摘要:
A process for the preparation of a composite multilayer product with selective optical properties comprises the operation of depositing, by thermal plasma spraying of powders, a coating of semiconductor oxides doped with oxides of elements chosen from the group consisting of transition metals and metals in the groups III-A and V-A of the periodic table of elements, in which the coating obtained maintains the composition and doping of the thermal plasma sprayed powders substantially unchanged. The figure shows the X-ray diffraction spectrum of a coating deposited according to the process of the present invention.
摘要:
A silicon carbide-based thermal spray powder contains at least one boride chosen from zirconium boride, titanium boride and hafnium boride. The powder is prepared by mixing and aggregation of powders containing the compounds in question. Said thermal spray powder is used to deposit, via the plasma spraying technique, a silicon carbide-based coating on a metallic or non-metallic substrate. The figure shows the X-ray crystallogram obtained, for a silicon carbide-based powder, according to the invention, after thermal spraying. The substantial identity of this crystallogram with the one obtained prior to thermal spraying demonstrates that the silicon carbide has been deposited on the substrate without decomposing.
摘要:
A process for the pyrolysis of YBCO powders, characterized by the preparation of a clear aqueous solution containing the ions yttrium, barium and copper, in the final proportions desired for the powder, in the form of complex compounds, preferably citric complex compounds, and in the presence of a detonating system, like for instance a combination of ammonium ions and of nitrate ions. The clear solution is then made to concentrate by means of evaporation, until triggering a violent combustion which is carried out at a high temperature, higher than 250°C and preferably higher than 850°C.