• Proceedings of the Korean Society For Composite Materials Conference
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• 2001.10a
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• pp.79-82
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• 2001

In this research, tile effects of reinforcements type on mechanical properties of MMCs were studied. Six kinds preform were fabricated by using Saffil short fiber, HTZ short fiber, $Al_2O_3$ particle, and SiC particle. MMCs were fabricated by using squeeze casting methods. Various tests were conducted to show the effects of reinforcements type on mechanical properties of MMCs. Tensile and compressive properties of MMCs depend on short fiber, however wear properties depend on particle reinforcement. Generally, properties of fiber/particle hybrid MMCs were excellent than those of MMCs with short fiber.

• Proceedings of the KSME Conference
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• 2001.11a
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• pp.27-31
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• 2001

Hi-Nicalon SiC fiber reinforced SiC composites (SiC/SiC) have been fabricated by the reaction sintering process. Braided Hi-Nicalon SiC fiber with double interphases of BN and SiC was used in this composite system. The microstructures and the mechanical properties of reaction sintered SiC/SiC composites were investigated through means of electron microscopies (SEM, TEM, EDS) and bending tests. The matrix morphology of reaction sintered SiC/SiC composites was composed of the SiC phases that the composition of the silicon and the carbon is different. The TEM analysis showed that the residual silicon and the unreacted carbon were finely distributed in the matrix region of reaction sintered SiC/SiC composites. Reaction sintered SiC/SiC composites also represented proper flexural strength and fracture energy, accompanying the noncatastrophic failure behavior.

• Journal of Powder Materials
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• v.30 no.5
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• pp.409-414
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• 2023

YSZ (Y₂O₃-stabilized zirconia)-based ceramics have excellent mechanical properties, such as high strength and wear resistance. In the application, YSZ is utilized in the bead mill, a fine-grinding process. YSZ-based parts, such as the rotor and pin, can be easily damaged by continuous application with high rpm in the bead mill process. In that case, adding WC particles improves the tribological and mechanical properties. YSZ-30 vol.% WC composite ceramics are manufactured via hot pressing under different pressures (10/30/60 MPa). The hot-pressed composite ceramics measure the physical properties, such as porosity and bulk density values. In addition, the phase formation of these composite ceramics is analyzed and discussed with those of physical properties. For the increased applied pressure of hot pressing, the tetragonality of YSZ and the crystallinity of WC are enhanced. The mechanical properties indicate an improved tendency with the increase in the applied pressure of hot pressing.

• International Journal of Concrete Structures and Materials
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• v.5 no.1
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• pp.3-10
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• 2011

Theoretical models for prediction of the mechanical properties of cement mortar are developed based on the morphology and interactions of cement hydration products, capillary pores and microcracks. The models account for intermolecular interactions involving the nano-scale calcium silicate hydrate (C-S-H) constituents of hydration products, and consider the effects of capillary pores as well as the microcracks within the hydrated cement paste and at the interfacial transition zone (ITZ). Cement mortar was modeled as a three-phase material composed of hydrated cement paste, fine aggregates and ITZ. The Hashin's bound model was used to predict the elastic modulus of mortar as a three-phase composite. Theoretical evaluation of fracture toughness indicated that the frictional pullout of fine aggregates makes major contribution to the fracture energy of cement mortar. Linear fracture mechanics principles were used to model the tensile strength of mortar. The predictions of theoretical models compared reasonably with empirical values.

• Proceedings of the Korean Society of Marine Engineers Conference
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• 2005.06a
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• pp.326-330
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• 2005

Aircraft composite structure with honeycomb core experiences core crush problem in manufacturing. To prevent core crush additional processes are needed such as core stabilization and prepreg material tie-down and this is the cause of increasing cost. Recent study shows that high friction prepreg prevent core crush without additional process. This paper presents the analysis of high frictional material which attracts lots of interests through physical property, mechanical property and microscopic

• Composites Research
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• v.33 no.5
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• pp.275-281
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• 2020

The mechanical property related to lap shear strength of the joint structure between carbon fiber reinforced polymer (CFRP) composite and metal (Ni-Cr Alloy) under varying environmental conditions (temperature and humidity) was studied in order to apply to the aircraft fan blade. Room temperature dry (RTD), elevated temperature wet (ETW), and cold temperature dry (CTD) environmental conditions were chosen for investigation based on the flight conditions of aircraft. Lap shear strength tests were conducted according to ASTM Standard D3528 to evaluate the shear strength. The microstructure characteristic of failure zone was analyzed by SEM images to check the adhesive shear strength with the three environmental conditions. In comparison with shear strength for the RTD condition, the shear strength in the ETW condition was reduced by 72.8% while those for the CTD condition increased by 56.5%. The moisture absorption and high temperature in ETW condition strongly had an affect on mechanical property of adhesive, while cold temperature could enhance the adhesive shear strength due to the higher brittleness.

• Proceedings of the Korean Powder Metallurgy Institute Conference
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• 2006.09a
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• pp.672.2-672.2
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• 2006

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2010.11a
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• pp.443-444
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• 2010

• Carbon letters
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• v.2 no.3_4
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• pp.165-169
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• 2001

Modification of C/C composite bipolar plate for improving electrical conductivity was carried out by addition of electroconductive carbon black (EC-CB). Carbon black was carefully mixed to methanol-containing phenolic resin, impregnated into 2D-carbon fabrics, hot pressed and then carbonized to obtain composite plate. Inclusion of electro-conductive carbon black enhanced the electrical conductivity of the C/C composites by increasing the conduction path. Addition of 10 vol% carbon black increased the electrical conductivity from 5.5/${\Omega}cm$ to 32/${\Omega}cm$ and reduced the crack formation by filling effect, resulting in the increase of flexural properties of composite plate. However, at carbon black content over 10 vol%, flexural properties decreased by delaminating role of excess carbon black at the interface in C/C composites.

• Proceedings of the Korea Concrete Institute Conference
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• 2000.10a
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• pp.785-792
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• 2000

Repair and retrofit system of concrete structures has been developed from conventional reinforced concrete overlaying, steel plate bonding and recently to fiber composite systems. Research and study on carbon, aramid, and glass fiber composite system has been actively carried out from all over the world Glass fiber composite is proved to be competitive technically and enconomically, among fiber composite system. CAF system is a system developed locally using all domestic materal, glass fabric and epoxy, and improved in shear bonding property by utilizing silica fume mixed with epoxy. All the tests on material properties, structural behavior, constructiveness at site and quality control procedure proved to be most appropriate system so far developed. Futher research work is and will be under progress for utilization of this system which will be applied to more adverse situation.