Effect of Applied DC Voltage on the Wettability of Zirconia by Liquid Iron and Strengthening of Sprayed Zirconia to Iron

Abstract

Field assisted bonding of metal to zirconia utilizing the oxygen ionic conductivity of zirconia has been examined. A strengthening of sprayed zirconia to iron was attempted after spraying zirconia onto the iron substrate. And the effect of applying a DC voltage to the interface on the wettability of zirconia by liquid iron was also investigated because the liquid phase would be formed at the interface by applying a DC voltage to the sprayed zirconia-metal system. According to applying a DC voltage, the interfacial chemical reaction occurs at the interface. The joining strength can be improved even after spraying zirconia onto the metal substrate. And the wettability of zirconia by liquid iron was also improved. Results are summarized as follows:
(1) Application of a DC voltage to the interface can bring about the oxidation of iron and the deoxidation of zirconia to metallic zirconium at the interface.
(2) Two mechanisms can be considered for joining of zirconia to iron. They are the penetration of iron-oxide formed at the interface into the grain boundary of zirconia and the reaction between iron and metallic zirconium at the interface.
(3) This joining method is the new one to strengthen the sprayed zirconia after spraying it.
(4) This joining method has the advantage of not needing pretreatment of the substrate (e.g., sand blast or spraying metallic bond coat between substrate and zirconia overlayer, etc.).