1. Zirconium
Zirconium is a chemical element, the element symbol Zr, the atomic number is 40, and the simple substance is a high melting point metal, which is light gray. The surface of zirconium is easy to form an oxide film with luster, so its appearance is similar to that of steel. It has corrosion resistance and is soluble in hydrofluoric acid and aqua regia. At high temperature, it can react with non-metallic elements and many metal elements to form solid solution.
2. Tantalum
Tantalumis a metal element with atomic number 73 and chemical symbol TA. The elemental substance corresponding to the element is steel gray metal and has high corrosion resistance. It does not react with hydrochloric acid, concentrated nitric acid and aqua regia under cold and hot conditions.
Tantalum mainly exists in tantalite and coexists with niobium. Tantalum has moderate hardness [1] and ductility. It can be pulled into thin wire foil. Its coefficient of thermal expansion is very small. Tantalum has excellent chemical properties and high corrosion resistance. It can be used to make evaporation vessels, etc. it can also be used as electrode, rectifier and electrolytic capacitor of electron tube. Medically, it is used to make thin sheets or thin threads to repair damaged tissue. Although tantalum has strong corrosion resistance, its corrosion resistance is due to the formation of stable tantalum pentoxide (Ta2O5) protective film on the surface.
3. Niobium
Niobium [1], chemical symbol Nb, atomic number 41, is a transition metal element. Niobium is a shiny gray metal. High purity niobium metal has high ductility, but it will harden with the increase of impurity content. Niobium has a very low capture cross section for thermal neutrons, so it is very useful in the nuclear industry.
4. Hafnium
Hafnium is a metal element with the symbol HF, atomic number 72 and atomic weight 178.49. Simple substance is a shiny silver gray transition metal. There are six natural stable isotopes of hafnium: hafnium 174, 176, 177, 178, 179 and 180. Hafnium does not react with dilute hydrochloric acid, dilute sulfuric acid and strong alkali solution, but is soluble in hydrofluoric acid and aqua regia. The element name comes from the Latin name of Copenhagen. In 1925, Swedish chemist hevisi and Dutch physicist Kost obtained pure hafnium salt by fractional crystallization of fluorine-containing complex salt, and reduced it with metal sodium to obtain pure metal hafnium. The content of hafnium in the earth's crust is 0.00045%, which is often associated with zirconium in nature.
Size:Φ3mm×Thickness3mm;5mm Under, 5mm Under,10×10×3
