Yu. V. Kontsevoi

Production of nickel and iron nanopowders by hydrogen reduction from salts

The formation of nickel and iron nanoparticles produced by a chemical—metallurgical method and steels made of composite iron powders with nanosized nickel additions is studied. A procedure is developed for calculating the nanopowder particle size and the activation energy of sintering. The results obtained make it possible to decrease the temperature of the process of powder production, to decrease the energy consumed for powder sintering, and to predict the powder nanoparticle size.

Production and application of new complex boron-containing ferroalloys

Effect of microalloying with boron on the properties of steel is studied using a new complex silicon-, manganese-, and boron-containing FSMB ferroalloy. The mechanical properties and structure of steel alloyed with this ferroalloy are comparable to or even higher than those of steel alloyed with ferroboron.

Interaction of iron and aluminum in the plastic deformation and fast heating of laminar Fe–Al composite

The influence of plastic deformation and the heating rate on the solid-phase interaction of steel strip and aluminum powder is investigated. Recrystallization of the contacting materials determines the phase formation. The layer thickness of the Fe–Al intermetallides is plotted as function of the strain and heating rate. On that basis, the parameters of the transition layer may be predicted in selecting the technological conditions.

Imparting Ductility to a Steel–Aluminum Composite Laminate in Forming Operations

One of the major disadvantages of corrosion-inhibiting aluminum coatings on steel is the presence of a brittle intermetallide layer between the steel substrate and aluminum coating. This paper reports results from an investigation of the problem. A manufacturing scheme based on the treatment of such laminated composites by forming operations is proposed.

Steel composites based on copper-clad iron powder

The structure and physicomechanical properties of materials produced from copper-clad iron powder with 0.3% C are investigated as a function of the sintering temperature, the copper concentration, the method of coating application, and the heat treatment of the copper coatings. The use of copper plating (0.5⎯2.0% Cu), when the reduction of the coatings is combined with the sintering of the parts, activates compaction (with 1.6% decrease in the porosity) and alloying. The mechanical properties of the steel may be increased by a factor of 1.4–1.7 relative to steel made from mixtures of micropowders.

Steel-aluminum layered composite with a nanostructured intermediate layer

The results of an investigation into the influence of the degree of deformation on the structure of components of the layered steel-aluminum composite are presented. It is shown that the noticeable structural variations start from reduction ratio ɛ > 75%, or e > 1.54 in logarithmic units. The plastic deformation mechanism of a brittle intermetallic layer is described. It is shown that the viscoplastic intermediate layer of the steel-aluminum layered composite can be obtained by rolling when bringing the deformation ratio to 90%. As for the submicron structure, it can be obtained at ɛ > 95%, or e > 3.

Conglomeration of metallic power and destruction of conglomerates

Theoretical principles describing the formation and disintegration of conglomerates are developed and used to formulate a method for mixing nanodisperse, ultradisperse, and highly disperse powders, with simultaneous disintegration of conglomerates. The operation of the corresponding mixing equipment is described.

Analysis of basic factors governing compacted powder density

Based on a theoretical analysis of the behavior of metal powders during compaction, basic factors governing the compacted powder density, i.e., the compaction pressure and the sizes of a powder particle and its grain, are determined. Mechanisms of the effect of these factors are considered, and a mathematical dependence for forecasting the compacted powder density is determined. According to the experimental data of other authors, the formula that is derived is verified in a large range of variations in the sizes of dispersoids under compaction.

Vibroaeratic Mixing of the Powders in a Gas Medium: Report 2. Computing Kinematics of a Valve and Powder and Determining Optimum Sizes of Mixer Elements

Principles of determining the functional parameters and optimum sizes of a mixing chamber and its operating units were developed. Using the example of mixer operation at the vibration frequency f = 15 Hz and amplitude A = 0.006 m, the correction factors in the motion equation for dispersoids with open and closed valves were obtained. Graphs of the powder flow in the mixing chamber were plotted and analyzed. On this basis, the optimum sizes of the valve, which provide the assigned time mode of its opening, were found. The objective data of the mixer operation are given in the form of charge photography at × 200 magnification and diffractograms of mixture compositions for four samples.

Vibroaeratic mixing of the powders in a gas medium: Report 1. Developing a method and theoretical foundations for vibroaeratic powder mixing and destroying conglomerates

Based on the already-known theory of processes that occur with powders in the state of vibrationboiling, a new method for mixing the powder (vibroaeration) and a device for implementing it were developed. The following tasks are noted and completed: (i) qualitatively mixing powders with different granulometric compositions, including finely dispersed ones, during the complete destruction of their conglomeratic formations and (ii) developing theoretical foundations for the processes in the powder mass under the effect of a compressed gas “cushion” on it. Experimental testing for different engineering solutions is presented, and the optimum design version of a mixer is selected based on these tests.