Zirconium alloys have good corrosion resistance, moderate mechanical properties, low atomic thermal neutron absorption cross section (0.18 target en for zirconium) in high temperature and high pressure water and steam at 300-400°C. They have good compatibility with nuclear fuel, so they can be used as core structural materials for water-cooled nuclear reactors (fuel cladding, pressure tubes, stents and orifice tubes), which are the main applications of zirconium alloys. Zirconium has excellent corrosion resistance to many acids (such as hydrochloric, nitric, sulfuric and acetic acids), bases and salts, so zirconium alloys are also used to make corrosion resistant parts and pharmaceutical devices. Zirconium has a strong affinity for gases such as oxygen and nitrogen, so zirconium and zirconium alloys are also widely used as non-evaporative vapor eliminators in the electric vacuum and light bulb industries (see Vapor Eliminating Materials). Zirconium has excellent luminescent properties, so it becomes a flash and fireworks material.
1. Zirconium is completely resistant to corrosion in hydrochloric acid of various concentrations up to 35°C and 20% concentration, and even in hydrochloric acid of temperature up to 130°C and 37% concentration, zirconium is not significantly corroded. The corrosion resistance of zirconium in pure hydrochloric acid is better than that of any other engineering metals.
2 When zirconium is exposed to sulfuric acid media, a 1 film forms on its surface to prevent further corrosion by sulfuric acid.
(1) When the sulfuric acid concentration reaches 80%, there is almost no sign of corrosion within the sulfuric acid solution at a temperature of 25°C.
(2) Sulfuric acid concentration is 75% or less. At 60°C, 100°C or boiling point, zirconium actually did not corrode.
(3) At 35°C. The corrosion rate increases fastest when the sulfuric acid concentration increases from 75% to 80%.
3 Zirconium is complete corrosion resistant at 35°C and 60°C in various concentrations of phosphoric acid, but at 100°C, only in phosphoric acid solutions with concentrations up to 60%. Zirconium in higher concentrations of phosphoric acid within the corrosion rate is much lower than titanium, in the introduction of air phosphoric acid solution within the corrosion resistance is also excellent than titanium.
4 Zirconium in the concentration of less than 90%, the temperature is less than 200 ℃ nitric acid, extremely excellent corrosion resistance, other metals only platinum has the same resistance to nitric acid corrosion with zirconium. In nitric acid with a concentration of more than 70%, if there is a large tensile stress, stress corrosion cracking may occur in zirconium. If F ions are present in nitric acid, the corrosion is proportional to the F ions.
5 Zirconium has good corrosion resistance to most organic substances. It is commonly used in the production of acetic acid and acetic anhydride. Zirconium also shows good corrosion resistance in citric acid, lactic acid, formic acid, oxalic acid, tartaric acid and chlorinated organic acids. Alloy Material Grade: Zr 702,Zr705.
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