THE DISPERSION OF MOLTEN SODA-LIME GLASS PROJECTILES FOLLOWING PENETRATION OF THIN ALUMINUM MEMBRANES

The debris plumes resulting from penetration experiments using soda-li me glass projectiles (3.2 mm diameter; at 6 km/s) and aluminum 1100-0 targets (1.0 and 0.8 mm thick) were intercepted with blued Cu-witness plates some 6, 12 and 49 cm from the target's rear. Scanning Electron Microprobe (SEM) methods and associated Energy Dispersive X-Ray Spectr oscopy (EDS) were used to detail the morphology of the witness-plate f eatures and to determine chemically which features were caused by targ et- or projectile-derived plume components. The projectile suffered co mplete melting and almost the entire melt volume dispersed into an int ricate, three-dimensional network of melt-ribbons and stringers that f orm a highly regular and reproducible web-like pattern in the central portion of the witness-plate spray. In contrast, the aluminum debris r emained solid and was largely concentrated in the peripheral parts of the plume. These experiments also produced prominent circles of closel y spaced craters, previously described as ''hole-saw rings''. EDS anal ysis reveals that such rings are caused by either projectile-derived m aterials or from fragments dislodged from the target.