H. Amaveda

Fabrication of Superconducting Coatings on Structural Ceramic Tiles

An alternative to fabricate high temperature superconducting materials with big sizes that could be used in power applications as fault current limiters is to develop superconducting coatings on structural ceramics substrates. The interaction between the substrate and the superconducting coating has been analysed using different buffer layers, as NiO and zirconate compounds. Different processing techniques have been used to prepare the buffer layer: dip coating, screen printing and thermo-spraying. This layer has been densified using a selective laser synthesis. The superconducting coatings have been fabricated with tape casting technologies and the desired texture is obtained by means of a laser induced melting process.

Electrodeposition of Silver Gold Alloys on

A metallic coating on the surface of bulk high temperature superconductors (HTS) is a promising alternative in order to increase the HTS stability for large scale applications. The coating provides an evacuation path for the heat generated by hot spots within the HTS, which improves their thermal stability. This is even more evident in thick films geometries, which are frequently used in fault current limiters. In this paper, silver-gold alloys have been deposited on 1.8 mm in diameter Bi-2212 textured bars using an electrodeposition technique in non-aqueous solvents. The deposition parameters have been adjusted to obtain a coating of different alloys with gold contents in the range 0-5 at % and with a thickness up to 45 mum. Electrical and thermal measurements have been performed. The results show the possibility of controlling the thermal and electrical conductivities of the composite material by adjusting the layer thickness and composition of the metallic coating.

{\rm Bi}_{2}{\rm Sr}_{2}{\rm CaCu}_{2}{\rm O}_{8+\delta}

A laser furnace (LF) apparatus, which applies laser irradiation to the surface of a material while it is moving inside a high temperature roller furnace, has been recently patented and demonstrated unprecedented potential in the development of ceramic materials. This apparatus has been used in this study to texture Bi-2212 bulk samples in planar geometries with dimensions of several centimeters. The process can be scaled-up to dimensions that could be interesting from a technological point of view. The influence of laser emission and furnace processing parameters, as well as the application of an electrical current, has been studied to define parameters which yield an improvement of the superconducting properties. These studies have also been initiated in Gd-123 bulk samples, analyzing the changes that a LF treatment is able to induce in their microstructure using an infiltration approach.