Cold-worked Metal Surface with Embedded Phosphor Particles for Wear-Resistant Authentication
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Solution Overview
Problem
Existing methods for authenticating metal articles, such as coins, face challenges due to the masking of magnetic signals from soft steel cores and the weak adherence of taggants, which are costly and prone to wear, making repeat authentication difficult.
Innovation Solution
Incorporating luminescent phosphor particles with a host crystal lattice material and active ions into the metal articles through a coating that is cold-worked, allowing the particles to be robustly embedded within the metal surface, enabling detection even under wear and masking conditions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If post metal-forming surface deposition of taggants is used, then taggant costs are reduced, but taggant adherence becomes weak and taggants easily wear off
Solution Approach 1:
The taggants are incorporated into the metal article during the manufacturing process before the final form is achieved. The coating containing taggants is applied to the metal substrate, then the entire structure undergoes cold-working to form the final article shape. This preliminary incorporation ensures taggants are embedded within the material structure rather than merely deposited on the surface, providing robust adherence that withstands wear over time.
Solution Approach 2:
The invention merges the taggant incorporation step with the metal forming process itself. Instead of separate operations, the coating with taggants is applied and then the cold-working process that forms the metal article simultaneously embeds the taggants into the material matrix. This combining of operations ensures taggants become an integral part of the article structure, achieving both cost-effectiveness and reliable adherence.
2Ease of manufacture
If soft steel core is used in metal articles, then manufacturing cost is reduced, but magnetic signal is masked making authentication difficult
Solution Approach 1:
The invention introduces luminescent phosphor taggants as an intermediary authentication mechanism that bypasses the magnetic signal masking problem entirely. Rather than attempting to detect magnetic signals through the soft steel core and plated metal layers, the system uses optically-active phosphor materials that can be excited by light sources and detected through their luminescent properties. This intermediary approach allows authentication without being affected by the multi-layer metal structure.
Solution Approach 2:
The invention replaces the magnetic field-based authentication system with an optical-based system. Instead of using magnetic sensors to detect metal composition, the system employs light sources to excite phosphor taggants and optical detectors to measure their luminescent response. This substitution of mechanical/electromagnetic field methods with optical methods eliminates the interference caused by the soft steel core structure.
3Reliability
If taggants are dispersed through entire material volume, then authentication reliability is improved, but taggant costs increase prohibitively
Solution Approach 1:
The invention applies taggants locally rather than uniformly throughout the entire material volume. The coating containing phosphor taggants is applied to specific regions of the metal substrate, and the cold-working process embeds these localized taggant concentrations into the final article. This local quality approach provides sufficient authentication capability at the surface and near-surface regions where detection occurs, eliminating the need for expensive throughout-volume dispersion.
Solution Approach 2:
The invention uses partial action by concentrating taggants only in the regions necessary for authentication rather than distributing them throughout the entire article. Since authentication only requires detecting taggants at or near the surface, applying and embedding taggants in a coating layer provides sufficient concentration where needed without the excessive cost of dispersing taggants through the complete material volume.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The luminescent phosphor particles provide a robust and durable authentication method that can withstand wear and masking, allowing for consistent and reliable detection of the metal articles' authenticity over time.
Implementation Method 1
The luminescent phosphor particles include a host crystal lattice material and at least one active ion that includes an absorbing ion and an emitting ion
Implementation Method 2
The luminescent phosphor particles are exposed to light produced by an exciting light source. The light produced by the exciting light source has sufficient intensity to excite the luminescent phosphor particles
Data Source
Figure 1~2B
Figure 3~4B
AI summary
Cold-worked metal articles, methods of forming cold-worked metal articles, and methods of authenticating cold-worked metal articles are provided. In an embodiment, a cold-worked metal article includes a cold-worked metal-containing surface that defines pores. The cold-worked metal-containing surface includes luminescent phosphor particles disposed within the pores. The luminescent phosphor particles include a host crystal lattice material and at least one active ion that includes an absorbing ion and an emitting ion that is different from the absorbing ion. The luminescent phosphor particles are harder than the cold-worked metal-containing surface.