Nano-porous Silica Coating with Cracks for Dust Repulsion
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Solution Overview
Problem
Current coatings for architectural glass surfaces are either expensive, difficult to prepare, or ineffective in reducing soiling and reflectivity, particularly for solar applications, as they either fail to repel dust and contaminants or are easily washed off by rain.
Innovation Solution
A dust repellant and anti-reflective inorganic coating comprising a nano-porous silica network with cracks, prepared through sol-gel processing, which is characterized by a specific microstructure that reduces dust deposition and reflectivity by forming cracks during rapid annealing and cooling, enhancing the anti-soiling and anti-reflective properties.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If anti-static polymeric film coating is applied to repel dust, then dust repulsion is improved, but the coating is easily washed off by rain
Solution Approach 1:
The patent applies a porous silica coating structure that creates a rough surface topology. This porous structure reduces dust adhesion by minimizing the contact area between dust particles and the glass surface, while the inorganic silica material provides rain resistance that polymeric films lack. The porous nature allows the coating to maintain its dust-repelling properties without being easily washed away.
Solution Approach 2:
The patent uses a composite approach by combining silica nanoparticles with a binder system to create a durable coating. The silica provides the dust-repelling porous structure while the binder ensures strong adhesion to the glass substrate, creating a composite material that overcomes the weaknesses of both pure silica and polymeric films alone.
2Ease of manufacture
If sol-gel processing is used to deposit anti-soiling nanostructured coatings, then large area coating is achieved, but the ingredients are considerably more expensive
Solution Approach 1:
The patent modifies the sol-gel process parameters by using simpler, more cost-effective silica precursors and optimizing the drying and heat treatment conditions. By adjusting the composition ratios, drying temperature, and heat treatment parameters, the patent achieves the desired porous nanostructure using less expensive materials while maintaining the ease of large-area coating application.
Solution Approach 2:
The patent employs inexpensive silica-based materials and simple organic binders that can be easily synthesized or sourced, replacing costly specialized nanostructured coating ingredients. The coating formulation uses economical raw materials that maintain effectiveness without requiring expensive proprietary components.
3Object-affected harmful factors
If TiO2 coating is applied for self-cleaning properties, then photo-catalytic degradation of organic contaminants is improved, but surface reflectivity increases and inorganic materials do not benefit from photo-catalysis
Solution Approach 1:
The patent creates a porous silica coating structure that reduces surface reflectivity through light scattering and multiple internal reflections. The porous topology increases the optical path length and reduces the specular reflection that occurs on smooth high-index surfaces like TiO2, thereby improving light transmission while maintaining dust-repelling properties.
Solution Approach 2:
The patent extracts the dust-repelling function from the photo-catalytic function. Instead of using TiO2 which provides both functions, the patent separates these functions by using a porous silica structure for dust repulsion and physical adsorption, eliminating the need for photo-catalytic activity while avoiding the high reflectivity problem of TiO2 surfaces.
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 coating significantly reduces dust deposition, improves transmittance by up to 10% compared to uncoated surfaces, and is cost-effective and easy to prepare, enhancing the performance of architectural glass, photovoltaic modules, and solar-thermal systems.
Implementation Method 1
an anti-static polymeric film with a sufficiently low surface energy that repels dust, soil and grime
Implementation Method 2
a dust repellant and anti-reflective inorganic coating which comprises a nano-porous silica network
Implementation Method 3
The cracks are about 0.3 micrometer (μm) to about 3 μm in length and about 0.01 μm to about 0.05 μm in width... improves transmittance by up to 10%
Implementation Method 4
prepared through sol-gel processing
Implementation Method 5
which is characterized by cracks during rapid annealing and cooling
Data Source
AI summary
The invention provides a dust repellant and anti-reflective inorganic coating and the method for preparing the coating. The dust repellant and anti-reflective inorganic coating includes nano-porous silica (SiO2) network of about 5 nm to about 35 nm and is characterized by cracks. The method of preparing the dust repellant and anti-reflective inorganic coating on a substrate includes mixing of aqueous SiO2 solution with a solvent. The aqueous SiO2 solution with the solvent is stirred to form a solution. The solution is coated on the substrate to form a film on the surface of the substrate. Thereafter, the film is annealed by heating the film to a temperature of about 500° C. to about 700° C. within a period of about 2 minutes to about 2 hours. Finally, the film is allowed to cool down.