• 한국분말재료학회지
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• 제22권3호
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• pp.208-215
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• 2015

Fe-TiC composite powders were fabricated by planetary ball mill processing. Two kinds of powder mixtures were prepared from the starting materials of (a) (Fe, TiC) powders and (b) (Fe, $TiH_2$, Carbon) powders, respectively. Milling speed (300, 500 and 700 rpm) and time (1, 2, and 3 h) were varied. For (Fe, $TiH_2$, Carbon) powders, an in situ reaction synthesis of TiC after the planetary ball mill processing was added to obtain a homogeneous distribution of ultrafine TiC particulates in Fe matrix. Powder characteristics such as particle size, size distribution, shape, and mixing homogeneity were investigated.

• 한국세라믹학회지
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• 제56권2호
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• pp.205-210
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• 2019

Bioactive glass (BG) finds limited use as a bone replacement material owing to its low mechanical properties. In order to solve this problem, the micro-sized 13-93 BG was prepared as a fabric composite with SiC microfibers, and its mechanical properties and biocompatibility were investigated in this study. The tensile strengths of BG-SiC fiber-bundle composites increased in proportion to the number of SiC fibers. In particular, even when only one SiC fiber was substituted, the tensile strength increased by 81% to 1428 MPa. In the early stage of the in-vitro test, a silica-rich layer was formed on the surface of the 13-93 BG fibers. With time, calcium phosphate grew on the silica-rich layer and the BG fibers were delaminated. On the other hand, no products were observed on the SiC fibers for 7 days, therefore, SiC fibers are expected to maintain their strength even after transplantation in the body.

• 공업화학
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• 제27권5호
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• pp.508-511
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• 2016

재활용이 가능한 자원인 MFB를 출발 물질로 하여 AMCA의 합성을 진행하였으며, AMBA로부터 AMCA로의 최적의 상업화 합성 조건을 찾고자 촉매, 수소 압력, 반응 온도, 반응 시간 같은 공정 변수를 조사하였다. 최적의 조건은 촉매는 [5% Pd/C : 5% Pt/C : 5% Rh/C (1 : 1 : 1)]의 복합 촉매를 반응 시간은 8 h, 반응 온도는 $130^{\circ}C$, 압력은 30 bar일 때(수율 90%, 순도 99.9%)임을 확인하였다.

• 한국주조공학회지
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• 제13권4호
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• pp.350-358
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• 1993

Aluminum base composites reinforced with various amount of SiC particles and Mg contents have been investigated by different fabrication method for twenty-years. In this paper, how the decomposition and dissolution behaviors of $SiCp(20{\mu}m)$ in the melt of Al composites arised was studied. As the results, the decomposition and dissolution of SiCp into the melt of Al composites increased with increase of the temperature above $720^{\circ}C$, and holding time at a given melting temperature. Because SiC is thermodynamically unstable in this Al-SiCp composite at temperature above the liquidus, SiCp dissolves and reacts with Al in matrix to form $Al_4C_3$ according to following chemical equation $4Al+3SiC{\rightarrow}Al_4C_3+3Si$, Si decomposed and dissolved from SiCp increases Si content of matrix, while liquidus temperature of matrix decrease with increase of SiC content in matrix. The hardness of SiCp decreased with increase of the melting temperature, the hardness of the matrix /particle interface increased with increase of the melting temperature due to increase of the $Mg_2Si$ and $Al_4C_3$ intermetallic compounds, etc.

• 한국세라믹학회지
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• 제50권6호
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• pp.378-383
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• 2013

Continuous fiber-reinforced ceramic matrix composites (CFCCs) have a complex distribution of porosity, consisting of interfiber micro pores and interbundle/interply macro pores. Owing to the complex geometry of the pores and fiber architecture, it is difficult to obtain representative microstructural features throughout the specimen volume with conventional, destructive ceramographic approaches. In this study, we introduce X-ray computed microtomography (X-ray ${\mu}CT$) to nondestructively analyze the microstructures of disk shaped and tubular $SiC_f$/SiC composites fabricated by the chemical vapor infiltration (CVI) method. The disk specimen made by stacking plain-woven SiC fabrics exhibited periodic, large fluctuation of porosity in the stacking direction but much less variation of porosity perpendicular to the fabric planes. The X-ray ${\mu}CT$ evaluation of the microstructure was also effectively utilized to improve the fabrication process of the triple-layered tubular SiC composite.

• 대한전기학회논문지:전기물성ㆍ응용부문C
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• 제53권5호
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• pp.242-242
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• 2004

The composites were fabricated 61 vol.%α-α-SiC and 39vol.% WC powders with the liquid forming additives of 12wt% Al₂O₃＋Y₂O₃ by pressureless annealing at 1700, 1800, 1900℃ for 4 hours. The result of phase analysis of composites by XRD revealed α-SiC(2H), WC, and YAG($Al_5Y_3O_{12}$) crystal phase. The relative density, the flexural strength, fracture toughness and Young′s modulus showed respectively the highest value of 99.4%, 375.76㎫, 5.79㎫ㆍ$m^{\frac{1}{2}}$, and 106.43㎬ for composite by pressureless annealing temperature 1900℃ at room temperature. The electrical resistivity showed the lowest value of 1.47×$10^{-3}$/Ω·㎝ for composite by pressureless annealing temperature 1900℃ at 25℃. The electrical resistivity of the α-SiC-WC composites was all positive temperature cofficient resistance (PTCR) in the temperature ranges from 25℃ to 500℃.

• 한국윤활학회:학술대회논문집
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• 한국윤활학회 2002년도 proceedings of the second asia international conference on tribology
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• pp.145-146
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• 2002

Tribological properties of co-sputtered Molybdenum disulfide $(MoS_2)/Carbon\;(C)$ films were studied and compared with those of sputtered $MoS_2$ films. Friction tests were carried out using pin-on-disk friction testers to evluated their friction and wear behaviors in a vacuum ($10^{-5}Pa$), air and humid air of 30, 50, 80% RH. $MoS_2/C$ (14%) composite films exhibited about 9 times longer wear life in a vacuum and about 6 times longer wear life in dry air than $MoS_2$ films did. They also showed stable low friction coefficient of about 0.02 in a vacuum. In humid air, however, $MoS_2/C$ composite films hardly showed good tribological properties.

• 한국세라믹학회지
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• 제52권4호
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• pp.234-236
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• 2015

$Y_2O_3$-SiC composite membrane was dip-coated using $Y_2O_3$ sol solution; this membrane was compared with a non- coated one. Each membrane was characterized by XRD, FE-SEM and BET techniques. Hydrogen and CO permeation were tested with self-manufactured Sievert's type equipment. $Y_2O_3$ coating was enhanced for the selectivity of the membrane ($H_2$ versus CO). The hydrogen permeation was measured at 1 bar with increasing temperatures. In case of the coated membrane, hydrogen permeation was found to be $1.24{\times}10^{-7}mol/m^2sPa$ with perm-selectivity of 4.26 at 323 K.

• 한국세라믹학회지
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• 제32권3호
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• pp.349-358
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• 1995

The ceramic composite membrane was synthesized by thermal oxidation after evaporation of Al on the support prepared by slip casting process. Oxidation was performed at $700^{\circ}C$ and 80$0^{\circ}C$ under dry oxygen atmosphere. It was considered as optimum oxidation condition that the membrane showed a knudsen behaviro. A further oxidation resulted in an increase of gas permeability because top layer became densified. Then, a multi-layered composite membrane was synthesized through a sol-gel method, evaporation and thermal oxidation of Al coating processes. While the membrane was thermally stable up to 80$0^{\circ}C$, gas permeability was rapidly decreased even at a slight amount of deposition of Al.

• 한국세라믹학회지
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• 제36권10호
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• pp.1080-1086
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• 1999

Mullite/zirconia composite was synthesized by adding zirconia and Zircon to mixture of Hapcheon kaolin(grade pink A) and aluminium nitrate salt in order to enhance strength of the mullite specimens. Kaolin and aluminium nitrate salt was mixed milled and calcined at 100$0^{\circ}C$ and then 5wt% mullite seed was added to increase mullite content. The influence of the additives(ZrO2 and ZrSiO4) and sintering temperature on the strength of the sintered specimens was investigated. The flexural strength of the specimens containing 10wt% zirconia was enhanced from 150MPa without the additive up to 300MPa after heat treatment at 156$0^{\circ}C$ In the case of addition of 15wt% zircon the strength of the specimens systhesized at 1$600^{\circ}C$ was 225 MPa.