Silico-Alumina Anti-Reflective Coating for Hydrolytic Stability
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Solution Overview
Problem
Inorganic oxide coatings, such as silica-based anti-reflective coatings on solar panels, are prone to hydrolytic degradation when exposed to outdoor conditions, leading to reduced functionality and increased production costs due to the need for additional protective layers or topcoats, which can compromise mechanical and optical properties.
Innovation Solution
A coating composition comprising inorganic oxide precursors from elements like aluminum, silicon, and lanthanoids, forming a mixed inorganic oxide that enhances hydrolytic stability and retains functional properties over time, even under varying temperature and humidity conditions, while maintaining transparency and adhesion.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a porous silica anti-reflective coating is applied to a substrate, then the anti-reflective functionality is achieved, but the coating becomes sensitive to hydrolysis and degrades under outdoor conditions
Solution Approach 1:
The patent applies a composite material approach by combining silica (SiO2) with alumina (Al2O3) to create a mixed oxide coating. This composite structure leverages the hydrolytic stability of alumina to protect the silica network from hydrolytic degradation, while maintaining the anti-reflective optical properties. The synergistic combination resolves the contradiction between achieving anti-reflective functionality and resisting hydrolytic degradation.
Solution Approach 2:
The patent changes the chemical composition parameters of the coating by incorporating alumina into the silica matrix. This parameter change modifies the network structure and chemical stability of the coating, transforming it from a pure silica system (prone to hydrolysis) to a silico-alumina system with enhanced hydrolytic resistance, thereby resolving the stability issue.
2Reliability
If additional protective topcoats or barrier films are applied to improve hydrolytic stability, then the durability is enhanced, but the production cost increases and mechanical/optical properties deteriorate
Solution Approach 1:
The patent merges the anti-reflective function and the protective function into a single integrated coating layer. Instead of applying separate protective topcoats or barrier films over the anti-reflective coating, the invention creates a unified silico-alumina coating that simultaneously provides both optical performance and hydrolytic protection, thereby reducing structural complexity and production costs.
Solution Approach 2:
The silico-alumina coating exhibits multi-functionality by simultaneously serving as an anti-reflective coating and a protective coating. This universal design eliminates the need for additional specialized layers, reducing the overall coating stack complexity while maintaining both optical and protective functions.
3Reliability
If other inorganic oxide precursors like aluminum salts are added to improve hydrolytic stability, then the resistance to hydrolysis increases, but the stability of the liquid coating composition prior to application is reduced
Solution Approach 1:
The patent carefully controls the composition parameters of the liquid coating, specifically the molar ratio of silicon to aluminum precursors (within 95:5 to 5:95), the water to precursor ratio (0.1 to 5), and the pH range (2 to 12). These parameter optimizations ensure that the coating composition remains stable during storage and application while still forming a hydrolytically stable silico-alumina network upon curing.
Solution Approach 2:
The patent applies different qualities to different stages of the coating process: the liquid coating composition is formulated to be stable and easy to apply (good processing quality), while the cured coating achieves high hydrolytic stability (good operational quality). This local quality differentiation resolves the apparent contradiction between composition stability and hydrolytic resistance.
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 mixed inorganic oxide coating composition significantly improves hydrolytic stability and storage stability of the coating liquid, maintaining functional properties and reducing the need for additional protective layers, thus enhancing the durability and performance of coated substrates like solar panels.
Implementation Method 1
Typical inorganic oxide precursors are metal alkoxides and metal salts, which undergo various forms of hydrolysis and condensation reactions.
Implementation Method 2
Typical inorganic oxide precursors are metal alkoxides and metal salts, which undergo various forms of hydrolysis and condensation reactions.
Implementation Method 3
In such process, the sol gradually evolves to a gel-like diphasic system containing both a liquid and solid phase.
Implementation Method 4
Removing remaining liquid (drying) is generally accompanied by shrinkage and densification
Implementation Method 5
Afterwards, a thermal treatment at elevated temperature is often needed to enhance further condensation reactions (curing) and secure mechanical and structural stability.
Data Source
AI summary
The invention relates to a coating composition comprising an inorganic oxide precursor AMOx based on at least one inorganic element A selected from the group consisting of aluminum, silicium, titanium, zirconium, niobium, indium, tin, antimony, tantalum, and bismuth; and an inorganic oxide precursor BMOx based on at least one inorganic element B selected from the group consisting of scandium, yttrium, lanthanum, and the lanthanoids; wherein AMOx and BMOx are capable of forming a mixed inorganic oxide. A coating made from this composition shows enhanced resistance to hydrolysis. The invention also relates to a process for applying a coating on a substrate using such composition, more specifically to a liquid coating composition for use in a process of applying an anti-reflective coating on transparent substrate; to a coated substrate obtained with such process, and to an article, like a solar panel, comprising such coated substrate.