Abstract
The main objective of this work was to study the efTect of pressed density of pellets prepared from an oxide powder on their fired density and to prove experimentally the parabolic relationship proposed by FORD. A-I6 and A-J7 alumina powders. which showed quite dlfrerent powder characteristics but were essentially very reactive powders, were employed, and a series of pelIets weIe pressed in a 1l.2mm diameter hardened steel die with a hydraulic press and a mechanically operated press in order to obtain a wide range of pressed demity. Density ranges from 35 to 65 % theoretical for A-16, and 46 to 66 % theoretical far A-17 were obtained and the highest pressed density achieved using lubricant was 67.8 % theoretical. CompactlOn mechanisms for A-16 and A-I 7 were deduced. Several plots of ($D_F$-$D_P$) against DpjDT showed reasonable parabola and temperature dependence and the maximum density increase occurred when the pressed density was approximately 50% theoretical. The parabolic relationship was confirmed by linear plot of ($D_F$-$D_P$) against (1-$\frac{D_P}{D_T})$).
본 논문은 알루미나의 초기 성형밀도가 소결후 소결밀도에 미치는 영향에 대한 것이다. 실험에서는 두가지의 Reactive alumina powder (ALCOA A-16, A-17)를 사용하였으며, 넓은 범위의 성형밀도를 얻기 위하여 낮은 성형압을 가할 수 있는 기계적으로 작동하는 press와, 높은 성형압을 가할 수 있는 유압식 press를 사용하여, 이론밀도의 35%에서 65% 범위의 시편들 (A-16 alumina powder)과 46%에서 66% 범위의 시편들 (A-17 alumina powder)을 준비하였다. 성형밀도를 Log (성형압)에 대해 plot해 A-16과 A-17 alumina powder들에 대한 Compaction mechanism이 추론되었다. 1350, 1450, 155$0^{\circ}C$에서 소결하여 밀도증가량 ($D_T$-$D_P$)을 상대 성형밀도($D_P$/$D_T$) 에 대해 plot해 Ford가 제안한 두 변수 사이의 포물선 관계가 잘 성립 함을 보였다.