The principal chemical components in iron ore sintering are Fe2O3, CaO, and SiO2. This sintering process consists of three key steps: heating, holding at peak temperature, and cooling. During the cooling stage, a liquid oxide solidifies to form the final sinter microstructures. To investigate the fundamental processes taking place during the cooling of sinters, a new experimental technique has been developed that allows the stages of solidification to be determined in isolation, rather than inferred from the final microstructures. Fe2O3-CaO-SiO2 oxide samples of a bulk composition having a CaO/SiO2 mass ratio of 3.46 and 73.2 wt pct Fe2O3 were cooled in air from 1623 K (1350 °C) at 2 K/s, quenched at 5 K temperature intervals from 1533 K to 1453 K (1260 °C to 1180 °C), and analyzed using Electron Probe Micro X-Ray Analysis (EPMA). During cooling, four distinct stages were observed, consisting of the phase assemblages Liquid + Hematite (I), Liquid + Hematite + C2S(II), Liquid + C2S + CF2(III), and C2S + CF2 + CF (IV). This solidification sequence differs from that predicted under equilibrium and Scheil–Gulliver Cooling. Importantly, no Silico-Ferrite of Calcium (SFC) phase was observed to form on solidification of the liquid. Based on the microstructures formed and liquid compositions, measured by EPMA, it was demonstrated that kinetic factors play a major role in determining the phases and microstructures formed under the conditions investigated.

中文翻译：

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“Fe2O3”-CaO-SiO2 液体在空气中受控凝固过程中的微观结构演变

铁矿石烧结的主要化学成分是 Fe2O3、CaO 和 SiO2。该烧结过程包括三个关键步骤：加热、保持在峰值温度和冷却。在冷却阶段，液态氧化物固化形成最终的烧结微结构。为了研究烧结体冷却过程中发生的基本过程，开发了一种新的实验技术，可以单独确定凝固阶段，而不是从最终的微观结构中推断出来。具有 CaO/SiO2 质量比为 3.46 和 73.2 wt pct Fe2O3 的整体组成的 Fe2O3-CaO-SiO2 氧化物样品在空气中以 2 K/s 从 1623 K (1350 °C) 冷却，以 5 K 的温度间隔从1533 K 至 1453 K（1260 °C 至 1180 °C），并使用电子探针微 X 射线分析 (EPMA) 进行分析。在冷却过程中，观察到四个不同的阶段，包括液体 + 赤铁矿 (I)、液体 + 赤铁矿 + C2S(II)、液体 + C2S + CF2(III) 和 C2S + CF2 + CF (IV) 的相组合。这种凝固顺序与在平衡和 Scheil-Gulliver 冷却下预测的不同。重要的是，没有观察到在液体凝固时形成硅铁酸钙 (SFC) 相。基于通过 EPMA 测量的微观结构和液体成分，表明动力学因素在确定所研究条件下形成的相和微观结构中起主要作用。这种凝固顺序与在平衡和 Scheil-Gulliver 冷却下预测的不同。重要的是，没有观察到在液体凝固时形成硅铁酸钙 (SFC) 相。基于通过 EPMA 测量的微观结构和液体成分，表明动力学因素在确定所研究条件下形成的相和微观结构中起主要作用。这种凝固顺序与在平衡和 Scheil-Gulliver 冷却下预测的不同。重要的是，没有观察到在液体凝固时形成硅铁酸钙 (SFC) 相。基于通过 EPMA 测量的微观结构和液体成分，表明动力学因素在确定所研究条件下形成的相和微观结构中起主要作用。