GRAPHITIZATION DYNAMICS OF SURFACE OF DETONATION NANO AND MICRO DIAMONDS

• Published in: IZVESTIYA VYSSHIKH UCHEBNYKH ZAVEDENIY KHIMIYA KHIMICHESKAYA TEKHNOLOGIYA Vol. 61; no. 11
• Main Authors: Shevchenko, Nikolay V., Gorbachev, Valentin A., Chobanyan, Vladimir A., Sigalayev, Sergey K., Rizakhanov, Rajudin N., Vysotina, Elena A., Blank, Vladimir D., Golubev, Alexander A.
• Format: Journal Article
• Language: English
• Published: 01.01.2018
• ISSN: 0579-2991; 2500-3070
• DOI: 10.6060/ivkkt.20186111.7y

The characteristic features, properties and phase composition of the surface of nano and microcrystals of diamond of detonation synthesis subjected to graphitization are studied. The patterns of this process and the accumulation of graphitization products have been studied by applying Raman scattering, electron microscopy on an electron microscope, and X-ray phase analysis of micropowder samples. As objects of research, samples of chemically purified detonation nano and microdiamonds obtained by detonation synthesis were used. The used samples of carbon particles were investigated in the temperature range of 20 - 1500 °C, in an inert gas atmosphere, at different heating rates of the object. The graphitization of nanodiamonds is characterized by rigorous stage transformations associated with the growth of Raman intensities of Raman peaks (1350 and 1610 cm-1) characterizing graphitization associated with the appearance and accumulation of sp2-type carbon bonds. The recorded manifestations of Raman scattering are associated with the appearance and accumulation of crystalline and amorphous products of nanodiamond graphitization. The final products of the process studied had a Raman peak at 1575 cm-1, which directly indicates the appearance of onion-like forms of carbon on the surface of the nanodiamond particles studied. The distinctive features of the dynamics of graphitization of the surface of carbon particles having different structural organization are established. Nanodiamond particles are more sensitive to graphitization processes than microdiamond particles, and their changes are deeper. The graphitization of nano and microdiamond particles is accompanied by the transition of the surface carbon from sp3 to the sp2 phase, as well as the appearance of various forms of the amorphous phase. This process is characterized by the appearance and accumulation of onion-like graphite products (onions). The peculiarities of graphitization of microdiamonds are associated with the appearance of onion-like extended structures, which are much larger in size than microstructures, in comparison with onions arising from detonation nanodiamonds.