In situ Ca-F cluster formation during crystallisation of mold fluxes

Mold fluxes are used as sort of ‘lubricants’ for molten steel, and are prepared as mixtures of calcite, flurite, some SiO2, and some Na: these mixtures are tailored to melt at certain temperature, providing a molten layer that works as a lubricant. These melts, at lower T, start to crystallise, forming a mineral called cuspidine and some other Ca-silicates. The very beginning of the process is the most interesting part, because what happens (likely the formation of Ca-F clusters) changes radically the rheological properties of the material, and therefore its ability to function as a lubricant. The idea behind this proposal is to first start the structure of these amorphous materials ex-situ, and then to study the onset of crystallisation from melt, looking for Ca-F clusters, which, if present and depending on their size, changes considerably the rheological properties of the material.

保护渣被用作钢水的一类“润滑剂”，其制备原料为方解石、萤石（flurite）、少量二氧化硅（SiO₂）及钠的混合物：这些混合物经定制可在特定温度下熔化，形成一层具有润滑作用的熔融层。这些熔融物在温度降低时开始结晶，生成枪晶石（cuspidine）及其他钙硅酸盐矿物。该过程的初始阶段尤为关键，因其发生的变化（可能为钙-氟簇（Ca-F clusters）的形成）会显著改变材料的流变性能（rheological properties），进而影响其润滑功能。本研究方案的核心思路是，先在非原位（ex-situ）条件下构建这些无定形材料的结构，再研究其从熔融态结晶的起始阶段，探寻钙-氟簇；若存在此类簇且其尺寸不同，则会显著改变材料的流变性能。