| 摘要 |
A process is described for producing a superconducting thick layer on a base material by thermally spraying a powder containing bismuth, lead, strontium, calcium and copper in oxidic form. First a powdered starting mixture is prepared which has a composition corresponding to the formula: Bi1.90-xPbxSr2-yCa2.2-zCu3.5-qOv, in which 0.1</=x</=0.7, 0</=y</=0.4, -0.5</=z</=+0.5, 0</=q</=1.2 and v is the oxygen content calculated from the starting materials. Then the powder is heated for not less than 1 hour at a temperature of not less than 750 DEG C. in an oxygen-containing atmosphere and cooled again. The powder pre-reacted in this way is applied to a thermally stable substrate in a layer thickness of 0.5 to 7 mm by means of a burner by plasma-jet spraying or by flame spraying. The layer applied is then sintered for a time of not less than 40 hours at a temperature of 842 DEG to 848 DEG C. The layer is cooled to a temperature of 550 DEG to 650 DEG C. after sintering, held at this temperature for not less than 20 minutes, reheated to the sintering temperature and again held for not less than 20 minutes at this temperature. This procedure is repeated not less than twice and then the layer is cooled. |
