Borosilicate Glass Coating with SiO2 Binder for Thermal Stress Reduction
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Solution Overview
Problem
Borosilicate glass panes used in vehicle windshields face challenges with coatings that compromise mechanical strength due to differences in thermal expansion coefficients, leading to reduced flexural strength and potential delamination when laminated with polymeric materials.
Innovation Solution
A glass pane with a coating comprising a SiO2-based binder, pigment, and optional filler, applied in a way that achieves a porosity gradient, maintaining sufficient flexural strength and optical density, and using a glass frit as the binder to form an enamel layer that minimizes thermal expansion mismatches with the glass substrate.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If a coating is applied to borosilicate glass panes, then optical density and UV protection are improved, but flexural strength is reduced due to thermal expansion coefficient differences
Solution Approach 1:
The patent changes the chemical composition parameters of the glass coating, specifically formulating it with SiO2 (40-70 wt%), B2O3 (10-30 wt%), and Al2O3 (5-20 wt%) to achieve a thermal expansion coefficient that closely matches borosilicate glass. This compositional adjustment reduces thermal stress during temperature cycling while maintaining the coating's optical density and UV protection properties.
Solution Approach 2:
The patent creates a composite material system by applying a specially formulated glass-based coating onto borosilicate glass panes. The coating acts as a composite layer that combines the optical protection benefits with thermally compatible properties, reducing the strength reduction typically caused by coating applications while maintaining flexural strength above 150 MPa after thermal cycling.
2Object-affected harmful factors
If a coating is applied to glass panes, then optical density is improved, but delamination risk increases due to thermal expansion mismatches
Solution Approach 1:
The patent adjusts the thermal expansion parameters of the coating by incorporating B2O3 (10-30 wt%) and Al2O3 (5-20 wt%) alongside SiO2, creating a glass-based coating whose thermal expansion coefficient closely matches that of borosilicate glass. This parameter matching prevents differential thermal stress that would otherwise cause delamination during temperature cycling between -40°C and +85°C.
Solution Approach 2:
The patent achieves homogeneity in thermal properties between the substrate and coating by formulating the coating with a glass composition that mirrors the thermal expansion characteristics of borosilicate glass. This homogeneous thermal behavior ensures the coating remains firmly bonded to the glass pane throughout thermal cycling, preventing delamination while maintaining optical density.
3Stability of the object's composition
If known ceramic paints are used for coating, then adhesion is improved, but mechanical strength is reduced due to coefficient of expansion differences
Solution Approach 1:
The patent fundamentally changes the binder material from organic ceramic paint binders to an inorganic glass-based binder system. The glass binder, composed of SiO2 (40-70 wt%), B2O3 (10-30 wt%), and Al2O3 (5-20 wt%), provides both strong adhesion to the borosilicate glass substrate and matched thermal expansion properties, eliminating the strength reduction caused by organic binder thermal mismatch.
Solution Approach 2:
The patent replaces complex organic ceramic paint formulations with a simpler, more stable glass-based coating system. The glass binder eliminates the need for organic polymers that degrade thermally, providing long-term adhesion stability and mechanical strength retention without the thermal expansion mismatches inherent in organic binder systems.
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 coated glass panes exhibit enhanced mechanical strength, maintaining at least 50% of the uncoated glass's flexural strength and sufficient optical density for laminated applications, while reducing the risk of delamination and maintaining transparency.
Implementation Method 1
The binder comprises a glass frit or consists thereof... applied in a way that achieves a porosity gradient, maintaining sufficient flexural strength and optical density, and using a glass frit as the binder to form an enamel layer
Data Source
AI summary
Coated glass panes having a glass pane and a coating in at least one region of at least one side of the glass pane. The glass pane is composed of glass with SiO2 and B2O3. The coating includes first coating applied in at least one region of the at least one side. The first coating has a binder with SiO2 and a pigment. The glass pane, in the at least one region, has a flexural strength between at least 5 and at most 170 MPa.