Synthesis and formation mechanism of nanocrystalline ZrB2–Al2O3 composite powders via an amorphous precursor

• Published in: Rare metals 2021-07, Vol.40 (7), p.1801-1807
• Main Authors: Song, Shao-Lei, Fan, Yong-Li, Li, Rong, Lin, Yue-Hua, Zhen, Qiang
• Format: Article
• Language: English
• Subjects: Aluminothermic reduction; Aluminum oxide; Biomaterials; Boron oxides; Chemistry and Materials Science; Energy; Materials Engineering; Materials Science; Metallic Materials; Nanoscale Science and Technology; Physical Chemistry; Precursors; Raw materials; Refractory materials; Zirconium compounds; Zirconium dioxide
• ISSN: 1001-0521; 1867-7185
• DOI: 10.1007/s12598-020-01428-y

ZrB 2 –Al 2 O 3 composite powders were synthesized at 1100 °C using a novel ZrB 2 precursor and Al powders as raw materials. The final ZrB 2 –Al 2 O 3 composite powders consisted of submicron Al 2 O 3 and nanosize ZrB 2 (50–100 nm) particles, which were homogeneously mixed in microscale. Combined with thermodynamic calculation and experiment results, the formation mechanism of ZrB 2 –Al 2 O 3 composite powders was proposed as follows: ZrB 2 precursor first decomposed into ZrO 2 and amorphous B 2 O 3 . Aluminothermic reduction of ZrO 2 and B 2 O 3 generated Zr and B atoms and the coproducts Al 2 O 3 , and then, a series of reactions between Zr atoms, B atoms and Al took place to form ZrB 2 and Al 3 Zr. Then, ZrB 2 , Al 2 O 3 and Al were obtained through a liquid–solid reaction between Al 3 Zr and B 2 O 3 , which is the limiting step in the conversion process. When the Al 3 Zr was exhausted, the reaction between Al, ZrO 2 and B became the main reaction to obtain ZrB 2 and Al 2 O 3 .