Experimental Measurements Of Sapphire's Elastic Modulus With Temperature Change

Sapphire is widely used as infrared window material with the advantages of excellent mechanical, physical and chemical properties. However, its mechanical properties change with the change of temperature, especially on the condition of very high temperature, its mechanical properties will be severely eroded, which leads to rupture of sapphire crystal. The elastic modulus is an important physical parameter influencing the mechanical properties of sapphire crystal, in order to study the high temperature mechanical properties of sapphire crystal, it is significant to study of the variation of the elastic modulus with the change of temperature.We use the laser pulse having the duration of 10ns and the wavelength of 532nm, thereby, producing ultrasound to do the experiment, sapphire has high transmittance on the wavelength, which makes it unable to generate ultrasonic, we spin CuO sintered inorganic medium on the sapphire surface which have a high absorption of 532nm pulsed laser, then we use laser ablation effect to generate ultrasound in sapphire, after the ultrasonic signal transmit to the sapphire surface, there will be a slight deformation on it, Michelson interferometer as a mirror reflector, optical path will be change, laser interference field strength will have a transient mutation, thereby, we detected the ultrasonic transmission speed, according to the relationship between elastic modulus of sapphire and ultrasonic transmission speed, we have a specific direction modulus sapphire in Non-contact, no damage way.In order to realize the elastic modulus changes with temperature of the sapphire crystal, we design heating equipment to control temperature, and temperature control range is from room temperature to 1100℃, the Sample fixes in the heating furnace, we control the warm equipment through the adjustment, surveyed the trend of sapphire elasticity coefficient along with the temperature. In order to confirm experiment's feasibility, we first detection the HB700-type colored glass which have a strong absorption of 532nm pulse laser, experimental results show that with increasing temperature, ultrasonic transmission speed reduction. in same way, the surface of sapphire sample spin-coating CuO which has a high absorption of 532nm pulsed laser, then, it placed in the high temperature heating device which is being programmed, temperature changes, we achieve the elastic modulus of sapphire along different temperatures, from room temperature to 1000℃, design interval of 100℃, we obtained the elastic modulus of sapphire at 11 different temperature points with along C33 axial, the results show that with increasing temperature, the elastic modulus of sapphire will show a gradual decline in the rule.