Measurement of Heat Transfer from Anodic Oxide Film on Aluminum in High Knudsen Number Flows
Measurement of Heat Transfer from Anodic Oxide Film on Aluminum in High Knudsen Number Flows
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DOI：
10.3390/mi11030234
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发表时间：
2020-03-01
期刊：
影响因子：
3.4
通讯作者：
Kito, Kenji
中科院分区：
文献类型：
--
作者：
Yamaguchi, Hiroki;Kito, Kenji
真空中的传热取决于气体与表面的相互作用。本文研究了不同阳极氧化时间的铝阳极氧化膜通过不同温度的两个表面之间的气体的热通量。我们制备了未经处理的表面、正常阳极氧化时间为30分钟的表面和90分钟的表面，其中形成的膜将通过长时间暴露于溶液而部分溶解。通过电阻检查膜的形成。扫描电子显微镜（SEM）图像获得的三个样品表面。尽管很难在阳极氧化膜上观察到六边形圆柱形单元结构，但30分钟样品表面显示为粗糙的，并且90分钟样品表面相对光滑且呈粉末状。从自由分子流到近自由分子流，测量了三个样品表面的热通量，并进行了分析，以获得能量调节系数。热通量的拟合曲线拟合良好。氦和氩的能量调节系数增加阳极氧化的铝样品表面，而他们随着阳极氧化时间增加到90分钟表示膜的溶解下降。
The heat transfer in vacuum depends on the gas-surface interaction. In this study, the heat flux from anodic oxide films on aluminum with different anodizing times through a gas confined between two surfaces with different temperatures was studied. We prepared a non-treated surface, a surface with a normal anodizing time of 30 min, and a surface with 90 min, where the formed film would partially dissolve by long time exposure to the solution. The formation of the films was checked by electrical resistance. Scanning electron microscope (SEM) images were obtained for the three sample surfaces. Even though it was difficult to observe the hexagonal cylindrical cell structures on anodic oxide films, the 30 min sample surface was shown to be rough, and it was relatively smooth and powdery for the 90 min sample surface. The heat fluxes from three sample surfaces were measured from the free-molecular to near free-molecular flow regimes, and analyzed to obtain the energy accommodation coefficients. The heat fluxes were well fitted by the fitting curves. The energy accommodation coefficients for both helium and argon increased by anodizing an aluminum sample surface, while they decreased with increasing the anodizing time up to 90 min indicating the dissolution of the film.