Thermal barrier coating application of zircon sand

Naturally occurring zircon sand was plasma spray coated on steel substrates previously coated with NiCrAlY bond coat. The coatings were characterized for their microstructure, chemical composition, thermal shock resistance, a nd the nature of structural phases present, The as-sprayed coatings consist ed of t-ZrO2 (major phase), m-ZrO2, ZrSiO4 (minor phases), and amorphous Si O2. These coatings, when annealed at 1200 degrees C/1.44 x 10(4) s yielded a ZrSiO4 phase as a result of the reaction between ZrO2 and SiO2, Dramatic changes occurred in the characteristics of the coatings when a mixture of z ircon sand and Y2O3 was plasma spray coated and annealed at 1400 degrees C/ 1.44 x 10(4) s, The t-ZrO2 phase was completely stabilized, and these coati ngs were found to have considerable potential for thermal barrier applicati ons.