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.

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.

Particle size effects in the selective hydrogenation of cinnamaldehyde over supported palladium catalysts

RSC Advances ◽  
2016 ◽  
Vol 6 (79) ◽  
pp. 75541-75551 ◽  
Author(s):  
Feng Jiang ◽  
Jian Cai ◽  
Bing Liu ◽  
Yuebing Xu ◽  
Xiaohao Liu
Keyword(s):  
Particle Size ◽  
Size Effect ◽  
Selective Hydrogenation ◽  
Size Effects ◽  
Palladium Catalysts ◽  
Particle Size Effect ◽  
Particle Size Effects ◽  
Supported Palladium Catalysts ◽  
Supported Palladium ◽  
Palladium Particles

Palladium particles of different sizes obtained directly and indirectly by various methods were studied to clarify the particle size effect in the selective hydrogenation of cinnamaldehyde (CAL).

Particle size effect in liquid-phase hydrogenation of phenylacetylene over Pd catalysts: Experimental data and theoretical analysis

2019 ◽  
Vol 358 ◽  
pp. 520-530 ◽  
Author(s):  
Pavel V. Markov ◽  
Igor S. Mashkovsky ◽  
Galina O. Bragina ◽  
Johan Wärnå ◽  
Evgenii Yu. Gerasimov ◽  
...  
Keyword(s):  
Experimental Data ◽  
Particle Size ◽  
Liquid Phase ◽  
Theoretical Analysis ◽  
Size Effect ◽  
Particle Size Effect ◽  
Pd Catalysts ◽  
Liquid Phase Hydrogenation

scholarly journals Simulated Microstructural Evolution and Design of Porous Sintered Wicks

2014 ◽  
Vol 136 (7) ◽  
Author(s):  
Karthik K. Bodla ◽  
Suresh V. Garimella
Keyword(s):  
Thermal Conductivity ◽  
Particle Size ◽  
Transport Properties ◽  
Effective Thermal Conductivity ◽  
Surface Area ◽  
Microstructural Evolution ◽  
Ad Hoc ◽  
Three Dimensions ◽  
Two Phase ◽  
Sintering Kinetics

Porous structures formed by sintering of powders, which involves material-bonding under the application of heat, are commonly employed as capillary wicks in two-phase heat transport devices such as heat pipes. These sintered wicks are often fabricated in an ad hoc manner, and their microstructure is not optimized for fluid and thermal performance. Understanding the role of sintering kinetics—and the resulting microstructural evolution—on wick transport properties is important for fabrication of structures with optimal performance. A cellular automaton model is developed in this work for predicting microstructural evolution during sintering. The model, which determines mass transport during sintering based on curvature gradients in digital images, is first verified against benchmark cases, such as the evolution of a square shape into an area-preserving circle. The model is then employed to predict the sintering dynamics of a side-by-side, two-particle configuration conventionally used for the study of sintering. Results from previously published studies on sintering of cylindrical wires are used for validation. Randomly packed multiparticle configurations are then considered in two and three dimensions. Sintering kinetics are described by the relative change in overall surface area of the compact compared to the initial random packing. The effect of sintering parameters, particle size, and porosity on fundamental transport properties, viz., effective thermal conductivity and permeability, is analyzed. The effective thermal conductivity increases monotonically as either the sintering time or temperature is increased. Permeability is observed to increase with particle size and porosity. As sintering progresses, the slight increase observed in the permeability of the microstructure is attributed to a reduction in the surface area.

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.

Particle size effect on thermal conductivity of AlN films with embedded diamond particles

2013 ◽  
Vol 114 (3) ◽  
pp. 973-978 ◽  
Author(s):  
T. S. Pan ◽  
Y. Zhang ◽  
J. Huang ◽  
M. Gao ◽  
Y. Lin
Keyword(s):  
Thermal Conductivity ◽  
Particle Size ◽  
Size Effect ◽  
Particle Size Effect ◽  
Diamond Particles

Microstructural Evolution and Transport Properties of Sintered Porous Media

2013 ◽  
Author(s):  
Karthik K. Bodla ◽  
Suresh V. Garimella
Keyword(s):  
Thermal Conductivity ◽  
Particle Size ◽  
Transport Properties ◽  
Effective Thermal Conductivity ◽  
Microstructural Evolution ◽  
Three Dimensions ◽  
Two Phase ◽  
Sintering Kinetics ◽  
Relative Change ◽  
Area Preserving

Sintering is a material-bonding phenomenon that occurs under the application of heat. The porous structures formed by sintering powders are commonly employed as capillary wicks in two-phase heat transport devices such as heat pipes. These sintered wick microstructures are often not truly optimized for fluid and thermal performance. Understanding the role of sintering kinetics, and the resulting microstructural evolution, on wick transport properties is important for fabrication of structures with optimal performance. In this study, a cellular automaton model for predicting microstructural evolution during sintering is developed. The model, which determines mass transport during sintering based on curvature gradients in digital images, is first verified against benchmark cases, such as the evolution of a square into an area-preserving circle. The model is then employed to predict the sintering dynamics of a side-by-side two-particle configuration conventionally used for the study of sintering. Data from previously published studies on sintering of cylindrical wires is used for validation. Randomly packed multi-particle configurations are then considered in two and three dimensions. Sintering kinetics are described by the relative change in overall surface area of the compact compared to the initial random packing. The effect of sintering parameters, particle size, and porosity on fundamental transport properties, viz., effective thermal conductivity and permeability, is analyzed. The effective thermal conductivity increases monotonically as either the sintering time or temperature is increased. Permeability was observed to be largely independent of sintering conditions, but increases with particle size and porosity.

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