Manufacturing Process of Honeycomb Ceramic

The regular pore structure and excellent performance of honeycomb ceramics are entirely due to their precise and mature manufacturing process. Each step is crucial, directly determining the performance and quality of the final product.

Raw Material Preparation and Formulation Design

This is the foundation of the process. Based on the final application of the product (e.g., automotive exhaust purification, industrial filtration), appropriate materials are selected:

Main base materials: such as cordierite (talc, kaolin, alumina), mullite, silicon carbide, etc. The particle size and purity of these powders have a decisive impact on sintering and performance.

The core technology of formulation design requires additives, mainly including:

Binders, which give the green body sufficient strength during molding, such as methylcellulose, polyvinyl alcohol, etc.

Plasticizers, which increase the plasticity of the powder and facilitate extrusion, such as glycerin, dibutyl phthalate.

Lubricants, such as paraffin wax and oleic acid, reduce friction between the material and the die during extrusion.

Pore-forming agents, which volatilize or burn during sintering, leave pores to control the porosity of the product.

Mixing and Plasticizing

Precisely proportioned raw materials are thoroughly mixed in mixing equipment (such as a kneader). The purpose of this process is to:

Uniform Distribution: Ensure that various additives are uniformly mixed with the ceramic powder. Through heating and stirring, the organic additives fully coat the ceramic particles, forming a uniform, soft, and highly plastic raw material.

Vacuum Degassing: The mixed clay is usually vacuum-processed to remove air bubbles, preventing cracks or voids in the extruded product.

Extrusion Molding – The Core Process

This is the crucial step in forming the honeycomb structure, completed using a specialized honeycomb ceramic extruder.

Feeding: The plastic clay is fed into the extruder's feed cylinder.

Compression and Preforming: The clay is propelled by a screw through a distributor with a complex internal flow channel, evenly distributing the clay to every inlet of the subsequent mold.

Forming: The core component is the honeycomb mold. This mold consists of two parts:

Upper mold (perforated plate): Covered with numerous small holes to guide the clay flow.

Lower mold (shaping plate): Covered with carefully designed slits through which the clay is extruded, forming a continuous honeycomb-shaped preform. The design and machining precision of the mold directly determine the pore density (CPI), wall thickness, and channel shape of the honeycomb.

Cutting: The extruded continuous honeycomb preform is cut to a preset length by an automatic cutter.

Drying

The preform immediately after extrusion has low strength and contains a large amount of moisture and organic solvents, requiring gentle and slow drying. This removes the physical moisture from the preform while maintaining its shape and preventing deformation and cracking.

Method: Typically, a temperature and humidity controlled drying oven is used. Drying conditions (temperature, humidity, time) need precise control, as excessively rapid moisture evaporation can lead to uneven shrinkage and cracking of the green body.

Sintering

This is the final and most crucial chemical and physical transformation process in ceramic forming. The dried green body is placed in a high-temperature kiln (such as a tunnel kiln or shuttle kiln) and fired under a strictly controlled temperature profile.

Post-processing and Inspection

The sintered product requires further processing:

Processing: Such as end-face grinding to ensure all channels are unobstructed; or cutting to meet specific dimensional requirements.

Coating: For catalyst supports, a high specific surface area coating (such as γ-alumina) needs to be applied to the inner wall of the pores of the honeycomb ceramic to provide a foundation for subsequent loading of active catalytic components (such as platinum, palladium, and rhodium).

Performance Testing: Rigorous testing of the finished product is conducted, including appearance dimensions, pore density, compressive strength, coefficient of thermal expansion, porosity, etc., to ensure compliance with usage standards.

Conclusion

The manufacturing of honeycomb ceramics is a complex process integrating materials science, mechanical engineering, and process control. Precise control at each step contributes to this uniquely structured and high-performance industrial material, enabling it to play an irreplaceable role in environmental protection, chemical engineering, energy, and other fields. We are a Chinese industrial ceramics manufacturer. For more information, please contact us via email at annayu@169chem.net or WhatsApp at +18909016373.