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Platinum–iridium alloys are alloys of the platinum group precious metals platinum and iridium. Typical alloy proportions are 90:10 or 70:30 (Pt:Ir). These have the chemical stability of platinum, but increased hardness. The Vickers hardness of pure platinum is 56 HV while platinum with 50% of iridium can reach over 500 HV.
The only three verifications occurred in 1889, 1948, and 1989. For instance, the US owns five 90% platinum / 10% iridium (Pt‑10Ir) kilogram standards, two of which, K4 and K20, are from the original batch of 40 replicas distributed in 1884. [Note 4] The K20 prototype was designated as the primary national standard of mass for the US. Both of ...
From 1889 to 1960, the meter was defined as the length of a platinum-iridium (90:10) alloy bar, known as the international prototype meter. The previous bar was made of platinum in 1799. Until May 2019, the kilogram was defined as the mass of the international prototype of the kilogram, a cylinder of the same platinum-iridium alloy made in 1879 ...
Elastic properties describe the reversible deformation (elastic response) of a material to an applied stress.They are a subset of the material properties that provide a quantitative description of the characteristics of a material, like its strength.
Metallic iridium is found with platinum and other platinum group metals in alluvial deposits. [23] Naturally occurring iridium alloys include osmiridium and iridosmine, both of which are mixtures of iridium and osmium. It is recovered commercially as a by-product from nickel mining and processing. [20]
Iridium compounds are used as catalysts in the Cativa process for carbonylation of methanol to produce acetic acid. [92] [93] Iridium complexes are often active for asymmetric hydrogenation both by traditional hydrogenation. [94] and transfer hydrogenation. [95] This property is the basis of the industrial route to the chiral herbicide (S ...
Abundance (atom fraction) of the chemical elements in Earth's upper continental crust as a function of atomic number; [5] siderophiles shown in yellow Graphs of abundance against atomic number can reveal patterns relating abundance to stellar nucleosynthesis and geochemistry.
AA-8000: used for electrical building wire in the U.S. per the National Electrical Code, replacing AA-1350. [1]Al–Li (2.45% lithium): aerospace applications, including the Space Shuttle