Fabrication and Characterization of Zirconia Coating on the API5L Steel

摘要

Four layers of zirconia coating were applied on surface of API5 steel samples by sol-gel processing using zirconium isopropoxide precursor. In the first group of samples, after each layer of coating and for the second group after four layer coating, heat treatment of calcination and sintering is carried out at the desired temperature (350-550 degrees C). X-ray diffraction and differential thermal analysis were used to evaluate the physicochemical reaction and phase changes caused by heat treatment of obtained gel. Microstructural features and corrosion resistance of coated samples were determined by SEM observation, microhardness and electrochemical corrosion testing respectively. The results show that by increasing of sintering temperature from 350 to 550 degrees C, structure evolve from amorphous to crystalline state. For the first group of samples, sintering at 450 degrees C and for the second group, sintering at 550 degrees C, offer a more homogenous microstructure and higher resistance of corrosion.