Corrosion-resistant alloy
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, , , , KOVALI, Alexandr, CHERNYSHEVA, Natalia. Corrosion-resistant alloy. In: Materials Science and Condensed Matter Physics, Ed. 8-th Edition, 12-16 septembrie 2016, Chişinău. Chişinău: Institutul de Fizică Aplicată, 2016, Editia 8, p. 317. ISBN 978-9975-9787-1-2.
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Materials Science and Condensed Matter Physics
Editia 8, 2016
Conferința "International Conference on Materials Science and Condensed Matter Physics"
8-th Edition, Chişinău, Moldova, 12-16 septembrie 2016

Corrosion-resistant alloy


Pag. 317-317

, , Kovali Alexandr, Chernysheva Natalia
 
Institute of Applied Physics, Academy of Sciences of Moldova
 
 
Disponibil în IBN: 6 august 2019


Rezumat

In the chemical and electrochemical industry even more often there is a need for the cast materials which are characterized by corrosion resistance in a number of aggressive environments in combination with high strength.   The nickel alloys with rhenium, which are in addition alloyed by metals IV and VI of groups, are known: molybdenum, tungsten and hafnium. These alloys are generally intended for use in electronic industry. But use them as corrosion-resistant materials not always yields positive result.   According to literary data an alloy from 10% of rhenium of the NR-10VP brand possesses good physicomechanical properties at a room and elevated temperature. However its shortcoming is low corrosion resistance that does not allow using it for the details working in aggressive environments in a stressed state.   During researches it was succeeded to create the alloy with high corrosion resistance in neutral, alkaline and acidic environments providing a possibility of production from this alloy of semifinished products in the form of bars, wire, plates, tape and foil.   This alloy contains three main components: nickel, rhenium and zirconium. But in addition enter palladium at the following content of ingredients, weight. %: 5-15 rhenium, 0.02-1.0 zirconium, 0.1-0.4 palladium, the rest - nickel.   The offered alloy can be made by the methods of arc or induction vacuum melting providing ingots with a uniform density and durability as in thin (foil, etc.), and in large (bar, plate) sections.   Tests showed, that introduction of palladium to a triple alloy of Ni-Re-Zr reduces corrosion losses in neutral and caustic solutions. So, in 20% solution of sodium chloride corrosion rate decreases by 2.25-3.5 times, and at addition 0.4 weight % Pd even stops corrosion process. In alkali corrosion rate decreases at introduction to 0.3 weight % Pd not less, than by 2.6 times, and at concentration of palladium 0.4 weight % process of corrosion stops, as well as in solution of sodium chloride.   Positive results of introduction to a palladium alloy at corrosion in acids are even more noticeable. For example, in concentrated hydrochloric acid corrosion rate decreases by 3.2-10 times. In 48% sulphuric acid corrosion of an alloy of Ni-15 Re-0.25 Zr at an additive 0.4 weight % Pd corrosion rate decreases almost much. A certain reduction of corrosion losses is observed also in 35% phosphoric acid.   At the same time it should be noted that, increasing corrosion resistance of alloys, additional introduction of palladium does not worsen their mechanical characteristics.   Combination of high corrosion resistance to considerable durability and stability of shape, and also good technological effectiveness (workability) allow using an alloy for work in the installations applied in chemical industry and also as constructional details of responsible assignment in different areas of new equipment.