Effect of TiO2 addition on thermal and mechanical properties of Y–Si–Al–O–N glasses

Y–Si–Al–O–N glasses are intergranular phases in silicon nitride based ceramics in which the composition and volume fraction of oxynitride glass phases determine the sintering/shrinkage behaviour. Several investigations on oxynitride glass formation and properties have shown that addition of nitrogen increases glass transition and softening temperatures, viscosity, elastic modulus and hardness. In the present study, effect of TiO2 addition on thermal and mechanical properties of Y–Si–Al–O–N glasses is investigated since the most typical Si3N4 ceramics for bearing applications are fabricated using a Si3N4–Y2O3–Al2O3–TiO2–AlN system. Addition of TiO2 is effective in preparing Y–Si–Al–O–N glasses with lower glass transition temperatures and with higher hardness.