Reaction Initiation Of Metal Spheres Upon Ballistic Impact With An Anvil

When a metallic projectile impacts an anvil at high speed, fragmentation of the projectile and ignition of the fragments may occur. In the present experimental study, small metallic spheres and cylinders are accelerated up to speeds of 1.2 km/s by a single-stage light-gas gun and impact an aluminum oxide anvil. Velocity thresholds for ignition are determined for aluminum, titanium, zirconium, and hafnium projectiles using optical diagnostics. A high-speed digital camera is utilized to observe the fragmentation process, emission spectroscopy is used to infer the temperature of the fragments, and a fast response avalanche photodetector is used to obtain the history of radiant emissions from the impact.