Preparation method of nano-titanium dioxide coated nano-aluminium oxide

The invention discloses a preparation method of nano-titanium dioxide coated nano-aluminium oxide, which comprises the following steps: firstly, dropwise adding an alkaline solution in an aluminium salt solution under the conditions of stirring and ultrasonication, controlling the pH value of a system, and still standing to acquire aluminum hydroxide sol; drying the aluminum hydroxide sol, mixing the aluminum hydroxide sol and water, ball milling, washing the mixture with water until eluate is neutral, filtering by decompression or centrifugalizing, and thermally decomposing to acquire nano-aluminium oxide powder; secondly, adding the nano-aluminium oxide powder into a mixed solution of glacial acetic acid, water and absolute alcohol to acquire the mixture under the conditions of ultrasonication and stirring; adding the mixed solution of butyl titanate and absolute alcohol into the mixture under the conditions of ultrasonication and stirring, still standing, drying and ball milling to acquire the powder; and placing the powder into a furnace at constant temperature, and thermally decomposing to acquire the nano-titanium dioxide coated nano-aluminium oxide powder. The grain diameter of nano-titanium dioxide coated nano-aluminium oxide composite material grains is 1-50 nm, and the purity is higher than 99.8 percent.