Abstract: A method for forming a layer of single-phase oxide (Fe, Cr)2O3 with a rhombohedral structure on a steel or super alloy substrate, may include, successively: (a) supplying a steel or super alloy substrate covered with a surface layer, the steel including at least 2 wt.-% chromium; (b) removing the surface layer in an atmosphere containing at least 0.2 atm O2, 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; and (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 in a range of from 400 to 1000° C., such as to grow the layer of rhombohedral oxide formed in the removing (b) to a thickness in a range of from 70 to 150 nm.

Abstract: A solar radiation absorber element for a thermal concentrating solar power plant is achieved by forming a selective coating on an outer surface of a substrate made from stainless steel, chosen from stainless steels presenting an aluminum content of more than 0.5% by weight. Formation of the selective coating includes a surface treatment step of the substrate, by polishing, and a heat treatment step of the substrate, in an oxidizing atmosphere, in a temperature range included between 550° C. and 650° C. The heat treatment in particular enables at least one intrinsically selective superficial thin layer to be formed on the outer surface of the substrate.

Abstract: A solar radiation absorber element for a thermal concentrating solar power plant is achieved by forming a selective coating on an outer surface of a substrate made from stainless steel, chosen from stainless steels presenting an aluminium content of more than 0.5% by weight. Formation of the selective coating includes a surface treatment step of the substrate, by polishing, and a heat treatment step of the substrate, in an oxidizing atmosphere, in a temperature range included between 550° C. and 650° C. The heat treatment in particular enables at least one intrinsically selective superficial thin layer to be formed on the outer surface of the substrate.

Abstract: A crystallization method, including: depositing a thin film of a crystalline material on a substrate; heating the substrate and the crystalline material deposited on the substrate to a first temperature for a time enabling internal strains present in the crystalline material to be relaxed; after the heating, subjecting the substrate and the crystalline material to a second temperature and to a uniform bending by placing the substrate on a bending bench, a quantity of bending and a difference between the first and the second temperature having values determined from elastic bending constants, thermal deformations and thermal expansion coefficients to favor a particular crystallographic orientation of the crystalline material along an azimuth direction in relation to a direction normal to the substrate.

Abstract: A crystalline layer (4) is subjected simultaneously to a bending of its substrate (3) and to a thermal expansion. It is possible to direct the orientation of the crystal that it forms in a determined azimuth direction around a direction perpendicular to the layer.