Condensation Process of Gaseous Molecules on Thermal and Chemical Active Surfaces

采用分子动力学方法，利用Lennard-Jones（6-12）势数值研究了气态氩气分子在冷凝物上的冷凝过程。此外，还在真空室内实验研究了金属（Ti, Zr, Fe, Co， Cu和Ag）和非金属（C和Si）蒸气在固体表面的非均相冷凝过程，考察了它们的团簇分布对冷凝过程的影响。(1)结果没有显示出明显的界面表面结构，但在凝结水内部观察到有序结构。(2)进入冷凝液的温度较高的分子在界面附近的集中程度高于聚集在界面周围的温度较低的分子。(3)凝结和蒸发的能量流在相变界面内有一个峰值。(4)金属蒸气中团簇的浓度相当高，即它们的数目密度不小于单体。(5)金属蒸汽形成的薄膜厚度随时间成比例增加，即凝结速率几乎恒定，而非金属蒸汽形成的薄膜厚度不呈线性增加。(6)随着腔压的降低，铁（Fe）的凝结率增大。

The condensation process of gaseous molecules of argon on their condensate is studied numerically by using the molecular dynamics method with the Lennard-Jones (6-12) potential. Further, the heterogeneous condensation process by metallic (Ti, Zr, Fe, Co, Cu and Ag) and nonmetallic (C and Si) vapors on solid surfaces is also studied experimentally in vacuum chamber to investigate the effect of their cluster distribution on the condensation process.(1) Any evidence of significant interfacial surface structure is not shown in the results, but inside the condensate ordered structures are observed.(2) The warmer molecules coming into the condensate concentrate more densely near the interface than the cooler molecules accumulating around the interface.(3) The energy flows of condensation and evaporation have a peak just inside the interface of phase change.(4) The concentration of cluster in metallic vapors are fairly high, that is, their number density is not less than that of monomer.(5) The thickness of films made by metallic vapors increases proportionally to time, which means condensation rate is nearly constant, while the thickness of nonmetallic films does not increase linearly.(6) The condensate rate of iron (Fe) increases with the decrease in chamber pressure.