• Composites Research
• /
• v.26 no.5
• /
• pp.322-327
• /
• 2013

Carbon fiber-reinforced SiC matrix composites have good oxidation resistance and thermal shock resistance. These properties have allowed the composites to be applied to high-temperature structures. In this study, $C_f/SiC$ composites were fabricated via precursor infiltration and pyrolysis (PIP) process, including liquid phase infiltration and chemical vapor curing using cyclohexene. The final $C_f/SiC$ composites, which have gone through the PIP process five times, showed a density of $1.79g/cm^3$, as compared to a density of $0.43g/cm^3$ for pre-densified bare carbon fiber preform. As for the oxidation resistance characteristics, the weight of $C_f/SiC$ composite was maintained at 81% at $1400^{\circ}C$ in air for 6 hours. Chemical vapor curing (CVC) using cyclohexene has shown to be an effective method to achieve high densification, leading to increased oxidation resistance.

• Fire Science and Engineering
• /
• v.24 no.3
• /
• pp.72-77
• /
• 2010

Honeycomb core structure with its excellent stiffness and strength is being utilized in many fields such as interior building material. Because it is inexpensive and renewable, honeycomb paper production is economically and environmentally helpful. However, the paper needs to be fireproofed because it is vulnerable to fire. In this study, we have undergone the performance evaluation process of the honeycomb paper which is widely used as interior material of a fire door and packing material. Four kinds of honeycomb (a honeycomb made of flame-resistant paper; a honeycomb attached with conventional flame-resistant film made in the laboratory; honeycomb impregnated with flame retardant; a honeycomb attached with flame-resistant film after impregnating fire retardant) were used in the study to compare the fire retardant performance. As a result, the honeycomb with impregnated flame retardant showed the highest performance. The flame-resistant film was effective in delaying the igniting time but had a negative effect on the rate of heat and smoke production.

• Proceedings of the Korean Society For Composite Materials Conference
• /
• 2000.04a
• /
• pp.116-119
• /
• 2000

본 연구에서는 온도의 상승에 의하여 부피가 팽창하는 열팽창 고무 치공구의 팽창 특성을 이용하여 열경화성 복합재료를 경화하고 압축하는 과정을 실험과 모델링을 통하여 해석하였으며, 열가소성 복합재료의 함침공정을 연구하였다. 열팽창 고무치공구가 사용되는 닫힌계와 열린계에서 예상되는 압력을 이론적으로 유도하였고, 경화가 수반되는 과정에 있어서는 실험을 통하여 열팽창치공구와 프리프레그가 나타내는 압력을 측정하였다. 온도가 상승하고 경화가 수반되는 경우에 등속도 압축실험에 의하여 얻어지는 응력-변형율 곡선은 비선형점탄성 특성을 보여주었는데, 본 연구에서는 Maxwell모델을 KWW(Kohlrausch-Williame-Watts)식으로 변형시킨 모델식을 이용하여 이를 매우 정확하게 표현할 수 있었다. 또한 고무치공구를 이용하여 열가소성 수지의 복합재료 성형공정을 실험하였고, 중성자 레디오그래피 촬영을 통하여 기공의 분포를 관찰하였다.

• Composites Research
• /
• v.14 no.2
• /
• pp.33-42
• /
• 2001

The cure kinetic equation fur 52-glass/polyester prepreg composites was established through DSC (differential scanning calorimetry). Using the established kinetic equation, the temperature distribution of the thick composite was calculated considering the change of heat transfer resistance due to resin impregnation of bleeder plies used. In order to reduce the overheat during cure of thick glass fiber composites, the cure cycle was modified by introducing the cooling and reheating steps. Then the thick glass composites were cured both by the conventional cycle without any cooling or reheating step and the modified cure cycle. The mechanical properties of the thick composites cured by the both cycles were tested by the short beam shear test and the Barcol hardness test, and then their results were compared.

• Journal of Ocean Engineering and Technology
• /
• v.23 no.2
• /
• pp.98-103
• /
• 2009

The resin infusion method is the latest technology of FRP laminating and cleaning to improve FRP hull quality. This method is focused on how to arrange infusion channels for the laminiating strategy. The laminating strategy using the resin infusion method has been utilized to complete the infusion work and remove the cavities on the FRP surface within the curing time. It is resulting from the arrangement of infusion and vacuum channels, the resin property, and the combination of FRP. This strategy has been depended on the field experience for manufacturing FRP without the resin infusion simulation. This study can help to improve the efficiency of FRP fabrication with the laminating strategy including the resin infusion simulation instead of the field experience.

• Composites Research
• /
• v.28 no.4
• /
• pp.197-203
• /
• 2015

Tensile properties of polypropylene based self-reinforced composites were investigated as a function of process variables of the double-belt lamination equipment such as pressure, temperature and cooling conditions. Elastic modulus was enhanced approximately 6 times from 0.2 to 1.2 GPa. The improvement mechanism was studied by identification of crystalline structure changes using DSC and XRD analysis. In addition, morphology change of self-reinforced composites was also investigated by SEM analysis in order to reveal the degree of impregnation.

• Journal of the Korean Wood Science and Technology
• /
• v.31 no.1
• /
• pp.41-45
• /
• 2003

In this study, woodceramics were made from MDF with various resin impregnation rate. To investigate the change of surface temperature of woodceramics, the impregnated MDF was burned at the temp. 600, 800, 1,000, 1,200℃. Surface temperature of woodceramics was increased as impregnation rate and burning temperature was increased. The specimen burned at 800℃ was lower than others. Change of temperature under given temperature increased as time passed and it showed more increased in temperature at burning temperature of 1,200℃. Change of surface temperature increased when floor temperature increased and the temperature was 49.2℃ at 70℃ in floor temperature of 1,200℃ specimen. The decent in surface temperature of woodceramics was the fastest decrease at the burning temperature of 800℃ specimen.

• Composites Research
• /
• v.35 no.4
• /
• pp.248-254
• /
• 2022

In this study, TiB₂-steel composite with high-fractional TiB₂ reinforcement was fabricated by gas pressure infiltration process and the microstructure analysis and compressive strength and hardness were evaluated. To elucidate the correlation between microstructure and mechanical properties for fabricated composite, after the compression test of TiB₂-steel composite, the fracture surface was analyzed and the fracture behavior on compression test was predicted. As a result of the compression fracture surface analysis, interfacial failure trace between the steel matrix and the reinforcement was observed, and the interface between the steel matrix and the reinforcement was analyzed using TEM. From the result of microstructure analysis on the fabricated composite, it was confirmed that, in addition to TiB₂ reinforcement and steel matrix, TiC phase and coarse (Fe,M)₂B (M=Cr,Mn) phase were formed. Throughout the thermodynamic calculation, it was confirmed that TiC and (Fe,M)₂B can be formed as a stable phase under the process condition. The fabricated TiB₂-steel composite had a significantly increased hardness, and the compressive strength and Young's modulus were improved by 3.07 times and 1.95 times, respectively, compared to steel matrix. It seems that the coarse (Fe,M)₂B (M=Cr,Mn) phase formed throughout the composite causes the deterioration of mechanical properties, and by controlling the formation of the (Fe,M)₂B (M=Cr,Mn) phase, it is judged that the mechanical properties of the TiB₂-steel composite can be further improved.

• Journal of the Korean Society of Propulsion Engineers
• /
• v.26 no.6
• /
• pp.21-27
• /
• 2022

C_f/SiC composites have low density, high mechanical strength, and good thermal stability, making them promising materials for high-temperature applications such as rocket propulsion and military fields. However, the remaining Si deteriorates physical and thermal properties. In this paper, the de-siliconization was introduced as a method to remove the Si of the C_f/SiC composite fabricated through Liquid Silicon Infiltration(LSI) process. The stability of composite has been tested under an oxyacetylene torch flame for up to 5 minutes. The oxidized surface and cross section of specimens were characterized by 3D scanning, X-ray diffraction(XRD), Optical microscope(OM) and Scanning electron microscope(SEM).

• Journal of the Korean Recycled Construction Resources Institute
• /
• v.5 no.4
• /
• pp.481-487
• /
• 2017

The purpose of this study is to develop the hybrid sound-absorbing materials that is made from organic polyurethane sponge impregnated with inorganic binder solutions. The inorganic slurry which is made from ${\alpha}$-hemihydrate gypsum mixed with 60% water, and various additives including plasticizer are used as binder. The test specimens are prepared and tested for sound absorption performance by the impedance tube methods. From the test results, noise reduction coefficient(NRC) of development materials specimen bound by the inorganic binder slurry is 0.41. They are 2 times or more higher than commercial products specimens bound by organic materials only which have NRC values in the range of 0.14 to 0.28. The polyurethane sponge specimens impregnated with inorganic gypsum slurry binder have a good balance between performance and cost, and have proper properties in density, thermal conductivity, non-combustible, and absence of harmful substances as sound-absorbing internal boards for noise barrier wall. It is apparent that the good sound absorption materials can be produced according to the optimum mix design that is recommended from this study.