Fabrication of aluminum titanate–glass composites with controlled thermal expansion and improved mechanical strength

Abstract

Aluminum titanate–glass sintered composites with a controlled thermal expansion coefficient were successfully prepared by the solid-state reaction of Al2O3, TiO2, and soda-lime glass powders. The thermal expansion of the specimens monotonically increased from negative to positive when the glass addition was increased from 0 to 30 wt%, indicating that a zero-thermal-expansion material could be obtained at a glass addition of 5–7 wt%. Chemical reaction between glass and Al2TiO5 was not observed during sintering, and the glassy state of the raw soda-lime glass was maintained. The scanning electron microscopy–energy-dispersive X-ray spectroscopy results indicate that the glassy phase penetrates the grain boundaries of the sintered composites with a glass addition of 5 wt%, thereby increasing the thermal expansion coefficient and apparent density. For the composites with a glass content of >5 wt%, a glassy phase that possibly forms outside the grain boundary could increase the thermal expansion coefficient and decrease the density. The glassy phase at the grain boundary also effectively improved the mechanical bending strength.