Long-term stability of coatings and alloys, however, remains a concern due to interdiffusion of alloying constituents, porosity formation at the metal-coating interface and microcracking and fissuring. 6.7A) have been commonly used to reduce the evaporation of chromium from the alloy surface. b.Įlectronically conducting coating for IC: Electrically conducting Co–Mn spinel coatings ( Fig. In addition, use of aluminization surface coatings (leading to the formation of alumina scale) has also been considered to reduce Cr evaporation. Use of alloys and coatings: Commonly practiced materials selection approach includes use of alumina scale forming ferritic and austenitic (iron and nickel based) alloys for the fabrication and assembly of the BoP components. (A) Chromium evaporation rates as a function of temperature and water vapor on different alloy materials, (B) cross-section SEM image and elemental mapping profile on manganese cobalt spinel coating, and (C) digital micrograph of Cr getter and Cr distribution profile after 500 h Cr capture test. Approaches for mitigation of chromium poisoning.

118 Moreover, hexavalent chromium compounds are considered to be human carcinogens. Hexavalent chromium is corrosive and may cause chronic ulceration and perforation of the nasal septum, chronic ulceration of other skin surfaces, as well as contact dermatitis and asthma.

High exposure to chromium may cause severe irritation of exposed tissues, while the accidental ingestion of high concentrations of chromium may cause acute renal failure. Once in the body, chromium compounds are distributed mainly to the liver, spleen and kidneys and are primarily excreted through urine. The absorption of chromium through inhalation or through the skin depends on the chemical form, the molecular vehicle and the condition of the skin, but hexavalent compounds have a higher absorption than trivalent chromium.

Amparo Casal, in Frontiers of Nanoscience, 2012 5.1.4 ChromiumĬhromium occurs in nature in two different states: hexavalent chromium (Cr VI) and trivalent chromium (Cr III), the latter is the more stable form and is an essential metal for body metabolism.