Compositions and methods for the protection of substrates from heat flux and fire
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Solution Overview
Problem
There is a need for a thermal barrier coating that can protect substrates from high temperatures while maintaining mechanical integrity and adhesion under harsh, cold conditions with high mechanical stresses, and effectively dissipate heat through radiation cooling.
Innovation Solution
A flame or heat flux protective coating composition is developed using a dispersion of fiberglass and/or hollow glass spheres in silicone, which provides high emissivity, low heat conductivity, and mechanical flexibility, allowing for effective radiation cooling and thermal insulation. The coating can be applied in various forms, including sheets, and is suitable for diverse substrates such as thermoplastics, metals, and ceramics.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If a thermal barrier coating is applied to protect substrates from high temperatures, then the substrate is protected from heat flux, but the coating may lose adhesion and mechanical integrity under harsh cold temperatures with high mechanical stresses
Solution Approach 1:
The patent employs a composite coating system consisting of multiple layers with distinct functions: an inner adhesive layer containing rubber particles and silica for cold temperature flexibility and bonding, and an outer thermal barrier layer with hollow glass spheres and glass flakes for heat reflection and insulation. This composite structure resolves the contradiction by combining materials with complementary properties that perform differently optimized functions for hot and cold conditions respectively.
Solution Approach 2:
The coating system applies local quality by creating spatially differentiated layers: the inner layer is optimized for adhesion and cold temperature ductility with higher rubber content, while the outer layer is optimized for thermal protection with hollow glass spheres and reflective glass flakes. Each layer's composition is locally tailored to its specific functional requirements, allowing the overall system to satisfy both thermal protection and cold temperature reliability demands.
2Loss of energy
If a coating provides high thermal insulation, then heat flux protection is improved, but heat dissipation through radiation cooling is reduced
Solution Approach 1:
The patent utilizes parameter changes by incorporating materials with high emissivity in the infrared range (0.85-0.95), such as hollow glass spheres and specific glass flakes, into the thermal barrier layer. These materials simultaneously provide thermal insulation through low thermal conductivity and enhance radiative heat dissipation through high emissivity, effectively managing both heat retention and heat release parameters to prevent thermal accumulation.
Solution Approach 2:
The composite structure combines hollow glass spheres (providing thermal insulation through air pockets and low conductivity) with high emissivity glass flakes (promoting radiative cooling) in the outer layer. This composite material configuration resolves the contradiction by integrating two materials with complementary thermal properties, achieving both insulation and radiation cooling functions within the same layer.
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 effectively protects substrates from high temperatures by radiating heat away and maintaining adhesion under mechanical stress, as demonstrated by passing low temperature flexural and flame tests, with the fiberglass/silicone composite showing superior performance in maintaining low temperature integrity and reducing maximum temperature during flame exposure.
Implementation Method 1
The glass component imparts high emissivity to the composition of the present invention. Emissivity is a material's ability to absorb and radiate energy as a function of its temperature... In order to dissipate heat, high emissivity values close to one are desirable.
Implementation Method 2
The glass component also provides the coating composition with relatively low heat conductivity and, thus, a high thermal insulation value.
Data Source
AI summary
A flame or heat flux protective coating composition, which includes a dispersion of fiberglass, hollow glass spheres, or a combination of both in silicone. A flame or heat flux protective sheet, which includes hollow glass spheres dispersed in silicone in a sheet form or fiberglass and silicone in a sheet form, wherein the fiberglass is dispersed in the silicone or the fiberglass is a woven cloth coated with the silicone is also presented. Articles incorporating the flame or heat flux protective coating or sheet form and methods for coating an article with the flame or heat flux protective coating composition are also presented.