Papers by Author: Yong Jin Kim

Abstract: In this study, two-dimensional (2D) ordered macroporous SiCN ceramics were prepared by infiltrating sacrificial colloidal silica (SiO2) templates with the low molecular weight preceramic polymer, polysilazane. This was followed by a thermal curing step, pyrolysis at 1250°C in a N2 atmosphere, and finally the removal of the templates by etching with diluted HF. In particular, 100large-scale monolayer silica crystals were prepared on the cleaned Si substrates by spin coating. Two-dimensional SiCN ordered pore arrays were fabricated by a solution-dipping template strategy.

Abstract: Hypereutectic prealloyed Al-20wt.%Si powders were prepared by the gas atomization process. Characteristics of the atomized Al-Si powders were investigated. With increasing gas pressure of the atomization, the average powder size and oxygen content decreased. Primary Si particles in the as-atomized powders were about 8-10 ㎛. Sintering behavior of the atomized Al-Si powders was discussed with sintering temperature. As-atomized powders were hot-pressed and extruded into a cylindrical shape. 96-99% of theoretical density was achieved by the hot consolidation. Microstructure changes as well as hardness and tensile properties of the samples were evaluated in this paper.