Synthesis and Mechanical Properties of Mullite-PSZ Composites by Sol-Gel Process

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J. Korean Ceram. Soc. > Volume 28(5); 1991 > Article

Journal of the Korean Ceramic Society 1991;28(5): 399.

Sol-Gel법에 의한 Mullite-PSZ 복합체의 제조 및 특성에 관한 연구

최용식, 박일주, 이경희¹, 이병하¹, 김영호¹

국립공업시험원 도자기시험소
¹명지대학교 무기재료공학과

Synthesis and Mechanical Properties of Mullite-PSZ Composites by Sol-Gel Process

ABSTRACT

Mullite-PSZ powders were synthesized by the sol-gel process using Al(sec-OC4H9)3, Si(OC2H5)4, ZrOCl2$.$8H2O and YCl3 solution and the characteristics of synthesized powders were studied. The sinterability and mechanical properties of powder compacts sintered at 1670$^{circ}C$ for 4hr were also studied for various PSZ contents. ${gamma}$-Al2O3(Al-Si spinel) formed at 980$^{circ}C$ from amorphous dried gel, and mullite as well as ZrO2 formed above 1200$^{circ}C$. At the room temperature, ZrO2 was a mixture of tetragonal and monoclinic phases. The specimens were densified to 97∼98% except the specimen containing 25 vol% PSZ which showed the relative density of 94%. The K1c value increased with the PSZ content and showed a maximum value of 4.1 MN/m3/2 at 25 vol% PSZ; this value was about 50% higher than that of the mullite without PSZ. Flexural strength had a maximum value of 280 Mn/㎡ at 20 vol% PSZ. In contrast, at 25 vol%, the flexural strength was even lower than that of the mullite possibly due to higher porosity of 6%.