Effect of the Content of Molybdenum Disilicide on the Microstructure and Phase Transformations of ZrB2-MoSi2-10Al Coatings upon Annealing in Air

Authors V.M. Beresnev1 , I.Yu. Goncharov2, 3 , M.G. Kovaleva2, M.N. Yapryntsev2, O.N. Vagina2, V.Yu. Novikov2, V.V. Sirota3, Yu.N. Tyurin4

1V.N. Karazin Kharkiv National University, 4, Svobody Sq., 61000 Kharkiv, Ukraine

2Belgorod National Research University, 85, Pobedy St., 308015 Belgorod, Russia

3Belgorod State Technological University named after V.G. Shoukhov, 46, Kostyukov St., 308012 Belgorod, Russia

4E.O. Paton Electric Welding Institute, NASU, 11, Bozhenko St., 03650 Kyiv, Ukraine

Е-mail goncharov@bsu.edu.ru
Issue Volume 13, Year 2021, Number 6
Dates Received 09 November 2021; revised manuscript received 02 December 2021; published online 20 December 2021
Citation V.M. Beresnev, I.Yu. Goncharov, et al., J. Nano- Electron. Phys. 13 No 6, 06013 (2021)
DOI https://doi.org/10.21272/jnep.13(6).06013
PACS Number(s) 68.37.Hk, 68.37.Yz
Keywords Carbon/carbon composites, ZrB2-MoSi2, Multi-chamber detonation accelerator, Microstructure (21) , In situ HT-XRD.

The advantages of carbon/carbon (C/C) composites are low density, high heat capacity, resistance to thermal shock, low coefficients of friction and linear expansion, etc. However, their use in oxygen-containing environment at high temperatures is only possible with special protective heat-resistant gas-tight coatings, which prevent the access of oxygen to carbon. In this work, ZrB2-based composite coatings with different contents of MoSi2 were fabricated on the surface of C/C composites by a Robotic complex for detonation spraying of coatings equipped with a multi-chamber detonation accelerator (MCDS). Flat specimens (10 x 10 x 5 mm3) of 3D C/C composites (density 1.9 g/cm3) were used as substrates. The evolution of the microstructure and phase composition of ZrB2-xMoSi2 (х = 24, 35, 45 wt. %)-10Al coatings were analyzed with differential scanning calorimeter, X-ray diffractometry (in situ HT-XRD) and scanning electron microscopy at temperatures from 25 to 1400 °C (normal atmosphere and pressure). During analysis, it was observed that m-SiO2 and ZrSiO4 appear at 960 °C. Also, upon reaching the temperature 1235 °C, cubic zirconia and mullite are formed in ZrB2-xMoSi2-10Al coatings. In ZrB2-xMoSi2-10Al coatings at a temperature of 1400 °C, an increase in the MoSi2 content in the initial coating leads to almost complete disappearance of the cubic phase of zirconium dioxide, and the mullite content increases. It was found that the microstructure of the coating changed with an increase in the MoSi2 content after oxidation at 1400 °C from a dense to a "more defective". ZrB2-24MoSi2-10Al coating has a uniform dense microstructure in comparison with coatings containing 35 and 45 wt. % of MoSi2. It is contributed to its good oxidation-resistant property at high temperature.

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