High purity aluminum top coat on substrate

A method of manufacturing a chamber component for a processing chamber comprising:

• forming an aluminum coating on a surface of the chamber component, wherein the chamber component comprises impurities, wherein the aluminum coating is substantially free from impurities and has a thickness in a range of about 0.8 mils to about 5 mils, and wherein the chamber component is a chamber component of a processing chamber that performs plasma processes;
• and
• anodizing the aluminum coating using an acid solution to form an anodization layer over the aluminum coating, wherein the anodization layer comprises Al2O3, and wherein performing the anodizing comprises:
• beginning the anodizing using a first current density;
• growing a dense barrier layer portion of the anodization layer using the first current density;
• reducing current density to a second current density that is below the first current density;
• and
• growing a porous columnar layer portion of the anodization layer using the second current density, wherein the porous columnar layer portion of the anodization layer comprises a plurality of columnar nanopores, wherein the plurality of columnar nanopores have a diameter of 10 nm to 150 nm, and wherein the porous columnar layer portion of the anodization layer has a porosity of about 40% to 50% as a result of the anodizing.