In-situ Synthesis of ZrO2/MgO Coating and Self-Repairing Cracks

The cracks will impact the toughness and wear properties in the coating formation process of micro-arc oxidation melting and cooling. This research used the ZrO2 to synthesize a ZrO2/MgO coating with self-repairing cracks, and investigated the effect of in-situ ZrO2 on the wear properties of the coating. It is found that the in-situ synthesized ZrO2 by micro-arc oxidation undergoes phase change in the high-temperature discharge channel to generate volume expansion, which causes microcracks in the zirconia interface and hinders the crack propagation at the crack tip, so as to realize the self-repairing coating crack. The ZrO2 content in the coating is controlled by controlling the content of zirconium source. When the in-situ ZrO2 content in the coating is 32%, the cracks of the ZrO2/MgO coating are finely dispersed, and the crack density is 63.4% lower than that of the traditional coating, the friction coefficient is reduced by 53.4%, the amount of wear is descended by 66.7%. It is believed that the in-situ synthesized ZrO2 realizes self-repairing of cracks during the coating preparation process, which can effectively reduce the friction coefficient and wear amount, and improve the surface wear properties of the ZrO2/MgO coating.