Light weight vault door

Claim 1

A security vault having a door of reduced weight constructed and arranged to delay penetration when being illegally entered, said door comprising a plurality of layers in the order as follows: an outer thin metal layer; a sheet of metal having thermal conductivity higher than said outer metal layer adhesively secured to said outer metal layer; a continuous layer of aluminum oxide tiles adhesively secured to said conductive metal layer, said tiles being disposed adjacent each other without gaps therebetween; a layer of energy-absorbing polymeric material selected from the group consisting of polycarbonate and an acrylic polymer adhesively secured to said layer of aluminum oxide tiles with a hard silicone rubber, and an inner metallic layer adhesively secured to and covering said layer of energy-absorbing polymeric material; said layers being chosen and designed whereby said door is light in weight; wherein the energy-absorbing polymeric layer protects said ceramic layer from being penetrated by pounding, and said door cannot be penetrated with a signle tool, so as to delay illegal entry.