Alumina ceramics are characterized by high hardness, light weight and good wear resistance.Among them, 99 alumina ceramic materials can be used for high-temperature crucible, furnace tube and special wear-resistant materials, such as ceramic bearing, ceramic seal, water valve sheet, etc. Alumina ceramics are mainly used as corrosion-resistant and wear-resistant parts. Because of the addition of talc powder, the electrical properties and mechanical strength of ceramics are improved.
1. Powder preparation:
Aluminum powder was prepared according to different product requirements and different molding processes. Powder particle size in 1 micron, if the manufacture of high purity alumina ceramic products, in addition to alumina purity in 99.99%, but also need ultra-fine grinding to make its particle size distribution uniform. When using extrusion molding or injection molding, it is necessary to introduce binding agent and plasticizer into the powder and evenly mix them at 150-200 degrees, which is conducive to molding operation.
Alumina ceramic molding methods include dry pressing, grouting, extrusion, injection, hot pressing, etc. Different products with different shapes, sizes, complex shapes and precision require different molding methods.
Sintering is the process of densifying a granular ceramic body into a solid material. Sintering is a method of removing particles in the body, removing a small amount of gas and impurities and organic matter, and making particles grow and combine with each other to form new substances.The electric furnace is the most widely used heating device for sintering.
Some alumina ceramics need to be finished after sintering. Due to the high hardness of alumina ceramics, grinding and polishing materials with higher hardness are required for finishing, such as SiC, B4C, etc. Grinding is usually carried out from coarse to fine.
In order to enhance the mechanical strength of alumina ceramics, one kind of alumina ceramic strengthening process has been developed in recent years. Alumina ceramics are toughened by coating alumina ceramics with a silicified film and heating at 1200 c to 1580 c.