• Journal of the Korean Crystal Growth and Crystal Technology
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• v.30 no.5
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• pp.168-173
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• 2020

To analyze and describe the behavior and mechanisms occurring in the thermal oxidation process of AlN, bulk AlN single crystals were thermally treated with different temperatures. As a result, it was confirmed that full-scale oxidation of bulk AlN and growth of Al-oxide occurred from the temperature of 800℃, which confirmed that the weight% of O elements tended to increase while the N elements decreased with increasing the temperature. In the case of thermal treatment at 900℃, the grown Al-oxides were merged with neighboring Al-oxides and began to form α-Al₂O₃ poly-crystals. During thermal treatment at the temperature of 1000℃, hexagonal pyramidal shaped poly-crystalline α-Al₂O₃ was clearly observed. Through the X-ray diffraction pattern analysis, the changes of surface crystal structure according to the temperature of bulk AlN were investigated in detail.

• Journal of the Korean Ceramic Society
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• v.26 no.4
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• pp.453-458
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• 1989

Aluminum nitride powder prepared from the hydroxides, AlOOH and Al(OH)3 which were obtained by hydrolysis of Al-isopropoxide, was densified at 1750 and 180$0^{\circ}C$ for 60 min by hot-pressing under the pressure of 25kg/$\textrm{cm}^2$. Theoretical density could be obtained at 175$0^{\circ}C$. Their flexural strengths were 450MPa and 395MPa for the specimens obtained from Al(OH)3 and AlOOH, respectively. There was no remarkable change in flexural strength up to 100$0^{\circ}C$. Fracture toughness values were 3.50MN/m3/2 for Al(OH)3 and 3.11MN/m3/2 for AlOOH. It is assumed that these differences in mechanical properties are due to the abnormal grain growth for the AlN ceramics obtained from AlOOH.

• Journal of the Korean Ceramic Society
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• v.32 no.2
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• pp.209-216
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• 1995

In order to investigate the effect o green microstructure on the sintering behavior and properties of AlN ceramics, samples were prepared by slip casting and dry pressing. The slip cast samples had high green density, fine pore size and narrow pore size distribution. They showed much higher sinterability and more homogeneous sintered microstructure compared to the dry pressed samples. Both increased thermal conductivity and flexural strength for samples prepared by slip casting could be attributed to the improved microstructural homogeneity with isolated second phase(s).

• Proceedings of the Korean Institute of Surface Engineering Conference
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• 2012.05a
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• pp.159-159
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• 2012

티타늄-알루미늄(Titanium-Aluminum) 질화물(Nitride)은 고경도 난삭재의 고능률 절삭 분야에 사용되는 공구의 수명 향상을 위한 표면처리 소재로 각광을 받고 있다. 본 연구에서는 아크 소스로 TiAl 타겟을 사용 하였으며, $N_2$ 유량을 변화시키며 코팅을 실시하였다. 그 결과 경도 883~2510 Hv로 나타나는 것을 확인하였다.

• Journal of the Korean Ceramic Society
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• v.31 no.8
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• pp.893-901
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• 1994

In this study, AlN powder of fine particle size and of high purity was synthesized by the carbothermal reduction-nitridation of monodisperse, spherical Al(OH)3 which had been prepared by sol-gel method using Al(O-sec-C4H9)3 as the starting material. Depending on the mixing order and kinds of reducing agents, the optimum condition for the preparation of AlN was determined as follows. AlN single-phase was produced by the carbothermal reduction-nitridation of (1) Benzene-washed Al(OH)3 and the reducing agent, carbon, which was mixed in a ball mill: for 5 hours at 140$0^{\circ}C$ under NH3 atmosphere; (2) The mixture prepared by hydrolysis of alkoxide solution into which carbon had been dispersed beforehand: for 5 hours at 135$0^{\circ}C$ ; (3) Al(OH)3 Poly(furfuryl alcohol) composite powder: for 2.5 hours at 135$0^{\circ}C$; (4) The mixture of Al(OH)3 and polyacrylonitrile: for 5 hours at 140$0^{\circ}C$. Addition of CaF2 increased the nitridation rate when carbon or polyacrylonitrile was used as the reducing agent; but it had no effect on the nitridation rate when furfuryl alcohol was used as the reducing agent.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.25 no.4
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• pp.127-134
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• 2015

Aluminum nitride (AlN) single crystals have attracted much attention for a next-generation semiconductor application because of wide bandgap (6.2 eV), high thermal conductivity ($285W/m{\cdot}K$), high electrical resistivity (${\geq}10^{14}{\Omega}{\cdot}cm$), and high mechanical strength. The bulk AlN single crystals or thin film templates have been mainly grown by PVT (sublimation) method, flux method, solution growth method, and hydride vapor phase epitaxy (HVPE) method. Since AlN suffers difficulty in commercialization due to the defects that occur during single crystal growth, crystalline quality improvement via defects analyses is necessary. Etch pit density (EPD) analysis showed that the growth misorientations and the defects in the AlN surface exist. Transmission electron microscopy (TEM) and electron back-scattered diffraction (EBSD) analyses were employed to investigate the overall crystalline quality and various kinds of defects. TEM studies show that the morphology of the AlN is clearly influenced by stacking fault, dislocation, second phase, etc. In addition EBSD analysis also showed that the zinc blende polymorph of AlN exists as a growth defects resulting in dislocation initiator.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2001.11b
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• pp.509-512
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• 2001

Aluminum nitride(AlN) thin films were deposited on silicon substrates using RF magnetron sputtering at various deposition conditions and investigated the characteristics. It was used XRD, AES, SEM, and HP-4145B semiconductor parameter analyzer to analysis deposited AlN thin films. The deposition conditions for the good c-axis orientation were 100 W of RF power, $200^{\circ}C$ of substrate temperature and 15 mTorr of working pressure. The leakage current density was less then $1.3{\times}10^{-7}A/cm^{2}$. And it was also investigated the etching properties of deposited AlN thin films for application.

• Journal of the Korean Ceramic Society
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• v.42 no.1
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• pp.69-75
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• 2005

To investigate the morphological effect on synthesis of aluminum nitride by SHS Process, two type of Al Powder (granular and flacky shape) with the mean size of 34 $\mu$m and the diluent AIN powders of four different mean sizes.0.12, 9.7, 39.3, 50.5 $\mu$m, were used to prepare green compact. The packing density was fixed to $35 TD\%. The initial pressure of $N_{2}$ and diluent fraction was varied in the range of $1\~10 MPa,\;0.4\~0.7$, respectively. AlN with high purity of $98\% or over and large particle size of about several tens fm can be synthesized by SHS reaction as a consequence of adjusting particle size of AlN dilutent similarly to that of Al reactant. This may be caused by improvement of $N_{2}$ gas permeation to compact after passing the propagation wave. In the case of flaky-shape aluminum used as reactant, instead of granular Al-powder, unstable combustion would be occurred. As the result, irregular propagation of combustion wave and falling-off of maximum temperature would be observed during the reaction.

• Journal of the Korean Society for Heat Treatment
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• v.13 no.3
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• pp.158-162
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• 2000

The high temperature oxidation behavior and the surface defect in Fe-25Mn-1.5A1-0.5C steel was investigated by XRD (X-ray Diffractin) and electron microscopy. The intra- and inter-granular oxides were formed by the selective oxidation of manganese and aluminum, which were identified to MnAl2O4 phase. Aluminum nitride (AlN) was formed in front of these oxides. The ${\gamma}$-matrix was transformed to ${\alpha}$- and ${\varepsilon}$- phases by the selective oxidation of manganese. The surface defect, micro-scab was induced by the difference of the high temperature ductility between the matrix and the inter-granular oxide.

• Nuclear Engineering and Technology
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• v.55 no.9
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• pp.3126-3132
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• 2023

To meet the increasing heating needs of the China Fusion Experimental Tokamak Reactor (CFETR), the output power in each Lower Hybrid Current Drive (LHCD) transmission line should be increased from 250 kW to 500 kW. Therefore, a new high-power water load must be developed for the 4.6 GHz 500 kW LHCD system. This paper aims to report the most recent research progress of the water load: aluminum nitride (AlN) ceramic is used as the media material to isolate the water and vacuum, and the radio frequency (RF) simulation results show that the return loss of the water load is less than -25dB at 4.6 GHz over a wide temperature range. Under 500 kW continuous wave (CW) operation, the maximum temperatures of the ceramic and water are separately 67 ℃ and 62 ℃, resulting in thermal deformation of the ceramic of approximately 0.003 mm. Moreover, the AlN water load was tested on the 4.6 GHz 250 kW high-power test bench and found to work well with low reflected power.