EFFECT OF ALUMINUM PARTICLE SIZE ON THE IMPACT INITIATION OF PRESSED PTFE/AL COMPOSITE RODS

A gas gun has been used to investigate the impact initiation of rods of a mixture of 72 wt% PTFE (polytetrafluoroethylene) and 28 wt% aluminum powders. The rods were sabot-launched in vacuum into steel anvils at impact velocities ranging from 468 to 969 m/s. A framing camera was used to observe the time sequence of events following impact. At the lowest impact stress of 25 kbar no light was observed. Above the initiation threshold, the initiation time dropped from 74 mus just above threshold to 14 mus at 64 kbar. These results are compared with earlier rod impact experiments for a similar material in which the only major difference is a smaller aluminum particle size.