V.V. Kurbatkina

Features of combustion in the Mo-Si-B system: Part 2. Effect of mechanical activation

This study is devoted to investigating the effect of mechanical activation (MA) on the kinetics and combustion mechanism of a reaction mixture in the Mo-Si-B ternary system, as well as ceramic material production by the self-propagating high-temperature synthesis (SHS) method. Elemental molybdenum, silicon, and boron powders are used as the initial components. The MA was carried out in a planetary mill. The MA modes with maximum heat release amount and rate were determined. MA results in an increase in the heat release rate and reactivity of the mixture because of the reagent size reduction, reduction of coherent-scattering regions, and increase in the density of structural defects and dislocations. In contrast with nonactivated mixtures, initial temperature dependences of the combustion temperature and rate are linear for MA mixtures. The MA contribution to the effective activation energy (Eeff) of the combustion process is evaluated quantitatively.

The features of influence of ZrO2 and WC nanodispersed additives on the properties of metal matrix composite

The features of influence of ZrO2 and WC nanoparticles on the properties of the iron-based metal matrix composite are investigated. The influence of nanoparticles on the compactibility of the powder material and mechanical and tribological properties of alloy is analyzed. It is revealed that the metal matrix composite particle reinforced with nanoparticles, which was fabricated by hot compression technology, is characterized by increased hardness and wear resistance.

Structure and properties of the precipitation-hardening Ti–Nb–C material with a binder

The influence of a metallic nickel-based binder on the structure and properties of the (Ti, Nb)C ceramic material is investigated. The samples are fabricated according to the SHS forced compaction technology with subsequent thermal treatment in a vacuum furnace at 850°C for 1 h. The composition and structure of fabricated samples were investigated by XRD, SEM, and EDS. Supersaturated solid solutions based on (Ti, Nb)C carbide decompose after annealing with the formation of nanodimensional NbCo2, Ni3NbAl, and Ni2NbAl phases. The β-(Ti, Nb) solid solution is a dispersed phase at a low binder content (5%) and the (Cr, Al) solid solution is a dispersed phase at a binder content of 20%. Properties of fabricated materials such as density, porosity, hardness, strength, and heat resistance are determined. The precipitation-hardening material of the Ti–Nb–C system with binder contents of 20 and 30% is recommended for the application as the constructive and functional ceramics.

Features of the influence of nanomodification and macrostructurization on the properties of the Fe-Mo binder for a diamond tool

The joint influence of two factors—(i) modifying an alloy by the alloying additive of the WC nanopowder using the mechanical activation of the mixture and (ii) combining the charge granules containing the alloying additive and without it—on the structure and physicomechanical properties of a hot-compacted Fe-Mo alloy is investigated. The occurrence of the concentration limit of alloy hardening under its nanomodification is established and the possibility of fabricating a material with high impact viscosity and an elasticity modulus under the mentioned combination of granules is shown.

Fabrication of submicron powders and nanostructured NiAl-based granules by the SHS method from a mechanically activated mixture

The influence of parameters of mechanical activation (MA) on the structure and phase composition of the Ni–Al reaction mixtures, as well as the products that are formed from them during the subsequent self-propagating high-temperature synthesis (SHS), is investigated using optical and electron microscopy, X-ray structural analysis, electron probe microanalysis, and laser diffraction. Optimal MA modes of reaction mixtures and optimal synthesis conditions of porous cakes are determined. Special functional additives of Al2O3, BN, and WC powders, which increase the cake porosity and facilitate the subsequent grinding, are selected and their amount is determined. It is revealed that boron nitride and tungsten carbide additives most efficiently promote the destruction of NiAl particles. Submicron powders with an NiAl-based nanoblock structure are prepared.