Abrasion-proof physical vapor deposition coating on gold-silver coin die surface and preparation method

Abstract

The invention discloses a wear-resistant physical vapor deposition coating on surfaces of silver and gold coin dies and a method for preparing the same. The coating consists of a pure Cr layer, a CrN transition layer, alternately overlapping layers of TiN layers and CrN layers and a pure Cr layer, wherein the thickness of the pure Cr layer is 0.1 mu m, and the thickness of the CrN transition layer is 0.2 mu m, the thickness of each TiN layer and CrN layer is 6 to 10 nanometers, and the whole thickness of the coating is 2 to 2.5mu m; a non-equilibrium field magnetic control sputtering device is used to prepare the coating, and two Cr targets and a Ti target are placed in a cylindrical vacuum chamber of a magnetic control sputtering stove around a workpiece rest arranged in the center, the working gas adopts argon gas, and the reacting gas adopts nitrogen. Microhardness of the coating reaches 1,900 to 2,100HV0.01; the surface of the coating is smooth and compact; the critical load of the combining force of the coating and a substrate is more than 60 N, and the tenacity is perfect and the combining force is excellent; and the preparing process has good stability, repeatability and reliability, therefore the preparing process can meet the requirements of large production.

Description

technical field [0001] The invention relates to the technical field of coinage, in particular to a wear-resistant physical vapor deposition coating on the surface of a gold and silver coin mold and a preparation method thereof. Background technique [0002] In recent years, with the increasingly fierce competition in the coinage industry, the extensive use of high-speed stamping machines, the emergence of new stamping metals and alloys, and the continuous improvement of public quality requirements for coins, the coinage technology of the Mint has been improved. reached a fairly high level. Therefore, it is extremely important to reduce the cost of mold making and improve product quality and output. At present, most mints in the world use the technology of applying a hard coating on the surface of the mold in the production of refined gold and silver coins, that is, the traditional chemical chrome plating coating. Due to the electroplating process from CrO 3 Cr released 6...

AI Technical Summary

Problems solved by technology

And the hardness of the electroplated hard chromium layer is not high, usually 750-800HV 0.01 , the mold often fails after imprinting one or two hundred products because of the serious "golden light" phenomenon on the surface

The phenomenon of "golden light" is that the chromium layer on the surface of the mold has short radial lines that radiate outward in the radial direction, especially on the large-area mirror-treated parts of the gold and silver coin mold, which greatly affects the quality of gold and silver coins.