Iridium ingot is a chemical element, the chemical symbol is Ir, and the atomic number is 77. Iridium ingot is a rare element with an annual output and consumption of three tons on the earth's crust. Iridium 191 and Iridium 193 are the only two natural isotopes and the only stable isotopes. Iridium 193 is more abundant than iridium 191.

The chemical properties of Iridium ingot are very stable. It is the most corrosion-resistant metal. Iridium ingot has extremely high chemical stability to acid and is insoluble in acid. Only spongy iridium will slowly dissolve in hot aqua regia. If it is dense Iridium ingot, even boiling king Water does not corrode; however, in a high-temperature pressurized closed reactor, Iridium ingot is significantly corroded in aqua regia above 250°C; a mixed acid composed of 20 parts of concentrated hydrochloric acid and 1 part of concentrated nitric acid is at Under pressure, the corrosiveness to Iridium ingot is about 20 times that of aqua regia, so it is often used as a reagent for the digestion of metal iridium in chemical analysis.

Iridium ingot is extremely resistant to corrosion in molten sodium hydroxide at 350°C (without air), and the corrosion rate is less than 0.005mm/year (about 3.5mdd), but molten sodium hydroxide above 400°C is very corrosive to iridium. Serious; molten potassium hydroxide can also strongly corrode iridium.

At room temperature, the dense metal Iridium ingot has excellent corrosion resistance to dry fluorine gas, and dry or wet chlorine, bromine, and iodine. There is no visible corrosion.