Overview of Zirconium And Zirconium Alloys
Posted by Cathie Montanez on October 12, 2019 8:05 AM EDT
Stanford Advanced Materials supplies high-quality zirconium products to meet our customers' R&D and production needs.
Zirconium is an active metal that easily undergoes an oxidation reaction, such as reacting with oxygen in the air at room temperature to form an oxide protective film. This protective film gives the best corrosion resistance of zirconium and zirconium alloys. This oxide film can be further strengthened by a heat treatment process, and the surface microhardness can be roughly as high as Vicat hardness meter 480 (Rockwell C scale 47). The properly treated reinforced oxide film acts as an excellent bearing surface to resist corrosion of various media, bringing high wear resistance to the high-speed system equipment and strong corrosion resistance to certain highly corrosive environments.
Zirconium has excellent corrosion resistance to reducing environments and excellent resistance to most acids. Zirconium has good corrosion resistance to boiling sulfuric acid of less than 10%. It can be applied to 100°C for 10~40% sulfuric acid, and 60°C for 50~60% sulfuric acid. Zirconium is only corrosive in mediums such as hydrofluoric acid, concentrated sulfuric acid and aqua regia. It also has good corrosion resistance to oxidizing environments such as nitric acid and chromic acid. However, if it contains chlorides (such as FeCl3, CuCl2), the corrosion increases sharply. Zirconium has excellent corrosion resistance to lye, molten alkali, and salt liquid, but it is not resistant to wet chlorine. It is mainly used in the chemical industry for hydrochloric acid, caustic soda, acetic acid, and other industries.
Zirconium alloys have good ductility even at low temperatures and strength comparable to other engineered alloys. In addition to being an indispensable component of the oxide film, the oxygen element is an alloying element in which the zirconium alloy fills the structural void and increases its strength. Zirconium alloys have no tendency to be plasticized to embrittled at low temperatures.
The total content of zirconium and hafnium of the zirconium alloy is 95.5% to 99.2%, and the content of hafnium is up to 4.5%. Non-nuclear zirconium alloys are available in two grades: zirconium 702 (Zr702) and zirconium 705 (Zr705). Both grades have excellent corrosion resistance and differ only in physical and mechanical properties. Zr702 is a commercial material and Zr705 is an alloy of zirconium and hafnium to enhance its strength and improve its die forging properties. Both grades of zirconium alloys are approved for use in the manufacture of pressure vessels designed to ASME's boiler and high-pressure vessel standards. Zr705 materials require stress relief heat treatment within 14 days of soldering.
Stanford Advanced Materials supplies high-quality zirconium products to meet our customers' R&D and production needs. Please visit https://www.samaterials.com/ for more information.