Joining dense Si3N4 to porous Si3N4 using a novel glass-ceramic interlayer with precipitated β-LiAlSi2O6/Mg2SiO4

Abstract In this work, we developed a new β-LiAlSi2O6/Mg2SiO4 glass-ceramic interlayer to join dense Si3N4 and porous Si3N4 ceramics for high-temperature applications. The microstructure and phases of the joint were investigated using systematic analysis methods and the mechanism for the interfacial bonding was proposed. The double crystalline phases of β-LiAlSi2O6 and Mg2SiO4 precipitated in the joint seam during the joining process, forming a novel glass-ceramic interlayer with high crystallinity. Due to the good wettability of liquid glass on porous Si3N4, a gradient and dense infiltration layer was formed in porous Si3N4 and reinforced it, which improved the mechanical strength of the whole joint. In this case, the shear strength of the joint reached 78 MPa, and it could still maintain 74 MPa up to 850 °C, which fully demonstrated the high-temperature resistance of the joint.