Abstract In this investigation, we studied the reaction-sintering between fluorapatite and alumina using natural phosphate and boehmite. The addition of alumina, resulting from the boehmite transitions, to the fluorapatite (FAp) has been carried out to obtain various composites based on FAp, yeelemite, mayenite, grossite (CA2), hibonite (CA6) and β-TCP. Several samples were prepared by varying the boehmite (AlOOH) amount to obtain six compositions which contain after sintering: 5, 10, 15, 20, 25 and 30 wt% of Al2O3. After ball-milling for 5 h, all compositions were sintered in the air for 2 h at different temperatures ranging from 1000 to 1500 °C. The reactions and phase transformations between fluorapatite and boehmite were studied and characterized by DTA/TG, XRD, FT-IR, apparent density and open porosity measurements, micro-hardness and SEM analysis. The micro-hardness and densification of the sintered body showed a marked improvement by increasing the alumina content and sintering temperature. Especially, sample containing 25% alumina exhibited the highest densification at 1400 °C (2.95 g/cm3) and excellent micro-hardness of about 6.5 ± 0.25 GPa. So the preparation of low cost composites based on fluorapatite, yeelimite and grossite from natural phosphate and alumina are feasible.

中文翻译：

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天然磷酸盐和氧化铝制备的氟磷灰石基复合材料的烧结行为

摘要 在这项研究中，我们研究了氟磷灰石和氧化铝之间使用天然磷酸盐和勃姆石的反应烧结。已经进行了由勃姆石转变产生的氧化铝添加到氟磷灰石 (FAp) 中以获得基于 FAp、yeelemite、钙铝石、格罗长石 (CA2)、hibonite (CA6) 和 β-TCP 的各种复合材料。通过改变勃姆石 (AlOOH) 的量来制备几个样品以获得六种组合物，其在烧结后包含：5、10、15、20、25 和 30 重量％的 Al 2 O 3 。球磨 5 小时后，所有组合物在空气中在 1000 至 1500 °C 的不同温度下烧结 2 小时。通过 DTA/TG、XRD、FT-IR、表观密度和开孔率测量研究和表征了氟磷灰石和勃姆石之间的反应和相变，显微硬度和SEM分析。通过提高氧化铝含量和烧结温度，烧结体的显微硬度和致密化表现出明显的改善。特别是，含有 25% 氧化铝的样品在 1400 °C (2.95 g/cm3) 下表现出最高的致密化和约 6.5 ± 0.25 GPa 的优异显微硬度。因此，用天然磷酸盐和氧化铝制备基于氟磷灰石、磷灰石和粗长石的低成本复合材料是可行的。