Influence of multi-walled carbon nanotubes on the fracture response and phase distribution of metakaolin-based potassium geopolymers
Influence of multi-walled carbon nanotubes on the fracture response and phase distribution of metakaolin-based potassium geopolymers
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DOI：
10.1007/s10853-021-06547-0
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发表时间：
2021-10-11
影响因子：
4.5
通讯作者：
Akono, Ange-Therese
中科院分区：
文献类型：
--
作者：
Chen, Jiaxin;Akono, Ange-Therese
研究了多壁碳纳米管（MWCNTs）对钾基偏高岭土地质聚合物的化学性质、微观结构、相分布和断裂响应的影响。我们制定了新的协议，铸造地质聚合物增强0.3，0.6和1.5重量%的多壁碳纳米管。我们使用XRD、FTIR和固态Si-29 NMR研究了化学。我们采用显微成像和高分辨率扫描电子显微镜表征了多壁碳纳米管地质聚合物的微观结构和分散状态。我们使用划痕试验和压痕试验评估断裂行为和机械性能。我们使用聚类分析的压痕结果来研究相分布。多壁碳纳米管分散良好，平均累积面积小于8.9 μ m（2）。XRD表明MWCNTs保持了非晶相。NMR结果表明，MWCNTs的加入降低了Q（4）（Al 2）的含量，但增加了Q（4）（Al 3）的含量。我们观察到的微观结构的致密化和孔隙率的减少。微观结构表明，多壁碳纳米管作为桥梁的断裂面和孔隙的连接。添加0.6重量%的多壁碳纳米管的强度增加了3.2%，刚度增加了11.1%。同时，添加1.5wt%的MWCNTs添加量增加了10.5%的断裂韧性。观察到内强化效应，因为多壁碳纳米管减少了微孔，导致主要微相的压痕模量和硬度增加。因此，多壁碳纳米管促进了地聚合反应，增强了地聚合物骨架，影响了孔结构，改善了力学性能。
This research investigated the effects of multi-walled carbon nanotubes (MWCNTs) on the chemistry, microstructure, phase distribution, and fracture response of potassium-based metakaolin geopolymers at the microscopic scale. We formulated novel protocols to cast geopolymers reinforced with 0.3, 0.6, and 1.5 wt% MWCNTs. We studied the chemistry using XRD, FTIR, and solid state Si-29 NMR. We characterized the microstructure and dispersion state of MWCNTs geopolymers using microscopic imaging and high-resolution scanning electron microscopy. We assessed the fracture behavior and mechanical properties using scratch tests and indentation tests. We used cluster analysis of indentation results to study the phase distribution. MWCNTs were well dispersed with an average accumulated area less than 8.9 mu m(2). XRD showed that MWCNTs preserved the amorphous phase. NMR showed that the addition of MWCNTs decreased Q(4) (Al2) fraction, but increased Q(4) (Al3) fraction. We observed a densification of the microstructure and a reduction in porosity. The microstructure showed that MWCNTs acted as bridges for fracture surfaces and connections for pores. The addition of 0.6 wt% MWCNTs increased the strength by 3.2%, and stiffness by 11.1%. Meanwhile, the addition of 1.5 wt% MWCNTs addition increased the fracture toughness by 10.5%. An inner strengthening effect was observed as MWCNTs reduced the microporosity, resulting in an increase in the indentation modulus and hardness for the dominant microphase. Therefore, MWCNTs promote the geopolymerization reaction, strengthen the geopolymer skeleton, affect the pore structure, and improve mechanical characteristics.