Protective layer for ceramic sheet, in particular for use in ceramic warmth exchangers of gas turbines and process for their preparation

摘要

1505882 Coated ceramic materials FORD MOTOR CO Ltd 13 March 1975 [15 April 1974] 10464/75 Heading B2E A material for use in gas turbine regenerator cylinders, comprises a substrate of a ceramic containing lithium and having a porous surface, and a surface layer of particulate material disposed in the cavities of the porous surface, the particulate material being such that sulphur oxides found in exhaust gases react with the surface of the particulate material to form an impervious layer. Suitable particulate material is made of Ca, Sr, Cr, Cu, Si, Ni, Sb, Zn, Ba, Al or the oxides, nitrates, or hydroxides of these elements. In a preferred method an organic slurry of particles in a methyl cellulose binder solution, or in a polyvinyl alcohol solution is deposited on by dipping a suitable ceramic surface, the binder is burnt off in an atmosphere which oxidises the particles, and the coated ceramic material is exposed to the oxides of sulphur. Alternatively, Cu, Ni or Zn particles may be applied by chemical precipitation.