• Journal of Adhesion and Interface
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• v.17 no.1
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• pp.7-14
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• 2016

Epoxy composites with concentrations of 5-70 wt% of silica particles were prepared in order to improve mechanical property and poor thermal stability. The mechanical and thermal properties were investigated and compared to the corresponding properties of neat epoxy composite. Furthermore, the effects of silane compound treatment on silica particles were observed by the experimental results of the tensile strength, glass transition temperature, and thermal stability of epoxy composite. Tensile strength of epoxy composites was measured by universal testing machine (UTM) and after that, the structure and morphology analysis of epoxy nanocomposites were analyzed by field emission scanning electron microscope (FE-SEM) and energy dispersive spectroscopy (EDS). The increased solid content of CA0030 particle improved the tensile strength of epoxy/ modified composites to give 30-50 MPa. The thermal expansion coefficients (CTE) of neat epoxy resin and epoxy/silica composites measured with a thermomechanical analyzer (TMA) showed that the incorporation of silica particles was helpful to reduce the CTE of neat epoxy resin.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2001.10a
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• pp.36-40
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• 2001

파인 세라믹은 대부분의 기계적 특성에 있어서 일반금속보다 우수한 특성을 가지기 때문에 각종기계 및 부품 재료로서의 기대가 크다. 그러나 세라믹재료의 고경강도, 고취성에 기인하는 난가공성 및 가공손상층의 발생은 이들 재료의 실용화에 큰 장애로 되어 있다. 현재, 다종의 세라믹이 개발되어져 있고, 이들을 어떠한 제품의 형태로 만들기 위해서는 기계적 가공을 필요로 하게된다. 오늘날, 세라믹의 기계적 가공법으로서 가장 일반적으로 사용되어지는 것은 다이야몬드숫돌에 의한 연삭가공이다.

• The Journal of the Korean dental association
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• v.47 no.12
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• pp.798-803
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• 2009

지르코니아는 물리적 성질이 금속과 가장 가까운 세라믹이며, 색상이 치아와 비슷하여 치과분야에서 사용빈도가 증가하고 있는 재료이다. 지르코니아는 zirconium dioxide 결정체로서, 1975년 Garvie가 'ceramic steer' 이라고 명명하였듯이 기존의 세라믹과 비교하여 뛰어난 물성을 지니고 있다. 즉, 높은 내열성과 낮은 열전도도, 산성에서 알카리성까지 이르는 내화학 안정성, 낮은 열팽창성, 높은 강도 및 경도, 내마모성을 가지고 있기 때문에 이전부터 공업용 재료로 넓게 시용되어 왔다. 지르코니아의 상변 이를 이용한 toughening방법이 Garvie에 의해 제시됨으로서 세라믹의 최대 단점인 취성은 어느 정도 극복할 수 있게 되었고 이를 계기로 금관 및 계속가공 의치, 임플란트 지대주, 인레이, 온레이 등 치과의 여러 분야에 지르코니아를 적용할 수 있게 되었다. 최근에는 임플란트 매식체에 있어서도 그 적용을 시도함으로서 심미치과치료에 있어서 중요한 부분으로 자리 잡고 있다. 현재 지르코니아는 치과용 세라믹 중에서 가장 높은 기계적 물성을 보이기 때문에 구치부 에서의 사용 가능성이 시도되고 있으며, 코어의 두께를 감소시킴으로써 보철 술식에서 필요한 강도 및 심미성 두 마리 토끼를 잡을 수 있도록 많은 연구가 이루어지고 있다. 이에 지르코니아의 역사 및 이론적 배경에 대하여 알아보고자 한다.

• Journal of the Korean Applied Science and Technology
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• v.37 no.4
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• pp.1034-1040
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• 2020

The mechanical properties of NATM resin of synthetic polyurethane-epoxy resin for stainless steel were measured by SEM, FT-IR, tensile properties, and specific mass loss by EIS analysis, etc. As interest in eco-friendly medium coatings increased, the Heavy duty coatings were synthesized for various metals such as stainless steel composed of Polyol, MDI, water bored Epoxy resin, filling agent, silicon surfactant, catalyst etc. The coatings of synthetic NATM resin were increased tensile strength due to various temperature change, and the low-Specific Mass Loss was measured in a highly electrolytic solution. In conclusion, the NATM coatings composed of polyurethane and waterbored Epoxy, polyurea resin were synthetic microstructure with cross linkage can be good material for coating of anticorrosion of metal substrates such as stainless steel.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.15 no.6
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• pp.3396-3402
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• 2014

The importance of shape design for strength is highly regarded when applied to thin plate products in Ceramic Injection Molding (CIM), such as cases for electronic goods. This study analyzed the characteristics of the mechanical strength of CIM product by measuring the flexural strength and elastic modulus through a 3-point bending test according to the thickness of a thin plate test piece prepared by CIM. The specimen with a thickness of 0.48mm required a 82.9~94.5N fracture load, whereas a 1.0mm thick test piece required 233.6~345.8N. The increase in thickness by 0.5mm resulted in a 3-fold increase in the fracture load, whereas the elastic modulus decreased by 20%. The thicker the specimen, the lower relative density and surface hardness of the specimen. This is because the thicker the specimen, the lower the powder fraction of the ceramic mixture, and the material properties partially change after sintering.

• Applied Chemistry for Engineering
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• v.8 no.2
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• pp.197-203
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• 1997

The effect of additives on the mechanical properties of polyurethane foam were investigated. The resin used in this study was prepared by adding catalyst, surfactant and cross-linker to both KONIX FA-703 polyether polyol(80%) and KONIX FA-733 polyether polyol(20%). The polyurethane was foamed by adding equivalent amount of isocyanate(TDI-80, prepolymer M-200, pure MDI) to the resin and was used in property measurements after 72 hours hardening. The physical properties of polyurethane foam were investigated in terms of density, tensile strength, tear strength, elongation, sound absorption coefficient and gel profile measurements. The effects of surfactant on the cell size was investigated by scanning electron microscopy(SEM). The sound absorption coefficient was directly related to the cell size. The physical properties were improved with increasing amount of surfactant(L-5309) until 1.0 part per hundred polyol(1.0pphp).

• Korean Journal of Materials Research
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• v.9 no.9
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• pp.905-912
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• 1999

Tensile properties of powder metallurgy (PM) processed Cu-7.5Ni-5Sn alloys, either as-received or additionally solution heat treated, were examined as a function of aging time. It was found that the as-received Cu-7.5Ni-5Sn alloys showed an abrupt increase in tensile strength after aging at $350^{\circ}C$ for 20 minutes, due to the metastable ${\gamma}$\\` precipitation and a marginal Spinodal decomposition. The resolutionized PM Cu-7.5Ni-5Sn alloys, on the other hand, showed a gradual increase in tensile strength from the very early stage of aging. The overall tensile strength of resolutionized PM Cu-7.5Ni-5Sn alloys, however, was lower than that of the as-received and aged counterparts, due to the grain growth during resolutionization. Afterprolonged aging for the as-received PM Cu-7.5Ni-5Sn alloys, a considerable amount of discontinuous precipitates formed along the grain boundaries. The formation and growth kinetics of such discontinuous precipitates appeared to be dependent on the heat treatment conditions, and affect the mechanical properties greatly.

• Proceedings of the Korean Ceranic Society Conference
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• 2004.10a
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• pp.95.1-95.1
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• 2004

• Proceedings of the Korean Ceranic Society Conference
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• 2003.04a
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• pp.47.1-47
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• 2003

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2009.06a
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• pp.795-796
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• 2009