Amorphous zones in flame sprayed alumina-titania-zirconia compounds

The formation of amorphous phases in thermally sprayed coatings is a common phenomenon. This work examines the distribution of the amorphous content in flame sprayed Al(2)O(3) TiO(2) ZrO(2)-compounds. An amorphous percentage appears even in pure alumina and the percentage increases with increasing amount of TiO(2)- and ZrO(2)-addition. Amorphous sub-lamellae appear in all examined compositions. If a system with a miscibility gap in the liquid slate, such as Al(2)O(3) ZrO(2), is applied, the formation of secondary amorphous regions is observed. The amorphous sub-lamellae or primary amorphous region is induced only by rapid cooling, the secondary amorphous regions are induced by rapid cooling plus a spinodal demixing effect. (C) 2010 Elsevier Ltd and Techna Group S.r.l. All rights reserved.