Weather-resistant Glazing Layer System with Sodium Barrier
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Solution Overview
Problem
Existing technologies fail to effectively prevent corrosion, weather contamination, and dew or frost on the outer surface of glazing, leading to frequent cleaning needs and potential damage.
Innovation Solution
A layer system comprising a blocker layer embedded between a transparent conductive oxide (TCO) layer and a photocatalytic TiO2 layer, with a Na diffusion barrier layer, designed to prevent space charge zone formation and maintain photocatalytic activity, combined with a low-emissivity SnO2:F layer to suppress heat radiation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a photocatalytic TiO2 layer is applied to the exterior surface to prevent weathering contamination, then self-cleaning effect is significantly increased, but sodium ions from the glass diffuse into the photocatalytic layer and destroy electrical charge carriers, negating the photocatalytic effect
Solution Approach 1:
A blocking layer is introduced as an intermediary between the glass substrate and the photocatalytic TiO2 layer. This blocking layer prevents sodium ions from diffusing into the photocatalytic layer while allowing the photocatalytic effect to occur on the exterior surface, thus resolving the contradiction between maintaining photocatalytic activity and preventing sodium ion contamination.
Solution Approach 2:
The coating system is segmented into multiple functional layers: a blocking layer adjacent to the glass substrate to prevent sodium ion diffusion, and a photocatalytic TiO2 layer on the exterior surface to provide self-cleaning. This segmentation allows each layer to perform its specific function without interfering with the other, solving the contradiction between sodium ion prevention and photocatalytic effectiveness.
2Object-affected harmful factors
If the outer surface of the glazing has high heat radiation to the sky, then heat loss increases and dew or frost forms, but applying layers with low emissivity suppresses heat radiation and prevents dew or frost
Solution Approach 1:
The emissivity parameter of the outer surface is changed by applying a low-emissivity coating (ε ≤ 0.2). This parameter change reduces heat radiation loss to the sky while simultaneously preventing dew or frost formation, as the suppressed heat radiation maintains the surface temperature above the dew point.
3Reliability
If rainwater spreads across the photocatalytic layer to wash away dirt, then cleaning effect is improved, but the spreading of rainwater makes the surface hydrophobic and increases pollution
Solution Approach 1:
Different local qualities are applied to different surfaces: the exterior surface of the photocatalytic layer is made hydrophobic to prevent pollution adhesion, while the interior surface facing the blocking layer is made hydrophilic to enable rainwater spreading and washing-cleaning. This local differentiation resolves the contradiction between cleaning effectiveness and pollution prevention.
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 layer system significantly extends cleaning intervals, prevents corrosion, and reduces dew and frost formation, maintaining transparency and cleanliness even in challenging climates.
Implementation Method 1
a photocatalytic process takes place on the layer's surface; hence the name 'photocatalytic' TiO2 layer. The basis of this effect is that hydrocarbons adsorbed from the outside atmosphere onto the TiO2 layer, which make the surface hydrophobic and thus increase pollution, are decomposed even by low levels of UV light
Implementation Method 2
when exposed to UV light, the coating's surface becomes so strongly and, above all, permanently water-wetting—i.e., super-hydrophilic—that rainwater spreads across it. This infiltrates deposited weathering dirt, loosens it from the surface, and washes it away
Implementation Method 3
applying layers to the outer surface of the glazing with an emissivity εa ≤ 0.2, which therefore suppress heat radiation to the greatest extent possible, to such an extent that frost can no longer occur and dew only occurs in exceptional cases
Implementation Method 4
This layer is designed to prevent the diffusion of sodium ions from the glass into the photocatalytic layer applied above it
Data Source
Figure 1
AI summary
The invention relates to a layer system applied to a transparent substrate with one or more barrier layers embedded in the functional layers.