离心力场中Al2O3纤维多孔体中的过临界渗透现象

Over-critical Infiltration of Mercury through Al_2O_3 Fiber Porous Perform in Centrifugal Force Field

针对离心渗透过程,以Al2O3纤维制成多孔预制体,在室温条件下,开展了水银在多孔预制体中的离心渗透试验研究,采用X射线透射仪对过临界渗透试样进行拍片。测试结果表明,水银在多孔预制体中的过临界渗透是以滴流、离散的柱状流和断续的片状流等形式向前渗透。初始界面上,在某些满足渗透条件的孔隙中先行发生离散渗透,到达预制体的尾部后积聚并反向密实填充。这种在初始界面上局部发生的离散渗透,使得同一界面上孔径相同的其他孔隙中发生渗透的几率大大降低,主要原因是固定转速下,初始界面的离心力随着水银的渗入而减小。渗透试样的透射结果显示,离心力场中产生的科氏力对离散渗透流型有重要的影响。

Over-critical infiltration behavior of mercury through Al2O3 fiber porous perform was observed by XRD(X-ray diffraction)and TEM(transmission electron microscope)at room temperature in centrifugal force field.The results reveal that during over-critical infiltration in the perform,mercury is advanced in such types as dribble flow,discrete column flow or intermittent laminar flow.Discrete infiltration is prior to appear in those porosities on the initial boundary where the infiltration condition is met,and it arrives at the end of the perform to accumulate then backward filling densely,which greatly decreases infiltration possibility in other porosities with the same diameters as a result of the decrease of centrifugal force on the initial boundary with increasing in mercury infiltration at a given rotary speed.XRD observation reveals that the Coriolis forces generated from the centrifugal forces field has the great effects on the discrete infiltration.