Crystallization kinetic of Li2O-MgO-Al2O3-SiO2 glass-ceramic and its application for joining of porous Si3N4 ceramic

Abstract A novel glass-ceramic of Li2O-MgO-Al2O3-SiO2 was developed to join porous Si3N4 ceramic itself for the first time. The crystallization kinetic and the microstructure evolution of the glass-ceramic were investigated. The crystallization activation energy E and Avrami exponent n illustrated that the glass-ceramic showed a high crystallinity and surface crystallization behaviour. The β- and γ- LiAlSi2O6 phases coexisted in the glass-ceramic and two minor phases of Mg2SiO4 and MgAl2O4 also precipitated. The porous Si3N4 was joined to itself successfully by using this glass-ceramic. A net-like LiAlSi2O6/MgAl2O4 glass-ceramic interlayer and an infiltration layer of glass/Si3N4 were formed in the joint. According to shear testing, the joint was reliable at room temperature and high temperature (850 °C). It demonstrates the feasibility of joining porous non-oxide ceramics by using glass-ceramic interlayers.