High Emissivity Coating Composition for Low Temperature Thermal Radiation
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Solution Overview
Problem
Existing high emissivity coatings for metal substrates face challenges such as low durability, micro crazing, and complex application processes, particularly at lower elevated temperatures, which affect their performance in heating equipment.
Innovation Solution
A high emissivity coating composition comprising a powder mixture of nickel ferrite, nickel chromite, and cobalt chromite spinel structures, combined with a binder of potassium silicate and a co-binder of silica-based silsesquioxane and cyclotetrasiloxane, applied using a straightforward process that reduces micro crazing and simplifies application.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If existing high emissivity coating compositions are used, then emissivity can be achieved at high temperatures (900°C or higher), but emissivity is insufficient at lower elevated temperatures (650°C or lower)
Solution Approach 1:
The patent modifies the chemical composition parameters of the coating by incorporating specific metal oxides (nickel ferrite NiFe2O4, nickel chromite NiCr2O4, cobalt chromite CoCr2O4) in controlled ratios to enable high emissivity performance across a broader temperature range including lower elevated temperatures (650°C or lower), while maintaining stability at higher temperatures
Solution Approach 2:
The patent uses a composite coating system combining multiple metal oxide compounds with specific binders (silica-based co-binder and potassium silicate binder) to achieve both high emissivity and durability across different temperature conditions, resolving the contradiction between temperature range and performance reliability
2Reliability
If coating compositions are applied to achieve high emissivity, then heat transfer efficiency is improved, but micro crazing and physical disintegration occur due to structural weaknesses
Solution Approach 1:
The patent adjusts the chemical composition by incorporating silica-based co-binders and potassium silicate binders in specific proportions to enhance the coating's structural integrity and resistance to micro crazing, while maintaining high emissivity properties
Solution Approach 2:
The patent employs a composite binder system combining silica-based co-binder and potassium silicate to create a durable coating matrix that prevents physical disintegration and micro crazing, ensuring both emissivity and long-term durability under thermal stress
3Reliability
If existing coating methods are used, then high emissivity can be achieved, but the application process becomes complicated and requires high temperature treatment
Solution Approach 1:
The patent modifies the coating composition to include water-soluble binders and silica-based co-binders that enable the coating to be applied as a water-based solution and cured at lower temperatures, eliminating the need for complex high temperature treatment processes while maintaining high emissivity performance
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 achieves emissivity values of 0.81-0.94 at 400-650°C, significantly higher than commercial coatings, with improved durability and ease of application, enhancing thermal and energy efficiency in heating equipment.
Implementation Method 1
Emissivity (ε) is the ability of material surface to transfer or receive heat via thermal radiation
Implementation Method 2
the binder provides the adhesion between the emissivity agent, fillers, and the substrate
Data Source
AI summary
To provide a high emissivity coating composition capable of exhibiting a higher emissivity at a low elevated temperature and substantially reduced formation micro craze when coated upon a substrate, and enabling a simplified application process, a high emissivity coating composition, comprising a powder mixture for providing emissivity; a binder for providing adhesion; and a co-binder for promoting adhesion and film-forming, characterized in that the powder mixture comprises at least three metal compounds of formula A(y−3)By/2Oy, wherein y is 4; A is selectable from a group of Ni and Co; B is selectable from a group of Fe and Cr; and O is oxygen; and the co-binder is an aqueous solution comprising silica in a compound of Formula (1), wherein R1 is H—Si—(CH3)2; and a compound of Formula (2), wherein R2 is CH3, is disclosed herein.