| 摘要 |
A slab or panel for use in a safe or similar structure comprises a layer of material resistant to drilling and other forms of mechanical attack backed by a layer of material, preferably graphite, which melts and vaporizes but does not substantially react exothermically with oxygen at the temperatures generated by a thermic lance, i.e., of the order of 3,000 DEG C. The melting and vaporization involves the provision of such large amounts of latent heat thus taking several times as long to burn a hole through the slab. The material for resisting mechanical attack preferably comprises nuggets of heard material in a ductile metal matrix and a convenient form of construction there is a single layer of this material and a single layer of the vaporizable material. The vaporizable material is preferably in the form of blocks of triangular section fitted into compartments defined by metallic spacing members supported between a pair of steel plates. |
