• 대한전기학회논문지:전기물성ㆍ응용부문C
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• 제50권11호
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• pp.544-549
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• 2001

The mechanical and electrical properties of the hot-pressed and pressureless annealed SiC-39vo1.%TiB$_2$electroconductive ceramic composites were investigated as functions of the liquid additives of $Al_2O_3+Y_2O_3$ and the sintering temperature. The result of phase analysis for the SiC-39vo1.%TiB$_2$ composites by XRD revealed $\alpha -SiC(6H),\; TiB_2,\; and YAG(Al_5Y_3O_{12})$ crystal phase. The relative density of SiC-39vo1.% $TiB_2$ composites was increased with increased $Al_2O_3+Y_2O_3$ contents. The fracture toughness showed the highest value of $7.8 MPa.m_{1/2}$ for composites added with 12 wt% $Al_2O_3+Y_2O_3$additives at $1750^{\circk}C$. The electrical resistivity of the SiC-39vo1.%$TiB_2$composites was all positive temperature coefficient resistance(PTCR) in the temperature range of $25S^{\circ}C \;to\; 700^{\circ}C$.

• 한국세라믹학회지
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• 제32권1호
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• pp.11-16
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• 1995

High reaction heat evolved from the oxidation of Al was used to synthesize SiC, which might be difficult to be formed by SHS. Al2O3-SiC composite powder was easily manufactured using KNO3 as an ignition and reaction catalyst. Unreacted Si and C were observed after reaction dependent upon the composition of starting powders, reaction atmosphere and relative densities of compacted bodies. The unreacted carbon could be removed by calcining at $600^{\circ}C$ and the remaining Si could be removed by dissolving in NaOH solution. The final powder particles were smaller than 1${\mu}{\textrm}{m}$ in size.

• 한국세라믹학회지
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• 제27권5호
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• pp.583-588
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• 1990

Glass films in the binary system B2O3-SiO2 and Al2O3-SiO2 were prepared on soda-lime-silica slide glass by the dip-coating technique from TEOS and boric acid or aluminum nitrate. Thickness of the films varying with viscosity and withdrawal speed were measured and effect of composition and firing temperature on the properties such as transmittance and refractive index were investigated. nM2O3.(100-n)SiO2(M=B or Al) films containing up to 20mol% B2O3 and 40mol% Al2O3 were transparent. Maximum transmittance at visible range were obtained for the sample containing 15mol% Ba2O3 and 32.5mol% Al2O3 and heat-treated at 50$0^{\circ}C$, respectively. Refractive index of the film containing 15mol% B2O3 was mininum in the B2O3-SiO2 binary system and minimal refractive index was appeared at the film containing 32.5mol% Al2O3. In IP spectra, addition of B2O3 were increased absorption peak intensity of B-O and Si-O-B bond and addition of Al2O3 were decreased absorption peak intensity of Si-O bond, respectively.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1998년도 추계학술대회 논문집 학회본부 C
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• pp.847-849
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• 1998

The effect of $Al_{2}O_{3}$ additives on the microstructure, mechanical and electrical properties of ${\beta}$-SiC+39vol.%$ZrB_2$ electroconductive ceramic composites by pressureless sintering were investigated. The ${\beta}$-SiC+39vol.%$ZrB_2$ ceramic composites were pressureless sintered by adding 4, 8, 12wt.% $Al_{2}O_{3}$ powder as a liquid forming additives at $1950^{\circ}C$ for 1h. Phase analysis of composites by XRD revealed mostly of $\alpha$-SiC(6H), $ZrB_2$ and weakly $\alpha$-SiC(4H), $\beta$-SiC(15R) phase. The relative density of composites was lowered by gaseous products of the result of reaction between $\beta$-SiC and $Al_{2}O_{3}$ therefore, porosity was increased with increased $Al_{2}O_{3}$ contents. The fracture toughness of composites was decreased with increased $Al_{2}O_{3}$ contents, and showed the maximum value of $1.4197MPa{\cdot}m^{1/2}$ for composite added with 4wt.% $Al_{2}O_{3}$ additives. The electrical resistivity of ${\beta}$-SiC+39vol.%$ZrB_2$ electroconductive ceramic composite was increased with increased $Al_{2}O_{3}$ contents, and showed positive temperature coefficient resistance (PTCR) in the temperature from $25^{\circ}C$ to $700^{\circ}C$.

• 한국분말재료학회지
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• 제14권6호
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• pp.354-361
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• 2007

The bi-materials with Al-Mg alloy and its composites reinforced with SiC and $Al_2O_3$ particles were prepared by conventional powder metallurgy method. The A1-5 wt%Mg and composite mixtures were compacted under $150{\sim}450\;MPa$, and then the mixtures compacted under 400 MPa were sintered at $773{\sim}1173K$ for 5h. The obtained bi-materials with Al-Mg/SiCp composite showed the higher relative density than those with $Al-Mg/Al_2O_3$ composite after compaction and sintering. Based on the results, the bi-materials compacted under 400 MPa and sintered at 873K for 5h were used for mechanical tests. In the composite side of bi-materials, the SiC particles were densely distributed compared to the $Al_2O_3$ particles. The bi-materials with Al-Mg/SiC composite showed the higher micro-hardness than those with $Al-Mg/Al_2O_3$ composite. The mechanical properties were evaluated by the compressive test. The bi-materials revealed almost the same value of 0.2% proof stress with Al-Mg alloy. Their compressive strength was lower than that of Al-Mg alloy. Moreover, impact absorbed energy of bi-materials was smaller than that of composite. However, the bi-materials with Al-Mg/SiCp composite particularly showed almost similar impact absorbed energy to $Al-Mg/Al_2O_3$ composite. From the observation of microstructure, it was deduced that the bi-materials was preferentially fractured through micro-interface between matrix and composite in the vicinity of macro-interface.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1999년도 하계학술대회 논문집 D
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• pp.1913-1915
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• 1999

The ${\beta}-SiC+ZrB_2$ ceramic composites were hot-press sintered and annealed by adding 1, 2, 3wt% $Al_2O_3+Y_2O_3$(6 : 4wt%) powder as a liquid forming additives at $1950^{\circ}C$ for 4h. In this microstructures, no reactions were observed between $\beta$-SiC and $ZrB_2$, and the relative density is over 90.79% of the theoretical density and the porosity decreased with increasing $Al_2O_3+Y_2O_3$ contents. Phase analysis of the composites by XRD revealed of $\alpha$-SiC(6H, 4H), $ZrB_2$, $Al_2O_3$ and $\beta$-SiC(15R). Flexural strength showed the highest of 315.46MPa for composites added with 3wt% $Al_2O_3+Y_2O_3$ additives at room temperature. Owing to crack deflection and crack bridging of fracture toughness mechanism, the fracture toughness showed the highest of $5.5328MPa{\cdot}m^{1/2}$ for composites added with 2wt% $Al_2O_3+Y_2O_3$ additives at room temperature.

• 한국세라믹학회지
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• 제26권2호
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• pp.167-170
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• 1989

Al2O3/SiC composite-material was synthesized by the birth-spread mechanism through the carbothermal reduction reaction of SiO2 in Ha-Dong Kaolin with carbon powder under H2 gas atmosphere at 1300~140$0^{\circ}C$. Average diameter of synthesized SiC whiskers were 1${\mu}{\textrm}{m}$ and aspect ratio (c/a) was 10~100. Al2O3 particles and SiC whiskers were mixed homogeneously in the reacted pellet.

• 전기전자학회논문지
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• 제22권4호
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• pp.1230-1233
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• 2018

에어로졸 데포지션 (aerosol deposition)공정을 통해 $Al_2O_3$막을 4H-SiC 상에 50 nm 두께로 제조하였고, 후열처리 공정에 따른 전기적 특성을 분석하였다. 그 결과 $N_2$분위기 열처리 시 $Al_2O_3$와 SiC 계면의 고정전하량이 감소하였으나 산소공공 생성에 의한 누설전류의 증가를 확인하였다. 본 결과로부터 계면특성 향상과 누설전류의 감소를 위해서는 적절한 $N_2$와 $O_2$가스의 혼합이 중요함을 확인하였다.

• 한국세라믹학회:학술대회논문집
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• 한국세라믹학회 2000년도 추계총회,초청강연,특별강연,연구발표회
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• pp.165.2-165
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• 2000

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2007년도 하계학술대회 논문집 Vol.8
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• pp.333-334
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• 2007

This paper describes the characteristics of poly (polycrystalline) 3C-SiC grown on SiOz and AlN substrates, respectively. The crystalline quality of poly 3C-SiC was improved from resulting in decrease of FWHM (full width half maximum) of XRD by increasing the growth temperature. The minimum growth temperature of poly 3C-SiC was $1100^{\circ}C$. The surface chemical composition and the electron mobility of poly 3C-SiC grown on each substrate were investigated by XPS and Hall Effect, respectively. The chemical compositions of surface of poly 3C-SiC films grown on $SiO_2$ and AlN were not different. However, their electron mobilities were $7.65\;cm^2/V.s$ and $14.8\;cm^2/V.s$, respectively. Therefore, since the electron mobility of poly 3C-SiC films grown on AlN buffer layer was two times higher than that of 3C-SiC/$SiO_2$, a AlN film is a suitable material, as buffer layer, for the growth of poly 3C-SiC thin films with excellent properties for M/NEMS applications.