TECHNOLOGICAL BASES OF OBTAINING INTERMETALLID CATALYST S BASED ON NICKEL ALUMINIDS

Abstract

The intermetallide systems of Ni-Al are chosen for the study. This system belongs to the group of intermetallic systems in which the adiabatic combustion temperature is equal to the melting point of the product formed (Tm = Tad). Analytic equations of the temperature-time dependences of the formation intermetallides in the NiAl system and their activation energy are obtained on the basis of experimental methods for studying the kinetics of the interaction intermetallic alloys under conditions of self-propagating high-temperature synthesis. An investigation of the laws of heat release during thermal autoignition made it possible to establish the following sequence of reactions: NiAl3 → Ni2Al3 → NiAl. Varying the synthesis temperature, and hence the speed below the ignition limit, allows us to find the value at which the required degree of chemical transformation is achieved within the established synthesis time. Thus, at a temperature of maximum ignition of 530 °C, the total depth of the chemical transformation is reached in 220 s, the temperature decrease to 490°C leads to an increase in the synthesis time by a factor of 2. It is established that for the reaction of the interaction nickel and aluminum with the formation of the first crystals of intermetallides, the activation energy is 42.917 kJ/mol. Also in the work, on the basis of the Johnson-Mel-Avrami-Kolmogorov model, dependences determining the temperature and the synthesis time at which the required degree of chemical transformation is reached are obtained. The results of the study can be used to obtain intermetallic catalysts. It is set that for the reaction of co-operation of nickel and aluminium with formation of the first crystals інтерметалідів energy of activating makes the 43 kJ/moth of clothes. The calculation of depth of chemical transformation on the Dzonson-Mel- Avrami -Kolmogorov model of showed, that at the temperature of maximum self-ignition 530 °С gives the complete depth of chemical transformation on 220 °С, decline of temperature to the size 490 °С results in the increase of time of converting ~ into 2 times. Receipt results can be using for the receipt of internetalide catalysts in the conditions of high temperature synthesis.