Coated Glazing Surface Topography for Thermal Bending
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Solution Overview
Problem
Coated glazings used in architectural, automotive, and technical applications often experience cohesive failures during thermal bending and tempering processes, which can lead to reduced performance and reliability, particularly in commercial refrigeration applications.
Innovation Solution
A coated glazing structure comprising a transparent glass substrate, a layer based on an oxide of a metal or metalloid, and a further layer, where the layer adjacent the glass substrate has a modified surface topography with an arithmetical mean height of at least 4.0 nm, reducing cohesive failures during thermal bending and tempering operations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a coated glazing undergoes thermal bending and tempering processes, then the desired product characteristics are achieved, but cohesive failures occur within the coating stack
Solution Approach 1:
The patent changes the physical-chemical parameters of the coating system by introducing a dielectric barrier layer with specific properties (low oxygen content, controlled composition) between the TCO layer and the oxygen-permeable coating. This parameter change prevents excessive oxygen diffusion to the TCO layer during thermal treatment, thereby preventing cohesive failures while maintaining coating integrity during thermal bending and tempering processes.
Solution Approach 2:
The dielectric barrier layer acts as an intermediary element between the TCO layer and the oxygen-permeable coating layers. This intermediate layer controls and regulates oxygen diffusion, preventing direct harmful interaction between oxygen and the TCO layer during thermal treatment, thus resolving the contradiction between achieving desired product characteristics and maintaining coating integrity.
2Illumination intensity
If the functional layer contains high oxygen content to achieve low emissivity, then the desired optical properties are obtained, but cracks form in the functional layer during thermal treatment
Solution Approach 1:
The dielectric barrier layer serves as a mediator that allows the functional TCO layer to maintain high oxygen content for optimal low emissivity properties while preventing uncontrolled oxygen diffusion during thermal treatment. This intermediary layer protects the TCO layer from excessive oxygen exposure, preventing crack formation while preserving the desired optical properties.
Solution Approach 2:
The patent modifies the oxygen diffusion parameters by introducing a barrier layer with controlled oxygen permeability. This allows the TCO layer to achieve and maintain the optimal oxygen content for low emissivity without undergoing harmful oxygen diffusion during thermal treatment, thus preventing cracks while maintaining optical performance.
3Strength
If the glazing is thermally bent or tempered to achieve desired product characteristics, then the mechanical properties are improved, but cohesive failures occur in the coating stack
Solution Approach 1:
The dielectric barrier layer acts as a protective intermediary that stabilizes the coating stack during thermal bending and tempering operations. By controlling oxygen diffusion and reducing internal stresses, this intermediate layer prevents cohesive failures while allowing the glazing to achieve the desired mechanical strength improvements from thermal treatment.
Solution Approach 2:
The patent changes the thermal and chemical parameters of the coating system by introducing a barrier layer that maintains coating stability during thermal treatment. This layer prevents harmful parameter changes (excessive oxygen diffusion, uncontrolled stress development) that would otherwise cause cohesive failures, enabling successful thermal bending and tempering to improve mechanical strength.
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 modified surface topography of the layer adjacent the glass substrate significantly reduces cohesive failures within the coating stack during thermal bending and tempering, enhancing the durability and reliability of the coated glazing.
Implementation Method 1
the layer that is adjacent said transparent glass substrate comprises a surface that, prior to a coating of said surface, has an arithmetical mean height of the surface value, Sa, of at least 4.0 nm
Implementation Method 2
exhibits reduced incidences of cohesive failures within the coating upon thermal bending and/or toughening operations
Data Source
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AI summary
A coated glazing comprising at least the following layers in sequence: a transparent glass substrate, a layer based on an oxide of a metal and/or a layer based on an oxide of a metalloid, and a further layer, wherein either said layer based on an oxide of a metal or said layer based on an oxide of a metalloid is adjacent said transparent glass substrate, wherein said layer that is adjacent said transparent glass substrate comprises a surface that, prior to a coating of said surface, has an arithmetical mean height of the surface value, Sa, of at least 4.0 nm when tested in accordance with ISO 25178-2:2012, and wherein the coated glazing exhibits an average haze value of at least 0.47% when tested in accordance with ASTM D1003 - 13.