Boron source and extra amount on formation of WB2–Al2O3 composites by combustion synthesis. (September 2020)

• Record Type: Journal Article
• Authors: Yeh, C.L.; Chen, W.L.
• Is Part Of: Vacuum. Volume 179(2020)
• Publication Date: 2020-09
• Subjects: WB2–Al2O3 composite -- Combustion synthesis -- B4C -- Excess boron; Vacuum -- Periodicals; 621.55
• DOI: 10.1016/j.vacuum.2020.109482
• Languages: English
• ISSNs: 0042-207X

Abstract

Abstract: Formation of WB2 –Al2 O3 composites was investigated by the reduction-based SHS scheme using WO3, B2 O3, Al, W, and B4 C as primary reactants. The effect of extra boron addition on combustion wave kinetics and product composition was studied. Excess boron supplied from four different boron compounds, including elemental boron, B4 C, B2 O3, and BN was examined. The addition of extra elemental boron led to an increase in combustion wave velocity and temperature, while the other three boron compounds caused a decrease. WB and WB2 were formed with WB2 fraction of 40% from the sample without extra boron. For the samples with 30 atom% excess boron, the use of elemental boron and B4 C as extra boron source contributed to high WB2 yield fractions of about 90% and 86.4%, respectively. Highlights: WB2 –Al2 O3 composites were fabricated by the reduction-based SHS scheme. Elemental boron and B4 C as the extra boron source showed significant improvement in the yield of WB2 . Excess boron of 30 atom% was required to produce WB2 up to 90% yield fraction.