Abstract
Welding of dissimilar materials in particular ceramics to metals is a technical challenge with attractive economical consequences. In this study a ceramic coating was processed by plasma transferred arc (PTA). ZrO2–7wt.%Y2O3 powders were deposited on low carbon steel plates and on Ni based alloys layers previously welded on a steel plate. Coatings were evaluated regarding the soundness and features of the metal/ceramic bond. Results showed that the pair ZrO2–7wt.%Y2O3 /metallic alloy played a major role on the quality of the processed surfaces determining the effectiveness of the bonding. The presence of Al in the Ni based intermediate layer was detrimental to the adhesion of the ceramic coating. Deposition of ZrO2–7wt.%Y2O3 on NiCrFe intermediate layers allowed for a metal/ceramic bond resulting on 3,0mm thickness coatings. Ceramic deposits exhibited cracks, whose features were altered after a stress relief treatment of the substrate (AISI 1020+NiCrFe layer) prior to the deposition of ZrO2–7wt.%Y2O3. Transverse section analysis revealed the presence of second phase particles in the ceramic coating and the diffusion of elements from the intermediate Ni based layer into the ceramic deposit.
