Properties of Aluminum Nitride
Theoretically, the thermal conductivity of aluminum nitride could reach 320W/m.K, which is 10 to 15 times higher than that of aluminum oxide, which is the conventional material used for substrates. In addition, it has comparable thermal expansion coefficients to Si, good electrical insulation, low dielectric loss, stable thermal and chemical properties, and good electrical insulation. It is the perfect heat dissipation and packaging material for high-power electronics, semiconductor module circuits, and large integrated circuits.
In addition to its use as a melting bath and crucible, aluminum nitride has non-wetting properties with many other non-ferrous metals and their alloys, including Al. Aluminum nitride can also be used as an additive for advanced refractory materials, a spark plug for electronic igniters, and a protective tube for thermocouples. It is possible to create high-temperature windows for light and electromagnetic waves using transparent aluminum nitride plates. To improve the thermal conductivity of resins or polymers, aluminum nitride can be added. People are paying increasingly more attention to the research and application of aluminum nitride ceramics because of their excellent overall performance in thermal, electrical, optical, and mechanical aspects.
Aluminum nitride is highly reactive with water and readily deliquesces into aluminum hydroxide in the presence of water and oxygen. Because even a tiny amount of oxygen will cause significant phonon scattering and decrease thermal conductivity in aluminum nitride, making storage, transportation, and subsequent processing extremely challenging. As a result, keeping aluminum nitride from hydrolyzing has become a crucial issue, and giving aluminum nitride a water-resistant surface treatment is necessary.
Therefore, the purpose of this paper is to propose a new method for preventing the hydrolysis of aluminum nitride, one that is simple to implement and that possesses a broad anti-hydrolysis capability. The difficulties associated with the storage, transportation, and subsequent processing of aluminum nitride powder can be successfully resolved because the treated powder is no longer hydrophobic and can be well infiltrated with water.
Method to Prevent Hydrolysis of Aluminum Nitride Ceramic Powder
The method prevents the hydrolysis of aluminum nitride by using a surface treatment process to chemically bond an organic silicate to the surface of aluminum nitride powder. This prevents water molecules from coming into contact with the aluminum nitride surface. The following steps are detailed:
(1) Soak the aluminum nitride powder in the tetraethoxysilane solution for 15 minutes while stirring, then leave it for one to two hours;
(2) After filtering the aforementioned mixture, ethanol solution is continuously used to wash the filtered aluminum nitride powder three times. The ethanol discussed here is industrial ethanol readily available on the market.
(3) To obtain aluminum nitride powder that does not hydrolyze in a humid environment below 100°C, dry the cleaned aluminum nitride powder.
Conclusion
This method is simple to implement and produces satisfactory results. In a humid environment below 100°C, the treated aluminum nitride powder does not hydrolyze. After being submerged in weak acid and strong alkaline solutions at temperatures below 100°C for 108 hours, there was no change in the solution's pH. The XRD results also demonstrated that no additional materials is produced in the powder, proving that aluminum nitride isn't hydrolyzed. The method addresses the issue that aluminum nitride is easily hydrolyzed in a humid environment without affecting the powder's original properties. This method can be used with bulk and thin film aluminum nitride materials in addition to aluminum nitride powder.