Synthesis and Characterization of Silicon Carbide Powders Converted from Metakaolin‐Based Geopolymer
Synthesis and Characterization of Silicon Carbide Powders Converted from Metakaolin‐Based Geopolymer
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DOI：
10.1111/jace.14254
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发表时间：
2016-07
影响因子：
3.9
通讯作者：
C. Bagci;Gregory P. Kutyla;Kevin C. Seymour;W. Kriven
中科院分区：
文献类型：
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作者：
C. Bagci;Gregory P. Kutyla;Kevin C. Seymour;W. Kriven
采用碳热还原法在含纳米碳粉的特殊地质聚合物中合成了碳化硅（SiC）陶瓷粉末。将含有碳并具有组成M2 O·Al 2 O3·4.5SiO2·12 H2O +18 C（其中M是碱金属阳离子（Na+、K+和Cs+））的地质聚合物分别在1400°C、1500°C和1600°C下在流动氩气下碳热反应2小时。通过SEM/EDS和TEM进行X射线衍射和显微结构研究。加热至1400°C以上时，地质聚合物逐渐结晶为SiC，并发生显着的重量损失。SiC被认为是由加热到≥1400°C的Na基地质聚合物产生的主要相，尽管也形成了少量的Al 2 O3。然而，随着温度的升高，产生相纯的SiC。虽然在钾地质聚合物中观察到Al 2 O3量的轻微增加，但在加热至1600°C时，Al 2 O3基本上取代了铯地质聚合物。SEM显示，SiC的形成和成分可变的Al 2 O3含量取决于碱性组合物。钠地质聚合物产生高的SiC转化为纤维状和球状形状，从~5 μm到纳米尺寸，如分别通过X射线衍射以及SEM和TEM所见。
Silicon carbide (SiC) ceramic powders were synthesized by carbothermal reduction in specific geopolymers containing carbon nanopowders. Geopolymers containing carbon and having a composition M2O·Al2O3·4.5SiO2·12H2O+18C, where M is an alkali metal cation (Na+, K+, and Cs+) were carbothermally reacted at 1400°C, 1500°C, and 1600°C, respectively, for 2 h under flowing argon. X‐ray diffraction and microstructural investigations by SEM/EDS and TEM were made. The geopolymers were gradually crystallized into SiC on heating above 1400°C and underwent significant weight loss. SiC was seen as the major phase resulting from Na‐based geopolymer heated to ≥1400°C, even though a minor amount of Al2O3was also formed. However, phase pure SiC resulted with increasing temperature. While a slight increment of the Al2O3amount was seen in potassium geopolymer, Al2O3essentially replaced cesium geopolymer on heating to 1600°C. SEM revealed that SiC formation and a compositionally variable Al2O3content depended on the alkaline composition. Sodium geopolymer produced high SiC conversion into fibrous and globular shapes ranging from ~5 μm to nanosize, as seen by X‐ray diffraction as well as SEM and TEM, respectively.