助烧剂和造孔剂对真空烧结SiC多孔陶瓷性能的影响

Effects of sintering aids and pore former on properties of porous SiC ceramics prepared by vacuum sintering method

以粒度≤0.063mm的SiC为主要原料,分别加入30%(质量分数)的Al2O3-Y2O3与10%的Al2O3-高岭土复合助烧剂,并外加不同量(分别为12.8%、26.3%、30.0%和36.4%)的造孔剂羧甲基纤维素钠(CMC),制样后首先在空气炉中经过300℃2h或1100℃4h的预烧,然后在真空炉中于1550℃4h真空烧结而制备成SiC多孔陶瓷,并研究了助烧剂种类以及造孔剂CMC外加量对SiC多孔陶瓷显微组织、显气孔率及抗折强度的影响。结果显示:采用Al2O3-Y2O3作为助烧剂的SiC多孔陶瓷比Al2O3-高岭土作助烧剂的具有较高的抗折强度,显气孔率稍有减小;随着羧甲基纤维素钠量的增加,加入两种助烧剂的SiC多孔陶瓷均表现为显气孔率增加,抗折强度降低。

Specimens are prepared by using SiC（ ≤0,063 mm） as main starting material, adding 30% Al2O3 -Y2O3 or 10% Al2O3-kaolin respectively as compound sintering aids.Carboxymethyl Cellulose （CMC） as pore former with different additions （26.3% ,30.0% and 36.4% respectively）. Then.the specimens were first）y preheated at 300 ℃ for 2 h or 1100 ℃ for 4 h in air furnace,and then fired at 1550 ℃ for4 h in vacuum furnace ,then porous SiC ceramics were made. The effects of sintering aid variety and the addition of pore former CMC on the microstructure,apparent porosity and modulus of rupture of the porous ceramics were studied. Results show that the porous SiC ceramics by adding Al2O3 - Y2O3 as sintering aid performed higher modulus of rupture and lower apparent porosity compared with those by adding Al2O3-kaolin, With the increase of CMC, porous SiC ceramics by adding either of sintering aids perform increasing apparent porosity and decreasing modulus of rupture,