Effect of sintering additive composition on the thermal conductivity of silicon nitride

1998 ◽  
Vol 13 (12) ◽  
pp. 3473-3477 ◽  
Author(s):  
Y. Okamoto ◽  
N. Hirosaki ◽  
M. Ando ◽  
F. Munakata ◽  
Y Akimune
Keyword(s):  
Thermal Conductivity ◽  
Silicon Nitride ◽  
Grain Growth ◽  
Gas Pressure ◽  
Sintering Additive ◽  
Maximum Value ◽  
Additional Agent

The thermal conductivity of silicon nitride prepared with varying sintering additive compositions was studied. Samples of Si3N4 + 0.5 mol% Y2O3 + 0.5 mol% Nd2O3 and a further additional agent were gas pressure sintered at 2173 K. MgO or Al2O3 was employed as the additional agent. While both agents improved sinterability, the former promoted grain growth and the latter suppressed it. Thermal conductivity increased with increasing MgO content, and a maximum value of 128 Wm-1 K-1 was attained when 2 mol% MgO was added. In contrast, addition of Al2O3 degrades thermal conductivity. This is probably due to the suppression of grain growth and the dissolution of Al2O3 into Si3N4 grains.

scholarly journals Microstructure and Thermal Conductivity of Sintered Reaction-Bonded Silicon Nitride: The Particle Size Effects of MgO Additive

2018 ◽  
Vol 2018 ◽  
pp. 1-5 ◽  
Author(s):  
Shin-Il Go ◽  
Yinsheng Li ◽  
Jae-Woong Ko ◽  
Ha-Neul Kim ◽  
Se-Hun Kwon ◽  
...  
Keyword(s):  
Thermal Conductivity ◽  
Particle Size ◽  
Silicon Nitride ◽  
Liquid Phase ◽  
Grain Growth ◽  
Microstructural Evolution ◽  
Size Effects ◽  
Phase Distribution ◽  
Particle Size Effect ◽  
Sintering Additive

The particle size effect of MgO as a sintering additive on the thermal conductivity of sintered reaction-bonded silicon nitride (SRBSN) was investigated. It was revealed that the size of MgO is critical for thermal conductivity with regard to the microstructural evolution process. That is, the abnormal grain growth promoted by an inhomogeneous liquid-phase distribution led to higher thermal conductivity when coarser MgO was added, whereas a relatively homogeneous liquid-phase distribution induced moderate grain growth and lower thermal conductivity when finer MgO was added.

scholarly journals Effect of Grain Growth on the Thermal Conductivity of Silicon Nitride

1996 ◽  
Vol 104 (1205) ◽  
pp. 49-53 ◽  
Author(s):  
Naoto HIROSAKI ◽  
Yusuke OKAMOTO ◽  
Motohide ANDO ◽  
Fumio MUNAKATA ◽  
Yoshio AKIMUNE
Keyword(s):  
Thermal Conductivity ◽  
Silicon Nitride ◽  
Grain Growth

Mechanical and Thermal Properties of Silicon Nitride Hot Pressed with Adding Rare-Earth Oxides

2005 ◽  
Vol 486-487 ◽  
pp. 181-184 ◽  
Author(s):  
Dae Ho Choi ◽  
Byung Kyu Moon ◽  
Rak Joo Sung ◽  
Seung Ho Kim ◽  
Koichi Niihara
Keyword(s):  
Thermal Conductivity ◽  
Thermal Properties ◽  
Rare Earth ◽  
Silicon Nitride ◽  
Flexural Strength ◽  
Grain Growth ◽  
Rare Earth Oxides ◽  
Lattice Oxygen ◽  
Mechanical And Thermal Properties ◽  
Si3n4 Ceramics

Mechanical and thermal properties of Si3N4 ceramics with various rare-earth oxides (La2O3, CeO2, Lu2O3, Dy2O3, Sm2O3, Nd2O3, Yb2O3, and RuO2) were investigated. Flexural strength of silicon nitride with addition of 5vol% Nd2O3, CeO2, Dy2O3, and Sm2O3 showed higher value than that of silicon nitride with Lu2O3 and La2O3 added because they form denser microstructure and smaller elongated grain. Thermal conductivity of silicon nitride with an addition of 5vol% RuO2 was more enhanced than that of silicon nitride added with Nd2O3, Sm2O3, and Dy2O3 because the addition of RuO2 depressed grain growth. It is also associated with lattice oxygen governing thermal conductivity of Si3N4 when added rare-earth oxides.

Grain Growth During Gas-Pressure Sintering of beta-Silicon Nitride

1990 ◽  
Vol 73 (8) ◽  
pp. 2441-2445 ◽  
Author(s):  
M. Mitomo ◽  
M. Tsutsumi ◽  
H. Tanaka ◽  
S. Uenosono ◽  
F. Saito
Keyword(s):  
Silicon Nitride ◽  
Grain Growth ◽  
Gas Pressure ◽  
Gas Pressure Sintering

Defects Analysis of Large Size Silicon Nitride Balls Sintered by Gas Pressure Sintering

2010 ◽  
Vol 434-435 ◽  
pp. 61-63
Author(s):  
Feng Sun ◽  
Wei Ru Zhang ◽  
Ting Yan Tian ◽  
Xiang Hong Teng ◽  
Min Chao Ru ◽  
...  
Keyword(s):  
Thermal Conductivity ◽  
Silicon Nitride ◽  
Temperature Gradient ◽  
Raw Materials ◽  
Gas Pressure ◽  
Sintering Process ◽  
The Core ◽  
Large Size ◽  
Defects Analysis ◽  
Gas Pressure Sintering

The sections of Φ55mm silicon nitride balls, sintered by gas pressure sintering were analyzed. The results show that temperature gradient during of the sintering process from the surface to the core of large size silicon nitride balls occurred because of the lower thermal conductivity of Si3N4. With the diameter increasing, the temperature gradient was more visible. The impurity of raw materials, such as free Si, free C and other metal oxides, like the SiO2 could produce gas, such as SiO, CO and so on, during the sintering process through the thermodynamic analysis. The producing gas exhausted more difficultly with the diameter of silicon nitride balls increasing. These factors were the most important to the defects of large size silicon nitride balls during the sintering process and made cracks and crescent on the surface of balls.

Thermal Conductivity of Gas-Pressure-Sintered Silicon Nitride

1996 ◽  
Vol 79 (11) ◽  
pp. 2878-2882 ◽  
Author(s):  
Naoto Hirosaki ◽  
Yusuke Okamoto ◽  
Motohide Ando ◽  
Fumio Munakata ◽  
Yoshio Akimune
Keyword(s):  
Thermal Conductivity ◽  
Silicon Nitride ◽  
Gas Pressure ◽  
Sintered Silicon

Fabrication of Silicon Nitride Ceramics with Magnesium Silicon Nitride and Yttrium Oxide as Sintering Additives

2010 ◽  
Vol 177 ◽  
pp. 235-237 ◽  
Author(s):  
Guo Jian Jiang ◽  
Jia Yue Xu ◽  
Hui Shen ◽  
Yan Zhang ◽  
Gui Hua Peng ◽  
...  
Keyword(s):  
Thermal Conductivity ◽  
Silicon Nitride ◽  
Hot Pressing ◽  
Uniaxial Pressure ◽  
Bend Strength ◽  
Si3n4 Ceramic ◽  
Sintering Additive ◽  
Sintering Properties ◽  
Hot Pressing Sintering ◽  
Si3n4 Ceramics

Si3N4 ceramics have been fabricated through pressureless sintering and hot-pressing sintering with MgSiN2-Y2O3 or only MgSiN2 as sintering additive, respectively. The effects of MgSiN2 and Y2O3 and sintering methods on sintering properties of Si3N4 ceramics were studied. The results indicate that the bend strength of Si3N4 ceramic with 5.6wt.%MgSiN2-15.8wt.%Y2O3 sintered at 1820°C for 4h could achieve 839MPa. The bend strength of Si3N4 ceramic with 4.76wt.%MgSiN2 produced by hot-pressing sintering at 1750°C for 1h under uniaxial pressure of 20MPa is 1149MPa. The thermal conductivity of the Si3N4 ceramic was 92Wm-1K-1 and could remarkably increase to 129Wm-1K-1 by prolonging the sintering time from 1 h to 12 h. The present work demonstrated that MgSiN2 additives and hot-pressing sintering were effective to improve the thermal conductivity of Si3N4 ceramic.

Densification and Thermal Conductivity of Y2O3-Doped AlN Ceramics by Spark Plasma Sintering

2007 ◽  
Vol 352 ◽  
pp. 227-231 ◽  
Author(s):  
Qiang Shen ◽  
Z.D. Wei ◽  
Mei Juan Li ◽  
Lian Meng Zhang
Keyword(s):  
Thermal Conductivity ◽  
Grain Boundaries ◽  
Spark Plasma Sintering ◽  
Particle Surface ◽  
Boundary Phase ◽  
Homogeneous Microstructure ◽  
Densification Mechanism ◽  
Sintering Additive ◽  
Plasma Sintering ◽  
Spark Plasma

AlN ceramics doped with yttrium oxide (Y2O3) as the sintering additive were prepared via the spark plasma sintering (SPS) technique. The sintering behaviors and densification mechanism were mainly investigated. The results showed that Y2O3 addition could promote the AlN densification. Y2O3-doped AlN samples could be densified at low temperatures of 1600-1700oC in 20-25 minutes. The AlN samples were characterized with homogeneous microstructure. The Y-Al-O compounds were created on the grain boundaries due to the reactions between Y2O3 and Al2O3 on AlN particle surface. With increasing the sintering temperature, AlN grains grew up, and the location of grain boundaries as well as the phase compositions changed. The Y/Al ratio in the aluminates increased, from Y3Al5O12 to YAlO3 and to Y4Al2O9. High-density, the growth of AlN grains and the homogenous dispersion of boundary phase were helpful to improve the thermal conductivity of AlN ceramics. The thermal conductivity of 122Wm-1K-1 for the 4.0 mass%Y2O3-doped AlN sample was reached.

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