Introduction and application of aluminum nitride ceramics

1.Introduction to aluminum nitride ceramics

Aluminum Nitride Ceramic 11 is a Ceramic known as (AIN) that is the dominant crystalline level. Aluminum nitride is a covalently bonded compound, belonging to the hexagon crystal system, wurtzite crystal structure, white or gray.

aluminum nitride powder

 

2.Aluminum nitride ceramic manufacturing process

(1) Aluminum nitride (AIN) powder manufacture

①Direct reaction of aluminum and nitrogen (or ammonia)

This method is often used in industry, but the aluminum powder should be treated to remove the oxides before the reaction, the temperature reaction is at 500~600℃, because the unreacted aluminum powder is easy to agglutinate, for this reason, a small amount of CaF2 or NaF is added, not only as a catalyst, but also to prevent the condensation of aluminum.

② Black Carbon reduction nitriding (Serpek)

The reaction is carried by heating Al2O3 and C mixed powder in N2 or NH3 gas.

(3) Halide of aluminum (AICl3, AIBr3, etc.) and ammonia reaction method

(4) Aluminum powder and organic nitrogen compound (dicyandiamide or melamine) reaction method

⑤Preparation method of ultrafine AIN powder

Ultrafine powder can be prepared by evaporating aluminum powder in arc plasma and reacting with nitrogen to form AIN. In addition, ultrafine powders can be prepared by evaporating aluminum at low pressure by heating it with an electron beam and reacting it with nitrogen gas (N2 or NH3).

(2) Manufacturing of aluminum nitride ceramics

The manufacturing methods of aluminum nitride ceramics include hot pressing sintering method, atmospheric pressure sintering method and reaction sintering method. The first two methods are usually used the AIN . It will hydrolyze, so injection molding can not be used, but can be used for molding, isostatic molding, etc. When AIN powder is granulated,

the binder is polyvinyl alcohol (PVA), because PVA is not soluble in anhydrous ethanol; polyvinyl butaldehyde (PVD) is used Instead.

The hot pressing sintering process is under the high temperature of 1800~2000℃. It is heated and pressurized at the same time with Al203, MgO and SiO2, so can be added or not.

Atmospheric sintering process rates at 1800~1900℃ high temperature, adding additives of Y2O3, Al203, SiO2, Be0,CaO and so on.

3. Properties and applications of aluminum nitride ceramics

Aluminum nitride ceramics have a high melting point of 2450℃ and good stability in high temperature non-oxidizing atmosphere within 2000℃. It has a high thermal conductivity and 10 times of alumina ceramics. Also it is similar to beryllium oxide ceramics and its thermal expansion coefficient is similar to silicon, high electrical insulation resistance, excellent dielectric constant and low dielectric loss, good mechanical properties, corrosion resistance, strong light transmittance.

In addition, aluminum nitride is free from the corrosion of molten aluminum and other molten metals and gallium arsenide, it is when especially has excellent corrosion resistance to molten aluminum. However, AIN ceramic high temperature is (> 800℃) poor oxidation resistance, easy to absorb moisture in the atmosphere, hydrolysis and other characteristics, should cause people's attention.

Aluminum nitride ceramics have high strength temperature, low coefficient of expansion and good thermal conductivity. Its used for high temperature components, heat exchange and equipment materials, etc.

Aluminum nitride ceramics can be used as crucible and casting mold material for Al, Cu, Ag, Pb and other metals melting by using corrosion resistance of iron, aluminum and other metals and alloys.

Aluminum nitride ceramics in a special atmosphere in the excellent high temperature performance (about 2000℃),  it can be used as lining material for nonoxidizing electric furnace.

Furnace village materials.

Aluminum nitride ceramics with high thermal conductivity and high insulation resistance can be used as insulation base for heat sinks and semiconductors slice. Aluminum nitride thin can be made into high-frequency piezoelectric elements in large set because they are the most important to use in aluminum nitride ceramics at present.

Aluminum NItride Substrate

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