Aluminum Nitride Powder Spheroidization via Reductive Nitridation
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Current methods for producing aluminum nitride powder with a spherical shape and large particle diameter for use as a high thermal conductivity filler in heat radiating materials face challenges such as angular shapes, low fluidity, and impurity infiltration, making it difficult to achieve dense filling in resins.
Innovation Solution
A method involving the reductive nitridation of a mixture of fine alumina powder, a carbon powder, and a eutectic melting agent, controlled under specific gas composition and temperature conditions to produce spherical aluminum nitride particles with a large particle diameter and low oxygen content, enhancing thermal conductivity and filling properties.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If the direct nitridation method is used to produce aluminum nitride powder, then the particle size can be controlled to several microns to several tens of microns, but the particles have an angular shape which decreases fluidity and makes it difficult to achieve dense filling
Solution Approach 1:
The patent changes the production method from direct nitridation with pulverization to reduction-nitridation with controlled atmosphere. By adjusting the gas composition (nitrogen ratio 60-85 vol%) and using a eutectic melting agent, the process produces spherical particles with large particle diameter exceeding 5 μm while maintaining high fluidity and dense filling capability.
Solution Approach 2:
The patent employs a nitrogen-based atmosphere with controlled composition (60-85 vol% nitrogen) during reduction-nitridation. This inert atmosphere prevents oxidation and angular shape formation, enabling the production of spherical aluminum nitride particles with smooth surfaces that achieve excellent fluidity and dense filling in heat radiating materials.
2Shape
If the reduction-nitridation method is used to produce aluminum nitride powder with spherical shape, then the particle diameter is about submicron size, but it is difficult to achieve large particle diameter exceeding 5 μm
Solution Approach 1:
The patent introduces a eutectic melting agent as an intermediary substance during reduction-nitridation. This agent facilitates particle growth and coalescence, enabling the formation of large spherical particles with diameter exceeding 5 μm while maintaining the spherical morphology and high fluidity characteristic of reduction-nitridation products.
Solution Approach 2:
The patent modifies the reduction-nitridation process parameters by controlling nitrogen ratio (60-85 vol%) and using a eutectic melting agent, which enables particle growth to large sizes exceeding 5 μm while preserving the spherical shape. This parameter optimization resolves the limitation of submicron particle size in conventional reduction-nitridation.
3Ease of operation
If the flux method is used to produce spherical aluminum nitride powder, then the fluidity and filling property are excellent, but impurities such as oxygen easily infiltrate into the powder during heat treatment
Solution Approach 1:
The patent replaces the flux method's open heat treatment with reduction-nitridation in a controlled nitrogen atmosphere (60-85 vol% nitrogen). This inert environment prevents oxygen infiltration and impurity contamination while maintaining excellent fluidity and filling properties, producing high-purity spherical aluminum nitride powder suitable for heat radiating materials.
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 method effectively produces aluminum nitride powder with a particle diameter exceeding 5 μm, achieving high thermal conductivity and excellent filling properties, while minimizing impurities and ensuring smooth filling in heat radiating materials.
Implementation Method 1
a eutectic melting agent, and a carbon powder are mixed to obtain a mixture, and the mixture is reductively nitrided by firing at a higher temperature than a melting point of the eutectic melting agent
Implementation Method 2
the alumina powder, a eutectic melting agent, and a carbon powder are mixed to obtain a mixture, and the mixture is reductively nitrided by firing at a higher temperature than a melting point of the eutectic melting agent, while maintaining a nitrogen ratio within a range of 60 to 85 vol % in an atmosphere of mixed gases of nitrogen and carbon monoxide
Data Source
AI summary
A method for producing an aluminum nitride powder includes mixing an alumina powder having an average particle diameter of not more than 5 μm; an eutectic melting agent; and a carbon powder are mixed to obtain a mixture thereof, and reductively nitriding the mixture by firing at a higher temperature than a melting point of the eutectic melting agent, while maintaining a nitrogen ratio within a range of 60 to 85 vol % in an atmosphere of mixed gases of nitrogen and carbon monoxide until a nitriding ratio of the alumina powder reaches at least 50%.