Method of forming a βSiAlON by spark plasma sintering

Patent metadata

Field	Value
Publication number	US-11479463-B2
Application number	US-201916530369-A
Country	US
Kind code	B2
Filing date	Aug 2, 2019
Priority date	Aug 2, 2019
Publication date	Oct 25, 2022
Grant date	Oct 25, 2022

Abstract

A method of making a β-SiAlON is described in involves mixing nanoparticles of AlN, Al 2 O 3 , and SiO 2 with particles of Si 3 N 4 and spark plasma sintering the mixture. The sintering may be at a temperature of 1450-1600° C. or about 1500° C. The particles of Si 3 N 4 may be nanoparticles comprising amorphous Si 3 N 4 , or 25-55 μm diameter microparticles comprising β-Si 3 N 4 .

First claim

The invention claimed is:

1. A method of making a β-SiAlON-comprising composite, comprising:
mixing nanoparticles of AlN, Al 2 O 3 , and SiO 2 with particles of Si 3 N 4 having an average diameter in a range of 15 nm-60 μm to form a powder mixture, wherein the Si 3 N 4 is present in the powder mixture at a weight percentage of 40-85 wt %, relative to a total weight of the powder mixture; and
spark plasma sintering the powder mixture at a temperature of 1450-1600° C. and a pressure of 40-60 MPa to form the β-SiAlON,
wherein the β-SiAlON-comprising composite comprises a β-SiAlON phase and an AlN polytype phase having a formula which is at least one selected from the group consisting of Si 1.62 Al 0.38 N 1.62 O 1.38 , Si 1.84 Al 0.16 N 1.84 O 1.16 and Si 3 Al 6 N 12 O 2 .

2. The method of claim 1 , wherein the powder mixture is ultrasonicated in an organic solvent and dried before the spark plasma sintering.

3. The method of claim 1 , wherein the spark plasma sintering is at a temperature in a range of 1480-1520° C.

4. The method of claim 1 , wherein the spark plasma sintering uses a heating rate in a range of 80-120° C./min.

5. The method of claim 1 , wherein the powder mixture is spark plasma sintered for a time in a range of 15-45 min.

6. The method of claim 1 , wherein the β-SiAlON-comprising composite is substantially free of Ca.

7. The method of claim 6 , wherein the β-SiAlON-comprising composite consists essentially of Si, Al, O, and N.

8. The method of claim 1 , wherein the SiO 2 nanoparticles have an average diameter in a range of 10-30 nm.

9. The method of claim 1 , wherein the β-SiAlON-comprising composite has a thermal expansion coefficient in a range of 2.20-2.45 ppm/K.

10. The method of claim 1 , wherein the particles of Si 3 N 4 are nanoparticles of amorphous Si 3 N 4 having an average diameter in a range of 15-100 nm, wherein the β-SiAlON-comprising composite has a mean grain size of 100 to 1,000 nm.

11. The method of claim 10 , wherein the particles of Si 3 N 4 are nanoparticles of amorphous Si 3 N 4 having an average diameter in a range of 20-40 nm and are present in the powder mixture at a weight percentage of 65-85 wt %, relative to a total weight of the powder mixture.

12. The method of claim 10 , wherein the β-SiAlON phase has the formula Si 5 AlON 7 .

13. The method of claim 10 , wherein the β-SiAlON-comprising composite has a Vickers Hardness (HV 10 ) in a range of 18-25 GPa, and a density in a range of 2.80-2.95 g/cm 3 .

14. The method of claim 10 , wherein the AlN polytype has a formula which is at least one selected from the group consisting of Si 1.62 Al 0.38 N 1.62 O 1.38 and Si 1.84 Al 0.16 N 1.84 O 1.16 .

15. The method of claim 10 , wherein the β-SiAlON-comprising composite has a mean grain size of 200 to 600 nm.

16. The method of claim 1 , wherein the particles of Si 3 N 4 are microparticles of β-Si 3 N 4 having an average diameter in a range of 25-55 μm, wherein the β-SiAlON-comprising composite has a mean grain size of 1,000 to 10,000 nm.

17. The method of claim 16 , wherein the particles of Si 3 N 4 are present in the powder mixture at a weight percentage of 40-65 wt %, relative to a total weight of the powder mixture.

18. The method of claim 16 , wherein the β-SiAlON phase has the formula Si 3 Al 3 O 3 N 5 .

19. The method of claim 16 , wherein the β-SiAlON-comprising composite has a fracture toughness in a range of 7.0-10.0 MPa·m 1/2 and a density in a range of 3.20-3.30 g/cm 3 .

20. The method of claim 16 , wherein the AlN polytype has a formula Si 3 Al 6 N 12 O 2 .

Assignees

• Univ King Fahd Pet & Minerals

Inventors

• Hakeem Abbas Saeed
• Ul-Hamid Anwar
• Muraza Oki
• Ehsan Muhammad Ali

Classifications

• C01P2004/64

  Nanometer sized, i.e. from 1-100 nanometer · CPC title

• C01P2002/72

  by d-values or two theta-values, e.g. as X-ray diagram · CPC title

• C01P2006/32

  Thermal properties · CPC title

• C04B35/597

  based on silicon oxynitride, {e.g. SIALONS} · CPC title

• C04B35/64

  Burning or sintering processes (C04B33/32 takes precedence {; powder metallurgy B22F}) · CPC title