活性填料对聚碳硅烷基悬浮液直写成形3D碳化硅的影响

分别采用纳米钛粉(Ti)和氧化亚镍粉(NiO)为活性填料,聚碳硅烷(polycarbosilane,PCS)为碳化硅(SiC)陶瓷先驱体,以正己烷作为溶剂制备浆料,然后通过3D直写成形和高温裂解制备SiC陶瓷基复合材料,对浆料的流变性能以及SiC陶瓷基复合材料的物相和微观形貌进行表征,研究活性填料纳米Ti粉和纳米NiO粉对3D-SiC陶瓷基复合材料的物相与微观形貌的影响。结果表明,浆料的黏度与PCS的质量分数成正比,具有剪切变稀现象,w(PCS)为75%的浆料具有稳定的打印性能。纳米Ti粉可有效降低成形坯体热处理过程中的质量损失率和线收缩率。随m(Ti)/m(PCS)的值从0增加到1.0,1 450℃高温裂解后陶瓷的质量损失率和线收缩率分别由18.29%和24.38%降低至14.05%和12.13%,所得陶瓷包含Ti C和SiC两相,相比于Ti粉,NiO可作为SiC的表面修饰催化剂,并通过气-液-固(V-L-S)生长机制使SiC陶瓷表面原位生长SiC晶须团簇。

Effect of active fillers on direct ink writing 3D SiC on polycarbosilane suspension

SiC ceramic matrix composites were prepared by 3D direct ink and phrolysis writing using nano Ti and NiO particles as active fillers,polycarbosilane(PCS)as SiC ceramic precursor,n-hexane as solvent to prepare slurries.The rheological properties of the slurries were investigated.The phase and morphology of the ceramic matrix composites were characterized.The effects of active fillers(nano Ti particles and nano NiO particles)on the phase and morphology of 3D-SiC ceramic matrix composites were studied.The results show that the viscosity of the slurry is proportional to the mass fraction of PCS,and it has shear thinning phenomenon.The slurry with 75%PCS has stable printing performance.The nano Ti powder can effectively reduce the mass loss rate and linear shrinkage rate during pyrolysis at 1450℃,and the mass loss and linear shrinkage decrease from 18.29%and 24.38%to 14.05%and 12.13%respectively,the ceramics contains TiC and SiC phases.Compared with Ti powder,NiO can be used as a surface modification catalyst for SiC,and SiC whisker clusters can be grown in situ on the surface of SiC ceramics through the gas liquid solid(V-L-S)growth mechanism.