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Relative Corrosion Resistance of Metals |
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> Home > Technology > Corrosion Performance > Relative Metal Corrosion |
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| Corrosion Rates of Metals in Hydrochloric and Sulfuric Acid from ISO corrosion Curves |
Corrosion of Titanium, Nickel Alloys, Zirconium and Tantalum Metals
The figures below show the relative corrosion resistances of the various specialty metals in sulfuric acid (H2SO4) and hydrochloric acid (HCl). Typically corrosion rates are shown in 5 mills (0.005”) per year. For valves and fittings that require tight tolerances, 5 mills per year would cause problems relatively quickly where creating tights seals and preventing leaks is critical.
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| The iso-corrosion curves of Titanium, Zirconium, Hastelloy C, Zirconium and Tantalum in hydrochloric acid. |
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| The iso-corrosion curves of Titanium, Zirconium, Hastelloy C, C-276, B-3, Zirconium and Tantalum in sulphuric acid. |
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As can be seen in these charts, the corrosion resistance of tantalum is second to none, followed by zirconium, nickel alloys (Hastelloy) like e.g. C-22 or C-276 and titanium. From a corrosion perspective, tantalum is the most corrosion resistant metal that is in common use. Tantalum is practically inert to most oxidizing and reducing acids, except fuming sulfuric and is attacked by hot alkalis and hydrofluoric acid. Taking no other factors into consideration tantalum metal is an ideal choice from a corrosion point of view giving the engineer the best chances for success. However tantalum metal is also a very expensive material and is typically cost prohibitive.
With Tantaline the typical tradeoff of costs versus performace does not exist. Tantaline has the superb corrosion performance of pure tantalum metal, the availability of stainless steel, at costs competitive with Hastelloy.
Why settle for less? |
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