What is a silicon nitride degassing rotor used for?

A silicon nitride degassing rotor is used in aluminum melt treatment to disperse nitrogen or argon into fine bubbles. The bubbles help remove dissolved hydrogen and support oxide flotation before casting.

Why choose Si₃N₄ instead of graphite for a degassing rotor?

Si₃N₄ offers better oxidation resistance, lower aluminum wetting, higher wear resistance, and better dimensional stability than graphite. It is often selected when the foundry needs more stable rotor geometry and reduced cleaning interruption.

Can the rotor and shaft be customized for existing degassing equipment?

Yes. ADCERAX can customize rotor head diameter, shaft length, gas inlet size, thread, taper, coupling interface, vane geometry, slot layout, and balance requirements according to drawings or equipment samples.

Can the rotor work with both nitrogen and argon?

Yes. Silicon nitride degassing rotors can be designed for N₂ or Ar gas flow. The final gas channel and outlet design should be matched to melt volume, bath depth, alloy type, and equipment layout.

What information is needed for quotation?

Useful RFQ information includes rotor drawing, shaft dimensions, machine model, rotor head OD and ID, shaft length, gas inlet size, connection type, operating temperature, gas type, melt volume, and order quantity.

How should a silicon nitride rotor be preheated before use?

The rotor should be kept dry and preheated according to the degassing equipment procedure before immersion into molten aluminum. A controlled preheat helps reduce thermal shock risk.

When should the rotor be inspected or replaced?

The rotor should be inspected when vibration increases, gas dispersion becomes uneven, gas outlets are blocked, vane edges are damaged, or melt treatment results become unstable. Replacement timing depends on operating cycle, alloy condition, cleaning method, and equipment alignment.

Customize Silicon Nitride Degassing Rotor for Aluminium Melt

Name: Silicon Nitride Degassing Rotor for Aluminum Melt Treatment
Brand: ADCERAX
SKU: AT-DHG-G3001

What Is a Silicon Nitride Degassing Rotor?

A silicon nitride degassing rotor is a Si₃N₄ ceramic impeller and shaft assembly used in aluminum melt treatment. During operation, nitrogen or argon flows through the shaft and exits through the rotor head, where rotation breaks the gas into fine bubbles. These bubbles help dissolved hydrogen escape from the melt and support oxide flotation before casting.

Silicon Nitride Ceramic Degassing Rotor Properties

Si3N4 Type	Gas pressure sintering Si3N4	Hot pressing sintering Si3N4	High thermal conductivity Si3N4
Density (g/cm3)	3.2	3.3	3.25
Flexural Strength (MPa)	700	900	600~800
Young Modulus (GPa)	300	300	300~320
Poisson's ratio	0.25	0.28	0.25
Compressive strength (MPa)	2500	3000	2500
Hardness (GPa)	15	16	15
Fracture toughness (MPa*m1/2)	5~7	6~8	6~7
Maximum working temperature (℃)	1100	1300	1100
Thermal conductivity (W/m*K)	20	25	80~100
Thermal expansion coefficient (/℃)	3*10-6	3.1*10-6	3*10-6
Thermal shock resistance (ΔT ℃)	550	800	/

Why Use Si₃N₄ Instead of Graphite?

Silicon nitride is selected when a foundry needs a more dimensionally stable and low-wetting rotor material than graphite. Its ceramic structure helps resist aluminum adhesion, oxidation during preheating, abrasive wear from dross, and geometry change during repeated treatment cycles. This makes Si₃N₄ suitable for aluminum foundries that require stable gas dispersion, predictable rotor balance, and reduced cleaning interruption.

Silicon Nitride Degassing Rotor Benefits

Stable Gas Dispersion
The rotor head and vane geometry can be designed to match bath depth, gas flow, and melt volume. Stable gas dispersion helps improve gas–metal contact while reducing excessive surface turbulence.
Low-Wetting Ceramic Surface
Si₃N₄ has low wettability against molten aluminum, which helps reduce aluminum adhesion and dross build-up on the rotor surface. This supports cleaner gas outlets and more predictable operation.
Improved Oxidation Resistance Compared with Graphite
Silicon nitride is more resistant to oxidation during air preheating and standby conditions than graphite. This helps reduce dimensional loss before the rotor enters the melt.
Wear Resistance in Dross-Containing Melts
The hard ceramic structure helps resist abrasive wear from oxide particles, dross, and mechanical cleaning. This is useful in secondary aluminum melting and remelt operations.
Drawing-Based Machine Fit
Rotor head diameter, shaft length, gas inlet size, thread, taper, coupling interface, and vane slot layout can be customized according to existing degassing equipment.

Si₃N₄ vs Graphite Degassing Rotor

Comparison Item	Silicon Nitride Rotor	Graphite Rotor
Aluminum wetting	Low wetting helps reduce metal adhesion.	More likely to build up dross and metal residue.
Oxidation during preheating	Better oxidation resistance in air.	Oxidizes faster during repeated heating.
Dimensional stability	Holds rotor geometry more consistently.	Geometry may change as the rotor wears.
Cleaning frequency	Usually easier to keep gas outlets clear.	More frequent cleaning may be required.
Initial cost	Higher initial cost.	Lower initial cost.
Best fit	Stable production, repeated use, custom equipment fit.	Shorter campaigns, lower-cost replacement needs.

Si3N4 Degassing Rotor Specifications

Type 1: Silicon Nitride Degassing Shaft

Silicon Nitride Degassing Shaft
Item No.	Outer Diameter (mm)	Inner Diameter (mm)	Length (mm)
AT-DHG-G3001	50	30	400-1500
AT-DHG-G3002	68.5	38	400-1500
AT-DHG-G3003	75	55	400-1500
AT-DHG-G3004	85	64.5	400-1500
AT-DHG-G3005	105	84	400-1500
AT-DHG-G3006	135	110	400-1500
AT-DHG-G3007	150	136	400-1500
AT-DHG-G3008	200	174	400-1500

Type 2: Silicon Nitride Degassing Rotor Disc

Silicon Nitride Degassing Rotor Disc
Item No.	Outer Diameter (mm)	Inner Diameter (mm)
AT-DHG-G3009	180	35
AT-DHG-G3010	200	40
AT-DHG-G3011	210	40
AT-DHG-G3012	220	40

Si3N4 Degassing Rotor Packaging

Each rotor is individually packed in foam-padded wooden boxes to prevent damage during transit.

Silicon Nitride Degassing Rotor Applications

Silicon nitride degassing rotors are widely used in aluminium melting, die casting, and continuous casting lines to control hydrogen content and melt cleanliness. Below are the main application scenarios where Si₃N₄ rotors show clear advantages over graphite in real production conditions.

Application Area	Application Challenge	Si₃N₄ Rotor Advantage
Aluminum die casting	Hydrogen porosity and oxide inclusions can affect casting consistency.	Stable bubble dispersion and low-wetting surface help support cleaner melt treatment before casting.
Secondary aluminum remelting	Dross, oxide particles, and mixed returns increase rotor wear and cleaning frequency.	Wear-resistant Si₃N₄ helps maintain rotor geometry and reduce adhesion during repeated treatment cycles.
Holding furnace treatment	Long standby and repeated preheating can accelerate graphite oxidation.	Silicon nitride provides better resistance to oxidation and dimensional change during heating cycles.
Continuous casting and inline treatment	Rotor balance, shaft alignment, and gas channel stability are critical.	Custom rotor-and-shaft assemblies can be matched to the machine interface and gas flow layout.
Degassing equipment OEMs	Standard rotor dimensions may not fit proprietary machine designs.	Drawing-based customization supports shaft length, coupling, vane layout, and gas inlet requirements.

Silicon Nitride Ceramic Degassing Rotor Usage Instructions

Installation

1. Inspect the silicon nitride degassing rotor and shaft for cracks, edge chipping, or thread damage. Check that the rotor fits securely with the coupling, seal block, and degassing unit.
2. Preheat the rotor as required by equipment manuals (typically 200–400 °C) to prevent thermal shock when entering molten aluminium. Ensure the rotor is completely dry before immersion.
Operation

1. Start N₂ or Ar gas flow before lowering the rotor into the melt. Gradually increase rotation speed until it reaches the required working range (around 1,200–3,000 rpm depending on alloy and furnace size).
2. Monitor hydrogen content using RPT or an online hydrogen analyzer. Adjust dwell time, gas flow, or rotor speed until melt hydrogen reaches the target range (commonly ≤0.10 mL/100 g Al).
Storage

Store the rotor in a dry, cushioned container away from graphite dust, moisture, and corrosive gases. If stored after use, clean and dry it before packing to prevent surface oxidation or metal adherence.
Cleaning and Maintenance

1. After the operation, allow the rotor to cool naturally in air or under controlled furnace cooling to avoid cracking.
2. Remove aluminium oxide build-up using non-metallic scrapers or ceramic tools. Avoid hammering or hitting the vane area, as Si₃N₄ is strong but brittle to impact.

Common Misuse & Solutions

Issue	Cause	Solution
Thermal shock cracks	Immersion without preheating or rotor absorbed moisture	Follow the preheating curve, ensure rotor dryness
High vibration during rotation	Rotor imbalance, worn coupling, or incorrect shaft alignment	Re-balance rotor, check shaft run-out, tighten fixture
Hydrogen level rising after replacement	Gas holes blocked or rotor depth incorrect	Clean vane slots, check the gas flow meter and immersion depth
Rapid dross accumulation	Wetting or incorrect rotation speed	Verify the Si₃N₄ surface is clean, adjust the rpm and gas flow
Surface oxidation during idle	Excessive air heating above 1000 °C	Maintain proper furnace atmosphere or use a protective preheat cycle

Silicon Nitride Ceramic Degassing Rotor FAQ

Q1: What is a silicon nitride degassing rotor used for?
A: A silicon nitride degassing rotor is used in aluminum melt treatment to disperse nitrogen or argon into fine bubbles. The bubbles help remove dissolved hydrogen and support oxide flotation before casting.
Q2: Why choose Si₃N₄ instead of graphite for a degassing rotor?
A: Si₃N₄ offers better oxidation resistance, lower aluminum wetting, higher wear resistance, and better dimensional stability than graphite. It is often selected when the foundry needs more stable rotor geometry and reduced cleaning interruption.
Q3: Can the rotor and shaft be customized for existing degassing equipment?
A: Yes. ADCERAX can customize rotor head diameter, shaft length, gas inlet size, thread, taper, coupling interface, vane geometry, slot layout, and balance requirements according to drawings or equipment samples.
Q4: Can the rotor work with both nitrogen and argon?
A: Yes. Silicon nitride degassing rotors can be designed for N₂ or Ar gas flow. The final gas channel and outlet design should be matched to melt volume, bath depth, alloy type, and equipment layout.
Q5: What information is needed for quotation?
A: Useful RFQ information includes rotor drawing, shaft dimensions, machine model, rotor head OD and ID, shaft length, gas inlet size, connection type, operating temperature, gas type, melt volume, and order quantity.
Q6: How should a silicon nitride rotor be preheated before use?
A: The rotor should be kept dry and preheated according to the degassing equipment procedure before immersion into molten aluminum. A controlled preheat helps reduce thermal shock risk.
Q7: When should the rotor be inspected or replaced?
A: The rotor should be inspected when vibration increases, gas dispersion becomes uneven, gas outlets are blocked, vane edges are damaged, or melt treatment results become unstable. Replacement timing depends on operating cycle, alloy condition, cleaning method, and equipment alignment.

Catalogue No.	AT-DHG-G3001
Material	Silicon Nitride Ceramic, Si₃N₄
Flexural Strength	≥600 MPa
Thermal Expansion Coefficient	≤3.2×10⁻⁶/K
Gas Media	N₂ or Ar

Silicon Nitride Degassing Rotor for Aluminum Melt Treatment

What Is a Silicon Nitride Degassing Rotor?

Silicon Nitride Ceramic Degassing Rotor Properties