摘要
采用球形纳米氧化铝颗粒制备氧化铝微晶陶瓷,研究造粒、烧结等工艺过程对陶瓷微观结构和力学性能的影响,并结合动力学计算分析球形颗粒在烧结过程中的传质特性。结果表明:通过液相造粒掺入0.8%(质量分数)的PVA能够优化球形颗粒的压制成型并提高坯体密度。烧结温度从1400℃提高至1550℃,陶瓷相对致密度由74.1%增大至97.5%,而晶粒尺寸由0.6μm仅增至1.4μm,这与球形颗粒自身稳定的形态及其堆积形成的均匀孔隙有关。在1550℃下烧结时间由30 min延长至120 min时,气孔率由4.8%降低至0.4%,晶粒尺寸则由1.2μm增至2.7μm。另外,通过动力学计算得出球形颗粒的烧结活化能为788 kJ/mol,证实球形颗粒在烧结前期和中期具有生长惰性,利于获得微晶结构。经1550℃保温90 min的陶瓷,其密度达到98.9%,平均晶粒尺寸仅为1.6μm,硬度达到26.4 GPa,弯曲强度为574 MPa。
The spherical and dense alumina nanoparticles were used to prepare alumina microcrystalline ceramics. The effect of granulation and sintering parameters on the microstructure and mechanical properties of the ceramics was studied. The results show that fine green body can be obtained with the addition of 0.8%(mass fraction) PVA, and the density of green body can also be improved. With the increase of sintering temperature from 1400 ℃ to 1550 ℃, the density is increased from 74.1% to 97.5%, while the grain size of the ceramics is only increased gradually from 0.6 μm to 1.4 μm owing to the stable spherical shape and the uniformly packed pores. With the increase of holding time from 30 min to 120 min at 1550 ℃, the porosity is decreased from 4.8% to 0.4%, and the grain size is then increased from 1.2 μm to 2.7 μm. Besides, the sintering activation energy of the employed spheres is 788 kJ/mol, which proves that the particles are inactive during earlier and medium stage of sintering, and the spheres are benefit to obtain microcrystalline ceramics. The ceramic sintered at 1550 ℃ for 90 min has a density of 98.9%, an average grain size of 1.6 μm, a hardness of 26.4 GPa and a bending strength of 574 MPa.
作者
孙志强
张剑
杨小波
王华栋
韩耀
吕毅
李淑琴
SUN Zhi-qiang;ZHANG Jian;YANG Xiao-bo;WANG Hua-dong;HAN Yao;LYU Yi;LI Shu-qin(Aerospace Institute of Advanced Materials&Processing Technology,Beijing 100074,China)
出处
《材料工程》
EI
CAS
CSCD
北大核心
2020年第3期127-133,共7页
Journal of Materials Engineering
基金
国家自然科学基金项目(51802298)
关键词
氧化铝陶瓷
微晶结构
球形颗粒
传质
alumina ceramics
microcrystalline structure
spherical particle
mass transfer
作者简介
通讯作者:孙志强(1989-),男,工程师,博士,研究方向:功能陶瓷,联系地址:北京市丰台区云冈北区40号,航天特种材料及工艺技术研究所(100074),E-mail:sunzhiqiang1203@126.com。
