Magnesium Oxide Powder Hydration Resistance Coating
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Solution Overview
Problem
Magnesium oxide powders used as thermally conductive fillers suffer from poor hydration resistance due to hydration reactions, leading to volume expansion and cracking in resin compositions, and existing methods require surface treatment agents or high-temperature processes that are costly or inefficient.
Innovation Solution
Forming a coating layer mainly composed of basic magnesium carbonate on the surface of magnesium oxide powders by treating them with carbon dioxide and water within specific temperature and humidity conditions, specifically between 30 to 50°C and 70 to 90% relative humidity for 10 to 1000 hours, to enhance hydration resistance without using special surface treatment agents.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If magnesium oxide is used as a thermally conductive filler, then thermal conductivity is improved, but hydration resistance deteriorates due to volume expansion from hydration reaction
Solution Approach 1:
The patent applies preliminary action by forming a protective coating layer on the magnesium oxide surface before the magnesium oxide is used as a filler. The coating layer is formed by treating magnesium oxide particles with water and carbon dioxide under controlled conditions (20-40°C, specific humidity) to create a basic magnesium carbonate layer that prevents subsequent hydration reactions, thus preventing future volume expansion and cracking while maintaining thermal conductivity
Solution Approach 2:
The patent creates a composite structure by forming a coating layer of basic magnesium carbonate on the surface of magnesium oxide particles. This composite structure combines the thermal conductivity benefits of magnesium oxide with the hydration resistance of basic magnesium carbonate, allowing the material to function as both a thermally conductive filler and a hydration-resistant component simultaneously
2Reliability
If surface treatment agents such as silica or phosphoric acid are used to coat magnesium oxide, then hydration resistance is improved, but manufacturing cost increases
Solution Approach 1:
The patent applies self-service by using water and carbon dioxide (which are inexpensive and readily available) to form the protective coating layer on magnesium oxide particles. The magnesium oxide particles themselves react with water and carbon dioxide under controlled conditions to form the basic magnesium carbonate coating, eliminating the need for expensive external surface treatment agents like silica or phosphoric acid
Solution Approach 2:
The patent changes the parameters of the coating formation process by using controlled temperature (20-40°C) and humidity conditions to enable the formation of basic magnesium carbonate coating. This parameter-controlled approach allows inexpensive water and carbon dioxide to effectively coat the magnesium oxide particles, replacing costly chemical surface treatments while achieving the desired hydration resistance
3Productivity
If magnesium oxide is treated at high temperature (60°C or more) to form coating layer, then coating formation is accelerated, but manufacturing cost and energy consumption increase
Solution Approach 1:
The patent changes the temperature parameter from conventional high-temperature treatment (60°C or more) to a lower temperature range (20-40°C). This parameter change is accompanied by controlled humidity conditions that enable effective coating formation at lower temperatures, thereby reducing energy consumption while still achieving adequate coating formation speed through the optimized environmental conditions
4Use of energy by stationary object
If magnesium oxide is treated with water and carbon dioxide at low temperature (20-40°C), then energy consumption is reduced, but coating formation time increases
Solution Approach 1:
The patent applies periodic action by controlling the treatment process in stages: first exposing magnesium oxide particles to water under controlled humidity conditions, then introducing carbon dioxide to form the basic magnesium carbonate coating. This staged, periodic approach to treatment allows the coating formation to proceed efficiently at low temperatures without excessive time requirements by optimizing the sequence and duration of each treatment phase
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 resulting magnesium oxide powders exhibit excellent hydration resistance, reducing volume expansion and cracking in resin compositions, and can be produced cost-effectively without surface treatment agents, ensuring improved thermal conductivity and stability.
Implementation Method 1
magnesium oxide is reacted in the presence of carbon dioxide (also including those contained in the air) and water (water vapor), thereby a coating layer including a reaction product of magnesium oxide, carbon dioxide and water is formed on the surface
Implementation Method 2
the magnesium oxide undergoes a hydration reaction to become magnesium hydroxide, and the volume change (expansion) occurs at this time
Implementation Method 3
bringing water vapor or a mixed gas of water vapor and carbon dioxide gas into contact with magnesium oxide particles
Data Source
AI summary
To provide magnesium oxide which is excellent in hydration resistance and hardly causes volume expansion due to hydration and the like, a resin composition containing the same, and a method for producing the magnesium oxide powder.Magnesium oxide powder having a coating layer mainly comprising basic magnesium carbonate in the surface layer, when the amounts of substances of water vapor and carbon dioxide among the gas generated by thermal decomposition at 50 to 500° C. are respectively designated as m-H2O and m-CO2, in a heating evolved gas analysis (EGA-MS) method, the molar fraction represented by m-CO2/(m-H2O+m-CO2) being within the range of 0.3 to 0.6.