Experimental Case: Silicon Nitride Air Classification on FJ Classifier — D100 from 8 to 5.6 µm

Silicon nitride powder with an as-received D100 of 8 µm was submitted for precision air classification on a Taixian FJ Coanda jet classifier. The customer required complete removal of all particles above 5 µm to meet downstream application tolerances. Conventional sieve screening cannot achieve reliable cuts in the sub-10 µm range. After a single-pass trial, the collected target fraction measured D90 2.7 µm and D100 5.6 µm — the cut point was met with no mechanical contact between the classifier and the material.

Challenge

Silicon nitride (Si₃N₄) is a high-performance structural ceramic used in precision cutting tools, bearings, and automotive engine components. Particle size consistency directly governs sintering density and final mechanical properties.

The as-received powder had a wide particle size distribution — D10 0.46 µm, D50 1.5 µm, and a coarse tail extending to D100 8 µm. The customer required a hard upper-limit cut at 5 µm. Below this size, no conventional screening technology can reliably separate particles without contamination risk or excessive yield loss.

Solution

The FJ Coanda jet classifier separates particles by exploiting differential inertia within a curved airflow field. It carries no rotating mechanical parts — eliminating both contamination risk and abrasion wear when processing sensitive ceramic powders.

Material

Parameter	Value
Material	Silicon nitride (Si₃N₄)
Grade	Confidential
As-received D10	0.46 µm
As-received D50	1.5 µm
As-received D100	8.0 µm

Equipment

Parameter	Value
Model	Taixian FJ Coanda Jet Classifier
Classification range	1–200 µm
Moving parts	None
Feed system	High-dispersion feed nozzle
Product streams	2/3 (fine / mid / coarse)
Closed-loop option	Inert gas recirculation available

Process Parameters

Parameter	Value
Target cut point	5 µm
Process parameters	Confidential

Procedure

Feed powder was introduced through the high-dispersion nozzle at a controlled rate. Airflow and blade-gap settings were tuned to the 5 µm cut point.

1. Feed powder introduced through the high-dispersion nozzle at a controlled rate. Pre-dispersion at the nozzle prevents agglomerates from masking the true cut point.
2. The Coanda effect deflects the airstream along the curved classifier blade. Particles below 5 µm follow the wall-hugging airflow; particles above 5 µm break away by inertia.
3. Three product streams exit simultaneously: fine, mid, and coarse fractions. Single-pass separation eliminates the need for multi-stage screening.
4. Fine fraction collected and particle size measured by laser diffraction. Results confirmed cut-point compliance before closing the trial.

Achievement

The target fraction measured D90 2.7 µm and D100 5.6 µm after a single pass. All particles above 5 µm were successfully removed. The result met the customer’s specification without additional downstream steps.

The validated outcome is cut-point compliance at 5 µm with zero mechanical contact — preserving material purity throughout. This positions the FJ classifier as a clean upstream step within dry-route surface modification workflows requiring tight feedstock control.

Metric	As-received	After FJ Classification
D10	0.46 µm	—
D50	1.5 µm	—
D90	—	2.7 µm
D100	8.0 µm	5.6 µm
Particles > 5 µm	Present	Removed
Mechanical contact	—	None

Tags

#SiliconNitride #Si3N4 #AirClassification #CoarseParticleRemoval #CeramicPowderProcessing

#TaixianFJ #FJClassifier #CoandaJetClassifier

#PrecisionAirClassification #DryClassification #SubMicronClassification #DryRouteSurfaceModification

#HosokawaAlternative #NETZSCHAlternative #AshizawaAlternative

#AdvancedCeramics #CuttingToolMaterials #BearingGrade #SinteringFeedstock

Enquiry

Tell us your material, target particle size, and throughput. We will advise on model selection and run a trial on your own powder before you commit to equipment.

Yibin Andy Wei — Application Engineer
Email: [email protected]
LinkedIn: Yibin Andy Wei
WhatsApp: +1 380 900 2442