Method of preparing a multimodal cubic boron nitride powder
View Patent ↗Multi-step milling processes to prepare cBN composite powder forms a first powder mixture by adding a binder and a first cBN component, mills the first powder mixture for a first time period, combines a second cBN component with the milled first powder mixture to form a second powder mixture, and mills the second powder mixture for a second time period (less than the first time period) to form the cBN composite powder. A ratio of the D50 value of the second cBN component to the D50 value of the first cBN component is at least 3.0. Two-step milling with different milling times for the two cBN component fractions controls the amount of mill debris in the cBN composite powder mixture. Further processing of the cBN composite powder under HPHT conditions forms a cBN-based ceramic with an average value of a cBN particle free diameter of less than 2.0 microns.
1. A method of preparing a cBN composite powder in a multi-step milling process with controlled milling debris production, the method comprising:
forming a first powder mixture by adding one or more binder component materials and a first cBN component to milling equipment, the one or more binder component materials having an initial D50 particle size;
milling the first powder mixture for a first milling time suitable to reduce the initial D50 particle size at least 50%;
combining a second cBN component with the milled first powder mixture to form a second powder mixture; and
milling the second powder mixture for a second milling time to form the cBN composite powder, the second milling time less than the first milling time,
wherein a ratio of the D50 value of the second cBN component to the D50 value of the first cBN component is at least 3.
2. The method of claim 1 , the method further comprising premilling the binder component before forming the first powder mixture.
3. The method according to claim 1 , wherein the D50 value of the first cBN component is between 0.2 micron and 2.0 microns and wherein the D50 value of the second cBN component is between 1.2 micron and 6.0 microns.
4. The method according to claim 1 , wherein the milled binder component materials include powders having a composition that is selected from the group consisting of oxides, nitrides, and carbides of Group IV, V and VI elements of the periodic table and combinations thereof.
5. The method according to claim 4 , wherein the milled binder component materials further include a composition that is selected from the group consisting of TiN, TiC, Ti(C,N), ZrN, Co, Al, and mixtures thereof.
6. The method according to claim 1 , wherein cBN is present in the milled second powder mixture in an amount between 5 and 70 wt %.
7. The method according to claim 1 , wherein the ratio of the mass of the first cBN component to the mass of the second cBN component is in a range from 0.04 to 2.0.
8. The method according to claim 7 , wherein the ratio of the mass of the first cBN component to the mass of the second cBN component is less than 0.11.
9. The method according to claim 7 , wherein the ratio of the mass of the first cBN component to the mass of the second cBN component is greater than 1.0.
10. The method according to claim 1 , wherein the cBN composite powder has a multimodal particle size distribution.
11. The method according to claim 1 , wherein the ratio of the D50 value of the second cBN component to the D50 value of the first cBN component is in a range of 3.0 to 10.
12. The method according to claim 11 , wherein the D50 value of the first cBN component is between 0.2 micron and 2.0 microns and wherein the D50 value of the second cBN component is between 1.2 micron and 6.0 microns.
13. The method according to claim 11 , wherein the ratio of the D50 value of the second cBN component to the D50 value of the first cBN component is in a range of 4.0 to 6.0.
14. A method of forming a cBN-based ceramic from a cBN composite powder that is prepared in a multi-step milling process with controlled milling debris production, the method comprising:
forming a first powder mixture by adding one or more binder component materials and a first cBN component to milling equipment;
milling the first powder mixture for a first time period;
combining a second cBN component with the milled first powder mixture to form a second powder mixture;
milling the second powder mixture for a second time period to form the cBN composite powder; and
forming a cBN-based ceramic by subjecting the cBN composite powder to a HPHT process,
wherein the first cBN component has a first D50 value and the second cBN component has a second D50 value,
wherein a ratio of the second D50 value to the first D50 value is at least 3,
wherein the cBN-based ceramic has an average value of cBN particle free diameter of less than 2.0 microns, and
wherein the ratio of the mass of the first cBN component to the mass of the second cBN component is in a range from 0.04 to 0.11.
15. The method of claim 14 , further comprising premilling the binder component before forming the first powder mixture.
16. The method according to claim 14 , wherein the standard deviation of the cBN particle free diameter is less than 0.35 micron.
17. The method according to claim 14 , wherein the first D50 value is between 0.2 micron and 2.0 microns and wherein the second D50 value is between 1.2 micron and 6.0 microns.
18. The method according to claim 14 , wherein the binder component materials include powders having a composition that is selected from the group consisting of oxides, nitrides, and carbides of Group IV, V and VI elements of the periodic table and combinations thereof.
19. The method according to claim 14 , wherein the binder component materials further include a composition that is selected from the group consisting of TiN, TiC, Ti(C,N), ZrN, Co, Al, and mixtures thereof.
20. The method according to claim 14 , wherein cBN is present in the milled second powder mixture in an amount between 5 and 70 wt %.
21. The method according to claim 14 , wherein the cBN composite powder has a multimodal particle size distribution.
22. The method according to claim 14 , wherein the ratio of the second D50 value to the first D50 value is in a range of 3.0 to 10.
23. The method according to claim 22 , wherein the first D50 value is between 0.2 micron and 2.0 microns and wherein the second D50 value is between 1.2 micron and 6.0 microns.
24. The method according to claim 23 , wherein the standard deviation of the cBN particle free diameter is less than 0.35 micron.
25. The method according to claim 14 , wherein the cBN-based ceramic has an average value of cBN particle free diameter of less than 1.5 micron.
26. The method according to claim 25 , wherein the cBN-based ceramic has an average value of cBN particle free diameter of less than 1.0 micron.
27. The method according to claim 26 , wherein the cBN-based ceramic has an average value of cBN particle free diameter of less than 0.90 micron.
28. The method according to claim 16 , wherein the standard deviation of the cBN particle free diameter is less than 0.30 micron.
29. The method according to claim 28 , wherein the standard deviation of the cBN particle free diameter is less than 0.20 micron.
30. The method according to claim 29 , wherein the standard deviation of the cBN particle free diameter is less than 0.15 micron.
31. The method according to claim 22 , wherein the ratio of the second D50 value to the first D50 value is in a range of 4.0 to 6.0.
32. The method according to claim 24 , wherein the standard deviation of the cBN particle free diameter is less than 0.30 micron.
33. The method according to claim 32 , wherein the standard deviation of the cBN particle free diameter is less than 0.20 micron.
34. The method according to claim 33 , wherein the standard deviation of the cBN particle free diameter is less than 0.15 micron.
35. A method of preparing a cBN composite powder in a multi-step milling process with controlled milling debris production, the method comprising:
forming a first powder mixture by adding one or more binder component materials and a first cBN component to milling equipment, the one or more binder component materials having an initial D50 particle size;
milling the first powder mixture for a first milling time suitable to reduce the initial D50 particle size at least 90%;
combining a second cBN component with the milled first powder mixture to form a second powder mixture; and
milling the second powder mixture for a second milling time to form the cBN composite powder, the second milling time less than the first milling time,
wherein a ratio of the D50 value of the second cBN component to the D50 value of the first cBN component is at least 3.
36. A method of preparing a cBN composite powder in a multi-step milling process with controlled milling debris production, the method comprising:
forming a first powder mixture by adding one or more binder component materials and a first cBN component to milling equipment, the one or more binder component materials having an initial D50 particle size;
milling the first powder mixture for a first milling time suitable to reduce the initial D50 particle size at least 50%;
combining a second cBN component with the milled first powder mixture to form a second powder mixture; and
milling the second powder mixture for a second milling time to form the cBN composite powder, the second milling time less than the first milling time,
wherein a ratio of the D50 value of the second cBN component to the D50 value of the first cBN component is at least 3, and
wherein the ratio of the mass of the first cBN component to the mass of the second cBN component is less than 0.11.