THERMAL-SHOCK FRACTURE TESTING FOR FLOAT GLASS BY INFRARED RADIATION TECHNIQUE

An infrared radiation heating method was proposed previously as a new technique for estimating thermal shock resistance of ceramics, and a c oncept of thermal shock fracture toughness and stress intensity factor s for a disk-shaped specimen with an edge crack was expressed. The met hod uses a thin circular disk. which is heated by infrared ray at the central area with a constant heat flux. The technique makes it possibl e to evaluate the thermal shock strength, R(1c), and thermal shock fra cture toughness, R(2c), directly from the electric power charged and t he time to fracture, despite the fact that R(1c) and R(2c) consist of the thermal properties of the material tested, In this report, the the rmal shock strength and the thermal shock fracture toughness for float glass at room and high temperature are evaluated by the infrared radi ation heating technique, and shown as a function of temperature when t he specimen failures. The thermal shock parameters obtained experiment ally are also compared with the estimated values which are calculated by combining the temperature-dependent mechanical properties of float glass.