활성환경에서 세라믹 수복 재료의 파괴 거동

배태성,윤선중,배태성,이민호 대한치과재료학회 2022 대한치과재료학회지 Vol.49 No.3

금속 재료와 세라믹 재료에 인장응력이 작용할 때의 파괴 거동을 비교해보면, 금속 재료는 소성변형으로 인하여 외부의 형상이 변화된 후 파절이 일어나고 또한 재료 내의 결함에서 비롯한 균열의 진전속도가 매우 느리므로 미세 결함은 파절 거동에 크게 영향을 미치지 않는다. 반면 세라믹 재료는 취성이 있고 거의 소성변형이 일어나지 않으므로 재료 내의 가장 취약한 결함부의 균열선단에서 응력의 집중과 확대가 일어나고 이 확대된 응력이 파괴 한계를 초과하면 균열이 빠르게 진전하여 파괴가 일어나므로 미세 결함이 파괴에 크게 영향을 미친다. 따라서 세라믹 소결체(포세린, 글라스-세라믹, 알루미나, 지르코니아)의 파괴 특성 평가 시는 결함의 영향을 고려하는 파괴인성의 측정이 요구된다. 세라믹 소결체는 내수성이 뛰어나고 산이나 알카리에 의해서도 침식이 일어나지 어렵기 때문에 이들 환경에 장시간 노출된 경우에도 강도는 그다지 크게 저하되지 않는다. 하지만, 이러한 액상의 조건에서 인장응력이 작용하는 활성환경에서 는 응력부식에 의한 침식이 일어나므로 시간이 경과하며 강도가 저하하여 기대수명이 단축되는 문제가 발생한다. 활성환경에서 응력부식에 의한 균열성장이 일어나는 경우에 강도에 비하여 작용력의 수준이 낮은 경우에는 응력부식에 의한 균열성장이 느리므로 문제가 되지 않지만, 반대로 강도에 비하여 작용력의 수준이 높은 경우에는 균열속도가 빨라서 내구수명이 크게 저하될 수 있으므로 강도가 높은 수복재료의 사용이 요구된다.

치과용 열가압 성형 글라스-세라믹스의 파괴인성

배태성,원대희,이민호,최운재,문영윤 한국생체재료학회 2004 생체재료학회지 Vol.8 No.3

This study was performed to evaluate the fracture toughness of two pressable glass-ceramic materials : Empress 2 and an experimental glass-ceramic material. Ten discs per material were prepared. Fracture toughness was measured by indentation fracture method. Vickers-produced indentation crack was made using a Vickers hardness tester at a load of 49.0 N and dwell time of 15 sec. Radial crack propagation at interface glass-ceramic core region was examined. Fracture toughness of the Empress 2 and experimental glass-ceramic material, EGC, were 1.20 and 1.30 MPa톗1/2, respectively. The finest lath-shaped interlocking microstructures of lithium disilicate crystals were observed in the Empress 2 and EGC, but the crystal shape of EGC was shotter than Empress 2. Lateral chipping was rapidly propagated toward veneer porcelain at the interface between glass-ceramic core and veneer porcelain. The EGC showed no sign of delamination between the glass-ceramic core and veneer porcelain but the Empress 2 showed a sign of delamination.

지르코니아 세라믹의 물성에 미치는 표면특성과 치과 응용

배태성 한국표면공학회 2013 한국표면공학회 학술발표회 초록집 Vol.2013 No.5

치과용 저온 및 초저온 용융형 도재의 파괴 특성 평가

배태성 대한치과재료학회 2003 대한치과재료학회지 Vol.30 No.3

양극산화된 Ti-6Al-7Nb 합금의 표면특성에 미치는 전해용액의 영향

배태성,원대희,이민호,이오연,권오성 한국생체재료학회 2004 생체재료학회지 Vol.8 No.4

This study was to investigate the surface properties and in vitro biocompatibility of electrochemically oxidized Ti-6Al-7Nb alloy by anodic spark discharge technique. Anodizing was performed at current density 30 mA/cm2 up to 300 V in electrolyte solutions containing glycerophosphate cacium salt (GP-Ca) calcium acetate (CA). Hydrothermal treatment was done at 300oC for 2 hours to produce a thin outermost layer of hydroxyapatite (HA). The bioactivity was evaluated from HA formation on the surfaces in a Hanks' solution with pH 7.4 at 36.5oC for 30 days. Anodic oxide films were porous with pore size of 1~3 mm and 3~4 mm thickness. The size of micropores, the thickness of oxide film, and the values of surface roughness increased with increasing CA content in electrolyte composition. The oxide films composed with strong anatase peak with presence of rutile peak, and showed the decrease in intensity of anatase peak but the increase in intensity of rutile peak. When increasing GP-Ca in electrolyte composition, the precipitated HA crystals showed the shape of thick and shorter rod. However, when increasing CA, the more fine needle shape HA crystals were appeared. It was shown that the intensity of anatase peak increased after hydrothermal treatment but was no difference in rutile peak. The corrosion voltage and the bioactivity in Hank's solution was accelerated when the anodic oxide film was formed in electrolyte composition of GP-Ca 0.02 mol/L and CA 0.3 mol/L.

Structural Design of a Main Starting Valve Based on the First Axiom

배태성,이권희 한국정밀공학회 2012 International Journal of Precision Engineering and Vol. No.

The main starting valve that is operated by a pneumatic actuator is used to start a diesel engine. It is composed of a ball valve, a check valve, an actuator, etc. In this study, the existing design of a main starting valve is analyzed by the first axiom of axiomatic design theory. The first axiom is introduced to analyze and evaluate the design of a main starting valve. The design parameters (DPs) are determined sequentially by considering the Independence axiom. Then, for the structural design of a main starting valve, the strength is investigated through CFD and structural analyses. In addition, structural optimization of the actuator piston is performed to satisfy the imposed constraint. In this process, metamodels of the maximum stress and weight are built by the Kriging method of interpolation.

CFRP 사교적층판의 충격손상에 관한 연구

배태성,입야영,양동률 대한기계학회 1993 대한기계학회논문집 Vol.17 No.2

본 연구에서는 CFRP 적층재를 구조재료로 사용할 경우 우수한 인장강도를 갖 지만, 충격하중에 취약한 특성을 갖기 때문에 구조안정성에 관한 큰 문제의 하나로 충 격손상을 받은 적층판의 잔류 압축강도가 현저히 저하되는 것이 문제점으로 지적되어 왔다.특히, 충격손상에 의한 압축강도의 저하는 인장강도보다 압축강도에 중점을 두는 항공기의 강도설계에서 중요한 문제가 되므로, 저속충격에 의한 복합재료 구조체 의 충격파괴의 문제를 잘 이해하는 것이 요구된다. 지금까지의 연구에 의하면 CFRP 복합적층재의 손상은 주로 층간박리현상과 손상역의 크기변화를 실험적으로 고찰하였 다. Carbon fiber reinforced plastics(CFRP) have gained increased application in aerospace structures because of their specific strength and stiffness, but are sensitive to impact-induced damage. An experimental investigation was carried out to evaluate the impact resistance of CFRP according to the ply angle. The specimens of angle ply laminate composites were employed with [0.deg. $_{6}$/ .deg.$_{10}$/0.deg.$_{6}$], in which 6 kinds of ply angle such as .deg.=15.deg., 30.deg., 45.deg., 60.deg., 75.deg. and 90.deg. were selected. The impact tests were conducted using the air gun type impact testing machine by steel balls of diameter of 5 mm and 10 mm, and impact-induced damages were evaluated under same impact speed of V=60m/s. The impact damaged zones were observed through a scanning acoustic microscope (SAM). The obtained results were summarized as follows: (1) Delaminations on the interfacial boundaries showed th directional characteristics to the fiber directions. The delamination area on the impact side (interface A) was considerably smaller compared to that of the opposite side (interface B). (2) Cracks corresponding to other delaminations than those mentioned in SAM photographs were also seen on the impact damaged zone. (3) The delamination patterns were affected by the ply-angle, the dimensions of the specimen, and the boundary conditions. (4) The impact damaged zone showed zone showed the delamination on the interfacial boundaries, transverse shear cracks of the surface layer, and bending cracks of the bottom layer.r.r.r.

同一한 衝擊에너지 條件下의 CFRP 斜交積層板의 衝擊損傷과 配向角의 關係

배태성,양동율,笠野英秋 대한기계학회 1992 대한기계학회논문집 Vol.16 No.10

본 연구에서는 충돌입자의 크기의 영향을 평가하기 위하여 동일한 운동에너지 를 갖는 직경 5mm 및 10mm의 강구를 시편에 충돌시킨 후 배항각 변화에 따른 손물역의 크기 변화를 초음파현미경(SAM)과 주사전자현미경(SEM)으로 관찰하였고, 충돌에 따른 압축강성의 변화를 고찰하기 위하여 충격전후의 압축탄성계수를 측정하였다. This study investigated the compressive Young's modulus and the impactinduced damage of CFRP angle-ply laminate under same impact energy condition. The specimens of angle-ply laminate composites [0.deg.$_{6}$/ .theta..deg.$_{10}$/ 0.deg.$_{6}$] with .theta..deg. =30.deg., 45.deg., 60.deg. and 90.deg. were employed, and damaged by steel balls of diameter of 5mm and 10mm propelled by air gun type impact testing machine. The impact damaged zones were observed through a scanning acoustic microscope(SAM), and their cross-sections were observed through a scanning electron microscope(SEM). The compressive Young's moduli before and after impact were measured, and compared with the theoretical values calculated. The results obtained were as follows: (1) The damage areas on the interfacial boundaries showed more severe change on the back side interface than on the impact side interface with increasing ply-angle. (2) The damage areas on the interfacial boundaries became larger with increasing impact velocity or ply-angle. (3) The impact damaged zone showed the delamination on the interfacial boundaries and transverse cracks inside laminas. (4) The impact damaged zone was affected by the impactor size and speed or ply-angle under same impact energy condition. (5) Compressive Young's moduli before and after impact were lower than theoretical value, but showed a similar change according to ply-angle. (6) Compressive Young's moduli after impact were higher than those before impact, but there was no remarkable change in apparent compressive modulus after impact.t.act.

시효와 Thermocycling 처리한 치관전장용 복합레진의 마모특성 평가

배태성,강정길,송광엽 대한치과기재학회 2001 대한치과재료학회지 Vol.28 No.5

전치부 임플란트의 기능적 심미적 수복을 위해 세라믹 재료를 사용할 때의 고려사항

배태성 대한치과재료학회 2023 대한치과기재학회 학술대회 Vol.2023 No.4