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.


Materials Science and Engineering


This material is based upon work supported by the U.S. Department of Energy, Office of Science, Office of Basic Energy Sciences, under Award Number DE-SC0017082.

Keywords and Phrases

Borides; Carbides; Joints/Joining; Phase Equilibria; Ultra-High Temperature Ceramics

International Standard Serial Number (ISSN)

0002-7820; 1551-2916

Document Type

Article - Journal

Document Version


File Type





© 2018 American Ceramic Society, All rights reserved.

Publication Date

01 Sep 2018