• Title/Summary/Keyword: AlN addition

Search Result 345, Processing Time 0.026 seconds

Effects of $Y_2O_3$ addition and sintering time on denazification and thermal conductivity of AlN ceramics during hot-press sintering ($Y_2O_3$ 첨가와 소결 시간이 AlN 세라믹스의 일축 가압 소결 거동 및 열전도도에 미치는 영향)

  • Chae, Jae-Hong;Park, Joo-Seok;Ahn, Jong-Pil;Kim, Kyoung-Hun;Lee, Byung-Ha
    • Journal of the Korean Crystal Growth and Crystal Technology
    • /
    • v.18 no.6
    • /
    • pp.237-241
    • /
    • 2008
  • Hot-press sintering of AlN ceramics were carried out with $Y_2O_3$ as sintering additive at a sintering temperature $1,750{\sim}1,850^{\circ}C$. The effect of $Y_2O_3$ addition and sintering time on sintering behavior and thermal conductivity of AlN ceramics was investigated. $Y_2O_3$ added AlN showed noticeably higher denazification rate than pure AlN. The thermal conductivity of AlN specimens was promoted by the addition of $Y_2O_3$ in spite of the formation of YAG secondary phase in AlN grain boundaries and grain boundary triple junction because $Y_2O_3$ addition could reduced the oxygen contents in AlN lattice which is primary factor of thermal conductivity. Typically, the thermal conductivity of 5 wt% $Y_2O_3$ added specimen was dramatically improved by the increase of sintering time because the elimination of YAG secondary phases from the grain boundary due to the evaporation, as well as the grain-growth of AlN grains.

Nitrogenation of Coal Ash in the Presence of Carbon and Product Distributions of AlN, SiC and $Si_3N_4$ (석탄회의 탄소가 첨가된 질화반응과 AlN, SiC 그리고 $Si_3N_4$의 생성분포)

  • 양현수;홍원표;노재성;서동수;손응권
    • Journal of the Korean Ceramic Society
    • /
    • v.27 no.8
    • /
    • pp.965-970
    • /
    • 1990
  • A nitrogenation of coal ash in the presence of carbon was carried out to examine the effects of reaction temperature, reaction time and carbon composition on the formation of AlN, SiC and Si3N4. Decreasing the particle size increased the formation of AlN and its maximum composition in the product was obtaiend under 1450~150$0^{\circ}C$, 2 hours of reaction time and about 30% of carbon addition(on the basis of sample weight). Compositions of SiC and Si3N4 were distributed to the opposite so that SiC showed a higher composition compared with Si3N4 at a lower temperature, a shorter reaction time and a greater carbon addition.

  • PDF

Growth of AlN Thin Film on Sapphire Substrates and ZnO Templates by RF-magnetron Sputtering (RF 마그네트론 스퍼터링법을 이용하여 사파이어 기판과 ZnO 박막 위에 증착한 AlN 박막의 특성분석)

  • Na, Hyun-Seok
    • Journal of the Korean Vacuum Society
    • /
    • v.19 no.1
    • /
    • pp.58-65
    • /
    • 2010
  • AlN thin films were deposited on sapphire substrates and ZnO templates by rf-magnetron sputtering. Powder-sintered AlN target was adopted for source material. Thickness of AlN layer was linearly dependent on plasma power from 50 to 110 W, and it decreased slightly when working pressure increased from 3 to 10 mTorr due to short mean free path of source material sputtered from AlN target by Ar working gas. When $N_2$ gas was mixed with Ar, the thickness of AlN layer decreased significantly because of low sputter yield of nitrogen. AlN layer was also deposited on ZnO template. However, it showed weak thermal stability that the interface between AlN and ZnO was deteriorated by rapid thermal annealing treatment above $700^{\circ}C$. In addition, ZnO layer was largely attacked by MOCVD ambient gas of hydrogen and ammonia around $700^{\circ}C$ through inferior AlN layer deposited by sputtering. And AlN layers were fully peeled off above $900^{\circ}C$.

Property and formation behavior of TiAlSiWN nanocomposite coating layer by the AIP process (AIP 공정 적용 TiAlSiWN 나노 복합체 코팅층의 형성 거동 및 특성 평가)

  • Lee, Jeong-Han;Park, Hyeon-Guk;Jang, Jun-Ho;Hong, Seong-Gil;O, Ik-Hyeon
    • Proceedings of the Korean Institute of Surface Engineering Conference
    • /
    • 2018.06a
    • /
    • pp.97.2-97.2
    • /
    • 2018
  • This study formed a hard TiAlSiWN coating layer using Ti, Al, Si and W raw powders that were mechanically alloyed and refined. The TiAlSi and TiAlSiW coating targets were fabricated using a single PCAS process in a short time with the optimal sintering conditions. The coating targets were deposited on the WC substrate by forming coating layers using TiAlSiN and TiAlSiWN nitride nano-composite structures with an AIP process. The properties of the nitride nano-composite coating layers were compared according to the addition of W. The microstructure of the nitride nano-composite coating layer was analyzed, focusing on the distribution of the crystalline phases, amorphous phases ($Si_3N_4$), and growth orientation of the columnar crystal depending on the addition of W. The mechanical properties of the coating layers were exhibited a hardness of approximately $3,000kg/mm^2$ and adhesion of about 117.77N in the TiAlSiN. In particular, the TiAlSiWN showed excellent properties with a hardness of more than $4,300kg/mm^2$ and an adhesion of about 181.47N.

  • PDF

Structural Analyses and Properties of $Ti_{1-x}Al_xN$ Films Deposited by PACVD Using a $TiCl_4/AlCl_3/N_2/Ar/H_2$ Gas Mixture ($TiCl_4/AlCl_3/N_2/Ar/H_2$ 반응계를 사용하는 플라즈마화학증착법에 의한 $Ti_{1-x}Al_xN$ 박막의 구조분석 및 물성)

  • 김광호;이성호
    • Journal of the Korean Ceramic Society
    • /
    • v.32 no.7
    • /
    • pp.809-816
    • /
    • 1995
  • Ti1-xAlxN films were successfully deposited on high speed steel and silicon wafer by plasma-assisted chemical vapor deposition using a TiCl4/AlCl3/N2/Ar/H2 gas mixture. Plasma process enabled N2 gas to nitride AlCl3, which is not possible in sense of thermodynamics. XPS analyses revealed that the deposited layer contained Al-N bond as well as Ti-N bond. Ti1-xAlxN films were polycrystalline and had single phase, B1-NaCl structure of TiN. Interplanar distance, d200, of (200) crystal plane of Ti1-xAlxN was, however, decreased with Al content, x. Al incorporation into TiN caused the grain size to be finer and changed strong (200) preferred orientation of TiN to random oriented microstructure. Those microstructural changes with Al addition resulted in the increase of micro-hardness of Ti1-xAlxN film up to 2800Kg/$\textrm{mm}^2$ compared with 1400Kg/$\textrm{mm}^2$ of TiN.

  • PDF

Microstructure and Mechanical Properties of Cr-Al-Si-N Coatings for Wear Resistant and Structural Applications (내마모 구조 코팅용 Cr-Al-Si-N 코팅막의 미세구조와 기계적 특성에 관한 연구)

  • Kang, Dong-Shik;Kim, Kwang-Ho
    • Korean Journal of Materials Research
    • /
    • v.15 no.11
    • /
    • pp.730-734
    • /
    • 2005
  • Cr-Al-Si-N coatings were deposited on WC-Co substrates by a hybrid coating system of arc ion plating and DC magnet :on sputtering technique in $N_2/Ar$ mixture. The Cr-tll-Si-N coatings were synthesized with different Si contents. Their microstructure and mechanical properties were systematically investigated. The average size of crystallites largely decreases with the increase of Si content compared with Cr-Al-N. The microhardness of Cr-Al-Si-N coatings largely increases from 24 to 55 GPa. The enhanced hardness is believed to originate from the microstructural change by the fine composite microstructure of Cr-Al-N coatings with Si addition. The average friction coefficient of Cr-Al-Si-N coatings decreases from 0.84 to 0.45 with increasing Si content up to $16\;at.\%$.

Mechanical Properties of $Al_2O_3-AlN$ Particulate Composite ($Al_2O_3-AlN$계 입자복합체의 기계적 성질)

  • 김영우;박홍채;오기동
    • Journal of the Korean Ceramic Society
    • /
    • v.33 no.1
    • /
    • pp.101-109
    • /
    • 1996
  • The mechanical propertieso f sintered AlN with the addition of alumina were investigated The flexural strength of the AlN dispersed ALON specimens was higher than that of ALON and fracture toughness showed similar tendency. The high-temperature flexural strength of specimens which 50 and 64.3 mol% alumina was added to AlN was constant up to 100$0^{\circ}C$ with about 290 and 420 MPa respectively but abruptly decreased at 120$0^{\circ}C$ In the specimens which contained 5 and 30mol% alumina the flexural strength increased to about 14% at 100$0^{\circ}C$ and did not decrease at 120$0^{\circ}C$ compared to at room temperature.

  • PDF

DC and RF Characteristics of AlGaN/InGaN HEMTs Grown by Plasma-Assisted MBE (AlGaN/InGaN HEMTs의 고성능 초고주파 전류 특성)

  • 이종욱
    • The Journal of Korean Institute of Electromagnetic Engineering and Science
    • /
    • v.15 no.8
    • /
    • pp.752-758
    • /
    • 2004
  • This paper reports on the DC and RF characteristics of AlGaN/InGaN/GaN high electron-mobility transistors (HEMTs) grown by molecular beau epitaxy(MBE) on sapphire substrates. The devices with a 0.5 ${\mu}$m gate-length exhibited relatively flat transconductance(g$\_$m/), which results from the enhanced carrier confinement of the InGaN channel. The maximum drain current was 880 mA/mm with a peak g$\_$m/ of 156 mS/mm, an f$\_$T/ of 17.3 GHz, and an f$\_$MAX/ or 28.7 GHz. In addition to promising DC and RF results, pulsed I-V and current-switching measurements showed little dispersion in the unpassivated AlGaN/InGaN HEMTs. These results suggest that the addition of In to the GaN channel improves the electron transport characteristics as well as suppressing current collapse that is related to the surface trap states.

Effect of AlN Addition on the Thermal Conductivity of Sintered $Al_2O_3$ (알루미나 소결체의 열전도도에 대한 AlN의 첨가효과)

  • 김영우;박홍채;오기동
    • Journal of the Korean Ceramic Society
    • /
    • v.33 no.3
    • /
    • pp.285-292
    • /
    • 1996
  • The effect of AlN on the thermal conductivity of aluminum oxide pressurelessly sintered at nitrogen atmos-phere was investigated. Increasing aluminium nitride content up to 1~10 mol% the thermal conductivity of $Al_{2}O_{3}$-AlN system was singnificantly decreased and was constant with adding 20 and 25 mol% aluminium nitride. The thermal conuctivity of $Al_{2}O_{3}$ containing 1~10 mol% the thermal conductivity of $Al_{2}O_{3}$-AlN system was singificantly decreased and was constant with adding 20 and 25mol% aluminum nitride. The thermal conctivity of $Al_{2}O_{3}$ containing 1~10 mol% AlN showed a maximum at $1700^{\circ}C$ and decrea-sed with increasing sintering tempertures. This phenomenon was attributed to $\alpha$-$Al_{2}O_{3}$ and ALON formed by reacting $Al_{2}O_{3}$ with AlN up to $1700^{\circ}C$ and the secondary phases such as ${\gamma}$-ALON ($9Al_{2}O_{3}$.AlN)and $\Phi$($5Al_{2}O_{3}$.AlN) phase above $1750^{\circ}C$ The thermal conductivity of $Al_{2}O_{3}$ containing 20 and 25 mol% AlN showed maximum value at $1800^{\circ}C$ Both $\alpha$-$Al_{2}O_{3}$ and ALON existed up to $1600^{\circ}C$ value at $1800^{\circ}C$ Both $\alpha$-$Al_{2}O_{3}$ and ALON existed up to $1600^{\circ}C$ while only AlON phase existed above $1650^{\circ}C$.

  • PDF

Effects of Amorphous Si3N4 Phase on the Mechanical Properties of Ti-Al-Si-N Nanocomposite Films Prepared by a Hybrid Deposition System (하이브리드 증착 시스템에 의해 합성된 나노복합체 Ti-Al-Si-N 박막 내 존재하는 Si3N4 비정질상이 기계적 특성에 미치는 영향)

  • An, Eun-Sol;Jang, Jae-Ho;Park, In-Uk;Jeong, U-Chang;Kim, Gwang-Ho;Park, Yong-Ho
    • Proceedings of the Korean Institute of Surface Engineering Conference
    • /
    • 2014.11a
    • /
    • pp.304-304
    • /
    • 2014
  • Quaternary Ti-Al-Si-N films were deposited on WC-Co substrates by a hybrid deposition system of arc ion plating (AIP) method for Ti-Al source and DC magnetron sputtering technique for Si incorporation. The synthesized Ti-Al-Si-N films were revealed to be composites of solid-solution (Ti,Al)N crystallites and amorphous $Si_3N_4$ by instrumental analyses. The Si addition in Ti-Al-N films affected the refinement and uniform distribution of crystallites by percolation phenomenon of amorphous silicon nitride, similarly to Si effect in TiN film. As the Si content increased up to about 9 at.%, the hardness of Ti-Al-N film steeply increased from 30 GPa to about 50 GPa. The highest microhardness value (~50 GPa) was obtained from the Ti-Al-Si-N film having the Si content of 9 at.%, the microstructure of which was characterized by a nanocomposite of $nc-(Ti,Al)N/a-Si_3N_4$.

  • PDF