Aluminum oxynitride powder, direct nitridation high-pressure synthesis method and application thereof
Aluminum oxynitride (AlON) powder, a synthesis method thereof by direct nitridation under high pressure and use thereof, which belongs to the field of ceramic powder are presented. In the method, pure-phase AlON powder is synthesized by direct nitridation under high pressure with aluminum powder and alumina powder as starting materials. The powder has a spherical-like morphology, with a particle size ranging from 5 μm to 15 μm. The powder has good dispersibility and uniformity, and higher sintering activity. AlON transparent ceramic (1.2 mm thick) prepared from the AlON powder has a linear transmittance of more than 84%. The batch yield is on kilogram-scale; therefore, the method is suitable for large-scale production of the AlON powder.
1 . A preparation method of AlON powder by direct nitridation, comprising:
step (1), mixing an aluminum powder, an alumina powder and absolute ethanol homogeneously to form a mixture;
step (2), removing the absolute ethanol from the mixture by rotary evaporation, followed by vacuum drying and sieving to obtain a mixed powder;
step (3), loading the mixed powder in a plurality of crucibles, stacking the plurality of crucibles in a staggered manner in a pressure sintering furnace, and introducing nitrogen to the pressure sintering furnace until an internal gas pressure thereof is 1.5-3.0 MPa; and
step (4), calcining the mixed powder at 1700-1800° C. in the pressure sintering furnace for 1-3 h, reducing the temperature to 900-1100° C., relieving the internal gas pressure in the pressure sintering furnace and cooling the temperature therein to room temperature to obtain the AlON powder,
wherein the AlON powder has a purity of at least 99.9%.
2 . The method according to claim 1 , wherein, in step (1), a mass of the absolute ethanol is 1-3 times a sum of the masses of the alumina powder and the aluminum powder; and
the mixing is mechanical stirring for 1-4 h.
3 . The method according to claim 1 , wherein the alumina powder is selected from at least one of α-alumina powder and γ-alumina powder;
the alumina powder has a particle size of no more than 80 μm;
the alumina powder has a purity of more than 99.9%;
the aluminum powder has a particle size of no more than 80 μm; and
the aluminum powder has a purity of more than 99.9%.
4 . The method according to claim 1 , wherein
sieving is performed using a 100-mesh sieve.
5 . The method according to claim 1 , wherein, in step (3),
the pressure sintering furnace is at a vacuum degree of no less than 10 −2 Pa at room temperature before the nitrogen is introduced;
the nitrogen has a purity of no less than 99.9%;
the nitrogen is introduced until the pressure sintering furnace has an internal gas pressure of 1.5-2.5 MPa; and
in step (4), the pressure sintering furnace is heated and/or cooled at a rate of 5-12° C./min.
6 . The method according to claim 1 , wherein the alumina powder has a particle size of no more than 60 μm, the aluminum powder has a particle size of no more than 60 μm.
7 . The method according to claim 1 , wherein the alumina powder has a particle size of no more than 35 μm, the aluminum powder has a particle size of no more than 35 μm.
8 . The method according to claim 1 , wherein the alumina powder has a particle size of no more than 10 μm, the aluminum powder has a particle size of no more than 10 μm.