Cr Free REAL

Development and testing of innovative Cr Free solution for REmoval of Anodic Layers

Projektkoordinator @ CEST: Dr. Carmen Vladu

Abstrakt:

In 2024 the use of hexavalent chromium (Cr(VI)) will be forbidden by REACH regulation. Many studies have been carried out to replace Cr(VI)-based coatings for lightweight metals such as aluminium and have resulted in the development of new protective layers (SAA, TSA, Cr(III)-conversion coating). However, the removal of protective oxide layers is still performed with Cr(VI)-based stripping processes. Cr(VI)-free stripping with NaOH leads to deterioration of the substrate if the process time exceeds the specification of the very narrow process window.

Commercially available or literature mentioned Cr(VI) free stripping agents will be tested and evaluated.

In the proposed approaches, it is planned to develop innovative acidic or alkaline stripping agents containing additives. Corrosion inhibitors, accelerators, surfactants and complexants will be employed.

The best performing stripping process will be tested on six types of machined and cast aluminium alloys for removal of Cr(VI)-based and Cr(VI)-free protective layers. The experiments will be performed on lab scale and pre-industrial samples, including complex-shaped parts with a size up to 400*300*200 mm.