Solidification of Welded SiC-ZrB₂-ZrC Ceramics
A silicon carbide-based ceramic, containing 50 vol% SiC, 35 vol% ZrB2, and 15 vol% ZrC was plasma arc welded to produce continuous fusion joints with varying penetration depth. The parent material was preheated to 1450°C and arc welding was successfully implemented for joining of the parent material. A current of 138 A, plasma flow rate of ~1 L/min or ~0.5 L/min, and welding speed of ~8 cm/min were utilized for repeated joining, with full penetration fusion zones along the entire length of the joints. Solidification was determined to occur through the crystallization of β-SiC (3C), then the simultaneous solidification of SiC and ZrB2, and lastly through the simultaneous solidification of SiC, ZrB2, and ZrC through a ternary eutectic reaction. The ternary eutectic composition was determined to be 35.3 ± 2.2 vol% SiC, 39.3 ± 3.8 vol% ZrB2, and 25.4 ± 3.0 vol% ZrC. A dual fusion zone microstructure was always observed due to convective melt pool mixing. The SiC content at the edge of the fusion zone was 57 vol%, while SiC content at the center of the fusion zone was 42 vol% although the overall SiC content was still nominally 50 vol% throughout the entire fusion zone.
D. King et al., "Solidification of Welded SiC-ZrB₂-ZrC Ceramics," Journal of the American Ceramic Society, vol. 101, no. 9, pp. 4331 - 4339, Blackwell Publishing Inc., Sep 2018.
The definitive version is available at https://doi.org/10.1111/jace.15570
Materials Science and Engineering
Keywords and Phrases
Borides; Carbides; Joints/Joining; Phase Equilibria; Ultra-High Temperature Ceramics
International Standard Serial Number (ISSN)
Article - Journal
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01 Sep 2018