The dark chromium oxide thus slowly replaces and covers the yellow color of the lead
chromate, causing the bright yellow areas in paintings to turn dark brown.
The suspended NH3 and hydrogen chloride can recombine in the atmosphere and form small particles of ammonium chloride which can settle on and contaminate the
chromate bath or the water used for quenching stages as well as all galvanized pieces lying on the floor.
CONCLUSIONS: These data illustrate that repetitive exposure to particulate
chromate induces chronic injury and an inflammatory microenvironment that may promote Cr(VI) carcinogenesis.
From the results we have so far, I am certain that we can develop a viable treatment for former industrial sites where
chromate compounds are a problem," said Dr Stewart.
Major studies pinpointing Cr(VI) as a human lung carcinogen have been performed on workers involved in
chromate production,
chromate pigment production and chromium plating.
Inorganic yellow pigments based on bismuth provide heat stability requisite for engineering thermoplastics to replace lead
chromates.
Most viable reformulations have already taken place; thus, declines in
chromate pigments will slow as they are replaced by various organic and complex inorganic types.
All units are phosphate washed, caulked with polyurethane sealant to prevent rust in seams, and painted with an epoxy primer using an acrylic enamel paint that is lead and
chromate free.
Most of be emphasis is centered on the traditional metal oxides, such as
chromate or permanganate salts, in spite of the hazards and waste management concerns associate with them.
All units feature V-shaped
chromate treated condensers and low noise fans (2dBA less than R22 models), double antifreeze protection and optimum water distribution.
The
chromate species is of particular concern because of its appreciable migratory potential and the resultant threat to groundwater supplies.
It still has the telltale green of aviation zinc
chromate paint on one side.
