Abstract We explore the influence (i) of the interaction between aluminium and alumina, and (ii) of sodium impurities present in Bayer alumina, on the pressure infiltration of alumina particle preforms with molten aluminium. At 1000°C or above, although the aluminium/alumina system is non-reactive, capillarity-driven solution-reprecipitation processes cause the liquid-solid interface to become mobile. Data show that this can result in infiltration kinetics that resemble those observed with reaction-driven pressure infiltration, namely a continuously increasing melt saturation under fixed infiltration pressure. Resulting isobaric saturation velocities are measured at 1000°C, 1050°C and 1100°C. The role of alumina particle shape and of Na-containing inclusions is investigated. It is found that the main factors affecting the rate of high-temperature isobaric infiltration in this system is the particle geometry. Measured steady infiltration rates give an activation volume on the order of ≈ 200 nm3 and an activation energy in the range of 300-500 k J m o l , suggesting that isobaric infiltration kinetics are governed by diffusion through the solid alumina. Sodium impurities of Bayer alumina are present within β″-Al2O3. They do not influence steady pressure infiltration but ease initial melt penetration into the preform, possibly because evaporated Na2O alters the oxide skin layer that lines the surface of molten aluminium.

中文翻译：

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Al高温压力渗入Al2O3的动力学过程

摘要 我们探讨了 (i) 铝和氧化铝之间的相互作用以及 (ii) 拜耳氧化铝中存在的钠杂质对氧化铝颗粒预制件与熔融铝的压力渗透的影响。在 1000°C 或更高温度下，虽然铝/氧化铝系统是非反应性的，但毛细管驱动的溶液再沉淀过程会导致液固界面变得可移动。数据表明，这会导致渗透动力学类似于反应驱动压力渗透观察到的那些，即在固定渗透压力下不断增加熔体饱和度。在 1000°C、1050°C 和 1100°C 下测量得到的等压饱和速度。研究了氧化铝颗粒形状和含钠夹杂物的作用。发现影响该系统中高温等压渗透速率的主要因素是颗粒几何形状。测量的稳定渗透率给出了大约 200 nm3 的活化体积和 300-500 k J mol 范围内的活化能，这表明等压渗透动力学受通过固体氧化铝的扩散控制。拜耳氧化铝的钠杂质存在于β″-Al2O3中。它们不会影响稳定压力渗透，但可以缓解初始熔体渗透到预制件中，这可能是因为蒸发的 Na2O 改变了排列在熔融铝表面的氧化皮层。测量的稳定渗透率给出了大约 200 nm3 的活化体积和 300-500 k J mol 范围内的活化能，这表明等压渗透动力学受通过固体氧化铝的扩散控制。拜耳氧化铝的钠杂质存在于β″-Al2O3中。它们不会影响稳定压力渗透，但可以缓解初始熔体渗透到预制件中，这可能是因为蒸发的 Na2O 改变了排列在熔融铝表面的氧化皮层。测量的稳定渗透率给出了大约 200 nm3 的活化体积和 300-500 k J mol 范围内的活化能，这表明等压渗透动力学受通过固体氧化铝的扩散控制。拜耳氧化铝的钠杂质存在于β″-Al2O3中。它们不会影响稳定压力渗透，但可以缓解初始熔体渗透到预制件中，这可能是因为蒸发的 Na2O 改变了排列在熔融铝表面的氧化皮层。