Yu. M. Maksimov

Combustion of vanadium-iron alloys in nitrogen

The starting alloys were prepared from specially pure carbonyl iron (99.8% Fe) and electrolytic vanadium VEL-1 (99.8% V) in a vacuum furnace, crushed to a powder with particle size less than 0.14 mm and pressed into pellets with a relative density of 0.48-0.64. The burning of the alloys is described. The nitrogen pressure in the bomb was varied from 1 to 130 atm. In the experiments the burning specimens were frequently quenched in water. The starting material and combustion products were analyzed radiographically and metallographically. The paper discusses effect of iron content of alloy on burning rate and extent of reaction, as well as laws of combustion of alpha- and sigma-ferrovanadium. A review is given of phase transition to sigma-ferrovanadium combustion. A discussion of the results is presented.

Effects of boundary kinetics in stationary combustion in a gas-free system

This article presents a qualitative study of the effects of the boundary reactions on the speed of the combustion wave and the propagation laws. The analysis is performed for stationary combustion in a model heterogeneous system consisting of ordered layers of the reacting components. Neglects the difusion of the material in the direction of combustion-wave propagation and assumes that in accordance with the phase diagram for the A-B system the reagents interact only to form a single layer of the product AB. The propagation of the combustion wave throughout the range in the relevant parameters is characterized by a reaction zone with a narrow temperature distribution.

Effect of mass forces on combustion of heterogeneous systems with condensed combustion products

This paper investigates the principles of combustion of the system Ti-B. The experiments used type PTEM-1 and PTEK-0 titanium powders and 98.8% pure amorphous boron. Results of combustion rate measurements as a function of metal particle size and g-force f value are shown. It is evident that G has an effect only for sufficiently coarse titanium particles. The effects of g-forces of opposite signs differ qualitatively: positive G leads to increase in the combustion rate; negative G to reduction. Compression of the combustion products due to change in specimen length increases with increase in g-force of either sign, but does not exceed 30%. Flow of the melt under the action of a mass force is illustrated. It is noted that forced flow of a liquid in a combustion wave may also lead to an increase in reaction rate due to more complete mixing of the reagents.

Sintering of the reaction products of combustion of alloys in nitrogen

An investigation of the mechanism of compacting of Fe-V alloy with a sigma-phase structure, a low porosity composite material consisting of alpha-iron and a filler of delta-vanadium nitride, is made after the synthesis surge. Alloys containing 50 wt.% Fe were prepared by sintering in a vacuum furnace of powders of type VEL-1 vandium and special purity carbonyl iron. The mechanism of compacting was studied on specimens in hardened water. Metallographic investigations were made on MIM-7 and PMT-3 instruments and the phase analysis on a DRON-2 instrument. Rapid compacting in combustion of sigma-FeV in nitrogen is determined by combining of the solid-liquid drops formed in the combustion front and consisting of molten iron and vanadium nitrides.

Theory of combustion of multicomponent systems with condensed reaction products

Problems of the formation in the combustion wave of a singlephase product layer or solid solution are examined. The starting mixture is simulated by a set of plane cells consisting of ordered layers of the reactants. The paper illustrates that the reactants may be the pure substances A, B, C or their alloys and compounds. The size of the cell is determined and the heat conduction equation is presented. A model of the medium, phase diagrams, and a schematic distribution of the elements in the cells are provided in the paper. Concentration distribution of the elements A and B in the cell corresponding to the maximum of the heat release rate is illustrated, and results of the calculations are presented in which the solution of condensed component, interaction through product layer, and mixture combustion are discussed.

Influence of ultrasonic vibrations on the combustion of condensed systems with solid-phase reaction products

It has been shown in the example of the combustion of the Ti-B system that high-frequency mechanical vibrations under the conditions of the limiting action of liquid titanium filtration result in significant increase in the combustion velocity. The influence of ultrasonic vibrations on the formation of the final reaction product is investigated in this paper, with the system Ti-B-Fe selected for the tests.

Regularities and mechanism of combustion of the system Ti-B-Fe

At the present time the gasless combustion of two-component systems has been studied most completely [i], while the regularities and mechanism of the combustion of multicomponent compositions have been investigated inadequately. Presented in the example of Ti--B--Fe in this paper are experimental results of the combustion of a three-component system. Stable stationary modes of combustion wave propagation are examined, nonstationary phenomena in the combustion of this system were studied earlier [2, 3].