Methods of forming polycrystalline diamond compacts
View Patent ↗Methods for forming cutting elements comprising polycrystalline materials, methods for forming polycrystalline compacts for cutting elements of a drilling tool, methods for forming polycrystalline diamond compacts, and resulting polycrystalline compacts and cutting elements are disclosed. Grains of a hard material are introduced to a press and subjected to a high-pressure, high-temperature (HPHT) process to sinter the grains. The system conditions (i.e., temperature and pressure) are then adjusted past a phase or state change point, after which, at least one of the system conditions is held during an anneal stage before the system conditions are adjusted to final levels. The resulting compacts and cutting elements may therefore include inter-granularly bonded hard material grains with a more stable microstructure (e.g., less stressed microstructure) than a polycrystalline compact and cutting element formed without an anneal stage during the HPHT process.
1. A method for forming a polycrystalline compact, the method comprising:
introducing grains of a hard material to a press;
elevating a system temperature to a plateau sintering temperature;
elevating a system pressure to a plateau sintering pressure;
lowering the system temperature to a hold temperature past a change point at a change point temperature, the hold temperature being lower than the change point temperature;
holding the system temperature at the hold temperature;
lowering the system temperature from the hold temperature to a second hold temperature past a second change point at a second change point temperature, the second hold temperature being lower than the second change point temperature;
holding the system temperature at the second hold temperature; and
lowering the system temperature to a final temperature.
2. A method for forming a polycrystalline compact, the method comprising:
introducing grains of a hard material to a press;
elevating a system temperature to a plateau sintering temperature;
elevating a system pressure to a plateau sintering pressure;
lowering the system temperature to a hold temperature past a change point at a change point temperature, the hold temperature being lower than the change point temperature;
holding the system temperature at the hold temperature;
lowering the system pressure to a hold pressure past the change point;
holding the system pressure at the hold pressure; and
lowering the system temperature to a final temperature.
3. The method of claim 2 , wherein holding the system pressure at the hold pressure is initiated simultaneously with holding the system temperature at the hold temperature.
4. A method for forming a polycrystalline compact, the method comprising:
introducing grains of a hard material to a press;
elevating a system temperature to a plateau sintering temperature;
elevating a system pressure to a plateau sintering pressure;
lowering the system temperature to a hold temperature past a change point at a change point temperature, the hold temperature being lower than the change point temperature;
holding the system temperature at the hold temperature;
lowering the system pressure while holding the system temperature at the hold temperature; and
lowering the system temperature to a final temperature.
5. A method for forming a polycrystalline compact for a cutting element of a drilling tool, the method comprising:
subjecting grains of a hard material to a press;
adjusting system conditions comprising a system temperature and a system pressure to plateau levels, comprising:
adjusting the system temperature to a plateau temperature; and
adjusting the system pressure to a plateau pressure;
sintering the grains of the hard material at the plateau levels;
adjusting at least one of the system conditions from the plateau levels past a eutectic point of the hard material to an anneal level;
holding at the anneal level the at least one of the system conditions adjusted to the anneal level; and
after holding the at least one of the system conditions at the anneal level, lowering the system conditions.
6. The method of claim 5 , wherein subjecting grains of a hard material to a press comprises subjecting coarse grains of the hard material and fine grains of the hard material to the press.
7. The method of claim 5 , wherein subjecting grains of a hard material to a press comprises subjecting grains of at least one of diamond and cubic boron nitride to the press.
8. The method of claim 5 , wherein adjusting at least one of the system conditions from the plateau levels past a eutectic point of the hard material to an anneal level comprises lowering the system temperature from the plateau levels past the eutectic point of the hard material to an anneal temperature below about 1320° C.
9. The method of claim 5 , wherein holding at the anneal level the at least one of the system conditions comprises holding at the anneal level the at least one of the system conditions for a duration in a range of about thirty seconds to about ten minutes.
10. A method for forming polycrystalline compact for a cutting element of a drilling tool, the method comprising:
subjecting grains of a hard material to a press;
adjusting system conditions comprising a system temperature and a system pressure to plateau levels, comprising:
adjusting the system temperature to a plateau temperature; and
adjusting the system pressure to a plateau pressure;
sintering the grains of the hard material at the plateau levels;
adjusting at least one of the system conditions from the plateau levels past a change point to an anneal level;
holding at the anneal level the at least one of the system conditions adjusted to the anneal level;
adjusting at least one of the system conditions from the anneal level past another change point to another anneal level;
holding at the another anneal level the at least one of the system conditions adjusted to the another anneal level; and
after holding the at least one of the system conditions at the another anneal level, lowering the system conditions.
11. The method of claim 10 , wherein adjusting at least one of the system conditions from the anneal level past another change point to another anneal level comprises lowering the system temperature from an anneal temperature of below about 1320° C. past the another change point to another anneal temperature of below about 800° C.
12. The method of claim 11 , wherein lowering the system temperature from an anneal temperature of below about 1320° C. past the another change point to another anneal temperature of below about 800° C. comprises lowering the system temperature from the anneal temperature of below about 1320° C. past the another change point to another anneal temperature of below about 650° C.
13. The method of claim 10 , wherein holding at the another anneal level the at least one of the system conditions adjusted to the another anneal level comprises holding at the another anneal level the at least one of the system conditions adjusted to the another anneal level for a duration in a range of about five minutes to about two hours.
14. The method of claim 10 , wherein holding at the another anneal level the at least one of the system conditions adjusted to the another anneal level comprises holding at the another anneal level the at least one of the system conditions adjusted to the another anneal level for a longer duration than that of holding at the anneal level the at least one of the system conditions adjusted to the anneal level.
15. The method of claim 10 , wherein:
subjecting grains of a hard material to a press comprises introducing diamond grains to a high-pressure high-temperature (HPHT) diamond press; and
sintering the grains of the hard material at the plateau levels comprises sintering the diamond grains in the HPHT diamond press to form a polycrystalline diamond material.
16. The method of claim 10 , wherein:
adjusting the system temperature to a plateau temperature comprises elevating the system temperature to which the grains are subjected to the plateau temperature;
adjusting the system pressure to a plateau pressure comprises elevating the system pressure to which the grains are subjected to the plateau pressure; and
adjusting at least one of the system conditions from the plateau levels past a change point to an anneal level comprises lowering at least one of the system temperature and the system pressure past the change point.
17. The polycrystalline compact of claim 16 , wherein elevating the system temperature to which the grains are subjected comprises elevating the system temperature to which grains comprising a multi-modal grain size distribution are subjected.
18. The method of claim 10 , wherein subjecting grains of a hard material to a press comprises subjecting the grains of the hard material to the press while in the presence of a catalyst material.