Study On The Technologies Of Manufacturing Metallic Substrates And Buffer Layers For Coated-conductor

High-Tc superconductivity has been discovered more than fifteen years . Now the practical application of high temperature superconductors is right on time, especially the Y-system superconducting materials. If we want to make progress in high temperature superconductors , one of the key factors is the technologies of manufacturing substrates and buffer layers. Some technologies of manufacturing substrates and buffer layers are reviewed in this paper. The microstructure and the crystal orientations of films were measured by means of optical microscope, scanning electron microscope (SEM) and X-ray diffraction (XRD), through which we improved on the methods of controling the textures of metallic substrates and buffer layers.We have succeeded in preparing biaxially textured Ni tape by electrodeposition process. The experiment results showed that {100} orientation of Ni films is obtained at 25℃, current .densities approaching 50 mA/cm2. Furthermore, 0.035% sodium lauryl sulfate is a good additive without influence on the texture of Ni films, elimilating pinholes in the coures of electrodeposition.On the other hand, we have succeeded in fabricating biaxially texture Ni-W alloy. Begin with a mixture of 90% Ni powder (99.9% purity) and 10% W powder. Mix and compact at appropriate pressures into a rod or billet. Then heat treat at 900℃ for 2 hours. Deform, by rolling, to a degree greater than 90% total deformation, preferably using 10% reduction per pass and by reversing the rolling direction during each subsequent pass. Anneal at about 1200℃ for about 60 minutes to produce a sharp biaxial texture. The biaxially (200) texture of Ni tape was successfully formed when the annealed Ni tape inspected by XRD.In the course of the preparation of oxide template using suface-oxidation epitaxy (SOE) method, NiO can be formed easily on Ni tape, but there are some difficulties in forming biaxially textured on it. Because this course relates to controlling temperature, pressure, time and ambience at the same time. By our test, we found that the best NiO buffer layer we achieved was annealed at 500℃ for 30 minutes, 700℃ for 30 minutes, 800 ℃ for 30 minutes, 900℃ for 1 hour and the pressure was 10Pa, this results is under improvement; Moreover, the ambience should be controled strictly and the pressure should be dominated if the ambience is atmosphere.The (111) texture of ZrO2 films has been deposited successfully on Ni substrates by sol-gel dip coating. The feasible drying and crystallizing conditions for dip coated ZrO2 buffer layer are 200℃ for 4 hours and 400 ℃ for 30 min in vacuum. The coated ZrO2 buffer layer is fairly smooth, dense, and has a good adhesion with Ni substrate.