TECHNOLOGY FOCUS - INORGANIC CHEMISTRY - Preferred Method: The step a) of oxidizing the nickel surface is carried out by heating the surface in an atmosphere which is oxidizing for nickel at 300-1300 (preferably 800-1100) degrees C, for 10000-300 seconds. The oxidation step a) is carried out in order to obtain an oxygen content bound to the nickel of not less than 0.05 g/m2. In step b) an aqueous silica sol capable of forming a continuous liquid film over the entire surface of the substrate is used. The step b) is carried out by applying a colloidal silica sol to form a liquid film having a silica content of not less than 0.1 g/m2. The step c) is carried out by heating to 300-1300 degrees C, for 10000-300 seconds. The step c) is carried out by heating to a temperature sufficient to cause vitrification of the silica layer. After step c) the method involves: e) treating the surfaces of the substrate with a solution comprising an acid compound selected from phosphoric acid, chromic acid and/or boric acid, at least one alkaline or alkaline earth compound which is a precursor of a vitrifying oxide and at least one water-soluble salt of a metal selected from nickel, palladium, platinum, rhodium, iridium and/or their salts, where the solution optionally includes colloidal silica. After step e) the method involves: f) heating the substrate to a temperature sufficient to cause vitrification of the silica. Activation step d) involves treatment of the substrate resulting from steps a), b) and c) or, if implemented, steps e) and f), in an atmosphere of hydrogen and/or its isotopes. The treatment in a hydrogen atmosphere is carried out at 120-900 degrees C, for 50-1200 seconds. Preferred Components: The substrate has a hydrogen/nickel atomic ratio of more than 0.3 following activation step (d). The silica sol comprises silica particles having dimensions of less than 30 (preferably less than 15) nm. The colloidal silica is an aqueous silica sol further comprising water-soluble salts of metals selected from nickel, palladium, platinum, rhodium and/or indium, where the soluble salts are capable of decomposing into their corresponding oxides when heated to a temperature lower than the temperature used in heating step (c). The colloidal silica or aqueous silica sol also comprises compounds selected from boric acid, phosphoric acid and/or chromic acid. The aqueous silica sol further comprises alkaline and/or alkaline-earth compounds which are totally soluble in the aqueous silica sol. EXAMPLE - A sheet of 99.6% nickel (35x 140x 0.065 mm), having a total surface area considering the two sides of 98 cm2, was carefully degreased with acetone and treated in a furnace beneath a light flow of pure argon at 550 degrees C for 30 minutes for the purpose of stress relieving and allowed to cool in argon in the cold zone of the furnace. The weight of the sheet after treatment was 2.8296 plus minus 0.0002 g. The hot zone of the furnace was raised to 900 degrees C in a light flow of air. The sheet was placed in that zone and kept there for 1800 seconds (operation a1)). The weight of the sheet after oxidation was 2.8333 plus minus 0.0002 g. The oxygen fixed on the surface was therefore 0.53 g/m2. The sol used to stabilize the anchoring layer comprised colloidal silica with 12 nm micelles having an SiO2 content of 30 wt.%. The sol was diluted 1 to 20 with twice-distilled water. The sheet was immersed in the liquid at ambient temperature (24 degrees C) for 30 seconds, removed and allowed to drain for 60 seconds (operation b1)). After this it was placed in the zone of the furnace at 900 degrees C in a light flow of air and kept there for 1200 seconds (operation c1)). The final weight of the sheet after this treatment was 2.8454 plus minus 0.0002 g. Operations a1), b1) and c1) were repeated a second time. The final weight of the treated sheet was 2.8634 plus minus 0.0002 g with a total increase in weight over the initial weight of 34 mg. The sheet treated in this way was placed in a stainless steel container. A 1.3x 10-3 bar vacuum was applied. Subsequently argon was introduced at 2 atmospheres and then 1.3x 10-3 mbar vacuum was applied again. When the temperature of the container was 26.5 degrees C, the same as ambient temperature, hydrogen was introduced in order to raise the pressure to 1.1 bar within a few seconds. After 5000 seconds the pressure was almost stabilized at 0.93 bar (98% of the final equilibrium) at 26.2 degrees C (ambient T 26.6 degrees C). It was thus possible to determine that the nickel sheet had adsorbed 0.014 moles of H2 achieving an H/Ni atomic concentration of 0.58.