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Growth of porous type anodic oxide films at micro-areas on aluminum exposed by laser irradiation

“…During immersion, most of the hydration occurs at the outermost part of the oxide film, where highly crystalline hydroxide layers are formed, and the thickness and crystallinity of the hydroxide increase with immersion time [9,20,[23][24][25][26][27]. The insulating properties and resistance to chemical dissolution in acid and alkaline solutions of oxide films increase with pore-sealing time [15], and this will be described in terms of the time-variations in the rest potential of specimens during immersion in acid or alkaline solutions.…”

“…Immersion of aluminum specimens covered with porous anodic oxide films in doubly-distilled boiling water causes the hydration of anodic oxide films via the following equation [15,[20][21][22].…”

“…In potentiostatic anodizing of electropolished specimens, porous oxide films grow at a steady rate due to a balance between oxide formation at the oxide/substrate interface and electrochemical dissolution of oxide at the pore bottom. The electrochemical dissolution rate is determined by the inward diffusion of H + and oxalate ions through the solution in the pores [20,31]. Therefore, potentiostatic anodizing results in a steady current, as shown at the initial stage before 2 h of anodizing in Fig.…”

Fabrication of a meniscus microlens array made of anodic alumina by laser irradiation and electrochemical techniques

“…The polished specimens were sputter-coated with platinum using a sputter coater (JFC-1600, JEOL) for SEM observations. The immersion of a porous anodic oxide film formed on an aluminum specimen in distilled boiling water results in the hydration of the oxide via the following chemical reaction [28][29][30]:…”

Fabrication of three-dimensional platinum microstructures with laser irradiation and electrochemical technique

“…In addition, a highly crystalline hydroxide layer is formed on the surface of the oxide films, and the hydroxide layer is highly dissolution-resistant in acid and alkaline solutions [17]. Thickness and the crystallinity of the hydrated oxide layer increase with pore-sealing time, t a , resulting in a high stability of the anodic oxide films in platinum electroplating solution.…”