High‐strength SiC joints fabricated at a low‐temperature of 1400°C using a novel low activation filler of Praseodymium

Abstract

High-strength SiC joints were successfully obtained by electric current fieldassisted sintering technique at a low temperature of 1400 • C using a Pr coating (100 nm) as the initial joining filler. A Pr 3 Si 2 C 2 transient phase was formed in situ by the interfacial reaction, while the eutectic reaction between Pr 3 Si 2 C 2 and SiC at ∼1150 • C resulted in the formation of a liquid phase. The liquid phase promoted the atomic diffusion at the interface and improved consolidation of the newly precipitated nano-sized SiC with the SiC matrix. This led to the formation of partially seamless joints of SiC. When the thickness of the joining layer decreased from 1 to 100 nm, the content of the residual Pr-O phase at the interface decreased, while the bending strength of the joints increased. A sound SiC joint with a bending strength of 227 ± 12 MPa was obtained at such a low temperature as 1400 • C when a 100 nm Pr coating was applied.