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Discussion Forums - The Hendrix Group
HomeHomeDiscussionsDiscussionsGeneral Corrosi...General Corrosi...corrosion of SS 316/304 in acidic beerages - phosphoriccorrosion of SS 316/304 in acidic beerages - phosphoric
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10/19/2003 9:00 AM
 
dear sir, im doing my thesis on corrosion of orhtodontic wire in acidic beverages - phosphoric acid based and citric acid based and comparing with artificial salova using anodic polarizationat 10mv/15sec. preliminary results show breakdown potential of ss316 in artificail saliva at 550mv whereas in acid beverages, current density was seen to increase steadilyu in small amounts till 1200 form then on current density decreases (Passivation ??) till 1400 from then on a rapid increase was noted. taking into consideration the low pH (2.4) aerated drink, carbonic acid, and phosporic acid i had expected the breakdown to be reached earlier. is there any passivation occuring here due to the presence of phosphoric acid? is this conc. of phosphoric acid (.1%) liable to passivate. i would b grateful if you could provide an opinion regarding this result.
 
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10/28/2003 9:00 AM
 
There are some theories that phosphoric acid will impart some passivation to the surface of 316 ss, but this is not born out by the data. Phosphoric acid will, in fact, remove iron, chromium and nickel from the surface, but there is no data showing that it will chromium enrich the surface in our tests. Is it possible to get some breakdown of the phosphoric acid under those low voltages? Citric acid will definitely passivate 316 ss, but it requires air drying or some other oxygen donor in the solution in order to form the oxide layer that is necessary for passivation of the surface while still in solution. I am very interested in working with you to help you on your thesis, if you are in need of further assistance.
 
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HomeHomeDiscussionsDiscussionsGeneral Corrosi...General Corrosi...corrosion of SS 316/304 in acidic beerages - phosphoriccorrosion of SS 316/304 in acidic beerages - phosphoric


  

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