氮气压力对Si3N4-SiC-TiN陶瓷自蔓延燃烧合成的影响

以TiSi₂为反应原料, SiC 作稀释剂, 利用自蔓延高温合成(SHS) 方法合成Si₃N₄2SiC2TiN 复相陶瓷。计算了氮气压力对毛坯反应物理论转化率的影响, 并在50 、100 和150 MPa 三种氮气压力下进行了燃烧合成。结果表明, 孔隙率为50 vol %的压坯在三种条件下反应都比较完全, 反应物转化率随氮气压力增加而提高。而孔隙率为40 vol %的压坯在较低氮气压力下燃烧反应变得不完全, 产物中残留大片Si 。当压力为150 MPa 时产物中未出现单质Si 。说明氮气压力增大有利于氮气向反应前沿的渗入, 进而提高反应物的转化率。 

Effect of nitrogen pressure on combustion synthesis of Si3N4-SiC-TiN ceramic

The Si3 N4-SiC-TiN multiphase ceramic was synthesized from TiSi2 and SiC powders by self-propagating high-temperature synthesis in which SiC is acting as a diluent. The effect of nitrogen pressure on the conversion degree of the reactant was calculated in theory, and combustion synthesis was carried out under nitrogen pressures of 50, 100 and 150 MPa, respectively. The results show that the green parts of 50 vol% porosity are well nitrified under the three pressures, while those of 40 vol% porosity can not be nitrified completely in which agglomerate Si is found when they were synthesized under lower pressure. However, there is no Si detected in the final products made by 40 vol% porosity parts under 150 MPa nitrogen pressure. Accordingly, the high nitrogen pressure is of advantage to the infiltration of nitrogen and the increase of conversion degree.