Open AccessMechanism of self-propagating hightemperature synthesis of AlB<sub>2</sub>‒Al<sub>2</sub>O<sub>3</sub>
Author(s) -
Пань Ян,
Гоцин Сяо,
Дунхай Дин,
Юнь Жэнь,
Чжунвэй Чжан,
Шоулэй Ян,
Вэй Чжан
Publication year - 2019
Publication title -
novye ogneupory
Language(s) - English
Resource type - Journals
ISSN - 1683-4518
DOI - 10.17073/1683-4518-2019-1-27-36
Subject(s) - combustion , dissolution , precipitation , quenching (fluorescence) , chemistry , reaction mechanism , composite number , autoignition temperature , materials science , analytical chemistry (journal) , crystallography , catalysis , fluorescence , organic chemistry , physics , composite material , quantum mechanics , meteorology
The mechanism of self-propagating high-temperature synthesis (SHS) of AlB 2 ‒Al 2 O 3 composite powders was studied by means of a combustion front quenching method (CFQM). The results showed that combustion reaction started with the melting of B 2 O 3 and Al particles. As the combustion reaction proceeded, the interpenetration of Al and B 2 O 3 in melts happened. The XRD results of the product revealed the reflections of Al 2 O 3 , suggesting there had been an exchange of oxygen atoms between Al and B, and evidencing the reaction, B 2 O 3 (l) + 2Al (l) → 2B (s) + Al 2 O 3 (l). Under higher temperature, some of B 2 O 3 volatilized and reacted with B forming gaseous B 2 O 2 , which deposited on the surface of Al to precipitate Al 2 O 3 and B. Then B made available dissolved into Al melt, and reacted with the Al in melt to precipitate AlB 12 particles. Finally, AlB 12 transforms to AlB 2 at the peritectic temperature under high cooling rate. Thus, this combustion reaction can be described by the dissolution-precipitation mechanism. In the final products, besides AlB 2 and Al 2 O 3 particles, some of Al was also detected. A model corresponding to the dissolutionprecipitation mechanism was proposed, and the ignition temperature of the combustion reaction was determined to be around 800 °C. Ill. 13. Ref. 47.