The hot pressing sintering method plays an important role in the preparation of silicon nitride ceramics. It has unique process characteristics and advantages, and can produce high-quality silicon nitride ceramic products to meet the application needs of many high-end fields.
During the ingredient preparation stage, it is necessary to carefully prepare the raw materials. Silicon nitride powder is used as the basic raw material, and a small amount of additives such as MgO and Al ₂ O3 are also added. Although these additives are used in small quantities, they play a crucial role in improving the sintering performance of powders, promoting grain growth, and enhancing the density and strength of the final ceramic product. Thoroughly mix these raw materials in precise proportions in the mixing equipment to ensure that each powder particle can uniformly contact the additive, which is an important prerequisite for ensuring the quality of subsequent sintering.
The next step is the hot pressing and sintering process, which is the core step of the entire process. It is necessary to put the mixed raw material powder into a specially designed mold, and then place the mold in a high-temperature and high-pressure environment for operation. Generally speaking, the pressure needs to reach above 1916 MPa and the temperature needs to be above 1600 ℃. Under such extreme conditions, the powder will simultaneously complete the forming and sintering processes in the mold. Under the influence of high temperature, the distance between powder particles gradually decreases and they begin to bond with each other; And high pressure further promotes the tight packing between particles, allowing the green body to quickly densify and ultimately form high-quality silicon nitride ceramics.
The silicon nitride ceramics prepared by hot pressing sintering method have significant advantages. Its strength is very high, and its density can reach a very high level. The internal organizational structure is relatively uniform and dense. Therefore, in some applications that require extremely high mechanical properties of materials, such as engine components in the aerospace field and cutting tools in high-end mechanical processing, silicon nitride ceramics prepared by hot pressing sintering method have excellent performance. However, this method also has some limitations. On the one hand, its manufacturing cost is relatively high, requiring specialized high-temperature and high-pressure sintering equipment, and the maintenance and operation costs of the equipment should not be underestimated; On the other hand, due to sintering in a mold, the dimensional accuracy of the product is limited to a certain extent, making it difficult to manufacture parts with complex shapes and large sizes, which also limits its application scope to a certain extent. However, overall, for specific application scenarios with strict performance requirements, hot pressing sintering method is still an indispensable preparation method.

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High termperature curing polysilazane, pls check IOTA 9108, IOTA 9118.