Scientists of the Novosibirsk State Technical University (NETI) have obtained refractory niobium silicide in laboratory conditions. The super-strong and refractory intermetallic compound is of interest in the aerospace industry as a replacement for heat-resistant nickel alloys.
Evgeny Golovin, PhD, Associate Professor, Head of the Department of Mechanical Engineering Technology at the Faculty of Mechanics and Technology of NSTU-NETI, said that niobium silicide was obtained in the Activator 2SL high-energy planetary mill. The report on this research was presented at the XXVIII International Scientific and Technical Conference of the Ural School of Metal Thermists "Actual problems of physical Metallology of steels and alloys", dedicated to the 100th anniversary of the birth of Honored Scientist, Doctor of Technical Sciences, Professor Leonid Innokentievich Tushinsky, founder of the School of Materials Science of NSTU-NETI.
"We conducted a series of experiments to produce niobium silicides in a ball mill by placing silicon powders, niobium, and grinding bodies there — balls made of a hard alloy VK8. Studies of the obtained powder material have shown that we were able to synthesize a large amount (up to 66%) of the target phase, namely niobium silicide Nb5Si3." The results of the experiments are published in a scientific article.
"We have not seen such a result in the literature," the scientist noted. — As far as I know, this is the first time we have received this compound in such conditions. There were only works by researchers who obtained other, less refractory niobium silicides by mechanosynthesis. We are specifically interested in Nb5Si3, which is the most refractory in the Nb-Si system."
Niobium silicide Nb5Si3, which belongs to the class of intermetallides, is of great interest in the aerospace industry due to its unique properties. "Niobium silicide is lighter than high—temperature nickel alloys, but most importantly, it is a very refractory compound — it melts at a temperature of 2500 ° C, which is a thousand degrees higher than the low-temperature alloys used in the aircraft industry today," said Evgeny Golovin.
At the same time, the compound is highly brittle and oxidizes at high temperatures. "All over the world, scientists are solving these problems in order to obtain the material of the future. We focused on the task of affordable synthesis of niobium silicide. We managed to obtain this refractory material in a ball mill at virtually room temperature. Other technologies, such as induction melting and casting, are extremely complex and expensive," Evgeny Golovin emphasized, adding that further research will be devoted to manufacturing parts from the obtained powders using electric spark sintering.
Earlier, scientists at NSTU-NETI developed a corrosion-resistant coating based on high-entropy alloys reinforced with refractory particles. Due to its increased corrosion resistance, wear resistance and ductility, the coating can be used in the chemical industry and the energy sector.