• 한국세라믹학회지
• /
• 제33권7호
• /
• pp.779-784
• /
• 1996

The spinel/cubic stabilized zirconia composites were fabricated via, The reaction sintering of monoclinic zirco-nia(baddeleyite) added with MgAl powder. During heating Mg and Al were oxidizedfirst and subsequently the oxides formed spinel (MgAl2O4) and finally remained MgO stabilized the zirconia, Because the oxides formed during the oxidation process would have very fine grain size (order of submicron) mainly due to the effects of attrition milling the reaction sintering was more effective in densification and improvement of strength and fracture toughness than conventional sintering with direct addition of MgO. The sintering behavior phase transformation during firing and mechanical properties of sintered body were investigated with emphasis on the relations between spinel formation due to MgAl addition and sintering and mechanical properties.

• 한국세라믹학회지
• /
• 제39권11호
• /
• pp.1028-1034
• /
• 2002

용융침투법을 이용 스피넬/지르코니아-유리 복합체를 제조하여 지르코니아 첨가가 복합체의 기계적 특성에 미치는 영향을 조사하였다. 유리 침투시간이 증가할수록 침투깊이는 Washburn식에 의한 포물선 관계로 증가하였으며 유리 침투상수 K는 기공 크기의 함수로 지르코니아 첨가량이 증가할수록 감소하였다. 지르코니아가 20 wt% 첨가되었을 때 스피넬/지르코니아-유리 복합체의 최적의 강도값(308 MPa)이 관찰되었지만 지르코니아 양이 증가함에 따라 유리 침투 상수와 투과율(transmittance)이 감소하였다. 지르코니아 첨가가 스피넬/지르코니아-유리 복합체의 기계적 특성 향상에 미치는 증진 효과는 크지 않은 것으로 관찰되었다.

• 한국세라믹학회지
• /
• 제32권11호
• /
• pp.1255-1261
• /
• 1995

Mullite-spinel-zirconia composites were prepared by reaction sintering of calcined alumina and magnesia, and zircon powders. The influence of calcining temperature on densification processes and on mechaical properties of subsequently sintered compacts was investigated. The mullite was formed by the reaction of $\alpha$-Al2O3 and amorphous SiO2 at firing temperatures over 141$0^{\circ}C$. The mullitization proceeded more rapidly in the specimen calcined at 110$0^{\circ}C$ than at either 120$0^{\circ}C$ or 130$0^{\circ}C$. Microstructures before and after the mullitization (or mullite dissociation) showed different morphologies, and their effects on mechanical properties were significant. The flexural strength and fracture toughness of the specimen calcined at 130$0^{\circ}C$ and subsequently fired at 145$0^{\circ}C$ were 316 MPa and 4.2Mpa.m1/2, respectively.

• 한국분말야금학회:학술대회논문집
• /
• 한국분말야금학회 2006년도 Extended Abstracts of 2006 POWDER METALLURGY World Congress Part 1
• /
• pp.525-526
• /
• 2006

Calcium-hexaluminate phase $(CA_6)$ is known to be effective for the crack shielding due to the spinel block crystal structure. In this study, we focused to the control of $CA_6$ morphology for good damage tolerance behavior in alumina and zirconia/calcium-hexaluminate $(CA_6)$ composites. Calcium-hexaluminate $(CA_6)$ composites were prepared from zirconia, alumina and calcium carbornate powders. Calcium-hexaluminate $(CA_6)$ phase was obtained by the solid reaction through the formation of intermediate phase $(CA_2)$. $CA_6$ phase showed the column type abnormal grain grown behavior composed of small blocks. Due to the typical microstructure of $CA_6$, alumina and zirconia/calcium-hexaluminate composites provide a well controlled crack propagation behavior.