Effects of Al content on formation of TaC, Ta2C, and Ta2AlC by combustion synthesis with aluminothermic reactions. Issue 17 (1st December 2017)

• Record Type: Journal Article
• Authors: Yeh, C.L.; Chen, Y.S.
• Is Part Of: Ceramics international. Volume 43:Issue 17(2017)
• Page Start: 15659
• Page End: 15665
• Publication Date: 2017-12-01
• Subjects: A. Powders: solid state reaction -- B. X-ray methods -- D. Carbides -- MAX phase -- Combustion synthesis; Ceramics -- Periodicals; Céramique industrielle -- Périodiques; Ceramics; Periodicals; Electronic journals; 666
• DOI: 10.1016/j.ceramint.2017.08.124
• Languages: English
• ISSNs: 0272-8842

Abstract

Abstract: Fabrication of TaC–, Ta2 C–, and Ta2 AlC–Al2 O3 composites was conducted by incorporating aluminothermic reduction of Ta2 O5 into self-propagating high-temperature synthesis (SHS). Starting materials of this study included Ta2 O5, Al, Al4 C3, and carbon black powders. The effect of elemental Al content was studied by adjusting the proportions of Al, Al4 C3, and carbon. Experimental results showed that the increase of elemental Al facilitated the reduction of Ta2 O5, increased the combustion exothermicity, and improved the evolution of carbide phases. Compared to Al4 C3, elemental Al was demonstrated to be a more effective reductant for Ta2 O5 . Formation of Al2 O3 -added TaC and Ta2 C composites with trivial minor phases was achieved by the Al4 C3 -free samples with molar ratios of Ta2 O5 :Al:C = 3:10:6 and 3:10:3, respectively. For the production of the Ta2 AlC–Al2 O3 composite, a significant loss of Al occurred in the samples especially for those containing Al4 C3 . As a result, Ta2 AlC and Ta2 C were present as the main carbide phases. The increase of elemental Al improved the yield of Ta2 AlC, and the need of excess Al was advised.