Zn-Al₂O₃ Composites with High Aluminum Content and Nanostructured Al₂O₃/ZnO Prepared by Electrochemical Technique from Non-Suspended Solution

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Zn-Al₂O₃ composites were electrodeposited from a non-suspended solution containing ZnSO₄·7H₂O and Al₂(SO₄)₃·14–18H₂O using benzyldimethyltetradecylammonium chloride dehydrate (BDTAC) as the additive at an electrodeposition current of 50–500 A/m² with an air or a nitrogen bubbling. Initial layers with a thickness of approximately 1 µm were observed in the Zn-Al₂O₃ composite on copper substrates. Furthermore, the Zn-Al₂O₃ composite was composed of two different crystallographic areas, namely, nano-level size deposited grains with 20–60 nm in width and 100–200 nm in length, and closely packed fine particle deposits with a diameter of approximately 5 nm containing more than 26 atomic% aluminum. The nano-level size deposited grains and the closely packed fine particle deposits comprised nano-size ZnO and θ-Al₂O₃, respectively. The oxygen concentration in Zn-Al₂O₃ composite by the air bubbling was higher than that in Zn-Al₂O₃ composite by the nitrogen bubbling. In contrast, the zinc content ratio in Zn-Al₂O₃ composite by the air bubbling was lower than that in Zn-Al₂O₃ composite by the nitrogen bubbling. The aluminum concentration in closely packed fine particle deposits in Zn-Al₂O₃ composite by the air bubbling was almost the same value as that in Zn-Al₂O₃ composite by the nitrogen bubbling.