The United States is a net importer of hafnium and there is no U.S. government stockpile of this geopolitically-essential commodity. Importantly, world primary hafnium production data and quantitative estimates of hafnium reserves are not available for analysis, making predictions about supply difficult – as a critical resource, many countries keep this information private.
With hafnium finding essential use in the nuclear, chemical, and aerospace industries, a hafnium supply crunch cannot be allowed and resources must be monitored closely. For these reasons, the United States has declared hafnium to be a Critical Mineral Resource necessary for national sovereignty.
Beyond the basics above, what else should we know about hafnium? Check out the 20 interesting facts below!
- The existence of hafnium was predicted by Russian chemist Dmitri Mendeleev. In his 1869 book “The Periodic Law of the Chemical Elements,” he predicted the existence of an element with similar properties to, but heavier than, titanium and zirconium.
- In 1911, Georges Urbain, the discoverer of the rare earth element lutetium, thought he had discovered element 72 (now called hafnium) during his spectral analysis of rare earths. He called this new element celtium, but three years later it was shown to be a mixture of already discovered lanthanides.
- In 1921, Neils Bohr suggested to Hungarian chemist Georg von Hevesy that he look for the missing element 72 in zirconium ores. According to Bohr’s quantum theory of atomic structure, these metals would have similar chemical properties, so there was a good chance they would be found in the same ores.
- Georg von Hevesy and Dutch physicist Dirk Coster discovered hafnium in 1923 using x-ray spectroscopy to analyze zirconium ores.
- Anton Eduard van Arkel and Jan Hendrik de Boer discovered a method for producing high purity hafnium in 1925.
- Element 72 was called Hafnium after the Latin name ‘Hafnia,’ meaning Copenhagen, the city where the element was discovered.
- From 2014 to 2017, United States primary hafnium import sources were: Germany, 47%; France, 30%; United Kingdom, 11%; China, 11%; and other, 1%.
- In May 2018, the U.S. Department of the Interior, in coordination with other executive branch agencies, published a list of 35 critical minerals (83 FR 23295), including hafnium. This list was developed to serve as an initial focus, pursuant to Executive Order 13817, ‘‘A Federal Strategy to Ensure Secure and Reliable Supplies of Critical Minerals” (82 FR 60835).
- Fresh, pure hafnium is a metal with a bright, silvery luster. However, hafnium oxidizes to form a beautiful rainbow colored surface effect.
- Hafnium is not found free in nature.
- Hafnium is classified as “incompatible” because it has physical and crystallochemical properties that excludes it from the crystal lattices of most rock-forming minerals.
- Zircon (ZrSiO4) is the primary source of hafnium, and zircon is a coproduct or byproduct of the mining and processing of heavy-mineral sands for the titanium minerals, ilmenite and rutile, or tin minerals.
- Hafnium metals are produced by the Kroll process, which involves reduction of zirconium oxychloride by magnesium metal in an inert atmosphere. The resulting metal contains a mixture of zirconium and up to 2 percent hafnium.
- The 45th most abundant element on Earth, hafnium in the Earth’s crust is 3.3 parts per million by weight.
- The abundance of hafnium in our solar system is 1 part per billion by weight.
- Hafnium carbide (HfC) has the highest melting point of any known two-element compound at nearly 7,034 degrees Fahrenheit, or 3,890 degrees Celsius.
- Hafnium is pyrophoric, meaning that it ignites spontaneously, in powder form.
- Through chemical analysis of the hafnium in a rare meteorite, researchers have been able to confirm that the Earth’s first crust formed around 4.5 billion years ago.
- Hafnium is widely used in chemical and nuclear industries in applications for which corrosion resistance, structural stability at high temperatures, specific alloying properties, and specific neutron absorption characteristics are required.
- The major end uses of hafnium are in nuclear control rods, nickel-based superalloys, nozzles for plasma arc metal cutting, high-temperature ceramics, photographic flash bulbs, light bulb filaments, electronic equipment as cathodes and capacitors, gate insulators in integrated circuits for computers, getters for scavenging oxygen and nitrogen, and various aerospace applications, such as rocket engines.
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