High-Purity Gold Alloy Hardening via Trace Alloying
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Solution Overview
Problem
High-purity gold alloys above 990 ‰ by weight face challenges in achieving sufficient hardness for luxury items like jewelry and watchmaking, as existing hardening techniques either fall short of desired hardness or compromise durability.
Innovation Solution
A gold alloy comprising at least 990 ‰ of gold, with specific amounts of silicon, yttrium, titanium, germanium, tin, and germanium as alloy elements, achieving a hardness of at least 90 HV without the need for additional aging treatments, through a process involving alloying, heat treatment, and hardening.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If pure or quasi-pure gold (≥990‰ by weight) is used, then the material maintains high purity and resistance to corrosion, but the hardness is insufficient (30-65 HV) for luxury jewelry and watchmaking applications
Solution Approach 1:
The patent applies parameter changes by precisely controlling the concentration of alloying elements (silicon: 0.01-10 ppm, yttrium: 0.01-10 ppm, titanium: 0.01-10 ppm, germanium: 0.01-10 ppm, tin: 0.01-10 ppm) to achieve the desired hardness while maintaining high gold purity (≥990‰). This quantitative adjustment of compositional parameters resolves the contradiction between purity and hardness.
Solution Approach 2:
The patent creates a composite material system by combining pure gold with trace amounts of multiple alloying elements (silicon, yttrium, titanium, germanium, tin) to form a multi-element alloy system. This composite approach enables the material to simultaneously exhibit the corrosion resistance of pure gold and the enhanced hardness provided by the alloying elements.
2Strength
If traditional hardening techniques (solid solution hardening, plastic deformation, precipitation hardening) are applied to increase hardness, then the hardness improves, but the durability and stability of the alloy are compromised
Solution Approach 1:
The patent applies preliminary action by pre-incorporating alloying elements (silicon, yttrium, titanium, germanium, tin) into the gold matrix during the alloying stage, before any hardening treatment. This preliminary compositional design enables the material to achieve adequate hardness (≥90 HV) through controlled deformation without requiring aggressive precipitation hardening that would compromise durability.
Solution Approach 2:
The patent changes the compositional parameters by introducing specific trace elements at controlled concentrations (0.01-10 ppm each) to modify the hardening behavior. This compositional modification allows the alloy to achieve ≥90 HV hardness through moderate plastic deformation while maintaining stability and durability, avoiding the need for aggressive precipitation hardening treatments.
3Strength
If alloying elements are added to improve hardness, then the hardness increases, but the purity of gold is reduced
Solution Approach 1:
The patent applies parameter changes by precisely controlling the concentration of alloying elements to remain in the range of 0.01-10 ppm each, which is such a small quantity that the gold purity remains ≥990‰. This quantitative control of compositional parameters enables simultaneous achievement of adequate hardness and high purity.
Solution Approach 2:
The patent applies partial action by adding only trace amounts of alloying elements (0.01-10 ppm each) rather than substantial quantities. This partial addition is sufficient to achieve the desired hardness improvement (≥90 HV) while having negligible impact on the overall gold purity (≥990‰), thus resolving the contradiction between hardness enhancement and purity maintenance.
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 gold alloy achieves a hardness greater than 90 HV, ensuring durability and resistance to scratches, making it suitable for high-quality luxury items without the need for specific aging treatments, thus enhancing the quality and durability of gold-based jewelry and watchmaking products.
Implementation Method 1
The solid solution hardening corresponds to the introduction into a metal matrix, which is generally pure, a minority element (solute, soluble in the metal matrix). The presence of the solute created obstacles to the movement of dislocations. Indeed, the solute atoms can slow down the movement of dislocations by interacting with them within the crystalline structure
Implementation Method 2
The hardening curing is made by plastic deformation of a metal or alloy. It comprises a heat treatment step during hardening, metal, or alloy, undergoing plastic deformations inducing dislocations
Data Source
Figure 1~2
AI summary
The present invention relates to a watch or jewelry article comprising a gold alloy, said alloy comprising: - at least 990‰ by weight of gold, - an amount greater than 0‰ and less than or equal to 10‰ of two alloying elements: * a first alloying element selected from silicon, yttrium, titanium, germanium, and mixtures thereof, and * a second alloying element selected from tin, germanium, and mixtures thereof.