Search results
Results from the WOW.Com Content Network
Gel-like chromium(III) phosphate is prepared through the reduction of ammonium dichromate, (NH 4) 2 Cr 2 O 7, using ethanol, CH 3 COOH, and nitric acid, HNO 3.This process is done in the presence of ammonium dihydrogen phosphate and urea at an elevated temperature where tetradecyltrimethylammonium bromide (TTBr) is used as structure directing agent.
In particular, concerns about the exposure of workers to chromates and dichromates while handling the immersion bath and the wet parts, as well as the small residues of those anions that remain trapped in the coating, have motivated the development of alternative commercial bath formulations that do not contain hexavalent chromium; [17] for ...
Chromium compounds are compounds containing the element chromium (Cr). Chromium is a member of group 6 of the transition metals. The +3 and +6 states occur most commonly within chromium compounds, followed by +2; charges of +1, +4 and +5 for chromium are rare, but do nevertheless occasionally exist. [3] [4]
Chromium has unique magnetic properties; it is the only elemental solid that shows antiferromagnetic ordering at room temperature and below. Above 38 °C, its magnetic ordering becomes paramagnetic. [7] The antiferromagnetic properties, which cause the chromium atoms to temporarily ionize and bond with themselves, are present because the body ...
1 Chemical properties. ... phosphate or orthophosphate is an organophosphate, ... copper, chromium, and uranium. Unless carefully managed, these waste products can ...
A phosphate coating is usually obtained by applying to the steel part a dilute solution of phosphoric acid, possibly with soluble iron, zinc, and/or manganese salts. The solution may be applied by sponging, spraying, or immersion. [6] Phosphate conversion coatings can also be used on aluminium, zinc, cadmium, silver and tin. [7] [8]
Hexavalent chromium (chromium(VI), Cr(VI), chromium 6) is any chemical compound that contains the element chromium in the +6 oxidation state (thus hexavalent). [1] It has been identified as carcinogenic, which is of concern since approximately 136,000 tonnes (150,000 tons) of hexavalent chromium were produced in 1985. [ 2 ]
Main page; Contents; Current events; Random article; About Wikipedia; Contact us