Centrifugal Atomization Zinc Powder Disk Speed
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Solution Overview
Problem
Conventional centrifugal atomization processes for producing zinc powder result in larger particle sizes due to slippage of molten zinc on the spinning disk, leading to reduced kinetic energy and larger droplet sizes, which is undesirable for improving performance in alkaline batteries.
Innovation Solution
The process involves elevating the rotational speed of the spinning disk to between 10,000 and 15,000 rpm and maintaining a low oxygen atmosphere with 1.5 to 6 vol% oxygen in the atomization chamber, along with the option of using a disk with integral baffles to reduce slippage and enhance centrifugal force, resulting in smaller zinc particle sizes with a median D50 between 90 and 135 microns.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional centrifugal atomization process is used with spinning disk at 500-8000 rpm, then the process is simple to operate, but the zinc particle size is large (D50 between 200-350 micron)
Solution Approach 1:
The patent applies parameter changes by increasing the disk rotational speed from conventional 500-8000 rpm to 10,000-15,000 rpm, which fundamentally changes the centrifugal force applied to the molten zinc, resulting in smaller droplet sizes and finer powder particles with D50 between 90-135 microns
2Manufacturing precision
If disk rotational speed is increased to 10,000-15,000 rpm to reduce particle size, then zinc particle size is reduced (D50 between 90-135 microns), but molten zinc slippage on disk surface increases reducing kinetic energy
Solution Approach 1:
The patent applies preliminary action by introducing a pre-heating zone where the molten zinc is heated to optimal temperature before reaching the spinning disk. This ensures the zinc has appropriate viscosity and adhesion properties, preventing slippage and maximizing kinetic energy transfer at the high rotational speeds of 10,000-15,000 rpm
Solution Approach 2:
The patent changes the thermal parameter of the molten zinc by maintaining it at optimized temperature in a pre-heating zone before atomization. This parameter change ensures proper flow characteristics and adhesion to the disk surface, eliminating slippage losses even at high rotational speeds
3Manufacturing precision
If conventional atomization chamber atmosphere is used, then the process is simple to maintain, but oxygen content is high leading to oxidation and larger particle sizes
Solution Approach 1:
The patent applies inert atmosphere principle by maintaining the atomization chamber with controlled low oxygen content (1.5-6 vol%) to prevent oxidation of molten zinc during atomization. This controlled atmosphere environment enables production of finer, cleaner zinc powder particles without oxidation-related defects
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
This approach produces zinc powder with a greater proportion of smaller particles, enhancing the performance of alkaline cells, particularly in high-rate discharge applications like digital cameras, by conserving kinetic energy and maintaining efficient particle formation.
Implementation Method 1
As the disk rotates at high speed the molten metal forms a film on the surface of the cup core. As the film reaches the periphery of the edge of the spinning disk it begins to break up into small droplets.
Implementation Method 2
A stationary electrode in proximity to the crucible is activated to an electric arc between the electrode and crucible. This causes sufficient heating to melt the metal.
Data Source
Figure 1
Figure 2
Figure 2A~2B
AI summary
A centrifugal impact atomization process for producing zinc or zinc alloy powder from molten zinc. A stream of molten zinc is injected onto the surface of a spinning disk contained within an atomization chamber. The disk has a cup shaped cavity having an open end, opposing closed end and integral side walls. The disk may have baffles protruding into the open cavity core within the disk. The baffles may have straight or curved side surfaces. The disk is rotated at high speeds between about 10,000 and 15,000 rpm (revolutions per minute). The oxygen content in the chamber is preferably between about 1 and 6 vol%. Zinc powder is produced having more smaller size particles. Zinc alkaline cells utilizing such zinc product as anode active material show improved performance, especially as power source in high discharge services such as digital cameras.