Joon-Soo Park

Microstructural and mechanical characteristics of SiC/SiC composites with modified-RS process

Abstract This paper deals with the efficiency of modified-reaction sintering techniques including a impregnation pressure and a cold pressure as well as the applicability of new high performance fiber, in order to develop high performance SiC/SiC composites. SiC/BN coated Hi-Nicalon fiber, SiC coated Tyranno ZMI fiber and Tyranno SA fiber were used in this composite system. Microstructural characteristics of reaction sintered SiC/SiC composites were investigated by means of SEM, EDS and TEM. Mechanical properties and fracture mechanisms of SiC/SiC composites were also evaluated through the three-point bending test. Improved SiC/SiC composites with high density and high strength were successfully fabricated by the sequential application of low pressure impregnation and cold pressing processes. An excellent chemical stability of Tyranno SA fiber during the reaction sintering process was also revealed. Tyranno SA fiber reinforced SiC/SiC composites with no interfacial coating exhibited good flexural strength and elastic modulus, compared to those reinforced by BN/SiC coated Hi-Nicalon and SiC coated Tyranno ZMI fibers. However, this composite system needed an appropriate interfacial coating for proper CMC composite behavior.

Process, microstructure and flexural properties of reaction sintered Tyranno SA/SiC composites

Abstract The preparation routes of fiber preform for the fabrication of RS-SiC/SiC composites have been investigated, based on the mechanical property–microstructure correlations. Tyranno SA SiC fiber reinforced SiC composites have been fabricated by a reaction sintering process, which is associated with the consecutive slurry infiltration process of low pressure slurry impregnation with various filler particles and with the magnitudes of the cold pressures. The characterization of RS-Tyranno SA/SiC composites was evaluated by means of SEM, EDS and three point bending test. The consecutive slurry infiltration process of low impregnation pressure and cold pressure for the preparation of fiber preform provided the required density for RS-Tyranno SA/SiC composites (>2.9 mg/m3), even if there was a large amount of Si rich SiC phases in the matrix of the intra-fiber bundle. The flexural properties of RS-Tyranno SA/SiC composites depended on the magnitudes of cold pressure used for the preparation of the fiber preform.

Mechanical properties and fabrication of silicon carbide ceramic by NITE method

Nano infiltration transient eutectic ceramic (NITE-SiC) was fabricated by hot pressing method using Al2O3 and Y2O3 as sintering additives. The ratio of the Al2O3/Y2O3 additives was changed between 6:4 and 4:6. The densification and mechanical properties were investigated for the sintered temperature. The starting powder was high purity β -SiC nano-powder with an average particle size of 30nm. The bending strength characterization and densification of NITE-SiC was investigated by the FE-SEM and three point bending test.