Additive Sintering Process in Aluminum Nitride Ceramics

1991 ◽  
Vol 249 ◽  
Author(s):  
H. Makihara ◽  
N. Kamehara
Keyword(s):  
Thermal Conductivity ◽  
Phase Diagram ◽  
Liquid Phase ◽  
Sintering Temperature ◽  
Early Stage ◽  
Sintering Process ◽  
Residual Oxygen ◽  
Nitride Ceramics ◽  
Calcium Compounds ◽  
Oxygen Impurities

ABSTRACTCalcium compounds and yttrium compounds are frequently used as additives to densify AlN ceramics[l,2]. They react with oxygen impurities, such as A1203 in the raw AlN powder and in aluminate forms. A phase diagram is helpful in deciding the amount of additives to add, but the AlN sintering process doesn't come to equilibrium. We investigated the differences between sintering AlN with CaCO3 and with Y2O3.With CaCO3 added, the calcium-aluminate liquid phase evaporates from the sintered AlN body at high sintering temperatures. The AlN thermal conductivity doesn't increase above a sintering temperature of 1700°C because residual oxygen substitutes into the AlN grains. With Y2O3 added, AlN sinters below 1850°C, as predicted by a phase diagram. With a large amount of Y2O3 added, 5 wt%, thermal conductivity doesn't depend on residual oxygen. This is because yttrium doesn't evaporate from the sintered AlN body and residual oxygen substitutes into AlN grains at an early stage of the AlN sintering.

Physical, Mechanical and Electrical Properties of W-20 wt.% Cu Composite Produced by Liquid Phase Sintering Process

2014 ◽  
Vol 879 ◽  
pp. 21-26
Author(s):  
Fauzi Ismail ◽  
Mohd Asri Selamat ◽  
Norhamidi Muhamad ◽  
Abu Bakar Sulong ◽  
Nurzirah Abdul Majid
Keyword(s):  
Particle Size ◽  
Liquid Phase ◽  
Electrical Properties ◽  
Microstructure Evolution ◽  
Sintering Temperature ◽  
Cold Isostatic Pressing ◽  
Liquid Phase Sintering ◽  
Sintering Process ◽  
Composite Powders ◽  
Mechanical And Electrical Properties

In this study, the effect of sintering temperature on the properties of tungsten-copper (W-Cu) composite produced by liquid phase sintering (LPS) process has been investigated. W-20 wt.% Cu composite powders with particle size less than 1 μm was prepared by cold compaction and followed by cold isostatic pressing. The green specimens were then sintered under nitrogen based atmosphere in the temperature range of 1100°C to 1300°C. The sintering studies were conducted to determine the extent of densification and corresponding to microstructure changes. In addition, the properties of the sintered specimens such as physical appearance, microstructure evolution, mechanical and electrical properties were presented and discussed.

scholarly journals Effect of Thermodynamic Melt Formation Characteristics on Liquid Phase Fluidity of Iron Ore in the Sintering Process

Metals ◽  
2019 ◽  
Vol 9 (4) ◽  
pp. 404 ◽  
Author(s):  
Shengli Wu ◽  
Heping Li ◽  
Weili Zhang ◽  
Bo Su
Keyword(s):  
Liquid Phase ◽  
Iron Ore ◽  
Sintering Temperature ◽  
Mixed Phase ◽  
Al2o3 Content ◽  
Phase Content ◽  
Sintering Process ◽  
Test Device ◽  
Sintering Characteristics ◽  
Factsage Software

The liquid phase fluidity of iron ore is a vital index of fundamental sintering characteristics. In this paper, FactSage software and a visible microsintering test device were used to research the influence of the thermodynamic melt characteristics on the liquid phase fluidity under fixed CaO content conditions. The results show that the laws governing liquid phase fluidity of iron ore are significantly different with a fixed alkalinity and fixed CaO content of the sample. The liquid phase content at the sintering temperature is the most important thermodynamic melt formation characteristic affecting the liquid phase fluidity. In addition to the liquid phase content, other minerals also have a greater impact on liquid phase fluidity. Decreasing the viscosity of the liquid phase improves the liquid phase fluidity of the iron ore, and the effect of the SiO2 content of the iron ore on the mixed phase viscosity is greater than that of the Al2O3 content.

The Influence of AST Doping on the Dielectric Properties of MgTiO3-Based Ceramics Fabricated by Soild-State Sintering

2013 ◽  
Vol 634-638 ◽  
pp. 2378-2382
Author(s):  
Chun Yuan Luo ◽  
Jing Xiao Liu ◽  
Fei Shi ◽  
Ji Wei Wu ◽  
Chao Qian ◽  
...  
Keyword(s):  
Dielectric Properties ◽  
Solid State ◽  
Liquid Phase ◽  
Dielectric Loss ◽  
Sintering Temperature ◽  
Liquid Phase Sintering ◽  
Sintering Process ◽  
Solid State Sintering ◽  
Doped Zno

AST-doped ZnO-MgTiO3-SrTiO3ceramics were prepared using a solid-state sintering process. The effects of AST (Al2O3-SiO2-TiO2) on the dielectric properties of MgTiO3-based ceramics were investigated. The results indicate that AST-doped MgTiO3-based ceramics could be obtained after 1205~1280°C sintering for 3 h. The XRD results indicate that the obtained MgTiO3-based ceramics contain high percentage of MgTi2O5 phase and the percentage increased with the increase of AST content. It was found that the occurred liquid-phase sintering by adding AST glass could effectively lower the sintering temperature and decrease the dielectric loss of MgTiO3-based ceramics. A minimum tanδ of 1.5×10-4 associated with εr=19.0 was achieved for 6.0 wt% AST-doped samples sintered at 1255°C.

scholarly journals Influence of Powder Characteristics on Sintering Process and Thermal Conductivity of Aluminum Nitride Ceramics

1995 ◽  
Vol 103 (1201) ◽  
pp. 891-900 ◽  
Author(s):  
Koji WATARI ◽  
Manuel E. BRITO ◽  
Masaki YASUOKA ◽  
Maria Cecilia VALECILLOS ◽  
Shuzo KANZAKI
Keyword(s):  
Thermal Conductivity ◽  
Aluminum Nitride ◽  
Sintering Process ◽  
Nitride Ceramics ◽  
Powder Characteristics

Effect of Sintering Temperature on the Properties of Porous Silicon Nitride Ceramics

2009 ◽  
Vol 66 ◽  
pp. 85-88
Author(s):  
Ling Li ◽  
Yong Li ◽  
Hong Lin Yu ◽  
Fei Chen ◽  
Hong Sheng Wang ◽  
...  
Keyword(s):  
High Temperature ◽  
Silicon Nitride ◽  
Porous Silicon ◽  
Sintering Temperature ◽  
Decomposition Reaction ◽  
Sintering Process ◽  
Nitride Ceramics ◽  
Low Permittivity ◽  
Properties Of Composites

In this study, the porous silicon nitride ceramics with low permittivity was prepared by decomposition reaction of Si2N2O. The effect of sintering temperature on the properties of composites was investigated. The results show that the sintering process of porous silicon nitride ceramics is liquid crease-densititive-crease gas in high temperature-forming close pore-break of close pores and crease open pores. The density is 0.9-2.44 g/cm3, the porosity of sample varies from 0-47%, and the permittivity can be well controlled from 2.2 to 4.8.

Effect of Fly Ash Pre-Sintering Temperature on Adiabatic Foam Fabricated by Sodium Silicate

2019 ◽  
Vol 295 ◽  
pp. 105-109
Author(s):  
Ye Li ◽  
Heng Ze Zhao ◽  
Xu Dong Cheng
Keyword(s):  
Thermal Conductivity ◽  
Compressive Strength ◽  
Fly Ash ◽  
Pore Structure ◽  
Pore Size ◽  
Sodium Silicate ◽  
Sintering Temperature ◽  
Raw Material ◽  
Sintering Process ◽  
Spherical Pore

Adiabatic foam was fabricated successfully using sodium silicate as the raw material with pre-sintered fly ash as additive. Fly ash was pre-sintered at 500 to 900 oC and the effect of the pre-sintering temperature on the performance, including the thermal conductivity, density, compressive strength and microstructure, was researched. The results show that the pre-sintering process effectively reduces the density of the samples while the thermal conductivity and compressive strength are higher than those of the samples fabricated by the fly ash without being pre-sintered. Moreover, the samples exhibit tri-modal spherical pore structure with macropores and mesopores. The pore size remains unchanged until the pre-sintering temperature exceeds 700 oC, and then starts to increase.

Fabrication and Properties of AlN/CNT Composite Ceramics

2012 ◽  
Vol 512-515 ◽  
pp. 898-901 ◽  
Author(s):  
Hai Long Liang ◽  
Yong Li Li ◽  
Jie Tang ◽  
Hai Lin Liu ◽  
Yan Li Huo ◽  
...  
Keyword(s):  
Thermal Conductivity ◽  
Composite Material ◽  
Structural Damage ◽  
Single Phase ◽  
Sintering Temperature ◽  
Sintering Process ◽  
Densification Process ◽  
Composite Ceramics ◽  
Volume Fractions ◽  
Spark Plasma

High thermal conductivity and dense AlN/CNT composite ceramics with additive Y2O3 were fabricated by spark plasma sintered (SPS) in this paper. The results indicated that CNT blocked the densification process in a certain extent, but in the sintering temperature of 1700°C, the relative density of composite ceramics were more than 97% with 1-10% volume fractions of CNT. The content of additive Y2O3 affected the thermal conductivity of AlN/CNT obviously. The thermal conductivity of composite material linearly decreased when the content of CNT increased and the tubular structure of CNT had been destructed during once sintering. The effects of the CNT structural damage to the thermal conductivity of composite ceramics were improved by adjusting the sintering process. The thermal conductivity of the composite ceramics with 3% volume fractions of CNT sintering in 1550°C/3min×3 was up to 145W/m•K, which higher than the single-phase AlN ceramics.

Thermal Conductivity of Mullite/Al2O3 Ceramics Sintered with Li2O, CaO and Y2O3

2006 ◽  
Vol 11-12 ◽  
pp. 129-132
Author(s):  
You Fen Li ◽  
Qing Liu ◽  
Wei Wei Liu ◽  
Min Li
Keyword(s):  
Thermal Conductivity ◽  
Liquid Phase ◽  
Low Temperature ◽  
Sintering Temperature ◽  
Al2o3 Particles

Dense Mullite/Al2O3 ceramics with a thermal conductivity of 45 W/m.K were obtained at the sintering temperature of 1500°C using Li2O, CaO and Y2O3 as additives. At temperature below 1500°C, the shrinkage of Mullite/Al2O3 ceramics is promoted by liquid LiAlSi2O6 and Al2Y4O9. Liquid LiAlSi2O6 mainly improves the densification of the sample when the sintering temperature increases to 1500°C. The formation of liquid phase at a relatively low temperature results in homogeneous Al2Y4O9 and Ca(Al2Si2O8) distributed around the Mullite/Al2O3 particles, which benefits the thermal conductivity improved.

Effects of Concentrations of NaCl on the Sintering and Thermal Conductivity of Forsterite

2016 ◽  
Vol 697 ◽  
pp. 437-440 ◽  
Author(s):  
Jun Ding ◽  
Hong Xi Zhu ◽  
Cheng Ji Deng ◽  
Ding Guo ◽  
Heng Shang
Keyword(s):  
Thermal Conductivity ◽  
Liquid Phase ◽  
Diffusion Mechanism ◽  
Salt Content ◽  
Liquid Phase Sintering ◽  
Sintering Process ◽  
Sintering Time ◽  
Two Samples ◽  
Insulation Effect ◽  
Better Than

This paper aims to study the effects of NaCl on the sintering of forsterite as well as the thermal conductivity of the sintering products. In the sintering process, NaCl played a role in the system by mainly providing a liquid phase sintering environment in order to promote grain growth and forsterite sintering. Moreover, the model of liquid phase sintering was established in this paper. In the initial sintering stage, the phenomenon of particle re-arrangement was not significant, and dissolution-precipitation was regarded as the dominant sintering mechanism. With the extension of the sintering time, the middle and later stages of the sintering process were mainly controlled by the diffusion mechanism. A test of the thermal conductivity of samples with 40% and 50% NaCl was carried out, which indicated that the thermal conductivity of the two samples ranged from 0.3 to 0.4 W·m-1·k-1. At the same temperatures, the thermal conductivity of the sample with a salt content of 50% was lower than that of the sample with a salt concentration of 40%. Also, the heat insulation effect of the sample with a salt content of 50% was better than that of the sample of 40% . Hence, it can be concluded that the higher the salt content in the sample, the lower the thermal conductivity of the sample.

AlN/CNT Composites Ceramics by Spark Plasma Sintering

2014 ◽  
Vol 602-603 ◽  
pp. 570-573
Author(s):  
Hai Long Liang ◽  
Chun Peng Wang ◽  
Yan Li Huo ◽  
Chuan Qi Hu ◽  
Xiao Ting Huang ◽  
...  
Keyword(s):  
Thermal Conductivity ◽  
High Temperature ◽  
Spark Plasma Sintering ◽  
Imaginary Part ◽  
Loss Factor ◽  
Sintering Temperature ◽  
Sintering Process ◽  
Composite Ceramics ◽  
Plasma Sintering ◽  
Spark Plasma

Highly dense AlN/CNT composite ceramics with 1-10% volume fractions of CNT were fabricated by spark plasma sintered (SPS) at 1400°C-1700°C. The results indicated that origination diameter of AlN had a great effect on microstructure and thermal conductivity. In details, for the system with AlN origination diameter of nanosized, the tubular structure of CNT has not been destructed, but when micro-sized AlN powder was adopted, the structure of CNT showed unstable at high temperature. Even though the degradation with incorporation of CNT into AlN, thermal conductivity of sintered AlN/CNT composites ceramics was evidently improved by adjusting content of additive Y2O3and the sintering process. Both the real part and imaginary part of the composites of Ka-Band (26.540.0 GHz) increase with the increase of CNT content, in which the increase of imaginary part is more than that of real part, resulting in an increase of loss factor. The AlN/ CNT thermal conductivity composites with appropriate CNT content and sintering temperature possess good dielectric dissipation and thermal conductivity.

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