(1-3) Typical examples are
chromates, molybdates, tungstates, vanadates, phosphates, phosphites, polyphosphates, borates, metaborates, nitrites, silicates, ferrites, and nitroph-thalates as their various metallic salts with polyvalent metals such as zinc, magnesium, calcium, strontium, barium, aluminum, and--more historically--lead.
"We now need a good population study that examines levels of ascorbic acid and
chromate in red blood cells along with any associated genetic damage."
It is a big step, but we are confident that by substituting lead
chromates with safer, high performing alternatives, we can make a big difference."
BASF's site in Besigheim, Germany, the location where the company exclusively produced lead
chromate pigments, is where the future production of alternative products will gradually be developed and expanded.
For aluminum surfaces used in the aerospace industry, the primer typically is an epoxy coating that contains a hexavalent chromium species such as strontium
chromate, and the topcoat is again polyurethane.
Whilst there is no legislation in place actually banning the use of
chromates, it is our view that it is only a matter of time.
BASF is going to stop producing lead
chromate pigments by the end of 2014 at the latest and concentrate worldwide on the production and marketing of alternatine products the company said.
"The means by which to deliver the level of corrosion protection provided by traditional inhibitors such as
chromates, while at the same time minimizing worker and environmental exposure, is central to ongoing studies," says Mr.
As an alternative to conventional lead
chromates, Engelhard, through its Harshaw Div., has introduced silica-encapsulated lead
chromate pigments, which have proven to significantly lower the level of acid-soluble metals released upon burning or burial in a landfill.
PPG Industries' aerospace business and Altair Nanotechnologies have formed an agreement for the development and commercialization of environmentally friendly nanoparticle technology to replace
chromate in aircraft primer that affords excellent corrosion resistance in high-solids and waterborne formulas.
"Dust is the no-no with the
chromates. If you ingest the dust it's a problem, since
chromates are carcinogenic," Mr.
In addition to being free from
chromates, the new primer provides users with numerous performance, appearance and application benefits, it said.