(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.