Microstructure and Properties of AlN Matrix Composites Fabricated by Reaction Synthesis

2008 ◽  
Vol 368-372 ◽  
pp. 973-976
Author(s):  
Tie Kun Jia ◽  
Wei Min Wang ◽  
Zheng Yi Fu ◽  
Hao Wang
Keyword(s):  
Thermal Conductivity ◽  
Heat Treatment ◽  
Grain Growth ◽  
Bending Strength ◽  
Treatment Schedule ◽  
Reaction Synthesis ◽  
Matrix Composites ◽  
Microstructure And Properties ◽  
Conductivity Increase ◽  
Dielectric Constant Increase

Based on the nitridation reaction of aluminum with boron nitride (BN), aluminum nitride (AlN) matrix composites were fabricated by reaction synthesis technique. The effect of the amount of Al on the microstructure and properties was investigated. The bending strength, thermal conductivity and dielectric constant increase with the content of aluminum. A heat-treatment schedule was performed to investigate the effect of the microstructure on the properties. The results showed that the heat-treatment leads to the grain growth and thermal conductivity increase with the grain growth.

Effect Of Heat Treatment On Microstructure And Properties of High Entropy Alloy Reinforced Titanium Metal Matrix Composites

2019 ◽  
Vol 18 ◽  
pp. 2409-2414
Author(s):  
CH.V. Satyanarayanaraju ◽  
Rahul Dixit ◽  
Pooja Miryalkar ◽  
S. Karunanidhi ◽  
A. AshokKumar ◽  
...  
Keyword(s):  
Heat Treatment ◽  
Metal Matrix Composites ◽  
Metal Matrix ◽  
High Entropy Alloy ◽  
Matrix Composites ◽  
Titanium Metal ◽  
High Entropy ◽  
Microstructure And Properties

The Effect of Heat-Treatment on Thermal Conductivity of Silicon Nitride Ceramics

2011 ◽  
Vol 484 ◽  
pp. 52-56
Author(s):  
Katsumi Yoshida ◽  
Yuki Sekimoto ◽  
Keiichi Katayama ◽  
Thanakorn Wasanapiarnpong ◽  
Masamitsu Imai ◽  
...  
Keyword(s):  
Thermal Conductivity ◽  
Heat Treatment ◽  
Grain Size ◽  
Grain Boundary ◽  
Grain Growth ◽  
Glassy Phase ◽  
Boundary Phase ◽  
Sintering Additives ◽  
Heat Treated ◽  
Si3n4 Ceramics

Alpha- or beta-Si3N4 powder with larger grain size was uses as starting material, and the effect of heat-treatment on thermal conductivity of Si3N4 ceramics using MgO, Y2O3 and SiO2 as sintering additives was investigated in terms of their microstructure and the amount of grain boundary phase. Most of the components derived from sintering additives existed as glassy phase in sintered Si3N4. After heat-treatment at 1950oC for 8 h, the amount of glassy phase significantly decreased, and then small amount of glassy phase existed in Si3N4 ceramics was crystallized as Y2O3 and Y2Si3N4O3. In the case of Si3N4 ceramics using SN-7 powder, thermal conductivity of heat-treated Si3N4 was around twice of the value of sintered Si3N4, and the thermal conductivity was increased from 41.4 to 87.2 W/m•K due to not only the reduction of grain boundary phase but also the grain growth. In the case of Si3N4 using SN-F1 powder, thermal conductivity of Si3N4 ceramics was also significantly increased from 36.0 to 73.2 W/m•K after heat-treatment. In this case, the reduction of grain boundary phase mainly affected the thermal conductivity of Si3N4 ceramics because the grain size of heat-treated Si3N4 was nearly the same as that of sintered Si3N4. The reduction of grain boundary phase from Si3N4 was effective for the improvement of their thermal conductivity in addition to grain growth of Si3N4.

Thermal Conductivity Improvement by Heat-Treatment in Si3N4 Ceramics Using SiO2-MgO-Y2O3 Additive System

2007 ◽  
Vol 352 ◽  
pp. 233-238 ◽  
Author(s):  
Thanakorn Wasanapiarnpong ◽  
Shigetaka Wada ◽  
Masamitsu Imai ◽  
Toyohiko Yano
Keyword(s):  
Thermal Conductivity ◽  
Heat Treatment ◽  
Liquid Phase ◽  
Low Temperature ◽  
Glassy Phase ◽  
Bending Strength ◽  
High Thermal Conductivity ◽  
Full Density ◽  
Additive System ◽  
Si3n4 Ceramics

Silicon nitride (Si3N4) ceramics have been interested for electrical substrate applications, because the ceramics can be made highly mechanical strength, fracture toughness, electrical resistivity and high thermal conductivity. Generally, relatively large amount of additives are required to obtain dense Si3N4 ceramics. During sintering, additives react with SiO2 including surface oxide of Si3N4 raw powder to form a liquid phase. Most of liquid phase changed into glassy phase during cooling down. In this study, Si3N4 ceramics were fabricated by gas pressure sintering. Yttrium oxide (Y2O3), silica (SiO2), and magnesia (MgO) were used for liquid-phase-enhanced sintering process. Dense materials were sintered by this process, but their thermal conductivities were not so high (30-40 W/m·K). Therefore, post-sintering heat-treatment process was performed to reduce the excess amount of glassy phase. An additive system (3 mass% SiO2 with 3 mass% MgO and 1-5 mass% Y2O3) was selected as the sintering aid. These ceramics could be sintered to almost full density at relatively low temperature as 1650oC for 2 h under 0.1 MPa-N2 without packing powder. The resulting materials have high bending strength, about 1 GPa, when 5mass% of Y2O3 was added. Based on the creation of low temperature pressureless sintering without packing powder, a novel two-step sintering (once firing) was proposed. The two-step sintering conducted by sintered at 1650oC under 0.1 MPa-N2 for 2 h for densification in the first step. Followed by heated up to and kept at 1950oC for 8 h under 1.0 MPa-N2 in the second step. The Si3N4 ceramics could be fabricated with relatively high thermal conductivity of 90 W/m·K. Mass loss, microstructure, mechanical properties, oxygen content and chemical composition were discussed.

Study on Pr6O11-Doped Superfine-Grained WC-Co Cemented Carbides

2014 ◽  
Vol 529 ◽  
pp. 57-61
Author(s):  
Jun Wang ◽  
Qi Kun Yang
Keyword(s):  
Grain Growth ◽  
Bending Strength ◽  
Experimental Results ◽  
Cemented Carbide ◽  
Cemented Carbides ◽  
Microstructure And Properties

Effect of Pr6O11addition on the microstructure and properties of superfine-grained WC-Co cemented carbide was studied by experiments. The experimental results show that Pr6O11can inhibit WC grain growth. In addition, the η phase firmed when the content of Pr6O11was more than 0.8%. When Pr6O11dopant amount is 0.4% and 0.8%, the alloy has the best bending strength and the best hardness respectively.

Improvement of the Thermoelectric Properties of the Chimney–Ladder Compounds in the Ru-Mn-Si System

2009 ◽  
Vol 1218 ◽  
Author(s):  
Norihiko L. Okamoto ◽  
Yutaka Hashimoto ◽  
Tatsuya Koyama ◽  
Hiroki Adachi ◽  
Kyosuke Kishida ◽  
...  
Keyword(s):  
Thermal Conductivity ◽  
Heat Treatment ◽  
Thermoelectric Properties ◽  
Growth Direction ◽  
Compositional Variation ◽  
Nominal Composition ◽  
Directionally Solidified ◽  
Conductivity Increase ◽  
Thermal Conductivity Increase ◽  
Metal Sublattice

AbstractDirectionally solidified alloys in the Ru-Mn-Si system exhibit a particular microstructure including columnar compositional variation due to the formation of many different chimney-ladder phases along the growth direction. Despite the existence of the compositional variation, the crystal orientations of the neighboring chimney-ladder phases are preserved. Over the compositional interfaces, the metal sublattice is considered to be continuous while the Si sublattice is not. Heat treatment of the directionally solidified alloy with the nominal composition of Ru0.10Mn0.90Si1.732 at 1100°C coarsens the compositional domains so as to reduce the density of the compositional interfaces. The values of the thermal conductivity increase with the decrease in the density of the compositional interfaces whereas those of the Seebeck coefficient and electrical resistivity are almost unchanged after the heat treatment. It is considered that the thermoelectric properties of the chimney-ladder compounds in the Ru-Mn-Si system can be enhanced by introducing a high density of the compositional interfaces.

Effect of Pressure on TiB2-Cu Composite via In-Situ Reaction Synthesis

2007 ◽  
Vol 280-283 ◽  
pp. 1437-1440
Author(s):  
Yue Feng Sun ◽  
Qiang Xu ◽  
Xing Hong Zhang ◽  
Jie Cai Han ◽  
Jin Huai Liu
Keyword(s):  
Mechanical Properties ◽  
Fracture Toughness ◽  
Bending Strength ◽  
Exothermic Reaction ◽  
Applied Pressure ◽  
Reaction Synthesis ◽  
Matrix Composites ◽  
Copper Powders ◽  
Fine Microstructure

TiB2-Cu matrix composites from titanium, boron and copper powders were in-situ fabricated by exothermic reaction. The effect of the applied pressure on the mechanical properties of the composite was investigated. The results showed that when the applied pressure increasing, the relative density, bending strength, fracture toughness and hardness of the composites were on the increase due to the formation of fine microstructure and the improvement of densification with the pressure increasing. The high pressure is beneficial to the better mechanical properties.

Phase Evolutionary Process of CaO-Al2O3-SiO2 System Glass and Glass-Ceramic

2010 ◽  
Vol 168-170 ◽  
pp. 1947-1952
Author(s):  
Feng He ◽  
Cai Ming Ping ◽  
Jin Shu Cheng
Keyword(s):  
Heat Treatment ◽  
Glass Ceramic ◽  
Bending Strength ◽  
Glass Ceramics ◽  
Evolutionary Process ◽  
Treatment Schedule ◽  
Nucleation Agent ◽  
Transmission Electron ◽  
New Type ◽  
Heat Treatment Schedule

Sintering glass-ceramics, a new type material for architectural decoration, belong to CaO-Al2O3-SiO2system (CAS) without nucleation agent. Combined by Differential thermal analysis (DTA), X-ray diffraction (XRD), Scanning electron microscopy (SEM) and Transmission electron microscope (TEM), phase evolutionary process of CaO-Al2O3-SiO2system glass and glass-ceramic was investigated. According the relation between heat treatment schedule and microstructure, the glass system has a very wide temperature range of crystallization. The crystalline phase is β-CaSiO3(β-wollastonite) and there is no other crystalline phases precipitated in these glass-ceramics. The influences of various heat treatment systems on the structure and properties of the glass-ceramics were investigated simultaneously. The optimal heat treatment schedule, microstructure and bending strength of the CAS glass ceramic were gained.

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