3. A Novel Approach for Plate Impact Experiments to Obtain Properties of Materials Under Extreme Conditions

In this paper we present a novel approach to conduct normal plate impact experiments at elevated temperatures up to 1000 °C. To enable this approach, custom adaptations are made to the breech-end of the single-stage gas-gun at Case Western Reserve University. These adaptations include a precision-machined steel extension piece, which is strategically designed to mate the existing gun-barrel by providing a high tolerance match to the bore and keyway. The extension piece contains a vertical cylindrical heater-well, which houses a resistive coil heater attached to a vertical stem with axial/rotational degrees of freedom. The assembly enables thin metal specimens held at the front-end of a heat-resistant sabot to be heated uniformly across the diameter to the desired test temperatures. Using the configuration, symmetric normal plate impact experiments are conducted on 99.6% tungsten carbide (no binder) using a heated (room temperature to 650 °C) WC flyer plate and a room temperature WC target plate at impact velocities ranging from 233 to 248 m/s. The measured free-surface particle velocity profiles are used to obtain the elastic/plastic behavior of the impacting WC plates as well as the temperature-dependent shock impedance of the flyer. The results indicate a dynamic strength of approximately 6 GPa for the WC used in the present study (strain-rates of about 10⁵), and a decreasing flyer plate longitudinal impedance with increasing temperatures up to 650 °C.