Al 2 O 3 greatly influences the formation of complex calcium ferrite, which is the main binder and iron-bearing phase in sinter. Experiments were carried out in air at 1200 °C with different amounts of Al 2 O 3 mixed with CaO·Fe 2 O 3 (calcium ferrite). The samples contained two phases: CaFe 2 O 4 and Ca 3.18 Fe 15.38 Al 1.34 O 28 (CFA). The results showed that the morphology of the complex calcium ferrite was massive ( w (Al 2 O 3 ) = 0 pct), columnar and plate-like ( w (Al 2 O 3 ) = 0.5 and 1 pct), and acicular and plate-like ( w (Al 2 O 3 ) = 2, 3, and 5 pct). A small amount of Al 2 O 3 solid solution in CaFe 2 O 4 increased the preferred orientation of the crystal. The gradual increase in Al 2 O 3 in the sintered samples caused the complex calcium ferrite composition to be closer to that of silico-ferrite of calcium and aluminum (acicular SFCA-I). When Al 2 O 3 dissolved into calcium ferrite, complex calcium ferrite was formed, which increased the hardness of the sample. The fracture toughness of the sample increased with increasing Al 2 O 3 content from 0 to 2 pct, possibly due to a decrease in grain size. When the Al 2 O 3 content exceeded 3 pct, Al 2 O 3 dissolved into calcium ferrite and decreased the fracture toughness of the sample.

中文翻译：

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氧化铝对铁氧体钙形貌和力学性能的影响及机理

Al 2 O 3 对复合铁酸钙的形成有很大影响，复合铁酸钙是烧结矿中的主要结合剂和含铁相。实验是在 1200 °C 的空气中用不同量的 Al 2 O 3 与 CaO·Fe 2 O 3 （铁酸钙）混合进行的。样品包含两相：CaFe 2 O 4 和Ca 3.18 Fe 15.38 Al 1.34 O 28 (CFA)。结果表明，复合铁酸钙的形貌为块状（w（Al 2 O 3 ）= 0 pct），柱状和板状（ w（Al 2 O 3 ）= 0.5和1 pct），针状和板状-like (w (Al 2 O 3 ) = 2、3 和 5 pct)。CaFe 2 O 4 中少量的Al 2 O 3 固溶体增加了晶体的择优取向。烧结样品中Al 2 O 3 的逐渐增加导致复合铁酸钙的组成更接近于钙和铝的硅铁酸盐（针状SFCA-I）。当Al 2 O 3 溶解在铁酸钙中时，形成复合铁酸钙，增加了试样的硬度。样品的断裂韧性随着 Al 2 O 3 含量从 0 pct 增加到 2 pct 而增加，这可能是由于晶粒尺寸的减小。当Al 2 O 3 含量超过3%时，Al 2 O 3 溶解在铁酸钙中，降低了试样的断裂韧性。