Дослідження структури Fe–Ti, утвореної методом СВС

Abstract

Розглянуто механізм спікання порошків титану, вуглецю та сталі ШХ15. Розглянуто основні закономірності, при яких відбувається СВС-процес. Показано, що характерною особливістю СВС-процесу є наявність двох продуктів реакції – тугоплавкого з’єднання і окису металу-відновника. Структура такого матеріалу залежить від багатьох факторів розчинності, відношення питомої ваги, розміру реакційної маси, тиску газу. Визначено оптимальний шихтовий склад сполук з використанням порошків титану, вуглецю, сталі ШХ15. Досліджено, що для системи титан-вуглець-сталь ШХ5 синтез здійснюється в інтервалі температур від 557–1677К з утворенням інтерметалідів FeTi, Fe2Ti. В інтервалі від 1083–1677К процес відбувається інтенсивніше, при цьому утворюється інтерметалід заліза. Як показали дослідження пористість отриманої структури становить 30%. Для підтвердження структури, яка визначена металографічним методом, додатково проводили рентгеноструктурний аналіз. На термограмі видно піки термоефектів, які відповідають поліморфним перетворенням та інтенсивній взаємодії між компонентами.

The mechanism of titanium, carbon and BBS15 steel powders sintering was considered. The powder of BBS15 steel is taken in such amount which allows to link titanium and carbon completely in chemically neutral compositions. The mixing lasts eight hours to form the homogeneous mass. The synthesis is carried out in the laboratory reactor. Basic regularities under which SHS-process takes place are analysed. It is shown that the characteristic feature of SHS- process is the availability of two products of reaction - refractory connection and metal-repairer oxide. The structure of such material depends on many factors: solubility, relation of the specific weight, reaction mass amount, gas pressure. Dynamics and structure-forming mechanism of the finished goods are not studied enough. The most important is the information on the change of the forming material microstructure in the SHS waves (distribution of the grains and pores according to their sizes). Manufacturing of the ШХ15 steel powder materials by the SVS method was carried out according to the scheme: mixing of the initial reagents powders due to the stochiometric calculation according to the certain reaction equations; drying of the reagent initial charge under protection environment conditions; pressing of the reagent initial charge in the cylinder blanks of different diameter and height at variation of the material density values of the obtained samples while changing the pressing pressure; realization of the SHS-process in the laboratory device and obtaining of the functional materials samples. The objective of the paper is to investigate the structure and the chemical composition of the materials obtained by the SHS method using powders of BBS15 (ШХ15) steel. The optional charge composition of compounds was found using the titanium, carbon powders, and ШХ15 steel. It was investigated that for the titanium – carbon – ШХ15 steel system the synthesis is carried out within the temperature interval 557–1677К with the formation of FeTi, Fe2Ti intermetallides. It was found that within the interval 1083–1677К the process is more intensive, the intermetallide being formed. As the investigations testified the porosity of the obtained structure is 30%. From the technological point of view this process can be divided into such stages: initiation of burning reaction, phase-forming, cooling of the reaction products. Only those processes were investigated, which take place in the stationary mode, that is, when the burning temperature is higher than that of the product melting, because the carbon takes place in the synthesis reactions, which causes additional heat release. To confirm the structure, which was found by the metallographic method, additional X-ray structural analysis was carried out. The picks of thermoeffects are seen on the thermogram, which are similar to polymorphic transformations and intensive interrelation between the components. One of the efficient ways of decreasing the cost price of parts manufacturing is recycling of wastes of the industrial production. It was proved that in order to obtain materials in the developed installation the wastes of the machine-building industry are worth being recycled, decreasing of the energy consumption is obtained due to SHS-processes. Refractory compounds materials will possess high strength and hardness.