Understand the secrets of molding, sintering and shape control of zirconia and silicon nitride in one article

2026-05-21

1. Basic process of industrial ceramic production process

The production of industrial ceramics (also known as advanced ceramics or engineering ceramics) is a rigorous process of converting loose inorganic non-metallic powders into precision parts with high strength, wear resistance, high temperature resistance or special electrical properties. . Its standard core manufacturing process usually includes the following Five main stages.

Powder preparation Precisely mix high-purity raw materials. In order to make the powder have good fluidity and binding force in subsequent molding, it is necessary to add an appropriate amount of organic binder, lubricant and dispersant. After high-performance ball mill mixing and spray drying, a granulated powder with uniform particle size distribution is produced.
Green body forming According to the geometric shape and mass production scale of the product, the granulated powder is pressed or injected into the mold through mechanical means. The main molding methods include dry pressing and cold isostatic pressing ( CIP ), ceramic injection molding ( CIM ) and tape casting.
Green processing and debinding The formed green body contains a large amount of organic binders. Before formal sintering, it must be placed in a debinding furnace and slowly heated in the air to cause pyrolysis or volatilization (degreasing). The hardness of the green body after debinding is low and it is easy to perform preliminary mechanical processing such as drilling and cutting.
High temperature sintering This is a critical step in achieving the final mechanical properties of the ceramic. The debonded green body is placed into a high-temperature sintering furnace. Mass transfer and bonding occur between the grains. The pores are gradually discharged. The green body undergoes severe volume shrinkage and finally achieves densification.
Precision machining and inspection Since ceramics after sintering have extremely high hardness (usually second only to diamond) and have a certain degree of sintering deformation, if they want to achieve micron-level dimensional tolerances or mirror-level surface roughness, they must be hard-stated and precision processed through diamond grinding wheels and grinding pastes, and finally comprehensive quality inspection through high-precision instruments such as three-dimensional coordinates.

2. Comparison of process characteristics between zirconium oxide and silicon nitride

Among modern advanced structural ceramics, zirconia and silicon nitride Two systems are represented. The former is a typical oxide ceramic with excellent high toughness and aesthetics; silicon nitride It is a non-oxide ceramic with high covalent bond and has excellent performance in hardness, thermal shock stability and extreme high temperature environment. The following is a comparison of the key production process parameters of the two.

Process dimension	Zirconia Ceramic (ZrO₂)	silicon nitride陶瓷 (Si₃N₄)
classic sintering temperature Degree	1350°C - 1500°C Densification can be completed under normal pressure air atmosphere, and the equipment cost is low.	1700°C - 1850°C High-pressure nitrogen (1-10 MPa) must be introduced for air pressure sintering to inhibit high-temperature decomposition.
Line shrinkage control	20% - 22% (large and stable) The powder packing density is uniform, and the mold amplification factor calculation is extremely regular.	15% - 18% (relatively small but highly volatile) Affected by the diffusion and phase change speed of liquid phase additives, size control technology is difficult.
Phase changes and volume effects	There is phase change stress When cooling, the tetragonal phase transforms into the monoclinic phase with a volume expansion of 3%-5%, and stabilizers such as yttrium oxide need to be introduced to prevent cracking.	Phase change modification During sintering, the α phase transforms into the β phase, forming an interlocking columnar crystal intertwined structure, which can significantly improve the toughness of the matrix.
Mainstream molding process	Dry pressing/cold isostatic pressing, ceramic injection molding (CIM) The powder has high density, good fluidity, easy compaction and mass production of special shapes.	Cold isostatic pressing (CIP), molding The intrinsic density of powder is low, fluffy and difficult to compact, so multi-directional high-pressure CIP is often used.

��Industrial landing production tips: The heart of industrial ceramic manufacturing lies in Perfect fit between ‘temperature-time curve’ and ‘shrinkage compensation’. The difficulty of zirconia mainly lies in the superhard grinding stage after sintering (high tool loss and low efficiency); while the core barrier of silicon nitride lies in its rigorous ultra-high temperature air pressure/hot isostatic pressing sintering process and the confidential formula of sintering aids for low melting point covalent bond liquid phase mass transfer.

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