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Briefly describe the performance characteristics of silicon nitride ceramic materials

wallpapers News 2020-04-24
Silicon nitride is a relevant structural ceramic material. It is a super-hard substance, which has lubricity and wears resistance, and is an atomic crystal; it is resistant to oxidation at high temperatures. And it can resist the impact of cold and heat, heating in the air to more than 1000 ℃, rapid cooling and then fast heating, will not crack. It is precise because silicon nitride ceramics have such excellent characteristics that people often use it to manufacture bearings, gas turbine blades, mechanical seal rings, permanent molds and other mechanical components. If silicon nitride ceramics that are resistant to high temperatures and difficult to transfer heat are used to manufacture the heating surface of engine components, not only can the quality of the diesel engine be improved, fuel can be saved, but also the thermal efficiency can be improved. China and the United States, Japan and other countries have developed such diesel engines.
What is the production process flow of silicon nitride ceramics?
The technological process for preparing silicon nitride ceramic products is generally composed of raw material processing, powder synthesis, powder processing, forming, green body processing, sintering and ceramic body processing.
The types of silicon nitride ceramic preparation processes are mainly distinguished by different methods and orders of synthesis, forming and sintering.
Silicon nitride ceramic molding process
Commonly used molding methods for ceramics include dry pressing, casting and injection. Dry pressing is one of the most widely used molding processes and one of the mainstream molding processes for mobile phone ceramic backplanes. The back cover of the Mi MIX series is dry Compression molded. Today, let's take a closer look at the ceramic dry pressing
1. Dry pressing
Dry compression molding, also known as compression molding, is one of the most commonly used molding methods. Dry press molding is to put the powder with good fluidity and granule gradation into the metal mold cavity, apply pressure through the indenter, the indenter is displaced in the mold cavity, and the pressure is transferred to make the powder in the mold cavity. The bulk particles are rearranged and deformed to be compacted to form a ceramic green body with a certain strength and shape.
2. The process principle and influencing factors of dry press forming
1. Process principle
The essence of dry press molding is that under the action of external force, the particles are close to each other in the mold, and the particles are firmly connected by the internal friction force to maintain a certain shape. This internal frictional force acts on a thin layer of binder around the particles that are close to each other.
As the pressure increases, the blanks will change shape, slide against each other, the gap will decrease, and gradually increase the contact and close to each other. As the particles get closer, the force between the colloidal molecules and the particles is strengthened, so the green body has a certain mechanical strength.
2. Influencing factors
①The main factors affecting dry pressing are:
②Powder properties: particle size, particle size distribution, fluidity, water content, etc .;
③ Selection of binders and lubricants;
④Mold design;
⑤Pressing force, pressing method, pressing speed and holding time during pressing.
In summary, if the gradation of the blank particles is appropriate, the binder is used correctly, the pressurization method is reasonable, and the dry press method can also obtain a relatively ideal green body density.
Trunnano is one of the world's largest manufacturers of silicon nitride."We have been supplying silicon nitride hexaboride, ensuring product quality, and guaranteein    g stable supply prices," said Rachel.Please contact Rachel if you are interested in silicon nitride.
Email: rachel@ihpa.net

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Tag: silicon nitr