Batch and Coil Anodizing

atch and coil anodizing are accomplished in five carefully controlled, calibrated, quality-tested stages:

1. Cleaning. Alkaline and/or acid cleaners remove grease, and surface dirt.

2. Pre-Treatment.

o Etching. An appealing matte surface finish is created with hot solutions of sodium hydroxide to remove minor surface imperfections. A thin layer of aluminum is removed to create a matte or dull finish.
o Brightening. A near mirror finish is created with a concentrated mixture of phosphoric and nitric acids which chemically smooths the aluminum's surface.

3. Anodizing. The anodic film is built and combined with the metal by passing an electrical current through an acid electrolyte bath in which the aluminum is immersed. The coating thickness and surface characteristics are tightly controlled to meet end product specifications.

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Aluminum electrolytic capacitor

An electrolyte capable of anodizing aluminum consists essentially of a solution of an amino acid having a pH of 5.5 to 8.5. The amino acid is preferably a 2-amino acid, more preferably a dicarboxylic acid, and specifically aspartic or glutamic acid. The electrolyte may be used to anodize aluminum foil to form a barrier layer oxide or as a fill electrolyte in aluminum electrolytic capacitors.

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