Alumina hydrate is typically white, but due to industry requirements, we can opt for coloring methods to dye it without affecting its usability. Next, we will discuss the main coloring methods available.
Alumina hydroxide is maintained within a specific range before being immersed in a particular molten salt, where it undergoes certain chemical reactions to form an oxidized film of a certain thickness, resulting in various different colors.
2. The chemical method involves forming the color of the film through chemical oxidation in a specific solution, but consistent coloration requires the use of reference controls. Chemical dyeing involves immersing oxidized aluminum materials into a solution of organic or inorganic dyes, where the dyes penetrate the pores of the oxide film and undergo chemical or physical reactions to achieve coloring. The equipment for chemical dyeing is simple, with low costs, a variety of color options, but poor resistance to light and corrosion, making it suitable only for indoor decoration.
3. The toughening of zirconia with alumina hydrate through ionic deposition of oxides or the oxide method is not suitable for small batch products due to its high cost and substantial investment.
4. A method of coloring aluminum with natural coloring during anodization, including alloy coloring and solution coloring. Alloy coloring involves controlling the composition of aluminum alloys to achieve different hues; solution coloring, also known as electrolytic coloring, controls hues by adjusting the composition and conditions of the electrolyte. In actual production, natural coloring typically uses organic acids as the electrolyte, with a small amount of sulfuric acid added to adjust the pH.
Therefore, for the coloring of aluminum hydroxide, we generally have the option to choose an appropriate coloring method, strictly adhere to the corresponding coloring process, and these coloring methods are relatively even in their application.
