Plasma Treatment of Glass Surfaces to Reduce Alkali Metal Ion Concentration
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Solution Overview
Problem
Existing methods for reducing alkali and alkaline-earth metal ions on glass surfaces are either ineffective or damage the glass structure, leading to contamination and reduced strength, especially in applications like pharmaceutical packaging and display glasses.
Innovation Solution
A plasma treatment method using process gases like hydrogen, ammonia, and noble gases to selectively reduce alkali and alkaline-earth metal ions in the superficial region of glass surfaces without damaging the glass, employing techniques such as dielectric barrier discharge and microwave plasma to maintain low substrate temperatures and prevent ion diffusion.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If chemical cleaning and leaching methods are used to reduce metal ion content, then the metal ion concentration is reduced, but the glass network is damaged and glass strength is reduced
Solution Approach 1:
The patent replaces chemical cleaning and leaching methods with a physical plasma treatment process. The plasma process uses ionized gas to remove metal ions from the glass surface through physical bombardment and chemical reactions in the plasma phase, avoiding the need for liquid chemicals that attack and damage the glass network structure.
Solution Approach 2:
The patent uses an inert or controlled gas atmosphere in the plasma process (such as nitrogen, oxygen, or noble gases) to treat the glass surface. This inert environment prevents unwanted chemical reactions that would damage the glass network while still enabling effective removal of metal ions through plasma mechanisms.
2Quantity of substance
If hot forming is used to reduce alkali metal ions on glass surface, then sodium ions are reduced, but alkali metal ions can reach the surface again by diffusion in further hot forming steps
Solution Approach 1:
The patent applies plasma treatment as a preliminary surface modification step before further hot forming operations. The plasma process creates a modified surface layer with reduced metal ion concentration that is more resistant to subsequent diffusion during hot forming, effectively preparing the surface in advance to prevent future contamination.
Solution Approach 2:
The patent changes the physical and chemical parameters of the glass surface through plasma treatment, creating a surface layer with different properties than the bulk material. This surface modification alters the diffusion characteristics and prevents alkali metal ions from reaching the surface during subsequent processing, providing long-term stability.
3Reliability
If barrier layers are applied as diffusion barriers, then metal ion diffusion is prevented, but the barrier layers are expensive and cannot be applied in all cases
Solution Approach 1:
The patent extracts and removes metal ions directly from the glass surface through plasma treatment, eliminating the need for additional barrier layers. By taking out the harmful metal ions through plasma bombardment and chemical reactions, the surface becomes inherently resistant to further ion diffusion without requiring separate protective coatings.
Solution Approach 2:
The plasma treatment process modifies the glass surface in situ, making the surface itself resistant to metal ion diffusion. The treated surface layer acts as its own barrier, eliminating the need for external barrier layers and simplifying the overall process while maintaining effectiveness.
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 plasma treatment achieves a significant, long-lasting reduction of alkali and alkaline-earth metal ions to depths of up to 30 nm, reducing contamination risks and maintaining glass strength, suitable for various applications including pharmaceutical packaging and display glasses.
Implementation Method 1
a substrate with a surface to be treated is provided, the substrate containing metal... by providing a process gas or a process gas mixture and striking a plasma, the metal component... is reduced by means of the plasma
Implementation Method 2
the tubes are hot-blown in a gas atmosphere containing oxygen. This leads to reduction at least of sodium ions on the glass surface
Implementation Method 3
a substrate having a reduced alkali and alkaline-earth metal concentration at least in the superficial region, the substrate being subjectable to further processing steps
Data Source
AI summary
The invention relates to a method for the plasma treatment of glass surfaces, the metal component, in particular the alkali and/or alkaline-earth metal component in the superficial region of the substrate being reduced by a plasma treatment of a substrate.