Cr(III)-Technology for Conversion Coating and the future trends for a Cr(free)-Technology

The developments on the Cr(III)-containing conversion coating technology of the past years was mainly driven by the REACH regulations. An update on the status of Henkel products regarding these regulations will be given.

Cr(III)-containing products form a Cr/Zr-layer whose corrosion resistance and paint adhesion properties are different from the known Cr(VI)-containing coating. In combination with a corrosive medium the Cr/Zr-layer reacts more sensitive to the type of alloy and therefore their alloying element. The product performance within the product line of the conversion coating process place a decisive role in how the alloying elements with higher corrosive potential will be eliminated or shielded.

The presentation will show the recent investigations on the influence of the products, here mainly the deoxidizer, the type of alloy and the conditions of the substrate surface. Considering the topic of paint adhesion, the presentation will present correlations between the configuration of the Cr/Zr-layer and its paint adhesion properties.

The results will show if the process can be optimized according more robustness and the formation of an optimal corrosion resistant Cr/Zr-conversion coating.

Furthermore, the presentation will give a status about the current investigations on the replacement of the Cr-containing technology and will show different approaches for creating a Cr-free conversion layer.