Jun 18 2018
An international team of researchers have projected a new superhard material for use in machine building, drilling, and other fields. The new tungsten boride discovered by them outperforms the extensively used ‘pobedit’ - a hard tungsten carbide and cobalt composite material with artificial diamond interspersing. The results of their research were reported in the renowned scientific journal, The Journal of Physical Chemistry Letters.
Image credit: MIPT
Superhard substances have a wide scope of application ranging from well drilling, machine building, and metalworking to the defense sector, surgical usage, and many other fields. The hardest known material, the diamond, is a high-priced luxury in a number of applications. Its distant competitor, pobedit, has remained unsurpassed in the past 80 years. Pobedit, created in the 1930s, was used during the Second World War to manufacture anti-tank shell caps (the term “pobedit” is essentially derived from the Russian “pobeda” which means victory) and has been used for numerous years to make drill bits for the drilling rigs. Harder materials either have much lower fracture toughness or need higher-pressure synthesis.
A team of researchers guided by Professor Artem Oganov of Skoltech and the Moscow Institute of Physics and Technology (MIPT) used their USPEX evolutionary algorithm to envisage a new material, WB5, that can be created at normal pressure and can effectively compete with pobedit in the two most vital parameters— fracture toughness and hardness—which are 20% lower and 50% higher, respectively, for WB5 as compared to pobedit. The new material is a formerly unknown compound that can be easily attained under regular conditions. The Skoltech researchers performed their study within the outline of Gazprom Neft’s large-scale project focused on developing new materials for drilling applications.
Before we discovered the new material, we had studied a lot of systems on the computer, trying to predict stable chemical compounds and calculate their properties. These were quite interesting substances, although they could hardly compete with pobedit. At some point, I thought we would never beat pobedit which has stood its ground for almost a century - and for good reason. But suddenly we saw a glimmer of hope and soon found a unique compound, WB5.
Artem Oganov, Study Lead
“The tungsten-boron system has been the subject of a multitude of experimental and theoretical studies, and it is surprising that this compound has not been discovered till now,” said the first author of the study Dr. Alexander Kvashnin
The study’s authors included scientists from Skoltech and MIPT in Russia, Yerevan State University in Armenia, and the following three Chinese universities: the School of Physics of the China University of Mining and Technology, the International Center for Materials Discovery of the Northwestern Polytechnical University, and the School of Physics and Optoelectronic Engineering of the Guangdong University of Technology.