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Contribution Oral

Budker INP - Conference Hall
X-ray structural analysis

The study of the phase composition of ceramic materials obtained by SHS from previously mechanically activated reaction mixtures Ti-Cr-B

Speakers

  • Dr. Victoria KURBATKIINA

Primary authors

Co-authors

Content

In this work, ceramic materials based on borides of transition metals were prepared by SHS compaction from the pre-mechanically activated (MA) of the powder mixtures. The use of МА enables SHS process in the low exothermic systems. The role of MA appeared in a simultaneous increase in heat evolution and heat evolution rate of the combustion reaction, a positive influence on the thermodynamics and kinetics of the process. Kinetics of the SHS process, stages of chemical transformations and structure formation in theTi Cr--B system were investigated. It is demonstrated that the interaction of the reagents on the solid phase mechanism takes place at a temperature of the combustion. MA was found to markedly affect the combustion temperature and burning velocity of Ti–Cr–B blends. SHS reactions in Ti–Cr–B blends with Cr contents above 10% proceeded with involvement of gas transport agents. The role of gas transport was found to grow with increasing MA duration, due to an increase in the amount of boron oxides. The mechanisms of combustion and structure formation in Ti-Cr-B were well characterized using different method such as stop combustion front, SEM, EDS, X-ray photoelectron spectroscopy, XRD including the use of synchrotron radiation. Results, the main reaction is the formation of the titanium borides. Then, the complex borides are formed in the post combustion zone and the secondary structure formation zone. Ternary phases Cr4Ti9B and Ti2CrB2 were detected. Сr4Ti9B phase is formed at a chromium content of up to 20%, second boride (Ti2CrB2) is formed with increasing chromium concentrations up to 30%. It is found that they are chemical compounds - borides hexagonal lattice (structural types hP28 / 5 and tP10 / 2). The technology of compact samples of pre-activated mixture Ti-Cr-B and their properties were studied.