Abstract: The invention relates to a method for forming a layer of single-phase oxide (30) (Fe, Cr)2O3 with a rhombohedral structure on a steel or super alloy substrate (10), comprising the following successive steps: a) supplying a steel or super alloy substrate (10) covered with a surface layer, the steel comprising at least 2 wt.-% chromium; b) removing the surface layer in an atomsphere containing at least 0.2 atm dioxygen, creating a level of micro-deformation in the crystal lattice of the steel or super alloy that is greater than 1.0.10?3, and a heating at a heating rate higher than 400° C./s, such as to form a layer of rhombohedral oxide (30) (Fe, Cr)2O3, c) carrying out a thermal treatment, in the presence of air, at a water partial pressure of less than 10.000 ppm, and at a temperature varying between 400° C. and 1000° C., such as to grow the layer of rhombohedral oxide formed in step (b) to a thickness from 70 nm to 150 nm.

Abstract: The covering is constructed on the site and adheres to a corrugated support 1 and to spaced-apart projections 2. It comprises a reinforcing element of metal or of a glass cloth 4, 6 having meshes which are small enough to retain a foaming product which is still in the liquid state but sufficiently rigid (for example ribbed) so as to be planar and have great strength. The reinforcing element is embedded in the foaming material in the course of the solidification of the latter and imparts thereto a planar outer surface. Air pockets are formed between the corrugation roots 10 and the solidified and reinforced foaming product. This reinforcing element may include two successive layers, namely a layer 4 having small meshes and a layer 6 having large meshes, the latter providing the desired strength.