Diborides of Some Transition Metals: Properties, Application and Production. Review. Part 1. Titanium and Vanadium Diborides

The properties, applications, and methods for producing titanium and vanadium diborides are considered. These diborides are oxygen-free, refractory metal-like compounds. As a result, they are characterized by high values of thermal and electrical conductivity. Their hardness is relatively high. Titanium and vanadium diborides exhibit significant chemical resistance in aggressive environments. Thus, these diborides have found application in current technology. They are used as surfacing materials when applying wear-resistant coatings on steel products. It is also possible to use vanadium diboride as a catalyst in organic synthesis and as an anode in renewable electrochemical current sources. The promising ceramics are B₄C–TiB₂ and B₄C–VB₂, which allow to obtain products based on boron carbide with high performance characteristics, in particular with increased crack resistance. Such composite ceramics are produced by hot pressing, spark plasma sintering, and pressureless sintering. The properties of refractory compounds depend on the content of impurities and dispersion. To solve the specific problem associated with the use of refractory compounds, it is important to choose the correct method for their preparation, as well as to determine the permissible content of impurities in the starting components. This leads to the presence of different methods for the synthesis of borides. The main methods for their preparation are: synthesis from simple substances (metals and boron); borothermal reduction of oxides; carbothermal reduction (reduction of mixtures of metal and boron oxides with carbon; metallothermic reduction of mixtures of metal and boron oxides; and carbide-boron reduction. Plasma-chemical synthesis (deposition from the vapor-gas phase) is also used to obtain diboride nanopowders. Each of these methods is characterized in the article.