Glass vessel
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Solution Overview
Problem
Existing methods for strengthening glass containers are either costly, complex, or require the use of expensive specialty glasses, limiting their economic viability for mass production.
Innovation Solution
A glass container with a surface layer enriched in potassium and depleted in sodium and/or lithium, and an inner layer that is not enriched in potassium and not depleted in sodium and/or lithium, achieving a compressive stress profile with a tensile stress maximum in the inner layer, which is produced using a combination of thermal and chemical hardening processes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If thermal prestressing is employed to increase fracture strength, then glass strength is improved, but production cost and complexity increase
Solution Approach 1:
The patent combines thermal prestressing and chemical prestressing into a single integrated process. The glass container undergoes both thermal hardening (heating to 600-700°C followed by quenching) and chemical ion exchange (soaking in molten salt bath) sequentially, creating a composite stress profile that achieves superior strength without requiring separate production lines or complex equipment modifications.
Solution Approach 2:
The glass container develops a composite stress structure with two distinct zones: a compressive stress zone at the surface (from chemical prestressing) and a tensile stress zone in the interior (from thermal prestressing). This composite stress profile acts like a multi-layered material structure, where each layer contributes different mechanical properties, resulting in overall enhanced fracture strength.
2Strength
If chemical prestressing with long treatment time is used, then glass strength is improved, but production time increases
Solution Approach 1:
The thermal prestressing is performed first as a preliminary action, creating a tensile stress profile in the interior. This prepares the glass structure to receive the subsequent chemical prestressing treatment, allowing the compressive surface layer to be formed more rapidly. The sequence optimizes the overall process time by preparing the substrate in advance.
Solution Approach 2:
The patent modifies the chemical prestressing parameters by using a molten salt bath at elevated temperatures (400-500°C) with specific composition ratios (NaCl:KCl in 70:30 to 90:10 ranges). These parameter changes accelerate the ion exchange rate, reducing treatment time from conventional 8-36 hours to 2-8 hours while maintaining effective compressive stress formation.
3Loss of time
If specialty glass is used to reduce treatment time, then production time is reduced, but material cost increases
Solution Approach 1:
The patent uses conventional, inexpensive alkali-containing silicate glass (soda-lime glass) as the base material instead of expensive specialty glasses. The process accepts that standard glass requires treatment but optimizes the treatment parameters (temperature, time, salt composition) to achieve effective strengthening at minimum cost, treating the glass as a disposable base material that gains value through the hardening process.
Solution Approach 2:
By changing the physical parameters of the treatment process (higher temperatures, optimized salt bath composition, controlled atmosphere), the patent achieves rapid ion exchange in conventional glass without requiring specialized glass formulations. This substitutes process optimization for material optimization, keeping material costs low while achieving fast treatment times.
4Strength
If multistage treatment methods are used, then glass strength is improved, but process complexity increases
Solution Approach 1:
The patent merges thermal prestressing and chemical prestressing into a single integrated production flow. The glass container moves through a continuous process: heating zone → quenching zone → salt bath zone → cooling zone. This unified approach creates a composite stress profile (compressive surface layer + tensile interior layer) that achieves superior strength without requiring multiple separate treatment cycles or complex process control systems.
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 glass container achieves significantly higher strength values, including flexural fracture strength, microhardness, and scratch resistance, while reducing production costs and material usage, allowing for mass production without expensive specialty glasses.
Implementation Method 1
chemical prestressing... processes involving low-temperature ion exchange... ion exchange which takes place usually in a bath of molten salt, between the glass surface and the salt bath. For example, sodium ions are replaced with potassium ions
Implementation Method 2
thermal prestressing... the glass workpiece to be strengthened is heated in a kiln to around 600° C. and then rapidly quenched to room temperature. This quenching causes the surface to solidify, and there is little subsequent change in the external dimensions of the component
Data Source
AI summary
The invention relates to a glass vessel having at least one wall and manufactured from a base material which is an alkali-containing silicate glass. It is a feature of the glass vessel that at least a surface layer is enriched in potassium and depleted of sodium and/or lithium, while an inner layer, especially one directly adjoining the surface layer, is not enriched in potassium and not depleted of sodium and/or lithium, and that the glass vessel has compressive stress up to a compressive stress depth and tensile stress beyond the compressive stress depth, wherein the tensile stress rises with increasing depth up to a tensile stress maximum within the inner layer and/or wherein the progression of the tensile stress as a function of depth does not have a linear section and/or wherein the progression of the tensile stress as a function of depth does not have a section in which tensile stress is constant.