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结合气固反应和重结晶烧结,制备了烧结颈结构可控的多孔重结晶SiC陶瓷。首先以微米SiC颗粒作为骨架,通过SiO气体和纳米炭黑的高温气固反应得到纳米碳化硅均匀分布的预烧结体;再对预烧结体进行重结晶处理,通过纳米SiC颗粒的低温蒸发凝聚获取高纯度的SiC多孔陶瓷。研究了重结晶过程中烧结温度对多孔SiC陶瓷的烧结颈、显微形貌、以及力学性能的影响规律。结果表明:SiC晶粒之间的烧结颈参数(烧结颈直径/微米SiC晶粒直径,d/d0)决定了多孔材料的抗弯强度。随着烧结温度增加,纳米SiC颗粒的饱和蒸气压升高,加速了蒸发–凝聚的进行,物质传输总量增加,多孔SiC材料的d/d0值增加,抗弯强度迅速升高,达到峰值后,基本保持不变或者略有下降。温度高于2100℃时,骨架SiC微米颗粒会发生分解反应产生残碳,导致材料的抗弯强度降低。原位合成的纳米SiC含量为20%,在Ar气氛中于2000℃保温1h后,材料组织性能最优,烧结颈面积的平均值为15.91μm2,d/d0值为99.7%,气孔率为42.4%,抗弯强度高达75.7MPa,其性能优于商用柴油颗粒物过滤材料。
Abstract：Porous SiC ceramics were prepared via vapor-solid reaction and subsequent recrystallization sintering. Firstly, the micron-sized SiC particles were used as a skeleton, and the pre-sintered SiC bodies with an uniform distribution were obtained via high-temperature gas-solid reaction between SiO gas and nano-carbon black. After recrystallization of pre-sintered SiC bodies, high purity SiC porous ceramics were obtained via evaporation condensation of nano-sized SiC particles at a lower temperature. The influence of sintering temperature on the sintering neck between SiC grains and mechanical properties of porous SiC ceramics during recrystallization was investigated. The results show that the parameter of sintering neck between SiC grains(the average diameter of neck/the average diameter of micron-size SiC grains, d/d0) determines the flexural strength of porous materials. The saturated vapor pressure of nano-size SiC increases with the increase of sintering temperature, accelerating the evaporation-condensation process, increasing the total amount of mass transfer and the d/d0 value of porous Si C material. Consequently, the bending strength considerably increases to a maximum value and then remains unchanged or slightly decreases. At >2 100 ℃, graphite phase is formed beside α-SiC phase due to the decomposition of silicon carbide. A remarkable average necking area of 15.91 μm2(at d/d0 of 99.7%) and outstanding flexural strength of 75.7 MPa for the porous SiC ceramics with 42.4% porosity sintered at 2 000 ℃ can be achieved when 20%(in mass fraction) nano-sized SiC particles are added. The performance of the porous SiC ceramics is better than that of commercial diesel particulate filter materials.
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基本信息:
DOI：10.14062/j.issn.0454-5648.2019.09.03
中图分类号:TQ174.758.12
引用信息:
[1]周小楠,张建飞,黄鑫,等.多孔重结晶碳化硅陶瓷的烧结颈结构调控与力学性能[J].硅酸盐学报,2019,47(09):1208-1213.DOI:10.14062/j.issn.0454-5648.2019.09.03.
基金信息:
国家自然科学基金面上项目(51872223;51672209);; 陕西省自然科学基金青年人才项目(2016JQ5046)
2018-12-31
2018
2019-07-12
2019-07-10
2019
1
2019-07-09
2019-07-09
2019-07-09