To start the process, a weak oxide layer that has formed on the bare aluminum surface needs to be removed. Heated alkaline cleaning is utilized to remove the oxide film and residual process lubricants. After cleaning, a neutral ph rinse is needed to stabilize the surface. An immersion application process deposits the zirconium oxide layer onto the coil surface. A conversion layer forms (nano-film build) on the surface providing improved fin edge build and adhesion. Zirconium corrosion resistance has been tested as a stand-alone material, showing improved protection. Over time, when a fin becomes exposed to the atmosphere, (micro-cracking from thermal movement, abrasion from airborne contaminants) the bond strength of the coating will be greatly diminished without a pretreatment, allowing for creep-back to occur.
After pretreatment, coils pass-through multiple rinse tanks to ensure a neutral ph surface. With our patented ZNET technology, film build is controlled to +- .0002. Anode control ensures no bridging and 100% coated to the center. Post rinse before curing ensures no loose material is left on the surface, contributing to an even film build. The final stage is an oven cure. Axalta E-coat material is a lower temperature cure (355F) than other E-coats on the market.