• 한국세라믹학회지
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• 제32권4호
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• pp.413-418
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• 1995

The (B.Si)C composite was prepared form the mixture of metal boron, silicon, and carbon powders in Ar atmosphere by Self-propagating High-temperature Synthesis Chemical Furnace. The characterization of synthesized power and sintered body were investigated. The microstructure of sintered body suggested that SiC boundary was made between B4C grains. The most excellent mechanical properties, the relative density of 95% oftheoretical value, 3 point flexural strength of 360MPa, and fracture toughness of 3.6MN/m3/2 could be obtained in 80wt% B4C-20 wt% SiC composite were obtained.

• Carbon letters
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• 제14권1호
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• pp.58-61
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• 2013

In this work, the effect of catalysts on the mechanical properties of carbon fibers-reinforced epoxy matrix composites cured by cationic latent thermal catalysts, i.e., N-benzylpyrazinium hexafluoroantimonate (BPH) was studied. Differential scanning calorimetry was executed for thermal characterization of the epoxy matrix system. Mechanical interfacial properties of the composites were studied by interlaminar shear strength (ILSS), critical stress intensity factor ($K_{IC}$), and specific fracture energy ($G_{IC}$). As a result, the conversion of neat epoxy matrix cured by BPH was higher than that of one cured by diaminodiphenyl methane (DDM). The ILSS, $K_{IC}$, $G_{IC}$, and impact strength of the composites cured by BPH were also superior to those of the composites cured by DDM. This was probably the consequence of the effect of the substituted benzene group of BPH catalyst, resulting in an increase in the cross-link density and structural stability of the composites studied.

• 비파괴검사학회지
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• 제32권2호
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• pp.115-121
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• 2012

Exploration in microelectromechanical systems(MEMS) and nanotechnology requires evaluation techniques suitable for sub-micron length scale so that thermal and mechanical properties of novel materials can be investigated for optimal design of miro/nanostructures. The ultrafast optical pump-probe technique provides a contact-free and non-destructive way to characterize nanoscale thin-films, and its ultrahigh temporal resolution enables the study of heat-transport phenomena down to a sub-picosecond regime. This paper reviews the principle of optical pump-probe technique and introduces its application to the area of micro/nano-NDE.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2007년도 춘계학술대회A
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• pp.1718-1723
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• 2007

The Probe Card is a test component which is to classify the good semiconductor chips before the packaging. The yield of semiconductor product can be better from analysis of probe test information. Recently the technology of the probe card needs narrow width and large amount of probe tip. In this research, the probe tip based on the MEMS(micro electro mechanical system) technology was designed and fabricated to improve the reliability of the test and to meet 2-dimensional Array of tip. The mechanical and electrical properties of proposed tip were evaluated and it has over 100,000 of repetition times in the condition of 5gf, $20{\mu}m$ Over Drive.

• 한국소성가공학회:학술대회논문집
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• 한국소성가공학회 1994년도 춘계학술대회 논문집
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• pp.139-148
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• 1994

An experimental study on material characterization and mechanical properties of SMC(Sheet Molding Compounds) compression molding parts was carried out. Simple compression test using grease oil as a lubricant was carried out to characterize flow stress of SMC at elevated temperatures. Two different mold temperatures, 130$^{\circ}C$ and 150$^{\circ}C$ and two different mold speeds, 15, 45mm/min were used for preparing the specimen of SMC compression molding parts. Surface roughness, tensile, and 3-point bending tests were used to determine the effects of molding temperatures and speeds on mechanical properties of compression molded SMC parts.

• 한국추진공학회:학술대회논문집
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• 한국추진공학회 1996년도 제7회 학술강연회논문집
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• pp.167-176
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• 1996

Flaw classification and sizing are very essential issues in quantitative ultrasonic nondestructive evaluation of various materials and structures including weldments. For performing of these tasks in an automated fashion, we are developing an intelligent ultrasonic evaluation system with a multi-axis portable scanner which can do consistent and efficient acquisition and processing of ultrasonic flaw signals. Here we present our efforts to develop of this intelligent system including design of the portable scanner, acquisition and processing of ultrasonic flaw signals, display of pseudo 3-D image of flaws, and classification and sizing of flaws in weldments.

• 한국소성가공학회:학술대회논문집
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• 한국소성가공학회 2006년도 춘계학술대회 논문집
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• pp.53-56
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• 2006

Magnesium alloy AZ31, which processed by conventional rolling or extrusion, has high anisotropy of mechanical properties in its strength and elongation at room temperature. We compared the influence of differential speed rolling with conventional rolling process on microstructure and mechanical properties of commercial AZ31 sheet. Commercial AZ31 alloy sheets were processed with conventional and differential speed rolling with thickness reduction ratio of 30% at a various temperature. The elongation of AZ31 alloy, warm-rolled by differential speed rolling is larger than those rolled by conventional rolling. Besides, grain size and distribution on microstructure of the conventional rolled materials were coarse and inhomogeneous, on the contrary, those of the differential speed rolled were fine and homogeneous.

• 한국복합재료학회:학술대회논문집
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• 한국복합재료학회 2003년도 추계학술발표대회 논문집
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• pp.190-194
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• 2003

Two different types of nondestructive evaluation (NDE) techniques were employed to investigate the tensile behavior of ceramic matrix composites (CMCs). Two NDE methods, ultrasonic testing (UT) and infrared (IR) thermography, were used to assess defects and/or damage evolution before and during mechanical testing. Prior to tensile testing, a UTC-scan and a xenon flash method were performed to obtain initial defect information in light of UT C-scans and thermal diffusivity maps, respectively. An IR camera was used for in-situ monitoring of progressive damages. The IR camera measured temperature changes during tensile testing. This paper has presented the feasibility of using NDE techniques to interpret structural performance of CMCs.

• 대한기계학회논문집A
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• 제29권3호
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• pp.425-431
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• 2005

The efficiency of complex slurry preparation route for developing the high performance SiC matrix of $RS-SiC_{f}/SiC$ composites has been investigated. The green bodies for RS-SiC materials prior to the infiltration of molten silicon were prepared with various C/SiC complex slurries, which associated with both the sizes of starting SiC particles and the blending conditions of starting SiC and C particles. The characterization of Rs-SiC materials was examined by means of SEM, EDS and three point bending test. Based on the mechanical property-microstructure correlation, the process optimization is also discussed. The flexural strength of Rs-SiC materials greatly depended on the content of residual Si. The decrease of starting SiC particle size in the C/SiC complex slurry was effective for improving the flexural strength of RS-SiC materials.

• 대한기계학회논문집A
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• 제26권12호
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• pp.2624-2630
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• 2002

Organic/inorganic hybrid materials have rapidly become a fascinating research field. In this study, $polyimide/TiO_2$ composites were synthesized from nano-sized anatase $TiO_2$ and two types of polyimide, that is, BPDA-PPD and PMDA-ODA. Nano-sized $TiO_2$ particles were prepared from $TiOEt_4$ solution by the sol-gel method. The synthesized PI/$TiO_2$ composites were characterized by using XRD, TGA, FT-IR, TEM, and Atomic Force Microscope(AFM). $TiO_2$ particles were dispersed well in polyimides and the mechanical and thermal stability of polyimide was improved with $TiO_2$ nano particles.