Vitreous carbon (VC) is an excellent material for glass molding due to its high hot hardness and low adhesion to glass materials. As a low-cost VC micro/nano mold fabrication method, carbonization of replicated Furan precursor has been investigated for various glass molded micro/nano optical and fluidic devices. One of the critical issues identified in the method is the substantial pyrolysis shrinkage (~22%) during the carbonization process. In this study, a method of minimizing pyrolysis shrinkage by adding VC powder to the initial Furan resin mixture was investigated. The mixing ratio of Furan resin, initiator, and ethanol was experimentally optimized for each VC powder mixing ratio, and the effects of the VC powder mixing ratio on the pyrolysis shrinkage of VC mold were examined. As the VC powder mixing ratio increased from 0% to 40%, we observed a reduction in the shrinkage ratio from 22.18% to 12.89% aligning closely with theoretical expectations.

In this paper, the DSC and TGA for phenol and silica/phenolic composite were carried out by increasing temperature up to 950℃ with variable heating rate, to figure out basic thermal and pyrolysis characteristics of the composite. Also, the aim was to obtain the activation energy and the frequency factor which are the main parameters of the Arrhenius equation based on the Kissinger theory. The activation energy and frequency factor were used for the ablation model as material property. To confirm surface temperature distribution and recession of missiles, the CFD analysis using ANSYS Fluent R18.2 was performed to examine the thermal fluid characteristics of the hypersonic flight environment. Subsequently, the analysis results were applied as boundary conditions to a 2D axisymmetric pyrolysis and ablation model. Finally, pyrolysis and ablation analysis were performed using the ablation analysis code SAMCEF AMARYLLIS V.17, which uses the specific ablation module based on finite element code by applying carbon/phenolic and cork materials up to t = 10 s.

In this study, pyrolytic graphite was applied to overcome the conventional cooling system. Pyrolytic graphite is an anisotropic material with high thermal conductivity in the X-Y direction and low thermal conductivity in the Z direction. The advantage of high thermal conductivity in the plane direction is applied to improve the performance of the cooling capacity transceiver module housing made of aluminum. In comparison with the housing using the aluminum, the housing applied to the PGS plate shows a higher cooling performance on the average temperature of chips and the temperature variations by 2.79% and 49.98%. The heat dissipation performance was investigated according to the thickness of the PGS and the via the shape. When the factor of thickness in PGS plate was “0.375”, the average temperature of the chip was the lowest, and the temperature variation decreased due to increasing the factor of thickness in the PGS plate. In the case of the via shape, the “separation plate” showed the lowest average temperature of chips and the “plate” showed the lowest temperature variation.

A chemical ablation analysis of hypersonic missile for thermal protection design was performed using SAMCEF AMARYLLIS V.17, the specific ablation module of commercial software based on a finite element code. The pyrolysis and surface recession models based on the effects of mass loss, pore gas diffusion, and endothermic reaction energy were applied for non-linearity of material and boundary. The numerical studies were carried out to confirm the tendency of the pyrolysis and chemical ablation of theoretical ablative composite for open testing (TACOT) with a chemical composition similar to charring carbon/phenolic composites. The frequency of variation in surface recession, temperature, density and gas mass flux was reviewed to determine the characteristics of multiple decomposition reactions and oxidation via pyrolysis of gas species.