High entropy nitride ceramics and methods of synthesizing the same
AssigneeThe Florida International University Board of Trustees
InventorsSuprabha Das, Zhe Cheng, Andriy Durygin
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Abstract
Provided are novel high entropy nitrides (HENs) exhibiting excellent physical and chemical properties. Also provided are systems and methods to synthesize bulk HENs by reaction flash sintering. Commercial metal nitride powders can be consolidated into near fully dense single-phase bulk ceramic with a proprietary flash sintering apparatus. A constant DC electrical field of ˜80 V/cm and pressure of ˜15 MPa at room temperature can trigger reaction flash sintering without pre-heating, and the entire process can finish in ˜250 seconds to ˜400 seconds.
Claims20
A sintered high entropy nitride (HEN) ceramic, comprising (AlaNbaTaxTiyZrz)N, where a is at least 0.17, x is either 0 or at least 0.17, y is at least 0.16, z is either 0 or at least about 0.17, and 2a+x+y+z is equal to 1.
A method for synthesizing a sintered high entropy nitride (HEN) ceramic, the method comprising:
- providing a powder comprising (AlaNbaTaxTiyZrz)N, where a is at least 0.17, x is either 0 or at least 0.17, y is at least 0.16, and z is either 0 or at least about 0.17;
- mixing the powder in an equimolar or near-equimolar ratio to form a reaction mixture where 2a+x+y+z is equal to 1;
- cold-pressing the reaction mixture at a cold-pressing pressure to form a green pellet;
- inserting the green pellet into an insulating tube;
- simultaneously applying a direct current (DC) voltage and a sintering pressure to the green pellet within the insulating tube, the DC voltage and the sintering pressure together being sufficient to flash sinter the green pellet, thus synthesizing the sintered HEN ceramic;
- removing the DC voltage and the sintering pressure;
- allowing the sintered HEN ceramic to cool to about ambient temperature;
- and
- removing the sintered HEN ceramic from the insulating tube.
A sintered high entropy nitride (HEN) ceramic, comprising (AlaNbaTiyZrz)N, where a is 0.20, y is 0.40, and z is 0.20.
Dependencies are inferred from the claim text.