• 한국세라믹학회지
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• 제34권8호
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• pp.908-913
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• 1997

Multilayer NbCxC1-x/Y2O3/Ti were sputter-coated on the alumina substrate, starting with a 0.7 ㎛ thick NbCxC1-x layer grown on substrate, followed by 0.7 ㎛ thick Y2O3 layer and 1 ㎛ thick Ti layer. To find out the optimum conditions for thickness uniformity and adhesion, sputtering works have been done with the variation of sputtering power and Ar pressure. After vacuum annealing at 950℃ and 1000℃, the thermal stability of the NbCxC1-x/Y2O3/Ti coated alumina substrates has been investigated by peel off test. The coating scheme didn't cause any debonded layer after an annealing at 950℃ for 3hrs. However, it was peeled off after annealing at 1000℃ for 3hr. It was found that the thermal stability of Al2O3/NbCxC1-x/Y2O3/Ti coating scheme changed with the NbCxC1-x composition.

• 한국세라믹학회지
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• 제26권3호
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• pp.409-415
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• 1989

Si3N4-TiN electro-conductive ceramic composites with 7wt% Al2O3＋3wt% Y2O3 or 5wt% MgO as sintering aids were fabricated by pressureless sintering at 1,80$0^{\circ}C$ for 1h. The 3pt. flexural strength, KIC and Vickers hardness were measrued in order to investigate the effects of TiN on the mechanical properties. Also oxidation behavior was observed by measuring the weight gain after exposure to air at 1,10$0^{\circ}C$ for 100h. the reaction products between Si3N4 and TiN was not detected by XRD and EDS. Mechanical properties of the composites were not influenced by the addition of TiN less than 30vol%, but oxidation resistance of the composites was rapidly decreased with the amount of added TiN.

• 한국재료학회지
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• 제9권3호
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• pp.315-321
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• 1999

금속기지 복합물은 구조용 재료로서 매우 우수한 성질을 지니고 있어 광범위하게 연구되어져 왔다. $Al_2O_3$와 SiC는 그들의 우수한 기계적 특성 때문에 일반적인 보강재로서 사용되어져 왔다. 그러나 이들 세라믹 보강재는 비싼 재조 비용 때문에 특별한 목적을 위해서만 한정되어 사용되어져 왔다. 본 연구에서는 우리는 Al 합금기지 복합물에서 SHS법에 의해 합성된 $Al_2O_3$-SiC 분말의 보강재로서의 응용 가능성을 살펴보았다. 또한 $Al_2O_3$단섬유를 Al기지 하이브리드 복합물에 적용하기 위하여 합성된 분말과 함께 첨가하였다. 25vol% 강화재의 복합물을 제조하기 위하여 용탕단조법을 사용하였다. 미세구조와 결정구조는 SEM, OM 그리고 XRD로 관찰하였고 압축시험과 마모시험으로 기계적인 성질들을 조사하였다.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2002년도 추계학술대회 논문집 전기물성,응용부문
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• pp.106-108
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• 2002

The composites were fabricated 61vol.% $\beta-SiC$ and 39vol.% $TiB_2$ powders with the liquid forming additives of l2wt% $Al_2O_3+Y_2O_3$ by pressureless annealing at $1700^{\circ}C,\;1750^{\circ}C,\;1800^{\circ}C$ for 4 hours respectively. The result of Phase analysis of composites by XRD revealed $\alpha-SiC$(6H), $TiB_2$, and YAG($Al_5Y_3O_{12}$) crystal phase. The relative density and the Young's modulus showed the highest value of 92.9701% and 92.884Gpa for composites by pressureless annealing temperature $1700^{\circ}C$ at room temperature.

• 대한금속재료학회지
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• 제47권8호
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• pp.508-515
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• 2009

Ti-6Al-4V biomaterial is widely used as a bone alternative. However, Ti-6Al-4V ELI alloy suffers from numerous problems such as a high elastic modulus and high toxicity. Therefore, non-toxic biomaterials with low elastic moduli need to be developed. Ti-HA(hydroxyapatite) composites were fabricated in the present work by pulsed current activated sintering (PCAS) at $1000^{\circ}C$ under 60 MPa using mixed Ti and HA powders. The effects of HA content on the physical and mechanical properties of the sintered Ti-HA composites have been investigated. X-ray diffraction(XRD) analysis of the Ti-HA composites, including Ti-40 wt%HA in particular, revealed new phases, $Ti_{2}O$, CaO, $CaTiO_3$, and TixPy, formed by chemical reactions between Ti and HA during sintering. The hardness of the Ti-HA composites decreased with an increase in HA content. The corrosion resistance of these composites was observed to be an excellent candidate as a commercial Ti-6Al-4 V ELI alloy. A Ti-5 wt%HA composite fabricated by PCAS is recommended as a new biomaterial, because it offers good corrosion resistance, compressive strength, wear resistance, and biocompatibility, and a low Young's modulus.

• 한국세라믹학회지
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• 제40권8호
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• pp.751-757
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• 2003

10 wt% A1$_2$O$_3$-Y$_2$O$_3$-CaO를 첨가한 SiC-30 wt% TiC 분말을 스파크 플라즈마 소결(SPS) 방법을 사용하여 급속 치밀화 하였다. SPS 공정은 매우 빠른 승온 속도와 짧은 시간에 완전 치밀한 시편을 얻을 수 있다. 본 실험에서, 승온 속도와 압력은 $100^{\circ}C$/min과 40MPa이고, 소결 온도 범위는$1600^{\circ}C$~$1800^{\circ}C$이었으며, 10min 동한 유지하였다. $Al_2$O$_3$, $Y_2$O$_3$ 및 CaO를 첨가한 SiC-30 wt% TiC 복합체는 $1700^{\circ}C$ 이상 온도에서 스파크 플라즈마 소결 방법으로 완전 치밀화가 이루어졌다. 모든 SPS 공정 온도에서 탄화큐소으 상전이나 YAG 결정상의 형성 없이 3C-SiC와 TiC 만이 XRD에서 나타났다. 급속 소결한 SiC-30 wt% TiC 복합체의 미세구조는 비교적 작은 등축상 SiC 결정립과 비교적 큰 TiC 결정립으로 구성되었다. $1750^{\circ}C$에서 제조한 시편의 이축강도능 635.2MPa이고, 파괴인성은 6.12 MPaㆍ$m^{1/2}$이었다.

• 한국세라믹학회지
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• 제35권10호
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• pp.1061-1069
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• 1998

The thermal instability of Al2TiO5 Ceramics was contrlled by solid solution with MgO SiO2 and ZrO2 through electrofusion in an arc furnace. The thermal expansion properties of Al2TiO5 composites show the hysteresis due to the strong anisotropy of The crystal axes of these material. These phenomena are ex-plained by the opening and closing of microcracks. The difference in microcracking temperatures e.g 587.6(ATG2), 405.9(ATG3) and 519.7$^{\circ}C$(ATG4) is caused by the difference in grain size and stabilizer type. The thermal shock behaviour under cyclic conditions between 750-1400-75$0^{\circ}C$ show no change in mi-crostructure and phase assemblage for all three stabilized specimens. After the thermal loading test at 110$0^{\circ}C$ for 100hrs. ATG1 and ATG2 materials decomposes completely to its components corundum and ru-tile in both cases. However with approximatelly 20% retention of the Al2TiO5 Thus in order to prevent decomposition of the stabilized material in the critical temperature range 800-130$0^{\circ}C$ it must be traversed within a short period of time.

• 한국결정성장학회지
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• 제8권4호
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• pp.626-633
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• 1998

본 연구에서는 고유전율의 저온소성용 글라스/세라믹을 제조하고자, SiO2-TiO2-RO계 결정화 유리를 제조하고 Al2O3를 필러 물질로 혼합하여 복합체를 제조하고 그 특성을 관찰하였다. 본 유리조성으로써 $900^{\circ}C$ 이하에서 결정화되는 유리의 제조가 가능하였고, RO (BaO, CaO, SrO)의 성분에 따라 결정화 온도는 변화함을 알 수 있었다. 본 유리조성에 $Bi_2O_3$를 플럭스로 첨가하고, 세라믹 필러로써 Al2O3를 사용하여 $860^{\circ}C$에서 소성함으로써 고유전율의 저온소성용 글라스/세라믹의 제조가 가능하였고, 이때 복합체의 밀도는 3.96g/$\textrm{cm}^3$ 이었고, 유전율은 17, Q.f 값은 600이었다.

• Journal of Welding and Joining
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• 제18권5호
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• pp.98-104
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• 2000

Aluminum alloys are being employed in automobile parts as strive to reduce overall vehicle weight to meet demands for improved fuel economy and reduction in vehicle emissions. Al-based composites reinforced with ceramic ($Al_2O_3,\;SiC,\;TiC\;and\;B_4C$) applications in a variety of components in automotive engines, such as liners, where the tribological properties of the material are important. In this study, Al-base composites reinforced with TiC particle powders has been developed for producing plasma spray coatings. The composite plasma spray powders were prepared Al-13Si-3Mg(wt%) alloy with TiC(40, 60 and 80wt%) particles ($0.2~5{\mu}textrm{m}$) by drum type ball milling. The composite powders ($36~76{\mu}textrm{m}$) were sprayed with plasma torch. Plasma sprayed coatings were heat-treated at $500^{\circ}C$ for 3 hours. The wear resistances of the plasma sprayed coatings were found to decrease with increasing TiC content and improved with heat treatment. AlSiMg-40% TiC heat-treated coatings were showed the best wear resistance in this study.

• The Korean Journal of Ceramics
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• 제5권4호
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• pp.317-323
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• 1999

Si3N4-TiC composites have been known as electrically conductive ceramics. $Si_3N_4-TiC$ composites with 2 wt% $Al_2O_3$ and 4 wt% $Y_2O_3$ were hot pressed in $N_2$ environment. The mechanical properties including hardness, fracture toughness, and flexural strength and tribological properties were investigated as a function of TiC content. $Si_3N_4-40$ vol% TiC composite was hot pressed at $1,750^{\circ}C$, $1,800^{\circ}C$, and $1,850^{\circ}C$ for 1, 3 and 5 hours in $N_2$ gas. Mechanical and tribolgical properties depended on microstructures, which were controlled by hte TiC content, hot press temperature, and hot press holding time. However, mechanical properties and tribological behaviors were degraded by the chemical reaction between TiC and N. The chemically reacted products such as TiCN, SiC, and $SiO_2$ were detered by the X-ray diffraction analysis.