Hexagonal diamond bulk sintered body and its manufacturing method

• US 10,167,569 B2
• Filed: 02/06/2013
• Issued: 01/01/2019
• Est. Priority Date: 08/16/2012
• Status: Active Grant

• Current Assignee: National University Corporation Ehime University
• Original Assignee: National University Corporation Ehime University
• Inventors: Ohfuji, Hiroaki, Irifune, Tetsuo
• Primary Examiner(s): Gregorio, Guinever S
• Application Number:
  US14/421,690
• Publication Number:
  US 20150292107A1
• Time in Patent Office: 2,155 Days
• Field of Search: None
• CPC Class Codes: B01J 2203/061 Graphite
• CPC Class Codes: B01J 3/067 Presses using a plurality of pressing members working in different directions
• CPC Class Codes: C04B 2235/425 Graphite
• CPC Class Codes: C04B 2235/5292 Flakes, platelets or plates
• CPC Class Codes: C04B 2235/81 Materials characterised by the absence of phases other than the main phase, i.e. single phase materials
• CPC Class Codes: C04B 2235/95 Products characterised by their size, e.g. microceramics
• CPC Class Codes: C04B 35/52 based on carbon, e.g. graphite
• CPC Class Codes: C04B 35/645 Pressure sintering
• CPC Class Codes: C30B 1/12 by pressure treatment during the growth
• CPC Class Codes: C30B 29/02 Elements
• CPC Class Codes: C30B 29/04 Diamond

Abstract

A method capable of obtaining pure single phase hexagonal diamond in an industrially usable size (bulk) is provided. Highly oriented and highly crystallized graphite having a mosaic spread of 5° or less is used as a starting material, and is subjected to a temperature ranging from 1000 to 1500° C. at a pressure ranging from 20 to 25 GPa. The size of the bulk sintered body of pure single-phase hexagonal diamond obtained by this method depends on the size of the starting graphite. However, as long as the pressure and temperature can be entirely provided (i.e., as long as the adequate high pressure and temperature are applied to the sample chamber of high pressure apparatus), any desired size can be obtained.

Claims

1. A method of manufacturing a bulk sintered body of pure single-phase hexagonal diamond, wherein highly oriented and highly crystallized graphite having a mosaic spread of 5°

or less kept at a temperature ranging from 1000 to 1500°

C. and at a pressure of at least 21 GPa for a time period ranging from 1 to 60 min.

2. The method of manufacturing a bulk sintered body of pure single-phase hexagonal diamond according to claim 1, wherein the highly oriented and highly crystallized graphite has a mosaic spread of 1°

or less.

3. The method of manufacturing a bulk sintered body of pure single-phase hexagonal diamond according to claim 2, wherein the pressure is at least 22 GPa, and the temperature ranges from 1200 to 1400°

C.

4. The method of manufacturing a bulk sintered body of pure single-phase hexagonal diamond according to claim 3, wherein the time period ranges from 1 to 20 min.

5. The method of manufacturing a bulk sintered body of pure single-phase hexagonal diamond according to claim 2, wherein the time period ranges from 1 to 20 min.

6. The method of manufacturing a bulk sintered body of pure single-phase hexagonal diamond according to claim 1, wherein the pressure is at least 22 GPa, and the temperature ranges from 1200 to 1400°

C.

7. The method of manufacturing a bulk sintered body of pure single-phase hexagonal diamond according to claim 6, wherein the time period ranges from 1 to 20 min.

8. The method of manufacturing a bulk sintered body of pure single-phase hexagonal diamond according to claim 1, wherein the time period ranges from 1 to 20 min.