Powder Annealing of Rotating Tilted Tube High Temperature Furnace

The rotating inclined tube high-temperature furnace significantly improves the performance uniformity of powder materials through dynamic annealing technology, especially suitable for heat treatment of high value-added metals, ceramics, and composite materials. Its core advantages and technological features are as follows:

1. Principle of dynamic annealing process
Rotating motion promotes uniform annealing
The furnace tube rotates at a speed of 0-15rpm, driving the powder to form a spiral motion trajectory inside the furnace. This dynamic rolling continuously updates the surface of the powder, avoiding the common “clumping” or “local overheating” phenomenon in static annealing. For example, when annealing titanium alloy powder, rotational motion improves the uniformity of grain growth and shortens the annealing period.
Tilt design optimizes material flow
The furnace body can be tilted at 0-45 degrees (some equipment supports a large tilt angle of 30 degrees), and the material is driven by gravity to flow along the axial direction of the furnace tube. This design is particularly suitable for the annealing of viscous powders or easily agglomerated particles, such as aluminum hydroxide gel. The synergistic effect of tilt angle and rotation speed can achieve continuous flow of materials from the feeding end to the discharging end, while maintaining annealing uniformity.
Multi temperature gradient annealing
The furnace is divided into 2-6 independent temperature zones along the axial direction (such as preheating zone 300-500 ℃, annealing zone 600-900 ℃, cooling zone 200-400 ℃), each equipped with independent heating elements and temperature control systems. This gradient temperature design can match the annealing requirements of powders at different stages:
Preheating zone: Slowly raise the temperature to avoid cracking of the powder due to excessive temperature difference;
Annealing zone: High temperature quickly eliminates internal stress and optimizes grain structure;
Cooling zone: Control the cooling rate to prevent degradation of thermosensitive components.
Atmosphere control to prevent oxidation
Create a low oxygen or oxygen free annealing environment by using a vacuum pump (capable of pumping up to 10 ⁻ Pa to 10 ⁻⁵ Pa) or by introducing inert gases such as nitrogen and argon. For example, when annealing lithium-ion battery cathode materials (such as NCM811), an argon atmosphere can prevent the oxidation of metal elements such as cobalt and nickel, while suppressing the reaction of the material with water vapor to form hydroxides.

2. Core advantages
Significant improvement in annealing uniformity
The dynamic annealing process continuously exposes the surface of the powder to high-temperature airflow, eliminating the problem of uneven internal stress distribution.
Prevent powder agglomeration and cracking
The rotating movement destroys the capillary force between particles through mechanical force, so as to avoid the formation of hard shell or cracking of viscous powder (such as aluminum hydroxide gel) during annealing. The inclined design promotes material flow through gravity and prevents excessive local annealing.
Energy saving and efficiency optimization
Multi zone temperature control technology can accurately match the powder annealing requirements and reduce ineffective heating. For example, when annealing graphene oxide, only centralized energy supply is required in the annealing zone (600 ℃), reducing energy consumption in the preheating and cooling zones and making the overall process more energy-efficient.
Strong adaptability and support for complex processes
It can handle nano powder, micron powder and other materials in various forms, and support segmented annealing (such as low-temperature dehumidification, and then high-temperature recrystallization water). For example, when annealing drug intermediates, the “annealing mixing” integrated process can be achieved by adjusting the tilt angle (15 degrees) and rotation speed (5rpm) to shorten the production cycle.

3. Application scenarios
new energy materials
Lithium ion battery materials: annealed positive electrode materials (such as NCM811, LFP), negative electrode materials (such as graphite, silicon carbon composites), eliminate processing stress, and improve cycle life.
Hydrogen fuel cell materials: annealed proton exchange membrane (PEM) precursor, optimized membrane material structure.
Ceramics and Glass
Advanced ceramics: Annealing ceramic powders such as alumina and zirconia to enhance sintering activity.
Fiberglass: Annealing glass raw materials (such as boric acid and sodium silicate) to eliminate internal stress and improve wire drawing quality.
Chemical Engineering and Catalysts
Molecular sieve catalysts: Annealing ZSM-5, SAPO-34 and other molecular sieves to maintain the integrity of pore structure.
Fine chemicals: Annealing high-purity inorganic salts (such as lithium carbonate, sodium hydroxide) to prevent moisture absorption and agglomeration.
Metal Powder and 3D Printing
Metal Injection Molding (MIM): Annealing metal polymer feed to enhance injection flowability.
3D printing sand mold: Annealing resin bonded sand mold to prevent deformation during the printing process.

4. Operating standards
Equipment inspection and pre-processing
Check if the sealing of the furnace body, heating elements, temperature control system, and vacuum system (if necessary) are functioning properly.
Clean the furnace to prevent residual materials from contaminating the new batch.
Pre start the rotation and tilt mechanism and confirm that it operates smoothly without any jamming.
Material loading and parameter setting
Choose the loading method (such as boat or fluidized bed) based on the characteristics of the powder to avoid accumulation or overflow.
Set annealing parameters:
Heating rate: ≤ 10 ℃/min (to prevent powder cracking);
Annealing temperature: set according to the thermal stability of the material (such as ceramic powder 600-900 ℃, drug intermediate 80-120 ℃);
Tilt angle: 15-30 degrees for viscous powder, 5-15 degrees for free flowing material;
Rotation speed: 2-8rpm for nano powder, 5-12rpm for micron powder.
Annealing process monitoring
Real time monitoring of furnace temperature, vacuum degree (if necessary), and powder status (such as color and shape).
Regular sampling and testing of internal stress (such as X-ray diffraction method) to ensure compliance with process requirements (such as ≤ 5MPa).
If powder clumping or abnormal temperature is found, immediately pause the equipment and adjust the parameters.
Post processing and equipment maintenance
After annealing, cool the powder according to the process requirements (such as natural cooling or forced air cooling).
Clean up residual powder in the furnace and check if the heating elements and seals are damaged.
Regularly calibrate the temperature control system and vacuum gauge to ensure equipment accuracy.