LPS-SiC 세라믹스 제조시 소결조제 SiO₂의 영향

Monolithic liquid phase sintered SiC (LPS-SiC) was made by hot pressing method with nano-SiC powder whose a particle size is 30nm and less on the average. Alumina (Al₂O₃), yttria (Y₂O₃) and silica (SiO₂) were used for sintering additives. To investigate effects of SiO₂, Al₂O₃/Y₂O₃ composition was fixed and then ratios of SiO₂ were changed as four kinds. Materials have been sintered for 1 hour at 1760 ℃, 1780 ℃ and 1800 ℃ under the pressure of 20MPa. The system of sintering additives which affects a property of sintering as well as the influence depending on compositions of sintering additives were investigated by measurement of density, mechanical properties such as flexural strength elastic modulus were investigated to make sure of the optimum condition which is about matrix of SiCf/SiC composites. Sintered density, flexural strength of fabricated LPS - SiC increased with increasing the sintering temperature. Particularly, relative density of sintered body at 1800 ℃ with the less content of SiO₂, specimen of AYSa-1800 was 95 %. Also, flexural strength and elastic modulus were 587.5 ㎫ and 216.3 ㎬, respectively. It is superior values than that of LPS-SiC with Al₂O₃-Y₂O₃ system.