Abstract: The invention pertains to a process to fasten an intrinsic element absorbing electromagnetic waves onto a wall of a structure or infrastructure.The process of the invention consists of coating a surface of a wall of a structure by means of a syntactic foam with the rheologic properties of a mastic and being transparent to electromagnetic waves, then placing an element absorbing electromagnetic waves into or onto the syntactic foam coating, and letting the syntactic foam harden. The process can be used to place an element absorbing electromagnetic waves onto surfaces of any shape and in a simple manner without requiring special equipment.

Abstract: The invention relates to a new class of high-hardness abrasive products and wear resistant parts based on alumina and aluminium oxycarbides. By fusing alumina in the presence of a carbonaceous substance and by controlled cooling, it is possible to obtain a large number of products in which the ratio .rho. of the number of carbon atoms to the number of carbon atoms plus oxygen atoms is between 0.01 and 0.50, and preferably between 0.02 and 0.20. These products are essentially constituted by primary alumina crystals in a eutectic matrix Al.sub.2 O.sub.3 - Al.sub.4 O.sub.4 C or Al.sub.2 O.sub.3 - Al.sub.2 OC.