DIY Hard Anodizing

Anodizing aluminum, which involves immersing aluminum in an electrolyte solution and passing a low-voltage current through the solution to facilitate surface oxide formation, has long been popular due to the increased strength and corrosion and wear resistance that anodization confers. When an even greater strength and surface oxide coating are required (ie, in the automotive and cookware industries) hard anodization procedures come into play. Hard anodized aluminum has a strength and corrosion resistance comparable to that of stainless steel, but retains the ductility of aluminum, allowing it to be manipulated for industrial applications. Hard anodization involves passing more substantial voltage currents through a three-component electrolyte, at a temperature that facilitates oxide adherence to aluminum.

Things You'll Need

  • Sulfuric acid
  • Oxalic acid
  • Succinic acid
  • Nonalkaline chemical cleanser
  • Two-electrode system
  • Platinum electrode
  • Voltage current source
  • Unreactive tub (i.e. ceramic)
Show More

Instructions

    • 1

      Thoroughly clean specimen surfaces of dirt and oils using a nonalkaline chemical cleanser. Grind specimen surfaces with abrasive paper to facilitate even aluminum oxide formation on the surface.

    • 2

      Prepare electrolyte bath. Combine sulfuric, succinic, and oxalic acids in the bath. Set up a two-electrode system. To the anode, connect the specimen to be anodized, along with the voltage source, which must provide current at 2-4 A. To the cathode, connect the platinum sheets. Oxides will accumulate on the anode. The cathode will produce positive hydrogen ions to counterbalance the negative charges from the anode.

    • 3

      Adjust the temperature of the bath. 20 degrees Celsius is the ideal temperature at which oxides undergo deposition on the specimen surface; furthermore, since 20 degrees Celsius is slightly below room temperature, this setting decreases the risk of the electrolyte bath dissolving the oxide layer forming on your specimen. Connect the voltage source. Leave the specimen in the bath for 20-80 minutes. Aluminum oxides, in an amorphous, fibrous layer, will form on the surface of the specimen.

Learnify Hub © www.0685.com All Rights Reserved