APPLICATION OF GRADED CERAMIC COATINGS FOR THERMAL BARRIERS

In this paper a new process (graded transition and remelting) is successfully developed to coat Al2O3-based composite thermal barriers on copper substrates by oxyacetylene flame spraying. The microstructure and microcomposition of the coating layer have been studied by scanning electron microscopy and energy-dispersive X-ray analysis. Particular attention has been paid to the diffusion reaction, liquid sintering and grain size in the coating layer. The effects of various microstructural features on the bonding strength, thermal conductivity, heat resistance and spalling resistance of the coating layer are discussed. With such a coating, the useful life of a slag hole in a blast furnace is increased twofold.