DIPSOL Europe GmbH presents heat-treatable cobalt-free passivations
and new zinc-nickel alloy plating systems with an excellent covering power.
Due to the European Union’s REACH regulation, various cobalt salts were discussed in late 2010
according to the controls by Substances of Very High Concern (SVHC) at the European chemical agency
ECHA. Because of the possible restrictions of various cobalt salts during that time, the development of
cobalt-free passivations were strong fostered and first systems were placed on the market.
The long-lasting standstill relating to the topic of cobalt as well as the technical restrictions of substitute
systems caused that the cobalt-contained passivations still have a dominating role in the industry.
However, since the announcement of several automotive manufacturers concerning the proposed
manufacturing units of electric vehicles in late 2016 which involves greater demand for cobalt, the price of
cobalt increases significantly. Therefore, cobalt-free substitute systems are currently highly interesting
from the economic point of view.
As a pioneer in this field, Dipsol Europe GmbH based in Düsseldorf is going to present their cobalt-free
passivation product line at the „Surface Technology“ from June 5th to 7th 2018 in hall 1 at the Stuttgart
Trade Fair. Previous tick-film passivations as well as black passivations for zinc and zinc alloy plating can
be replaced without any limitations.
Cobalt-free: highly interesting from the economic point of view
The results of the field trials have partially surpassed the previous results.
This is basically achieved by the substitution of cobalt by an alternative metal and the implementation of
colloidal silica in the passivation layer. Compared to the so called nano passivations which contain
spherical colloidal silica, rather aliphatic colloids are directly incorporated into the passivation layer which
lead to higher stability regarding the agglomeration and improves the process stability.
The systems are working at higher pH-values. The enrichment of zinc and thus the thickness in the
interlayer region of the zinc passivation will be decreased and a thicker film with high contents of silicon
oxide are generated.
Furthermore, the passivation layers incorporate less than 70% water so that crack-free closed layers with
shorter drying time will be generated. The solubility of the passi-vation layer will be reduced through the
implementation of a substitute material for cobalt and allows lower concentration of trivalent chromium in
the passivation solution.
The new patent applicated systems offered high performance in the first practical trails. Downstream
thermal processings do not affect the corrosion resistance.
Another focus at the exhibition stand of Dipsol Europe GmbH at the Stuttgart Trade Fair will be the zinc-
nickel alloy plating process IZ-250/252YKN. This especially features high covering power for materials
with poor coatability which is granted through the application of special complexing agents. Die-cast
materials or hardened high carbonaceous materials are exemplary. For the plasticity which is referred to
as ductility, the nickel co-deposition of alkaline zinc-nickel electrolyte based layer is limited from 12-16 %.
The plasticity of the layers is restricted due to the high ratio in the 6-0-0-crystal structure in conventional
procedures. The application of a new additive system implements a very low carbon content in the deposit
layer. Also, the ratio of the 3-3-0-crystal structure increases the ductility compared with the previous
procedures. Thus, a high corrosion resistance of the zinc-nickel layers can be performed for subsequently
deformed parts. The procedure is applicable from semi-gloss to bright appearances.
