An Zeyu, Sun Shiyang, Dong Binghai
School of Materials Science and Engineering, Hubei University, Wuhan, Hubei, 430000, People's Republic of China.
School of Mechanical Engineering, Inner Mongolia University of Science & Technology, Baotou, Inner Mongolia, 014010, People's Republic of China.
Sci Rep. 2024 May 7;14(1):10454. doi: 10.1038/s41598-024-58975-y.
In order to elucidate the diffusion behaviour of ions in alumina during the anodic alumina process, the effects of electric field strength, hydration content, and electrolyte on amorphous alumina and hydrated alumina were studied using ab initio molecular dynamics. The results show that the diffusion rate of ions in alumina increases with the increase in electric field strength, but there is an extreme value. The maximum diffusion rate of Al ions in alumina monohydrate is 21.8 μm/ms/V, while in alumina trihydrate, it is 16.7 μm/ms/V. The ionic diffusion rate of hydrated alumina is one to two orders of magnitude larger than that of anhydrous amorphous alumina due to the effect of the drag of H ions, which reduces the migration activation energy. Electrolytes also affect the diffusion rate of alumina through the action of H ions. The increase in H ions will not only enhance the diffusion rate of hydrated alumina but also render the hydrous compound more vulnerable to breakdown.
为了阐明阳极氧化铝过程中离子在氧化铝中的扩散行为，采用从头算分子动力学研究了电场强度、水合含量和电解质对非晶氧化铝和水合氧化铝的影响。结果表明，氧化铝中离子的扩散速率随电场强度的增加而增大，但存在一个极值。一水合氧化铝中铝离子的最大扩散速率为21.8μm/ms/V，而三水合氧化铝中为16.7μm/ms/V。由于H离子的拖拽作用降低了迁移活化能，水合氧化铝的离子扩散速率比无水非晶氧化铝大1至2个数量级。电解质也通过H离子的作用影响氧化铝的扩散速率。H离子的增加不仅会提高水合氧化铝的扩散速率，还会使含水化合物更容易分解。
