What are the desired effects of using Alodine or Bonderite on aluminum alloy?

Using Alodine or Bonderite on aluminum alloy is primarily aimed at enhancing the corrosion resistance of the material. These chemical treatments create a protective conversion coating on the surface of the aluminum, which significantly improves its resistance to oxidization and environmental factors that can lead to corrosion.

Additionally, this treatment can result in a slightly roughened surface finish, which is beneficial for subsequent paint adhesion or bonding processes if additional coatings or finishes are applied. This slightly rough surface texture can also help in mechanical interlocking when combined with other materials.

The focus on corrosion resistance makes B the most appropriate choice, as it addresses the essential purpose of these chemical coatings, providing long-term protection for aluminum alloys used in various applications.