용융염계에서 자전연소합성법에 의한 α-Si3N4분말의 제조 - 2. 반응물의 증가 |
윤기석, 양범석, 박영철, 원창환 |
충남대학교 급속응고센터 |
Preparation of α-Si3N4 Powder in Reaction System Containing Molten Salt by SHS - Part 2. Scale-Up |
Yun Ki Seok , Yang Beom Seok , Park Young Cheol , Won Cang Whan |
|
|
|
|
ABSTRACT |
The variation of the reaction pressure and reaction product during the reaction was investigated according to the total mass of the reaction mixture at the optimum composition for the preparation of u-Si3N4 powder which had been confirmed in the former investigation; 'Preparation of $alpha$-Si$_3$N$_4$ powder in reaction system containing molten salt by SHS - part 1. synthesizing of powder'. When the total mass of the reaction mixture was 100g, the minimum pressure for a complete reaction was 60atm in 5L reactor, whereas the reaction was incomplete in the case that the mass exceeded 200g because of pressure increase. Also, as the mass of the reaction mixture increased, the reactivity linearly decreased. Hence, the complete reaction was realized by decreasing an initial $N_2$ pressure, and thus obtained minimum initial pressure was recorded 20 atm for the initial mixture of 500g. The reason of the incomplete reaction with pressure Increase was found to be that NH$_4$Cl vapour which was suppressed by the gas pressure acted as a diluent. |
Key words:
SHS, Initial pressure, Total mass, $NH_4$Cl vapour |
|
|
|