Martynov, R. S.

Pak, Aleksandr Yakovlevich

English

Electronic archive of Tomsk Polytechnic University

DIRECT CURRENT ARC-PLASMA SYNTHESIS OF B-C POWDER PRODUCT* A.Y. PAK1, R.S. MARTYNOV1 1Tomsk Polytechnic university, Lenin av. 30, Tomsk, 634050, Russia, ayapak@tpu.ru, +7 953 922 00 03  Boron carbide is widely spread, super-hard material, which is characterized by low density (~2.5 g/cm3) high melting temperature (~2620–2740 °C), high resistivity to some radiation and other unique properties [1]. Boron carbide can be synthesized by several methods, such as: carbo-thermal reduction of boron oxide, plasma spraying, melt crystallization, and CVD [2-5]. Last years a new method of direct current arc discharge has been developed for carbon nanostructures [6] and boron carbide [7] synthesis. The main feature of this method is the possibility to  operate at generating the ambient air plasma. This procedure is becoming possible due to carbon monoxide generation during arcing, that results in gas, which  can insulate the reaction zone and prevent oxidation from synthesis products. The procedure implementation has been discussed before in [6-7]. In this paper we study the crystalline phase composition and crystallinity of powder products in link with a synthesis process time. The arc discharge experiments were conducted by DC APAS-method (direct current arc plasma air synthesis) at a plasma chemical reactor that is introduced in [7].         According to X-ray diffraction data (Shimadzu XRD 7000s, λ=1.54060 Å, CuKα) a typical product consists of three main crystalline phases: graphite (C (graphite)), boron oxide B2O3, as initial raw materials, and synthesized boron carbide B13C2. The phase composition depends on arc discharge tome as mentioned below in Fig. 1. 02040608010010 12 21Arcing durability (sec)Phase content (%)B2O3C (graphite)B13C2 Fig. 1. Phase composition and arcing time dependence The maximum time is 21 seconds that can lead to full mass of initial boron oxide consumption. At this time the content of graphite increases owing to the anode erosion effect [8]. According to these data we make a conclusion that arcing time influences the phase composition through energy input variation by time control. Besides, it is possible to obtain two phase composition of a product by full mass of the  boron oxide consumption.      REFERENCES [1] R. A. Andrievski // Russ. Chem. Rev.  2012.  81.  549. [2] P. Foroughi and Z. Cheng// Ceram. Int.   2016. – 42. – 15189.  [3] A. Mishra, R. K. Sahoo, S. K. Singh, and B. K. Mishra // J. Asian Ceram. Soc. – 2015. – 3. – 373.  [4] R. Tu, N. Li, Q. Z. Li, S. Zhang, L. M. Zhang, and T. Goto //J. Eur. Ceram. Soc. – 2016. – 36. – 3929.  [5] A. Bute, Jagannath et. al. // Mater. Chem. Phys. – 2016. – 182. – 62.  [6] Y. Su, H. Wei, T. Li, H. Geng, and Y. Zhang //Mater. Res. Bull. – 2014. – 50. – 23.  [7] A. Ya. Pak and G. Ya. Mamontov // Technical Physics Letters. – 2018. – 44. – 7. 26.   [8] Neha Arora, N.N. Sharma // Diamond and Related Materials. – 2014. – 50. – 135.                                                       * This work was supported by the Russia President ‘s grant for young scientists (MK-633.2019.8) 283

Direct current arc-plasma synthesis of B-C powder product

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Direct current arc-plasma synthesis of B-C powder product

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