Indenter made of polycrystalline diamond, and method and apparatus using the same for evaluating crack initiation load

Patent metadata

Field	Value
Publication number	US-11041791-B2
Application number	US-201816306079-A
Country	US
Kind code	B2
Filing date	Mar 29, 2018
Priority date	Aug 10, 2017
Publication date	Jun 22, 2021
Grant date	Jun 22, 2021

Abstract

An indenter is made of polycrystalline diamond and has a tip having a spherical surface with a radius of 10 to 2000 μm.

First claim

The invention claimed is:

1. An indenter made of polycrystalline diamond and having a tip having a spherical surface with a radius of 10 to 2000 μm, wherein the spherical surface of the tip is a portion with a roundness measured according to JIS B 0621 of 0.001 μm or more and 0.05 μm or less.

2. The indenter according to claim 1 , wherein the spherical surface of the tip is a portion with a surface roughness Ra measured according to ISO 25178 of 0.0001 μm or more and 0.03 μm or less.

3. The indenter according to claim 1 , wherein the polycrystalline diamond further includes boron.

4. The indenter according to claim 3 , wherein the proportion of the boron is 100 ppm or more and less than 10000 ppm.

5. A method for evaluating a load which cracks a test piece including a hard material having a diamond-like crystal structure, comprising the steps of:
fixing the test piece at a predetermined location and bringing a tip of the indenter according to claim 1 into contact with a surface of the test piece;
applying a load increasing with time to the indenter in a direction perpendicular to the surface of the test piece toward the surface of the test piece; and
recording a load applied when the test piece has the surface cracked by the indenter.

6. The method according to claim 5 , wherein the hard material includes diamond or cubic boron nitride.

7. The method according to claim 5 , further comprising:
in the step of applying a load to the indenter, detecting a frequency spectrum of oscillation of the test piece, and
in the step of recording the load, removing a signal of a noise component, based on a frequency of a threshold preset in order to separate a signal attributed to cracking and a signal attributed to the noise component, to detect and record the signal attributed to the cracking.

8. An evaluation apparatus for evaluating a load which cracks a test piece including a hard material having a diamond-like crystal structure, comprising:
an indenter according to claim 1 ;
a test table allowing a test piece including a hard material having a diamond-like crystal structure to be fixed thereto at a predetermined location;
a load application unit configured to apply a load increasing with time to the indenter in a direction perpendicular to a surface of the test piece toward the surface of the test piece;
a detector configured to detect a frequency spectrum of oscillation of the test piece; and
a recorder configured to record the load and the frequency spectrum.

Assignees

• Sumitomo Electric Industries

Inventors

• Hamaki Kensei
• Yamamoto Katsuko
• Sumiya Hitoshi
• Ishida Yuh

Classifications

• C01B32/26 Primary

  Preparation (by using ultra-high pressure B01J3/06; by crystal growth C30B29/04) · CPC title

• G01N2203/0019

  Compressive · CPC title

• C04B2235/425

  Graphite · CPC title

• G01N2203/0647

  Image analysis · CPC title

• G01N2203/0078

  using indentation · CPC title