Effect of thermal treatment on yttria doped zirconia coated DIN 1˙4306

Abstract

Thin films of 8 wt-% yttria doped zirconia (YZ) sol were deposited by a dip coating process on stainless steel (DIN 1˙4306) substrate for surface protection of this material widely used for corrosion resistance. The YZ sol coated specimens were heat treated in the temperature range of 500–1100°C for 30 min. The characterisation of the thin layer deposited was performed using thermal (TG-DTA) methods. The microstructure and phase identification analysis were carried out using scanning electron microscopy (SEM) having an energy dispersive system (EDS) as an attachment and X-ray diffraction (XRD). The coated surface specimen heat treated at 900°C showed fine grain surface without porosity, while specimens heat treated at 1100°C showed coarse grain structure with porosity. Three different phases, i.e. FeCr2O4, (Fe0˙6Cr0˙4)2O3 and ZrO2, were identified on the surface of coated specimens heat treated at 900 and 1100°C for 30 min. The YZ coated specimens show improved resistance in acidic environment. Tape adhesion testing has shown that YZ coatings on stainless steel are adherent. Good adhesion at the interface indicated that the sol–gel route is a feasible method for applying YZ coating on stainless steel substrates.