MULTILAYER SOL-GEL ZIRCONIA COATINGS ON 316-STAINLESS-STEEL

Multilayer alkoxide based sol-gel zirconia coatings were fired under t wo regimes. SET I coatings were fired by drying each layer at 380 degr ees C and then performing a final firing at 800 degrees C. For SET II coatings, each layer was fired to 380 degrees C and then 800 degrees C in a single firing. The structure of the SET I coatings was found to be thickness dependent. In addition, significant substrate reaction wa s found to occur with increasing thickness. For SET II samples the coa ting structure did not change significantly after a thickness of 600 n m was reached. Substrate reaction also appeared to be lessened. This b ehaviour indicates that the phase change rate within the coatings duri ng firing is related to the amount of reaction with the substrate. In addition, the higher amount of monoclinic phase present in the SET II coatings suggests that the phase changes occurring may be dependent on total firing time at 800 degrees C.