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Views: 0 Author: Site Editor Publish Time: 2026-06-12 Origin: Site
With the rapid development of new energy materials, advanced ceramics, powder metallurgy, pharmaceuticals, and electronic materials, ultrafine powders have become critical raw materials in many industries.
However, for powder engineers, ultrafine powders are often among the most challenging materials to process.
In practical production, manufacturers frequently encounter issues such as:
Long mixing times with poor uniformity
Powder floating inside the mixer
Severe agglomeration and caking
Difficulty dispersing trace additives
Formation of large agglomerates
Poor flowability and feeding problems
Re-segregation after mixing
As a result, there is a common saying in the powder industry:
Mixing ultrafine powders is not simply about mixing—it is about dispersion.
So, what exactly is an ultrafine powder, and why is it so much more difficult to handle than conventional powders?
This article explores the answer from the perspective of powder engineering.
Ultrafine Powder generally refers to powders with extremely small particle sizes.
Although definitions vary slightly across industries and countries, in powder engineering ultrafine powders are commonly defined as:
Powders with particle sizes smaller than 10 μm (micrometers)
In some advanced material industries:
Powders below 5 μm are classified as ultrafine powders.
Powders below 1 μm are classified as submicron powders.
Powders below 100 nm are classified as nanopowders.
Common Examples of Ultrafine Powders
Examples include:
Carbon Black
Silica
Graphite Powder
Aluminum Oxide (Al₂O₃)
Zirconium Oxide (ZrO₂)
Calcium Carbonate (CaCO₃)
Titanium Dioxide (TiO₂)
Lithium Battery Materials
Conductive Additives
Nanomaterials
These materials are widely used in:
Lithium-ion Batteries
New Energy Materials
Pharmaceuticals
Coatings
Plastic Modification
Powder Metallurgy
and many other industries.
Many people assume that ultrafine powders are simply smaller versions of ordinary powders.
In reality, once particle size decreases below a certain threshold, powder behavior changes fundamentally.
At this scale:
Gravitational effects decrease
Surface area increases dramatically
Surface energy rises significantly
Interparticle forces become dominant
As a result, ultrafine powders exhibit behaviors that are rarely observed in conventional powders.
The primary reason is:
Ultrafine powders no longer follow the same movement mechanisms as ordinary powders.
For conventional particles:
Gravity is much stronger than air resistance.
Therefore, particles settle easily.
However, as particle size decreases:
Particle mass decreases rapidly
Air resistance becomes increasingly significant
Eventually, air drag can become comparable to or greater than gravitational forces.
As a result, ultrafine powders tend to:
Remain suspended in air
Become airborne easily
Settle very slowly
This phenomenon is known as Powder Floating
Typical Examples
Materials such as:
Carbon Black
Graphite Powder
Nano-Alumina
often generate visible dust clouds during feeding and handling.
What appears to be smoke is actually a large number of ultrafine particles suspended in the air.
One of the most significant characteristics of ultrafine powders is agglomeration.
As particle size decreases:
Surface area increases dramatically
Surface energy increases significantly
This leads to stronger interparticle forces such as:
Van der Waals Forces
Electrostatic Forces
Capillary Forces
These forces cause particles to stick together and form agglomerates
Why Agglomeration Is a Problem
A powder with an original particle size of 1 μm may form agglomerates measuring:
50 μm
100 μm
or even larger
As a result:
Dispersion becomes difficult
Mixing uniformity decreases
Product performance may suffer
In many cases, mixing equipment is actually handling agglomerates rather than individual particles.
The smaller the particle size, the more significant electrostatic effects become.
This is particularly true during:
Dry conditions
High-speed movement
Frictional contact
Ultrafine powders can:
Adhere to equipment walls
Stick to containers
Attract each other
This leads to:
Material loss
Agglomeration
Reduced mixing efficiency
and ultimately lower mixing uniformity.
As discussed in previous articles powder flowability is a critical property in powder processing.
Ultrafine powders typically exhibit:
High internal friction
Strong cohesion
High compressibility
As a result, their flowability is significantly lower than that of conventional powders.
In industrial applications, ultrafine powders rarely exist as completely separate particles.
Instead, they often form pseudo-particles.
For example, a primary particle size of 1 μm may become a 50/100 μm agglomerated cluster.
Although the cluster appears large, its internal composition may remain highly non-uniform.
As a result, a mixture may appear uniform at the macro level while remaining non-uniform at the micro level.
Many people assume that smaller particles are less likely to segregate.
In reality, ultrafine powders often exhibit complex segregation mechanisms due to:
Agglomeration
Floating behavior
Electrostatic interactions
Examples include:
Air-Induced Segregation
Agglomerate Segregation
Density Segregation
These mechanisms can significantly reduce mixture uniformity.
Traditional mixing equipment such as:
V-Blenders
Double Cone Mixers
Three-Dimensional Mixers
Two-Dimensional Mixers
primarily rely on Gravity Diffusion Mixing.
The mixing process is achieved through vessel rotation and particle repositioning.
This approach works well for:
Free-flowing powders
Conventional granular materials
However, ultrafine powders present a different challenge:
Agglomerates do not break apart automatically.
Simple tumbling action is often insufficient to overcome:
Electrostatic attraction
Van der Waals forces
Cohesive bonding
As a result:
Mixing times increase
Uniformity decreases
Dispersion remains inadequate
For ultrafine powders, the objective is not simply macro-mixing but rather micro-dispersion.
Effective processing requires:
Dispersion mechanisms
Shear forces
Agglomerate breakdown
Anti-segregation capabilities
Only then can a system achieve micro-uniform mixing which is increasingly required in advanced material industries.
As industries such as new energy, advanced materials, and high-performance manufacturing continue to evolve, powder mixing technology is shifting from “Making Powders Move” to “Controlling Particle Behavior”
Future developments will focus on:
Agglomerate Breakup
Micro-Scale Dispersion
Segregation Prevention
Multi-Scale Mixing
Micro-Uniformity Control
These technologies are becoming increasingly important in modern powder engineering.
Ultrafine powders generally refer to powders with particle sizes below 10 μm.
Compared with conventional powders, they exhibit:
Strong floating tendencies
Severe agglomeration
Significant electrostatic effects
Poor flowability
Pseudo-particle formation
Increased segregation risk
Therefore, the essence of ultrafine powder processing is not simply mixing—it is efficient dispersion.
As advanced manufacturing, new energy, and high-performance materials continue to develop, ultrafine powder mixing has become one of the most challenging and important topics in modern powder engineering.
