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通过模压成型和高温烧结制备了不同SiCP颗粒尺寸(20、50、100和150 μm)的预制体,采用高分辨率(～1.0μm)三维X射线断层扫描和三维孔隙网络结构模型,研究了SiCP颗粒尺寸对预制体孔洞三维特征的影响.结果表明:随着SiCP颗粒尺寸的增大,淀粉的间隙膨胀作用逐渐减弱,而颗粒堆积间隙逐渐增大.当SiCP颗粒尺寸由20 μm增大到100 μm时,截面孔洞形貌更加平齐,面孔隙率均值减小,孔洞体积的空间分布均匀性和连通性都变差,孔洞和喉道的平均尺寸增大,而小尺寸孔喉数量减少,平均孔洞配位数减小;当颗粒尺寸继续增大至150μm时,间隙被更多较小尺寸颗粒填充,且颗粒表面残留网状粘结剂,都大大降低了孔洞体积的空间分布均匀性和连通性,使小尺寸孔喉数量增多,平均孔洞配位数增大.

Silicon carbide particle (SiCP) preforms with the particles sizes of 20 μ m,50 μm,100 μm and 150 μm were prepared by compression mold forming and sinter process.High resolution (～ 1.0 μm) 3D X-ray microcomputed tomography combined with 3D pore-network models was used to study the effect of SiCP particle size on the 3D morphologies and spatial structures of pores in the SiCP preforms.The results show that the increase of the SiCP particle size reduces the gap expansions caused by the starch decomposition and enlarges the interval voids among the packed particles.As the SiCP particle size increasing from 20 μm to 100 μm,the pore shapes in the preform sections become more irregular,and hence the average area porosity of pores decreases as well as the spatial volume distribution homogeneity and the connectivity of pores become worse.In the pore-networks,the average effective sizes of both pores and throats increases,whereas the number of small pores or throats and the average pore coordination number decrease.When the SiCP particle size reaches up to 150 μm,the larger gaps can be filled by more small particles and the pore spaces are segmented by the residual netlike binders on the particles surface,so that the spatial distribution homogeneity of pore volumes and the connectivity decrease significantly.Therefore in the pore-networks,the number of small pores or throats and the average pore coordination number increase.