UV Radiation Source for Trivalent Chromium Plating Bath Efficiency
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Solution Overview
Problem
Trivalent chromium plating baths containing sulfur compounds experience significant efficiency loss over time, leading to reduced plating thickness and corrosion resistance, making it challenging to maintain high production throughput in industrial settings.
Innovation Solution
Incorporating an ultraviolet (UV) radiation source into the plating bath to inhibit the reduction in plating efficiency by oxidizing sulfur compounds, thereby maintaining the chromium in a trivalent state and preventing its complexation with chromium, which reduces the bath's effectiveness.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If sulfur compounds are added to trivalent chromium plating bath to produce dark deposits, then the aesthetic quality and corrosion resistance of the coating are improved, but the plating efficiency of the bath decreases over time
Solution Approach 1:
The patent applies UV radiation (changing the chemical state through photochemical oxidation) to convert sulfur compounds from a harmful form that reduces plating efficiency to a beneficial form that maintains efficiency while preserving the dark coating properties. This parameter change restores the bath's plating efficiency without removing the sulfur compounds needed for dark deposit formation.
Solution Approach 2:
The patent uses UV radiation as a strong oxidizing agent to oxidize sulfur compounds in the plating bath. This oxidation process converts sulfur that would otherwise complex with chromium and reduce plating efficiency into oxidized forms that do not interfere with chromium deposition, thereby maintaining high plating efficiency while preserving corrosion resistance.
2Shape
If sulfur compounds are present in the plating bath to darken the deposit, then the coating appearance is improved, but chromium complexation with sulfur reduces the available chromium for plating
Solution Approach 1:
The patent changes the chemical parameter of sulfur compounds through UV-induced oxidation, transforming them from chromium-complexing agents into non-complexing oxidized forms. This allows sulfur to remain in the bath for darkening the deposit while no longer sequestering chromium, thus maintaining both coating appearance and chromium availability.
Solution Approach 2:
The patent converts the harmful effect of sulfur compounds (chromium complexation reducing available chromium) into a beneficial effect through UV oxidation. The oxidized sulfur compounds no longer complex with chromium, effectively turning the problematic sulfur presence into a non-interfering state that allows both dark coating formation and high chromium availability for plating.
3Productivity
If the plating bath is used continuously to maintain production throughput, then the productivity is maintained, but the plating efficiency decreases over time due to sulfur compound accumulation
Solution Approach 1:
The patent implements continuous UV irradiation of the plating bath during operation, maintaining constant oxidation of sulfur compounds. This continuous action ensures that sulfur compounds are consistently converted to non-complexing forms, allowing the bath to maintain high plating efficiency throughout continuous production operations without efficiency degradation over time.
Solution Approach 2:
The patent employs continuous UV oxidation as an accelerated oxidation process to continuously convert sulfur compounds throughout the bath volume. This prevents the accumulation of harmful sulfur species that would otherwise reduce plating efficiency over time, enabling sustained high productivity with maintained plating efficiency.
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 UV treatment significantly increases plating efficiency by preventing the sulfur compounds from rendering chromium non-platable, allowing for consistent deposition of at least 10 microinches of dark trivalent chromium with extended bath life and improved corrosion resistance.
Implementation Method 1
an ultraviolet (UV) radiation source that provides UV radiation to the bath effective to inhibit a reduction in plating efficiency of the bath over time
Implementation Method 2
The apparatus includes an electroplating bath, which comprises trivalent chromium ions and a sulfur compound
Implementation Method 3
The apparatus can further include a cathode workpiece in the bath and an anode contacting the bath
Data Source
AI summary
An apparatus for maintaining trivalent chromium plating bath efficiency includes an aqueous electroplating bath, which includes trivalent chromium ions and a sulfur compound, and an ultraviolet (UV) radiation source that provides UV radiation to the bath effective to inhibit a reduction in plating efficiency of the bath.