CaO–SiO2–Al2O3–Y2O3 glasses as model grain boundary phases for Si3N4 ceramics

Thermal expansion investigation of iron rich glass-ceramic

“…A similar behaviour was found in the devitrification of other glass systems such as CaO-SiO 2 -Al 2 O 3 -Y 2 O 3 and MgO-BaO-Al 2 O 3 -SiO 2 . 13,14 Moreover, in our previous investigation 9 on the same glass composition, a bent in curve of dilatometric glass transition temperature, T g , and of the dilatometric softening point, T s , was observed when the crystal phase exceeded about 30%.…”

Thermal properties of single-phase Y2SiO5

“…And it is confirmed that Y 2 SiO 5 can improve the high-temperature performance of silicon nitride. [12][13][14] The melting point of Y 2 SiO 5 is up to 1950 • C guaranteeing its potential high-temperature structural applications. 15 Although the spectroscopic studies of doped Y 2 SiO 5 have been widely performed, the fundamental properties of the host crystal itself are still in dearth.…”

“Snow flake” structures in silicon nitride ceramics – Reasons for large scale optical inhomogeneities

“…Similar stress levels can occur due to crystallisation of the grain boundaries. 18,[21][22][23]25 Recent investigations of oxynitride glasses showed that a formation of pores can take place during crystallisation of Y-Ca-Al-Si-O-N glasses. 25 The stress relaxation in materials with Al 2 O 3 /Y 2 O 3 or MgO additives is fast at temperatures above 1400-1500 • C due to the relative low viscosity of the grain boundaries.…”

“…18,[21][22][23]25 Recent investigations of oxynitride glasses showed that a formation of pores can take place during crystallisation of Y-Ca-Al-Si-O-N glasses. 25 The stress relaxation in materials with Al 2 O 3 /Y 2 O 3 or MgO additives is fast at temperatures above 1400-1500 • C due to the relative low viscosity of the grain boundaries. The relaxation stops near the glass transition temperature of the amorphous grain boundary phase at 800-1000 • C. The internal stresses can relax in different ways 25 : • Relaxation by solution, diffusion and precipitation mechanism: this mechanism was found for creep deformation.…”