Liquid Phase Sintering of Aluminum Nitride

Liquid-phase sintering of aluminum nitride (AlN) with additives was reviewed. The most important innovation was the discovery of critical sintering aids for AlN densification, specifically rare-earth compounds and alkali-earth compounds. These additives are extremely valuable for increasing thermal conductivity by trapping and removing oxygen in the AlN lattice during firing. Consequently, thermal conductivities in AlN ceramics of 100 to 260W/mK were developed. We also studied the effects of parameters such as raw powder, additives, composition, and firing condition in liquid-phase sintering with AlN-sintering aids, focusing on oxygen impurities in the system. The sintering behavior of powder compacts was investigated by evaluating the densification, the lattice constant c for AlN, and the dihedral angle of the interface between the AlN grains and the grain boundary liquid-phase. In our results, the change in densification was closely related to changes in the lattice constant c and the dihedral angle. That is, the sintered density increased with an increase in the oxygen dissolved in the AlN grains and with the improvement in wettability between the solid and liquid phase.

Download Full-text

Antiphase domain boundaries in liquid-phase sintered aluminum nitride

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100104947 ◽

1988 ◽

Vol 46 ◽

pp. 576-577

Author(s):

R.A. Youngman

Keyword(s):

Thermal Conductivity ◽

Liquid Phase ◽

Aluminum Nitride ◽

Integrated Circuit ◽

Charge Compensation ◽

Antiphase Domain ◽

Liquid Phase Sintering ◽

Oxide Surface ◽

Sintered Aluminum ◽

Domain Boundaries

Liquid phase sintering of aluminum nitride is currently being developed for the production of Integrated circuit substrates In high power applications due to the high Inherent thermal conductivity of AIN. The sintering is usually conducted with oxide additives which form low melting eutectic compositions with AIN and its ever-present oxide surface layer. In this study Y2O3 (1-2wt/o) has been utilized for liquid phase formation where the eutectic compositions Y3Al5O12, YAlO3, and Al2Y4O9 form by reaction with “A12O3” on the surface of the AIN. The AIN particles themselves will contain oxygen (˜l-2wt/o)and this is also availible for reaction although not as readily since It has been accomodated In the bulk crystal. Since It has been established that the thermal conductivity of the resulting ceramic is controlled by the lattice oxygen content, which In turn controls the number of aluminum vacancies due to charge compensation, It Is important to understand the defect structure developed during sintering.

Download Full-text

Effect of furnace atmosphere and silica content on the consolidation behaviour of magnesia partially stabilised zirconia

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100178410 ◽

1990 ◽

Vol 48 (4) ◽

pp. 1056-1057

Author(s):

J. Drennan ◽

R.H.J. Hannink ◽

D.R. Clarke ◽

T.M. Shaw

Keyword(s):

Liquid Phase ◽

Silica Content ◽

Liquid Phase Sintering ◽

Furnace Atmosphere ◽

Boundary Phase ◽

Analytical Electron ◽

Analytical Electron Microscope ◽

Series Of Experiments ◽

Compositional Gradients ◽

Mobile Liquid

Magnesia partially stabilised zirconia (Mg-PSZ) ceramics are renowned for their excellent nechanical properties. These are effected by processing conditions and purity of starting materials. It has been previously shown that small additions of strontia (SrO) have the effect of removing the major contaminant, silica (SiO2).The mechanism by which this occurs is not fully understood but the strontia appears to form a very mobile liquid phase at the grain boundaries. As the sintering reaches the final stages the liquid phase is expelled to the surface of the ceramic. A series of experiments, to examine the behaviour of the liquid grain boundary phase, were designed to produce compositional gradients across the ceramic bodies. To achieve this, changes in both silica content and furnace atmosphere were implemented. Analytical electron microscope techniques were used to monitor the form and composition of the phases developed. This paper describes the results of our investigation and the presentation will discuss the work with reference to liquid phase sintering of ceramics in general.

Download Full-text

Microstructure and microanalysis of sintered Fe-Nd-B permanent magnets

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100178082 ◽

1990 ◽

Vol 48 (4) ◽

pp. 990-991

Author(s):

Mahesh Chandramouli

Keyword(s):

Electron Microscope ◽

Liquid Phase ◽

Permanent Magnets ◽

Phase Distribution ◽

Energy Dispersive Spectrometer ◽

Nucleation And Growth ◽

Liquid Phase Sintering ◽

Domain Wall Energy ◽

Oxide Phases ◽

Scanning Electron

Magnetization reversal in sintered Fe-Nd-B, a complex, multiphase material, occurs by nucleation and growth of reverse domains making the isolation of the ferromagnetic Fe14Nd2B grains by other nonmagnetic phases crucial. The magnets used in this study were slightly rich in Nd (in comparison to Fe14Nd2B) to promote the formation of Nd-oxides at multigrain junctions and incorporated Dy80Al20 as a liquid phase sintering addition. Dy has been shown to increase the domain wall energy thus making nucleation more difficult while Al is thought to improve the wettability of the Nd-oxide phases.Bulk polished samples were examined in a JEOL 35CF scanning electron microscope (SEM) operated at 30keV equipped with a Be window energy dispersive spectrometer (EDS) detector in order to determine the phase distribution.

Download Full-text

SOLID SOLUTION FORMATION DURING LIQUID PHASE SINTERING

Le Journal de Physique Colloques ◽

10.1051/jphyscol:1986166 ◽

1986 ◽

Vol 47 (C1) ◽

pp. C1-441-C1-445

Author(s):

E. KOSTIĆ ◽

S. J. KISS ◽

D. CEROVIĆ

Keyword(s):

Solid Solution ◽

Liquid Phase ◽

Liquid Phase Sintering ◽

Solid Solution Formation ◽

Solution Formation

Download Full-text

Microstructure development during liquid-phase sintering

Zeitschrift für Metallkunde ◽

10.3139/146.101011 ◽

2005 ◽

Vol 96 (2) ◽

pp. 141-147 ◽

Cited By ~ 10

Author(s):

Sung-Min Lee ◽

Suk-Joong L. Kang

Keyword(s):

Liquid Phase ◽

Liquid Phase Sintering ◽

Microstructure Development

Download Full-text

ChemInform Abstract: Liquid Phase Sintering of Silicon Carbide.

ChemInform ◽

10.1002/chin.199632315 ◽

2010 ◽

Vol 27 (32) ◽

pp. no-no

Author(s):

F. K. VAN DIJEN ◽

E. MAYER

Keyword(s):

Silicon Carbide ◽

Liquid Phase ◽

Liquid Phase Sintering

Download Full-text

Synthesis and Na+ Ion Conductivity of Stoichiometric Na3Zr2Si2PO12 by Liquid-Phase Sintering with NaPO3 Glass

Materials ◽

10.3390/ma14143790 ◽

2021 ◽

Vol 14 (14) ◽

pp. 3790

Author(s):

Yongzheng Ji ◽

Tsuyoshi Honma ◽

Takayuki Komatsu

Keyword(s):

Solid State ◽

Liquid Phase ◽

Sintering Temperature ◽

Liquid Phase Sintering ◽

Ion Conductivity ◽

X Ray Diffraction ◽

Conventional Solid State Reaction ◽

X Ray ◽

Sintering Time ◽

Lower Activation

Sodium super ionic conductor (NASICON)-type Na3Zr2Si2PO12 (NZSP) with the advantages of the high ionic conductivity, stability and safety is one of the most famous solid-state electrolytes. NZSP, however, requires the high sintering temperature about 1200 °C and long sintering time in the conventional solid-state reaction (SSR) method. In this study, the liquid-phase sintering (LPS) method was applied to synthesize NZSP with the use of NaPO3 glass with a low glass transition temperature of 292 °C. The formation of NZSP was confirmed by X-ray diffraction analyses in the samples obtained by the LPS method for the mixture of Na2ZrSi2O7, ZrO2, and NaPO3 glass. The sample sintered at 1000 °C for 10 h exhibited a higher Na+ ion conductivity of 1.81 mS/cm at 100 °C and a lower activation energy of 0.18 eV compared with the samples prepared by the SSR method. It is proposed that a new LPE method is effective for the synthesis of NZSP and the NaPO3 glass has a great contribution to the Na+ diffusion at the grain boundaries.

Download Full-text