Zinc Oxide Particle Size Control via Ammonium Bromide Baking
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Solution Overview
Problem
Zinc oxide particles with large diameters and specific particle size distributions are needed for various applications, but existing methods result in broad distributions and contamination with coarse particles, limiting their use as exoergic fillers due to high thermal resistance and insufficient exoergic properties.
Innovation Solution
Producing zinc oxide particles with a median size of 1 to 30 μm and a D90/D10 ratio of 4 or less by baking a zinc oxide source in the presence of ammonium bromide, with 0.1 to 10 weight % addition, at 600 to 1200°C, to achieve sharp particle size distribution and prevent coarse particle contamination.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If zinc oxide fine particles (≤1 μm) are used, then they are easily obtainable and inexpensive, but the heat resistance between particles is high and exoergic property is insufficient
Solution Approach 1:
The patent changes the particle size parameter from fine particles (≤1 μm) to coarse particles (5-30 μm) through controlled baking processes. This parameter change fundamentally improves the exoergic property by reducing heat resistance between particles, while the specific baking conditions (temperature, time, atmosphere) ensure manufacturability and consistent particle size distribution.
2Length of moving object
If conventional baking methods are used to increase particle diameter, then particle diameter increases, but broad particle size distribution and coarse particle contamination occur
Solution Approach 1:
The patent optimizes baking parameters including temperature (600-1200°C), time (1-24 hours), atmosphere (oxidizing or neutral), and initial particle size (0.1-10 μm) to achieve precise control over particle growth. These parameter changes enable particles to reach the desired diameter (5-30 μm) with narrow size distribution (D90/D10 ≤ 4) while preventing coarse particle formation.
Solution Approach 2:
The patent employs feedback control by monitoring particle size development during baking and adjusting process parameters accordingly. The controlled atmosphere and temperature profiles allow real-time control of particle growth kinetics, ensuring uniform particle size distribution and preventing contamination with coarse particles while achieving the target particle diameter.
3Temperature
If alumina is used as exoergic filler, then high thermal conductivity is achieved, but kneading machines become extremely worn due to high hardness
Solution Approach 1:
The patent replaces expensive and machine-wearing alumina with zinc oxide particles that have intermediate thermal conductivity and lower hardness. The zinc oxide particles provide sufficient exoergic performance while being gentler on equipment, effectively substituting a harder, more damaging material with a softer, more durable alternative that achieves the same functional outcome.
Solution Approach 2:
The patent changes the material composition from alumina to zinc oxide, fundamentally altering both the thermal conductivity and hardness parameters. This material substitution maintains adequate thermal performance for exoergic applications while dramatically reducing machine wear, solving the contradiction between thermal conductivity and manufacturing ease.
4Temperature
If aluminum nitride is used as exoeric filler, then high thermal conductivity is achieved, but poor filling property and high cost occur
Solution Approach 1:
The patent substitutes expensive aluminum nitride with more cost-effective zinc oxide particles. The zinc oxide particles provide comparable thermal conductivity while offering superior filling properties and lower cost, making them a more practical choice for industrial exoergic applications.
Solution Approach 2:
The patent changes the filler material from aluminum nitride to zinc oxide, altering both cost and filling property parameters while maintaining thermal conductivity. This material parameter change enables better processing performance and economic viability without sacrificing the essential thermal management function.
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 zinc oxide particles are suitable for use as exoergic fillers, offering improved thermal conductivity and reduced coarse particle contamination, suitable for applications in electronic components, cosmetics, and other fields without compromising exoergic properties.
Implementation Method 1
baking a source of the zinc oxide particle in the presence of ammonium bromide
Implementation Method 2
baking a zinc oxide source in the presence of ammonium bromide, with 0.1 to 10 weight % addition, at 600 to 1200°C
Data Source
AI summary
The present disclosure provides a zinc oxide particle that can be used more suitably than common zinc oxide in the application such as an exoergic filler and the like, and can be used in the other applications. A zinc oxide particle having a median size of 1 to 30 μm and D90/D10 of 4 or less is provided.