An investigation of ceramic/aluminium composites as shields for hypervelocity impacts

The protection efficiency of single-shield bumpers made of composites based on the aluminum matrix containing the disperse ceramic inclusions of SiO2 or Al2O3 is considered for a Whipple-type shield. The aim of the paper is to compare the protection efficiency of the first bumpers made of the metal composites with that for the duralumin shield by impact of spherical steel projectile with the velocity of 5.5 and 7.5 km/s. Mass fraction of the ceramic inclusions accounts for 15 and 30 percent of the total composite. A thick backwall plate was used, and the maximum depth of fragment craters on the witness plate is taken as a protection characteristic of shields made of different materials: reference aluminum alloy, composites under study, and loosely-packed metal powder bumpers. The bumpers made of the metal composites, Al-matrix plus embedded ceramic inclusions, are shown to have the poorer protection efficiency than those made of the duralumin alloy when used with steel impactors. It is shown that by impact of the hypervelocity steel projectile the shield material strength, if it is rather low bur not zero, may essentially affect the damage pattern of the backwall in spite of the high level of realized impact pressures. (C) 1999 Elsevier Science Ltd. All rights reserved.