Method for preparing nano-flake boehmite sol by lifting film coating machine

There are also many methods of coating, including spin coating, pulling and spraying. Among them, the dipping and pulling coating method has become the main research method of this experiment because of its simplicity and easy operation. The dip-pulling method is easy to prepare transparent thin films or multilayer films on different substrate materials (such as glass, quartz, etc.).

Preparation of seed film: use boehmite sol, put the cleaned glass substrate into the automatic film coating machine, set the working temperature to 50 bar, lift the rising speed of 100 mm/min, and the falling speed of 100 mm/min, The residence time in the sol was 30 s, the drying time was 300 s, and the y-Al0OH nanoparticle seed film was obtained by pulling 10 times.

The prepared seed film is then subjected to hydrothermal treatment to obtain a nano-flaky boehmite film. In a typical synthesis process, a certain amount of sodium metaaluminate and urea powder were sequentially dissolved in 40 mL of distilled water, and stirred for 15 min to completely dissolve the powder. Then the solution was transferred to a 50 mL hydrothermal kettle lined with polytetrafluoroethylene, put into the prepared seed film, reacted at 160 bar for 3 h, and then cooled naturally to room temperature. The prepared film was taken out, washed 5 times with distilled water, and dried in a vacuum oven at 50 bar for 12 hours to obtain a nano-flaky boehmite film. In order to study the mechanism, we introduced several groups of comparative experiments, keeping other conditions unchanged, changing the reaction time at 160 bar to 0.5h, 3h and 12h; or changing the concentration of sodium metaaluminate to 0.05 M, 0.10 M, 0.15 M and 0.20M; or change the temperature of the reaction at 140 bar, 16o bar and 200 bar respectively.

The picture b shows boehmite film