With the development of society, some aspects of metal materials can no longer meet our needs for better production and life. New materials have emerged, among which alumina materials are the most common. Alumina ceramics are made of alumina materials by sintering.
Alumina ceramics have higher hardness and strength, better wear resistance, better stability, excellent biocompatibility, etc. than common metal parts, and are oxidized Aluminum materials are relatively cheap to prepare and are currently the main new ceramic varieties.
The Mohs hardness of alumina material is 9, second only to some materials such as diamond, and the ceramics made from it have better hardness and strength. Compared with common steel structural parts, the wear resistance of the ceramic structural parts made by it is also a qualitative leap. The wear resistance is dozens, hundreds or thousands of times that of steel structural parts; alumina ceramics have good stability and high melting point. Alpha Alumina does not react with strong acids and alkalis, and its melting point is as high as 2054 degrees Celsius. Alumina ceramics have excellent biocompatibility and can be directly used on the human body and organisms.
The production of alumina ceramics and the production of traditional ceramics have something in common. A good ceramic product must have good raw materials + good molding technology + good sintering system + good Grinding + other excellent production links. Let’s start with the raw materials. The material of alumina ceramics generally refers to alpha alumina. Choose the corresponding material according to the type of ceramic you want to make. For example, for dielectric ceramics, we mainly look at whether its sodium oxide content is low-sodium alumina powder. For wear-resistant ceramics, we have to look at the D50 of its powder and the overall particle size distribution of its powder. Talking about alumina materials, some of the main indicators we look at are as follows: alumina purity, content of various impurities, alpha conversion rate, average particle size of the powder, which is D50, overall particle size distribution of the powder, and original crystal of the powder. Size, specific surface area, green density, sintering density, shrinkage, etc.
Good alumina ceramic products require good molding technology. Good molding technology can obtain good green embryo density. Green embryo density affects the porcelain density of ceramics, which also affects the ceramics. performance. At present, the main alumina ceramic molding processes on the Chinese market include dry pressing, isostatic pressing, hot die casting, Injection, grouting, tape molding, etc., depending on the molding process, the powder must be processed in advance, such as Dry pressing. Isostatic pressing requires granulation first, and injection molding requires preparing slurry first.
Good alumina ceramic sintering system, good sintering system can obtain higher density and lower poresCeramics with higher efficiency and stronger mechanical properties. A good heating curve can drain out the glue and water in the embryo body, avoid over-firing, and shorten the firing time. At present, the main sintering systems are normal pressure sintering, pressure sintering, atmosphere sintering, reaction sintering, etc.
With good grinding and processing, the fired ceramics always have edges and corners that need to be processed. As the old saying goes: without diamonds, there is no porcelain job, especially alumina ceramics, which are harder and more wear-resistant than traditional ceramics, and are more difficult to grind and process. The grinding process of some products accounts for a large part of the cost, especially how to process high-precision industrial parts well. Reducing errors is one of the key points of making ceramics well.
