Funct. Mater. 2019; 26 (2): 267-275.
Multifunctional ceramics LaB6-SiC-B4C of eutectic composition: thermionic properties
1National Aerospace University Kharkiv Aviation Institute, 17 Chkalov Str., 61070 Kharkiv, Ukraine
2Saint-Petersburg State Institute of Technology (Technical University), 26 Moskovsky Ave., 190013 Saint-Petersburg, Russian Federation
The article presents the results of thermionic studies (temperature dependences of the thermionic current density and the electron work function, Schottky lines to current-voltage characteristics) of LaB6-SiC-B4C multifunctional ceramics eutectic composition obtained by free sintering. The obtained data indicate a substantially low emission activity of both the entire emitting surface of the studied composite and the individual LaB6 grains on its surface as compared with the individual lanthanum hexaboride. Based on the X-ray phase analysis and X-ray energy dispersive microanalysis, it was concluded that the observed decrease in the emission activity is caused by carbonization of the entire surface due to thermal decomposition of SiC into carbon and silicon.
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