cBN COMPOSITE FORMATION METHOD INCLUDING CONSOLIDATION

• US 20190330117A1
• Filed: 07/10/2019
• Published: 10/31/2019
• Est. Priority Date: 10/20/2017
• Status: Active Grant

• Current Assignee: King Fahd University Of Petroleum And Minerals
• Original Assignee: King Fahd University Of Petroleum And Minerals
• Inventors: Hakeem, Abbas Saeed, Laoui, Tahar, Irshad, Hafiz Muzammil, Ahmed, Bilal Anjum, Ehsan, Muhammad Ali
• Granted Patent: US 10,843,971 B2
• Time in Patent Office: Days
• CPC Class Codes: C04B 2235/3217 Aluminum oxide or oxide forming salts thereof, e.g. bauxite, alpha-alumina
• CPC Class Codes: C04B 2235/386 Boron nitrides
• CPC Class Codes: C04B 2235/405 Iron group metals
• CPC Class Codes: C04B 2235/5436 micrometer sized, i.e. from 1 to 100 micron
• CPC Class Codes: C04B 2235/5445 submicron sized, i.e. from 0,1 to 1 micron
• CPC Class Codes: C04B 2235/5454 nanometer sized, i.e. below 100 nm
• CPC Class Codes: C04B 2235/6562 Heating rate
• CPC Class Codes: C04B 2235/666 Applying a current during sintering, e.g. plasma sintering [SPS], electrical resistance heating or pulse electric current sintering [PECS]
• CPC Class Codes: C04B 2235/96 Properties of ceramic products, e.g. mechanical properties such as strength, toughness, wear resistance
• CPC Class Codes: C04B 2235/9607 Thermal properties, e.g. thermal expansion coefficient
• CPC Class Codes: C04B 35/103 containing non-oxide refractory materials, e.g. carbon C04B35/106 takes precedence
• CPC Class Codes: C04B 35/117 Composites
• CPC Class Codes: C04B 35/62842 Metals
• CPC Class Codes: C04B 35/64 Burning or sintering processes C04B33/32 takes precedence ; powder metallurgy B22F
• CPC Class Codes: C22C 2026/003 Cubic boron nitrides only
• CPC Class Codes: C22C 29/00 Alloys based on carbides, oxides, nitrides, borides, or silicides, e.g. cermets, or other metal compounds, e.g. oxynitrides, sulfides C22C26/00 takes precedence
• CPC Class Codes: C22C 29/12 based on oxides

Abstract

Conventional sintering processes convert a portion of cBN to hBN which is softer than cBN which negatively affects functional properties of an alumina composite. The invention is directed to method for making an alumina-cubic boron nitride (Al₂O₃-cBN) composite that contains substantially no hexagonal boron nitride (hBN) by non-conventional spark plasma sintering of cBN with nano-sized alumina particles. The invention is also directed to Al₂O₃-cBN/Ni composites, which contain substantially no hBN, and which exhibit superior physical and mechanical properties compared to alumina composites containing higher amounts of hBN.

Claims

1. A method for making an alumina-cubic boron nitride (“

Al₂O₃-cBN”

) composite comprising;

forming a mixture of cBN particles and nano-sized alumina particles;

consolidating the mixture;

spark plasma sintering the mixture of the cBN particles and the nano-sized alumina particles at constant pressure to form the alumina-cubic boron nitride composite;

wherein an average particle size of the nano-sized alumina particles is no more than 50 nm.

2. The method of claim 1, wherein the cBN particles are substantially cBN without a nickel coating.

3. The method of claim 1, wherein the cBN particles are coated with nickel.

4. The method of claim 1, wherein the cBN particles are coated with nickel and comprise 20-80 wt % nickel, based on a total weight of the nickel-coated cBN particles.

5. The method of claim 1, wherein the cBN particles are coated with nickel and comprise 50-70 wt % nickel, based on a total weight of the nickel-coated cBN particles.

6. The method of claim 1, wherein an average particle size of the nano-sized alumina particles is no more than 25 nm.

7. The method of claim 1, wherein an average particle size of the nano-sized alumina particles is no more than 10 nm.

8. The method of claim 1, wherein an average particle size of the nano-sized alumina particles is no more than 5 nm.

9. The method of claim 1, wherein an average particle size of the nano-sized alumina particles is no more than 2 nm.

10. The method of claim 1, wherein an average particle size of the cBN particles ranges from 1 to 100 μ

m.

11. The method of claim 1, wherein an average particle size of the cBN particles ranges from 5 to 50 μ

m.

12. The method of claim 1 that produces an alumina-cubic boron nitride (Al₂O₃-cBN) or alumina-cubic boron nitride/nickel (Al₂O₃-cBN/Ni) composite having a higher Vickers hardness than an otherwise identical composite that was not spark plasma sintered at 1,200-1,600°

C.

13. The method of claim 1 that produces an alumina-cubic boron nitride (Al₂O₃-cBN) or alumina-cubic boron nitride/nickel (Al₂O₃-cBN/Ni) composite having a higher Vickers hardness than an otherwise identical composite sintered from alumina particles having an average particle size of 1,000 nm.

14. The method of claim 1 that produces an alumina-cubic boron nitride (Al₂O₃-cBN) or alumina-cubic boron nitride/nickel (Al₂O₃-cBN/Ni) composite having a higher Vickers hardness than an otherwise identical composite sintered from cBN particles that are not coated with nickel, wherein the spark plasma sintering is performed at a temperature above 1,350°

C. and wherein at least 99 wt. % of the boron nitride in the composite is cBN or less than 1 wt. % of the boron nitride is hBN.

15-20. -20. (canceled)