Metallic Materials with Embedded Luminescent Particles

Abstract

Formation of an authentication element by deposition of a metal layer with embedded particles on a metal substrate, wherein the embedded particles are configured to convert energy from one wavelength to another. The embedded particles may be upconverters, downconverters, or phosphorescent phosphors, which can be detected and measured with analytical equipment when deposited in the metal layer. A metal substrate may include coinage.

What is claimed is: 
     
         1 . A method for depositing a metal layer having embedded luminescent particles onto a metal substrate, comprising:
 mixing the luminescent particles with a metallic material to produce a plating solution;   inserting the metal substrate into the plating solution; and   performing an electroplating plating process to coat the metal substrate with the metal layer, wherein the metal layer contains embedded luminescent particles, wherein the electroplating process is a dip or rack plating process.   
     
     
         2 . A method according to  claim 1 , wherein the embedded luminescent particles have a composition configured to emit energy comprising a second wavelength when excited by energy comprising a first wavelength. 
     
     
         3 . The method of  claim 2 , wherein the electroplated metal layer is selected from the group consisting of nickel, nickel-phosphorus, copper, brass, gold, silver, and platinum. 
     
     
         4 . The method of  claim 3 , wherein the metal substrate is selected from the group consisting of copper, brass, bronze, mild steel, stainless steel, and titanium. 
     
     
         5 . The method of  claim 1 , wherein the metal substrate is a negotiable coin. 
     
     
         6 . The method of  claim 1 , wherein the luminescent particles have a density of 5.0 g/cm3 or more. 
     
     
         7 . The method of  claim 1 , wherein the density of the luminescent particles is greater than 7.4 g/cm3 
     
     
         8 . The method of  claim 1 , wherein the luminescent particles comprise rare earth doped yttrium oxide-based phosphors. 
     
     
         9 . The metal substrate of  claim 1 , wherein the luminescent particles comprise rare earth doped gadolinium oxide-based phosphors.