Structure and rheology of iron-bearing Na2O-Al2O3-SiO2 melts
Structure and rheology of iron-bearing Na2O-Al2O3-SiO2 melts
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含铁Na2O-Al2O3-SiO2熔体的结构和流变学
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发表时间：
2005
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通讯作者：
S. Webb
中科院分区：
文献类型：
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作者：
S. Webb
用微渗透法测定了Na2O-FeO-Fe2O-Al_2O_3-SiO_2系熔体的粘度。在SiO_2含量不变的情况下，含Fe熔体的粘度与不含Fe的Na2O-Al_2O_3-SiO_2熔体具有相同的组成趋势：粘度随着过碱度的降低而增加，而对于过铝领域中所研究的所有成分，粘度几乎保持不变。在无铁过铝组分中加入1摩尔%的Fe_2O_3使粘度降低~1log10Pa.S，而在过碱组分中加入~3摩尔%的Fe_2O_3才能产生类似的粘度降低。过铝熔体结构中需要更多的电荷平衡阳离子似乎控制了Fe2+/Fettal，过铝组分具有较大的Fe2+/Fettal(0.6)，而过碱性组分的Fe2+/Fettal(0.3)。尽管过铝组分熔体中可能存在三团簇，但在粘度为1012PaS[Be/Sconf(Tg)]下计算的组态熵项表明，流动过程不是在三团簇位置开始的。因此，过碱熔体和过铝熔体不仅具有不同的结构，而且流动过程也略有不同。这些差异反映在粘性流动的粘度、活化能和计算的Be/Sconf(Tg)项上。
The viscosity of a series of Na2O-FeO-Fe2O3-Al2O3-SiO2 melts has been measured by micropenetration methods. The viscosity of the Fe-bearing melts follows the same compositional trend as the Fe-free Na2O-Al2O3-SiO2 melts as a function of Na/Al at constant SiO2 content: viscosity increases with decreasing peralkalinity and remains almost constant for all investigated compositions in the peraluminous field. The addition of 1 mol% Fe2O3 to the Fe-free peraluminous compositions causes ~1 log10 Pa s decrease in viscosity, while ~3 mol% Fe2O3 needs to be added to the peralkaline compositions to produce a similar decrease in viscosity. The need for more charge-balancing cations in the peraluminous melt structure appears to control the Fe2+/Fetotal, with the peraluminous compositions having a large Fe2+/Fetotal (0.6) compared with that for the peralkaline compositions (0.3). Although triclusters probably exist in peraluminous composition melts, the configurational entropy term at a viscosity of 1012 Pa s [Be/Sconf(Tg)] calculated for these melts suggests that the flow process is not initiated at a tri-cluster site. Thus the peralkaline and peraluminous melts have not only different structures but also slightly different flow processes. These differences are reflected in the viscosity, activation energy for viscous flow and calculated Be/Sconf(Tg) term.