Functional Coating With Stabilizing Layers For Thermal Stress
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Solution Overview
Problem
Existing coated articles with transparent conductive oxides (TCOs) face challenges in maintaining stability during heat treatment, leading to defects and undesirable changes in optical properties and color.
Innovation Solution
A coated article structure comprising a substrate with a base layer, a first protective layer, an optional stabilizing layer, a transparent conductive oxide layer, another optional stabilizing layer, and a second protective layer, where the stabilizing layers comprise zinc oxide, tin oxide, or their combinations, and the protective layers include titania, alumina, or silicon aluminum oxide, to enhance mechanical and chemical durability and reduce defect formation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If TCO layer thickness is increased to reduce sheet resistance, then electrical conductivity is improved, but color distortion increases
Solution Approach 1:
The patent divides the single TCO layer into multiple TCO sub-layers separated by stabilizing layers. This segmentation allows each TCO sub-layer to be thinner, reducing individual color impact while achieving the required total thickness for low sheet resistance. The stabilizing layers between sub-layers prevent defect formation that would otherwise occur in thicker single TCO layers.
Solution Approach 2:
Stabilizing layers comprising zinc oxide, tin oxide, or their combinations are introduced as intermediary layers between TCO sub-layers. These intermediary stabilizing layers reduce thermal stress and prevent defect formation, allowing the TCO structure to maintain both the required thickness for electrical conductivity and the thinness needed for color neutrality.
2Reliability
If protective overcoats are applied to prevent corrosion, then chemical resistance is improved, but mechanical durability and defect resistance are insufficient
Solution Approach 1:
The patent employs a composite coating structure combining multiple materials with complementary properties. Protective layers provide chemical resistance, while stabilizing layers comprising zinc oxide and tin oxide provide mechanical strength and defect resistance. This composite approach allows the coating stack to simultaneously achieve chemical resistance, mechanical durability, and resistance to defect formation during heat treatment.
3Productivity
If heat treatment is applied to complete post-deposition process, then coating completion is achieved, but defects form and optical properties change
Solution Approach 1:
Stabilizing layers are incorporated into the coating structure before heat treatment to cushion against thermal stress during the post-deposition process. These stabilizing layers comprising zinc oxide, tin oxide, or their combinations are positioned between TCO sub-layers to prevent defect formation and maintain optical properties during heat treatment, allowing complete process completion without compromising coating stability.
4Ease of manufacture
If TCO layer thickness is reduced to maintain color neutrality, then color accuracy is improved, but sheet resistance increases
Solution Approach 1:
The patent segments the TCO coating into multiple thinner sub-layers, each contributing to the overall electrical conductivity while individual layers remaining thin enough to maintain color neutrality. The cumulative effect of multiple sub-layers achieves the required low sheet resistance without the color distortion that would result from a single thick TCO layer.
Solution Approach 2:
The patent combines multiple TCO sub-layers with stabilizing layers to achieve the functional equivalent of a thicker TCO layer for electrical conductivity while maintaining the optical properties of thinner layers. The merging of these layers creates a composite structure that delivers both low sheet resistance and color neutrality.
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 proposed structure significantly improves the thermal stress resistance and durability of the coated articles, reducing the occurrence of defects and maintaining the desired optical properties and color both before and after heat treatment.
Implementation Method 1
transparent conductive oxide layer over the first stabilizing layer or the first protective layer
Implementation Method 2
improves the thermal stress resistance and durability of the coated articles
Data Source
AI summary
The invention is directed to a coated article having a functional layer over a substrate. The functional layer includes at least one stabilizing layer that reduces the occurrence of defects during heat treatment. The functional layer includes a base layer over the substrate, a first protective layer over the base layer, an optional first stabilizing layer, a transparent conductive oxide layer over the first stabilizing layer or first protective layer, an optional second stabilizing layer positioned over at least a portion of the transparent conductive oxide layer, and a second protective layer over at least a portion of the second stabilizing layer and/or the transparent conductive oxide layer. The first and/or second stabilizing layer can comprise zinc oxide, tin oxide, or combinations thereof. The base layer can include a first film formed from tin oxide in direct contact with the portion of the substrate.