• Composites Research
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• v.20 no.4
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• pp.18-24
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• 2007

The mechanical and thermal properties of PAN-based/rayon-based carbon fabrics interply hybrid composite materials have been studied. Mechanical properties including tensile and interlaminar shear strengths were improved with increasing amount of continuous PAN-based carbon fabrics. The erosion rate and insulation index were determined through the torch test. Continuous rayon-based carbon fabrics composite indicated relatively low ablation resistant property. The thermal conductivity of hybrid composite of spun PAN-based/continuous rayon-based carbon fabrics is lower than that of the continuous PAN-based carbon fabrics composite.

• Proceedings of the Korean Society For Composite Materials Conference
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• 2005.04a
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• pp.107-110
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• 2005

Tribological behaviors of carbon epoxy composites whose surfaces have many small grooves were compared with respect to coating method under dry sliding and water lubricating conditions. The surface coating materials were epoxy (Ep) and polyethylene (PE) mixed with self-lubricating $MoS_2$ and PTFE powders. The wear morphology of the composites observed with a scanning electron microscopic (SEM) revealed that the surface coating layer mixed with the self-lubricating powder on the grooved surface significantly improved the wear resistance under water lubricating condition because the surface coating layer blocked water to penetrate the composite surface and the self-lubricating powder reduced the wear on the coating by suppressing the generation of blisters.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2006.05a
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• pp.81-85
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• 2006

Through-the-thickness properties of thick-walled cylindrical composites are required to determine structural performances because interlaminar tensile stress is primarily responsible for structural failure of the composites during their curing process. It is necessary for evaluating the tensile properties to find individual test methods to find appropriate methods because there are no recognised international standards(test methods and test specifications) available for generating reliable tensile properties in the direction. This paper has performed an experimental Study to measure that properties of carbon fabric/phenolic composites are produced by domestic company. Several test methods using an aluminum specimen were compared and evaluated. The best method, found out, was adopted to measure transverse through-the-thickness properties of composite materials. The results show that strain trends on four faces of composite specimen are the same.

• Journal of the Korean Society of Propulsion Engineers
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• v.10 no.3
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• pp.48-52
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• 2006

Through-the-thickness properties of thick-walled cylindrical composites are required to determine structural performances because interlaminar tensile stress is primarily responsible for structural failure of the composites during their curing process. It is necessary for evaluating the tensile properties to find individual test methods to find appropriate methods because there are no recognised international standards(test methods and test specifications) available for generating reliable tensile properties in the direction. This paper has performed an experimental study to measure that properties of carbon fabric/phenolic composites which are produced by domestic company. Several test methods using an aluminum specimen were compared and evaluated. The best test method to measure transverse through-the-thickness properties of composite materials was developed by the experimental results that strain trends on all faces of composite specimen are the same.

• Journal of the Korean Society of Propulsion Engineers
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• v.10 no.4
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• pp.47-53
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• 2006

In this paper, the thermal insulator structure of a real rocket which is fabricated in a way that laminated composite rings are connected in series is analyzed using 3-dimensional axisymmetric finite element models. Simulation of cowl zone using a real operating conditions provides that the stress distribution in the laminated composite ring is largely influenced by ply-angles, axial dimensions, and boundary conditions. Notably the plylift that is the precursor to the wedge-out occurs in the ring-to-ring bonding region. It is hypothesized that after the plylift the wedge is dropped out due to the shear stresses in the ply-angle direction and axial compressive stresses.

• Journal of the Korean Society of Propulsion Engineers
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• v.9 no.2
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• pp.25-31
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• 2005

The theory developed in a preceding paper [1] for poroelastic composite material behavior under thermal and gas diffusion is applied to thermo-chemical decomposition of a carbon-phenolic composite rocket nozzle liner under typical operating conditions. Specifically, the structural component simulated is the cowl ring for which distributions of pressure in the material pores, temperature and across-ply stress are presented. The results for particular composite designs show that across-ply failure occurs due to tensile stress in the material which is indicative of plylift. This prediction corroborates observations of plylift in a nozzle cowl. Simulations suggest designs to avoid plylift in the cowl zone.

• Carbon letters
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• v.14 no.2
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• pp.110-116
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• 2013

This study investigated a developed process for producing a composite bipolar plate having excellent conductivity by using coal tar pitch and phenol resin as binders. We used a pressing method to prepare a compact of graphite powder mixed with binders. Resistivity of the impregnated compact was observed as heat treatment temperature was increased. It was observed that pore sizes of the GCTP samples increased as the heat treatment temperature increased. There was not a great difference between the flexural strengths of GCTP-IM and CPR-IM as the heat treatment temperature was increased. The resistivity of GPR700-IM, heat treated at $700^{\circ}C$ using phenolic resin as a binder, was $4829{\mu}{\Omega}{\cdot}cm$ which was best value in this study. In addition, it is expected that with the appropriate selection of carbon powder and further optimization of process we can produce a composite bipolar plate which has excellent properties.

• Carbon letters
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• v.14 no.1
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• pp.40-44
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• 2013

The bipolar plate is the most important and most costly component of proton exchange membrane fuel cells. The development of a suitable low density bipolar plate is scientifically and technically challenging due to the need to maintain high electrical conductivity and mechanical properties. Here, bipolar plates were developed from different particle sizes of natural and expanded graphite with phenolic resin as a polymeric matrix. It was observed that the particle size of the reinforcement significantly influences the mechanical and electrical properties of a composite bipolar plate. The composite bipolar plate based on expanded graphite gives the desired mechanical and electrical properties as per the US Department of Energy target, with a bulk density of 1.55 $g.cm^{-3}$ as compared to that of ~1.87 $g.cm^{-3}$ for a composite plate based on natural graphite (NG). Although the bulk density of the expanded-graphite-based composite plate is ~20% less than that of the NG-based plate, the I-V performance of the expanded graphite plate is superior to that of the NG plate as a consequence of the higher conductivity. The expanded graphite plate can thus be used as an electromagnetic interference shielding material.

• Journal of the Korean Society of Propulsion Engineers
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• v.22 no.1
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• pp.36-44
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• 2018

The thermal response of carbon/phenolic used in a solid rocket nozzle liner was analyzed. In this paper, the numerical analysis of the thermal response of carbon/phenolic consists of (1) the integration equation of the boundary layer to obtain the convective heat transfer coefficient of the combustion gas on the rocket nozzle wall and (2) 1-D finite difference method for heat conduction of carbon/phenolic to calculate the ablation, char, and temperature. The calculated result was compared with the result of a blast-tube-type test motor. It is found that the calculated result shows good agreement with the thermal response of the test motor, except at the vicinity of the throat insert.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.42 no.10
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• pp.809-815
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• 2014

The co-bonded dissimilar composite under a wide range of temperature change shows thermal distortion due to the differences in thermal expansion characteristics of the composite materials. Analysis of the thermal expansion characteristics of each composite is required for the design of co-bonded dissimilar composite structure with considering the shape distortion during the manufacturing process. In this work, digital image correlation (DIC) technique is introduced for measuring the thermal distortion characteristics of co-bonded dissimilar composite specimen, carbon/epoxy and silica/phenolic. The thermal distortion of co-bonded dissimilar composite specimen is numerically estimated and compared with the experiments. The estimated results is successfully validated using the measured results.