The heterogeneous nucleation behaviors of NHaCI crystal on a rough chilling surface of aluminum immerged in NHaCI-H20 solution were experimentally analyzed and the relationship between the surface roughness and the nu...The heterogeneous nucleation behaviors of NHaCI crystal on a rough chilling surface of aluminum immerged in NHaCI-H20 solution were experimentally analyzed and the relationship between the surface roughness and the nucleation site selection behaviors on polished aluminum substrate was investigated, and it was discovered that the number of nucleation sites decreases significantly with decreasing the roughness of the polished substrate. Further nucleation experiments were carried out on chemically etched aluminum substrate with regular micro- morphology on its surface. It has been shown that both the micro-morphology and the wettability vary with the substrate surface prepared by different etching process. The prepared surface with step-like structures has a strong wettability with NH4CI-70 wt% H20 solution and the nucleation density of NH4CI on the its surfaces is significantly higher than that of the reference surfaces, which shows that the geometrical morphology features have important effects on both the wettability and the nucleation behaviors.展开更多
基金supported by the National Natural Science Foundation of China (No. 50901061 and 50971102)the National Key Basic Research Project of China (No. 2011CB610402)the research fund of the State Key Laboratory of Solidification Processing (NWPU), China(Grant No. 02-TZ-2008, 36-TP-2009)
文摘The heterogeneous nucleation behaviors of NHaCI crystal on a rough chilling surface of aluminum immerged in NHaCI-H20 solution were experimentally analyzed and the relationship between the surface roughness and the nucleation site selection behaviors on polished aluminum substrate was investigated, and it was discovered that the number of nucleation sites decreases significantly with decreasing the roughness of the polished substrate. Further nucleation experiments were carried out on chemically etched aluminum substrate with regular micro- morphology on its surface. It has been shown that both the micro-morphology and the wettability vary with the substrate surface prepared by different etching process. The prepared surface with step-like structures has a strong wettability with NH4CI-70 wt% H20 solution and the nucleation density of NH4CI on the its surfaces is significantly higher than that of the reference surfaces, which shows that the geometrical morphology features have important effects on both the wettability and the nucleation behaviors.
