气氛烧结短切碳纤维增强硅基陶瓷型芯的致密化行为  

Densification behavior in short carbon fiber reinforced silica-based ceramic cores via atmosphere sintering

作　　者：陈义斯 芦刚 严青松 毛蒲 占红星 徐翩 廖青春 CHEN Yisi;LU Gang;YAN Qingsong;MAO Pu;ZHAN Hongxing;XU Pian;LIAO Qingchun(National Defence Key Discipline Laboratory of Light Alloy Processing Science and Technology,Nanchang Hangkong University,Nanchang 330063,China)

机构地区：[1]南昌航空大学轻合金加工科学与技术国防重点学科实验室,南昌330063

出　　处：《复合材料学报》2022年第5期2412-2420,共9页Acta Materiae Compositae Sinica

基　　金：国家自然科学基金(51861027);江西省优势科技创新团队重点项目(20181BCB19001)。

摘　　要：为获得满足高温合金单晶叶片熔模精密铸造用高性能陶瓷型芯,本论文采用超声振动和机械搅拌将短切碳纤维(C_(sf))均匀分散在SiO_(2)基陶瓷浆料中,通过压注法制备型芯生坯并分别在空气和氮气中烧结。观察并分析升温过程中型芯的组织演变及物相转化规律,揭示两种气氛下C_(sf)增强型芯的烧结致密化行为。结果表明,立体互锁C_(sf)网络可以增加陶瓷颗粒之间传质距离,在提供碳源生成原位SiC晶体的同时影响方石英析晶,进而抑制高温下固相的扩散和迁移以及液相的黏性流动。在两种烧结气氛下,随C_(sf)含量的增加,硅基陶瓷型芯的气孔率逐渐上升,收缩率逐渐下降。当C_(sf)含量为1.5vol%时,空气和氮气气氛烧结试样获得的开气孔率最大值为42.95%、39.50%,而最低的收缩率分别为0.64%、0.48%,证实了C_(sf)及高熔点晶体对型芯烧结的致密化行为影响显著。In order to obtain high performance ceramic cores for investment casting of superalloy single crystal blade.In this paper,the short carbon fibers(C_(sf))were uniformly dispersed in silica-based ceramic slurry though synergistic effect of ultrasonic vibration and mechanical stirring,and the green cores were prepared by injection molding method and sintered in air and N_(2) atmosphere,respectively.The microstructure evolution and phase transformation during heating process were thoroughly observed and analyzed,and further revealed the densification behavior of C_(sf) reinforced silica-based ceramic cores under two sintering atmospheres.The results indicate that the C_(sf) can increase the mass transfer distance between ceramic particles,and provide carbon source to grow insitu SiC crystals and affect the crystallization of cristobalite in matrix.Therefore,the diffusion and migration of solid phases and viscous flow of liquid phase in ceramic cores are inhibited by the stereo interlocked network of C_(sf) and the high melt point crystalline phases at high temperature.Moreover,the open porosity of silica-based ceramic cores sintered in both air and N2 atmosphere is increased with the increase of C_(sf) content,while the shrinkage is gradually decreased.When the fiber content is 1.5vol%,as for samples sintered in air atmosphere,the highest open porosities in air and N_(2) sintering atmospheres are about 42.95%and 39.50%,while the least shrinkages are about 0.64%and 0.48%,respectively.It can prove that the C_(sf) and high melting point crystals have significantly influence on the sintering densification behavior of silica-based ceramic cores.

关 键 词：陶瓷型芯 短切碳纤维 致密化 SiC 方石英 收缩率 

分 类 号：TG249[金属学及工艺—铸造]