| 摘要 |
PURPOSE: A precious metal coating method is provided to simplify manufacturing process of metallic powder for coating precious metal by reducing activation treatment process of metallic powder and secure uniformed precious metal coating layer by suspending metallic powder in reducer and adding silver nitrate aqueous solution to plating solution later. CONSTITUTION: The manufacturing method of precious metal coated metallic powder comprises the steps of preparing metallic powder, i.e., an object to be coated by directly synthesizing the metallic powder just before coating precious metal on the metallic powder; suspending the metallic powder into a reducer aqueous solution; and adding a precious metal compound aqueous solution to the suspension containing the metallic powder so that precious metal is coated on the metallic powder that is a coating material, wherein the metallic powder that is an object to be coated is a base metal including Cu, Ni and Co, and the coating material is a precious metal including Au, Pd, Ag and alloy thereof, and wherein concentration of precious metal ions in the precious metal compound aqueous solution is 0.05 to 3 M, concentration of NH4OH is 0.1 to 1 M, a reducer aqueous solution in which the metallic powder is suspended is a reducer selected from the reducer group consisting of formalin, hydrazine, sodium sulfite, ammonium bicarbonate, NaKC4H4O6 and C6H8O6, and concentration of the reducer aqueous solution is 0.2 to 5 M.
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