Joining B <sub>4</sub>C–TiB <sub>2</sub> ceramics with Ti interlayer via spark plasma sintering: Temperature-dependent interfacial microstructure and mechanical strength
Wei Wang, Lei Zhao, Ao Han, Yaxin Wang, Gang Wang, Songlin Ran, Xing Jin
Abstract
To investigate the bonding behavior of SiC-free composite ceramics via spark plasma sintering, this study demonstrates the successful joining of B<sub>4</sub>C–40 vol% TiB<sub>2</sub> ceramics using a Ti foil interlayer within the temperature range of 1000–1400 <sup>o</sup>C. The bonding mechanisms across temperatures were systematically elucidated through integrated approaches, including phase composition analysis, microstructural observation, thermodynamic and diffusion kinetic calculations. Results reveal that the competitive reactions between active Ti and ceramic phases drive a sequential compositional evolution at the joint interface: starting from pure Ti, the interface transitions to a mixture of TiB<sub>2</sub>, TiC, TiB, and residual Ti, ultimately forming a stable TiB<sub>2</sub>–TiC–TiB ceramic assemblage as temperature increases. Kinetic analysis shows that between 1000–1300 °C, reaction layer thickness follows a diffusion-controlled growth model, directly correlated with temperature via Arrhenius-type kinetics. At the highest temperature of 1400 °C, complete consumption of Ti yields a full-ceramic joint. Mechanical characterization indicates that these temperature-dependent microstructural changes significantly affect joint performance: the maximum shear strength of 72 MPa is achieved at 1300 °C, accompanied by crack penetration through the ceramic, reaction layer, and residual Ti layer.