NiCr-Cr2C3-Cr2O3 composite multilayer coating and preparation method thereof

The invention discloses a NiCr-Cr2C3-Cr2O3 composite multilayer coating and a preparation method thereof. The NiCr-Cr2C3-Cr2O3 composite multilayer coating comprises a NiCr alloy layer prepared on the surface of a die-casting die matrix by adopting an electric spark discharge technology in an argon protective atmosphere; a Cr2C3 single layer and a NiCr single layer are alternately prepared by adopting an electric spark discharge technology to form a NiCr-Cr2C3 composite layer with a gradient composite structure; preparing a NiCr/Cr2O3 alloy layer by adopting an electric spark discharge technology; the whole coating fully utilizes a multi-layer structure, a gradient structure, high hardness and high-temperature stability of a ceramic material and high toughness of metal, the binding force of the coating on the surface of the die-casting die and a base body is improved, the die-casting die is prevented from being corroded by high-temperature molten aluminum, the service life of the aluminum alloy die-casting di