Preparation method for electroplating thick tungsten coating on pure copper or copper alloy substrate with molten salt

The invention discloses a method for electroplating a thick tungsten coating on the substrate surface of pure copper or copper alloy with molten salt, belonging to the technical field of surface engineering. The method comprises the steps of: carrying out surface and drying process on electrodes, wherein the working electrode (substrate metal) is CuZrCr or oxygen-free copper (OF-Cu) or dispersion-strengthening copper alloy, and the counter electrode (anode) is pure metal tungsten piece; weighing the molten salt according to a certain molar ratio and drying, wherein the molten salt is Na2WO4-WO3 binary system; equally blending and heating to a molten state; connecting the cathode with the anode; and setting the current parameters and adjusting the electroplating time to obtain the metal tungsten coating with a needed thickness, wherein the current is unidirectional pulse current, the fixed mean current density is 100-150 mA/cm2, the pulse frequency is 10-1000 Hz, the duty ratio is 0.1-0.75, and the tungsten co