Platinum Jewelry Alloy Hardness and Formability Balance
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Solution Overview
Problem
Existing platinum jewelry alloys face challenges in achieving high hardness, resistance to abrasion, ease of processing, and maintaining the original gray-white color while being cost-effective, as they often compromise on one or more of these properties due to the addition of other metals like palladium or gold.
Innovation Solution
A platinum jewelry alloy composition of 94.0 wt% to 96.5 wt% platinum, 2.5 wt% to 4.5 wt% tungsten, 0.5 wt% to 3 wt% copper, and 0.02 wt% to 2.0 wt% ruthenium, rhodium, or iridium, which balances hardness, cold formability, and polishability, allowing for easy machining and diamond coating without significant tool wear.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If platinum is alloyed with ruthenium or tungsten to increase hardness, then resistance to abrasion is improved, but cold formability deteriorates and tool wear increases
Solution Approach 1:
The patent employs a multi-element alloy system comprising platinum (95.0-96.5 wt%), ruthenium (1.0-3.0 wt%), copper (0.5-2.0 wt%), and tungsten (0.5-2.0 wt%). This composite material approach combines the hardness-enhancing effects of ruthenium and tungsten with the ductility-providing copper, achieving a balance where the alloy attains sufficient hardness for abrasion resistance while maintaining adequate cold formability for manufacturing. The synergistic interaction of multiple alloying elements resolves the contradiction between strength and ease of manufacture.
2Strength
If platinum is alloyed with iridium to increase hardness, then resistance to abrasion is improved, but processability without cutting deteriorates
Solution Approach 1:
The patent optimizes the concentration parameters of alloying elements to achieve the desired balance. Specifically, ruthenium is limited to 1.0-3.0 wt% and tungsten to 0.5-2.0 wt%, with copper at 0.5-2.0 wt%. These controlled parameter ranges ensure that hardness is enhanced sufficiently for abrasion resistance while preventing excessive hardness that would compromise processability. The precise parameter optimization allows the alloy to be processed with reduced tool wear while maintaining adequate manufacturability.
3Ease of manufacture
If palladium is added to platinum to improve processing properties, then cold formability is improved, but hardness decreases and color shifts toward gray
Solution Approach 1:
The patent extracts palladium from the alloy composition entirely, setting its content at 0 wt%. Instead of relying on palladium to provide cold formability, the invention achieves adequate formability through the synergistic combination of copper (0.5-2.0 wt%) and controlled amounts of ruthenium (1.0-3.0 wt%) and tungsten (0.5-2.0 wt%). This extraction of the problematic element eliminates the color shift toward gray and prevents hardness reduction while maintaining sufficient processing properties through alternative alloying strategies.
4Ease of manufacture
If gold is added to platinum to improve processing properties, then cold formability is improved, but color shifts and cost increases
Solution Approach 1:
The patent replaces expensive gold with more cost-effective alloying elements. Instead of using gold (Au) to improve cold formability, the invention employs copper (0.5-2.0 wt%), ruthenium (1.0-3.0 wt%), and tungsten (0.5-2.0 wt%), which provide similar or adequate formability benefits at lower cost. This substitution achieves the desired processing properties while avoiding the high material cost and color shift issues associated with gold addition, making the alloy more economically viable for jewelry applications.
Data Source
AI summary
The invention relates to a platinum alloy for jewelry, comprising or consisting preferably of the following components: - 94.0 wt.-% to 96.5 wt.-% platinum, - 2.5 wt.-% to 4.5 wt.-% tungsten, - 0.5 wt.-% to 3.0 wt.-% copper, and - 0.02 wt.-% to 2.0 wt.-% of at least one element from the group ruthenium, rhodium and iridium.