• 한국분말야금학회:학술대회논문집
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• 한국분말야금학회 2006년도 Extended Abstracts of 2006 POWDER METALLURGY World Congress Part2
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• pp.912-912
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• 2006

• 대한치과기공학회지
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• 제23권2호
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• pp.161-170
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• 2002

The Purpose of this study was to investigate the chemically improvement of metal-ceramics bond strength in the course of recasting Ni-Cr metal composite system with 10wt.%, 20wt.% and 30wt.% aluminum respectively. We have tested the bond strength, micro-structure, chemical composition of each metal composites and metal- ceramic bond interfaces by 3-point bending strength tester, SEM and EDS. We have made the conclusions through this study as follow: 1. The most suitable amount of aluminum to the Ni-Cr metal composite recasting is 20wt. % for improving metal-ceramics bond strength with debonding strength value of 49.54 kgf/mm2. 2. The aluminum must be changed to small spread alumina like phases and second aluminum-metal composites phases in the morphology of Ni-Cr metal composite system by adding during it's casting. These second phases have inclined functional oxide phases mixed with metal elements and they must take roll to improvement of metal-ceramics bond strength. 3. In the case of 30wt.% aluminum appended to Ni-Cr metal composite system, an excess of second inclined functional oxide phases produce cracks and spalling of them apart from it's base material. It must be a important factor of reduction of metal-ceramics bond strength.

• 대한치과보철학회지
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• 제45권3호
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• pp.295-302
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• 2007

Statement of problem. Fracture of the tooth-colored superstructure material is one of the main prosthetic complications in implant-supported prostheses. Purpose. The purpose of this in vitro study was to compare the fracture strength between the cement-retained implant-supported metal-ceramic crowns and the indirect composite resinveneered metal crowns under the vertical compressive load. Material and methods. Standard implants of external type (AVANA IFR 415 Pre-mount; Osstem Co., Busan, Korea) were embedded in stainless steel blocks perpendicular to their long axis. Customized abutments were fabricated using plastic UCLA abutments (Esthetic plastic cylinder; Osstem Co., Busan, Korea). Thirty standardized copings were cast with non-precious metal (Rexillium III, Pentron, Walling ford, Conn., USA). Copings were divided into two groups of 15 specimens each (n = 15). For Group I specimens, metal-ceramic crowns were fabricated. For Group II specimens, composite resin-veneered (Sinfony, 3M-ESPE, St. Paul, MN, USA) metal crowns (Sinfony-veneered crowns) were fabricated according to manufacturer's instructions. All crowns were temporary cemented and vertically loaded with an Instron universal testing machine (Instron 3366, Instron Corp., Norwood, MA, USA). The maximum load value (N) at the moment of complete failure was recorded and all data were statistically analyzed by independent sample t-test at the significance level of 0.05. The modes of failure were also investigated with visual analysis. Results. The fracture strength of Sinfony-veneered crowns ($2292.7{\pm}576.0N$) was significantly greater than that of metal-ceramic crowns ($1150.6{\pm}268.2N$) (P < 0.05). With regard to the failure mode, Sinfony-veneered crowns exhibited adhesive failure, while metal-ceramic crowns tended to fracture in a manner that resulted in combined failure. Conclusion. Sinfony-veneered crowns demonstrated a significantly higher fracture strength than that of metal-ceramic crowns in cement-retained implant-supported prostheses.

• 한국분말야금학회:학술대회논문집
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• 한국분말야금학회 2006년도 Extended Abstracts of 2006 POWDER METALLURGY World Congress Part2
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• pp.850-850
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• 2006

• 한국복합재료학회:학술대회논문집
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• 한국복합재료학회 2005년도 추계학술발표대회 논문집
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• pp.66-69
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• 2005

Mechanical strength of functionally graded composite plates that composed of ceramic, functionally graded material and metal layers is investigated using 3-D finite element method. In FGM layer, material properties are assumed to be varied continuously in the thickness direction according to a simple power law distribution in terms of the volume fraction of a ceramic and metal. The 3-D finite element model is adopted by using an IS-node solid element to analyze more accurately the variation of material properties in the thickness direction. Numerical results are compared with those of the previous works. In addition, the displacements, the tensile stresses and the compressive stresses are analyzed for the variation of FGM thickness ratio and volume fraction distribution.Mechanical strength of functionally graded composite plates that composed of ceramic, functionally graded material and metal layers is investigated using 3-D finite element method. In FGM layer, material properties are assumed to be varied continuously in the thickness direction according to a simple power law distribution in terms of the volume fraction of a ceramic and metal. The 3-D finite element model is adopted by using an IS-node solid element to analyze more accurately the variation of material properties in the thickness direction. Numerical results are compared with those of the previous works. In addition, the displacements, the tensile stresses and the compressive stresses are analyzed for the variation of FGM thickness ratio and volume fraction distribution.

• 한국복합재료학회:학술대회논문집
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• 한국복합재료학회 2001년도 추계학술발표대회 논문집
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• pp.144-148
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• 2001

A proper estimation of the mechanical properties for composites has been required for better design/selection of constituents for composite materials. Present investigation shows the simulation results for ceramic reinforced metal matrix composite under uniaxial transverse tensile loading. The resulting transverse mean stress with the transverse mean strain was described for composites as a function of the volume fraction with two different types of interfacial bonding: (1)strongly bonded interface, and (2)no bonded interface. A two-dimensional finite element modeling and analysis were conducted based on the unit-cell concept with an assumption of a regular square arrangement of the reinforcement within the composite. The mean stress was generally increased with the ceramic volume fraction for composite with strong interface bonding. The micromechanics concept combined with finite element modeling for composite can be used in order to predict the transverse properties of composites with a priori known properties of constituents.

• 한국세라믹학회지
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• 제49권4호
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• pp.369-374
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• 2012

Based on the structure feature of a tree, a cylindrical $Ti_2AlC$/graphite layered composite has been fabricated through heat treating a graphite column and six close-matched thin wall $Ti_2AlC$ cylinders bonded with the $Ti_2AlC$ powders at $1300^{\circ}C$ and low oxygen partial pressure. SEM examination reveals that the bond interlayers between cylinders or that between cylinder and column are not fully dense without any crack formation. During the compressive test, the strain of the $Ti_2AlC$/graphite layered composite is about twice higher than that of the monolithic $Ti_2AlC$ ceramic, and the compressive strength of the layered composite is 348 MPa. The layered composite show the noncatastrophic fracture behaviors due to the debonding and shelling off of the layers, which are different from the monolithic $Ti_2AlC$ ceramic. The mechanism of the improved deformation capacity and noncatastrophic failure modes are attributed to the presence of the central soft graphite column and cracks deflection by the bond interlayers.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2002년도 추계학술대회 논문집 Vol.15
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• pp.79-82
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• 2002

In this paper, a single phase driven piezoelectric motor design was presented for linear motion. Two metal/ceramic composite actuators, a piezoelectric ring which was bonded to a metal endcap from one side, were used as the active elements of this motor. The motor was composed of a piezoelectric ceramic, a metal ring which has 4 arms, and a guider. Motors with 30.0[mm] and 35.0[mm] diameter were studied by finite element analysis and experiments. As results, the maximum speed of motor was obtained at resonant frequency. When the applied voltage of the motor increased, the speed was increased. Also, bidirectional motion of the motor was achieved by combining two motors which have different resonant frequency.

• 대한치과보철학회지
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• 제52권3호
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• pp.202-210
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• 2014

목적: 이 연구의 목적은 abfraction병소가 있는 금속도재관수복 치아를 수복하거나 하지 않을 때 나타나는 응력집중과 분포를 유한요소분석으로 평가하는 것이다. 재료 및 방법: 상악 제1 소구치를 선정하여 총 10개의 유한요소모델을 만들었다. 모델 1은 자연치; 모델 2는 협측과구개측 백악법랑경계 상방 2 mm에 변연이 위치한 금속도재관; 모델 3은 협측과구개측 백악법랑경계에 변연이 위치한 금속도재관; 모델 4는 abfraction병소를 가진 자연치; 모델 5와 6은 다른 조건은 각각 모델 2와 3과 동일하면서 abfraction병소를 가진 치아; 모델 7은 abfraction병소를 가지고 composite resin으로 수복된 자연치;모델 8과 9는 각각 모델 5와 6과 동일한 모델에 abfraction병소를 composite resin으로 수복한 후 금속도재관 장착한 치아; 모델 10은 composite resin으로 abfraction lesion을 수복하고 금속도재관의변연을 abfraction병소보다 하방에 위치시킨 치아였다. 위치를 서로 달리한 하중 load A와 load B를 가하여, 각 기준점에서의 von Mises stress값들을 측정하여 비교하였다. 결과: Abfraction병소가 있는 치아에 load A 또는 load B를 주었을 때, 응력은 lesion의 apex에 집중되었다. 반면, abfraction병소를 composite resin으로 충전한 치아에 load A 또는 load B를 주었을 때 응력값은 apex에서 감소하였다. 결론: Abfraction이 있는 치아는 복합 레진으로 수복해주는 것이 응력의 집중을 줄여서 병소의 예후에 유리한 것으로 나타났으며, Abfraction이 발생된 치아를 금속 도재관으로 수복할 경우 협측변연을 법랑질 상에 위치시키는 것이 유리하였다.

• 한국세라믹학회지
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• 제52권5호
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• pp.350-355
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• 2015

To develop ceramic composite anodes of solid oxide fuel cells without metal catalysts, a small amount of barium carbonate was added to an $(La_{0.8}Sr_{0.2})(Cr_{0.5}Mn_{0.5})O_3(LSCM)$ - YSZ ceramic composite anode and its catalytic effects on the electrode performance were investigated. A barium precursor solution with citric acid was used to synthesize the barium carbonate during ignition, while a barium precursor solution without citric acid was used to create hydrated barium hydroxide. The addition of barium carbonate to the ceramic composite anode caused stable fuel cell performance at 1073 K; this performance was higher than that of a fuel cell with $CeO_2$ catalyst; however, the addition of hydrated barium hydroxide to the ceramic composite anode caused poor stability of the fuel cell performance.