Thermal barrier coatings

The use of Thermal Barrier Coatings (=TBC) in gas turbines allows to increase the working temperature and therefore the yield of gas turbines. Conventional TBC's (Y2O3-stabilised ZrO2) are produced by plasma spraying and electron beam evaporation. CVD processes for the production of TBC's are under investigation. In this paper, different methods to produce TBC's are compared. Especially discussed are the results concerning CVD processes. It is possible to obtain TBC's with a desired columnar structure at high deposition rates by CVD

MOCVD of Ag thin films

The new mixed ligand complex [(n-Bu3P)Ag((CH3)3CCOO)] (I) is suggested as precursor for MOCVD of Ag thin films. It was characterized by elemental, TG analysis and by mass-spectrometry. It was shown that gas phase consisted only from monomeric molecules of I. X-ray study of (I) shows that crystal structure is build up from dimeric units with van der Waals interactions between them. Ag films were grown on Si and oxide substrates using I and [(Ag((CH3)3CCOO)] (II) precursors by CVD technique in presence of oxygen. The dependence of the films thickness, orientation and microstructure on the process parameters was defined. The use of the adduct was found to be at least 20 times more effective (regarding the film thickness) in comparison to that of II

Current-carrying capability of GdBa2Cu3O7-x HTSC tapes in magnetic fields in the temperatute range of 2-100 K

International audienceThe current-carrying capability of the second-generation HTSC tapes based on GdBa2Cu3O7-x (GdBCO), produced by the SuperOx Company by the pulsed laser deposition method is studied. Critical currents inmagnetic fields aremeasured by resistive andmagnetic (using a SQUID magnetometer) methods. The results obtained are compared with characteristics of an YBCO tape grown by chemical deposition (SuperPower, USA)

Current-carrying capability of GdBa2Cu3O7-x HTSC tapes in magnetic fields in the temperatute range of 2-100 K

International audienceThe current-carrying capability of the second-generation HTSC tapes based on GdBa2Cu3O7-x (GdBCO), produced by the SuperOx Company by the pulsed laser deposition method is studied. Critical currents inmagnetic fields aremeasured by resistive andmagnetic (using a SQUID magnetometer) methods. The results obtained are compared with characteristics of an YBCO tape grown by chemical deposition (SuperPower, USA)

Excitation of Vortex-Antivortex Pairs in Thin Superconducting Films and Superlattices

Direct imaging of the accumulation of magnetic flux and antiflux resulted from the excitation of vortex-antivortex pairs inside thin superconducting films is reported. Thin-film superconductors, like YBa2Cu3O7/PrBa2Cu3O7 superlattices or NbN films grown by pulsed laser deposition, were used in experiments. The superlattices provide enhanced pinning for vortices, facilitating imaging of accumulated flux, and feature nanoscale fractures ideal for excitation of vortex-antivortex pairs. The idea of the experiment is to record images using a specific magneto-optical mode that allows distinguishing between positive and negative magnetic field in the sample. Two types of flux-antiflux patterns are observed. In one type, flux and antiflux are entering on permanent defects, like nano-fractures formed in the process of film deposition. In another type, flux and antiflux patterns are formed by application of a strong localized magnetic field and not are linked to permanent defects. In the first type, the amount of flux and antiflux entering superconductor from the defect is strongly affected by an external magnetic field. In the second type, the permanently frozen pattern is hardly influenced by the field. An unusual and dramatic effect of the excitation of flux-antiflux dendritic avalanches is also reported

Electrical Insulation Systems at Cryogenic Temperatures

International audienceThis TB focuses on the electrical insulation systems at cryogenic temperatures as one of the common and critical issues for the efficient, reliable and practical development of superconducting power apparatus, fusion reactors, accelerators and industry applications. The dielectric and thermomechanical properties with physical mechanisms of insulation materials at cryogenic temperatures, and the state-of-the-art R&D projects on superconducting power apparatus with their design, test and failure experiences are summarized