 1900oC for 10min in N2 atmosphere under a pressure of 30MPa. With increasing amount of the AlN additive, the size of SiC grains decreased and the shape changed from globular to columnar. The fully densified SiC at AlN:Y2O3=95:5mol% had an average grain size of 0.5-1µm and 50-100nm in diameter by using sub-micron and nano-sized SiC starting powders, respectively. Flexural strength of the specimen having grain size of 0.5-1µm was approximately 1200MPa at room temperature.

Spark Plasma Sintering of High-Energy Ball-Milled ZrB2 and HfB2 Powders with 20vol% SiC

2018 ◽  
Vol 941 ◽  
pp. 1990-1995
Author(s):  
Naidu V. Seetala ◽  
Cyerra L. Prevo ◽  
Lawrence E. Matson ◽  
Thomas S. Key ◽  
Ilseok I. Park
Keyword(s):  
Particle Size ◽  
Grain Size ◽  
Ball Milling ◽  
Milling Time ◽  
High Energy ◽  
Micro Hardness ◽  
Plasma Sintering ◽  
Spark Plasma ◽  
Energy Ball ◽  
Ball Milling Time

ZrB2 and HfB2 with incorporation of SiC are being considered as structural materials for elevated temperature applications. We used high energy ball milling of micron-size powders to increase lattice distortion enhanced inter-diffusion to get uniform distribution of SiC and reduce grain growth during Spark Plasma Sintering (SPS). High-energy planetary ball milling was performed on ZrB2 or HfB2 with 20vol% SiC powders for 24 and 48 hrs. The particle size distribution and crystal micro-strain were examined using Dynamic Light Scattering Technique and x-ray diffraction (XRD), respectively. XRD spectra were analyzed using Williamson-Hall plots to estimate the crystal micro-strain. The particle size decreased, and the crystal micro-strain increased with the increasing ball milling time. The SPS consolidation was performed at 32 MPa and 2,000°C. The SEM observation showed a tremendous decrease in SiC segregation and a reduction in grain size due to high energy ball milling of the precursor powders. Flexural strength of the SPS consolidated composites were studied using Four-Point Bend Beam test, and the micro-hardness was measured using Vickers micro-indenter with 1,000 gf load. Good correlation is observed in SPS consolidated ZrB2+SiC with increased micro-strain as the ball milling time increased: grain size decreased (from 9.7 to 3.2 μm), flexural strength (from 54 to 426 MPa) and micro-hardness (from 1528 to 1952 VHN) increased. The correlation is less evident in HfB2+SiC composites, especially in micro-hardness which showed a decrease with increasing ball milling time.

Improving Mechanical Properties of Ceramic Composites by Harmonic Microstructure Control

2014 ◽  
Vol 896 ◽  
pp. 570-573 ◽  
Author(s):  
Lydia Anggraini ◽  
Ryohei Yamamoto ◽  
Kazuma Hagi ◽  
Hiroshi Fujiwara ◽  
Kei Ameyama
Keyword(s):  
Mechanical Properties ◽  
Milling Time ◽  
Milled Powder ◽  
High Energy ◽  
Ceramic Composites ◽  
Design Tool ◽  
Powder Mixtures ◽  
Plasma Sintering ◽  
Spark Plasma ◽  
Relationship Of

In this research, several ceramic composites such as SiC-ZrO2, Al2O3-ZrO2, and Si3N4-ZrO2containing nominally equal ratio 1:1 were prepared through high energy mechanical milling and spark plasma sintering. The relationship of microstructure and mechanical properties were investigated. Harmonic microstructures consisting of fine and ultra-fine grains forming a network were obtained by the optimum milling time for 144ks with high mechanical properties. The non-milled powder mixtures and too long milling time powder mixtures have low mechanical properties sintered by spark plasma. The crack propagates through ultra-fine grains and deflected by larger fine grains were obtained on the harmonic microstructure sample resulting in high toughness. Thus, the harmonic microstructure can be considered a remarkable design tool for improving the mechanical properties of SiC-ZrO2, Al2O3-ZrO2, and Si3N4-ZrO2as well as other ceramic composites.

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.

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