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Pre-graphitized polycrystalline diamond compact

A technology of polycrystalline diamond and graphitization, which is applied in the direction of metal layered products, chemical instruments and methods, layered products, etc., can solve the problems of poor affinity, diamond single crystal falling off, easy falling off, etc. Long service life and strong bonding effect

Inactive Publication Date: 2015-04-29
莱州市原野科技有限公司
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

This kind of diamond composite sheet has made contributions to oil drilling and drilling engineering, but it also has the following disadvantages or shortcomings: ① After the diamond composite sheet is synthesized, the affinity of various materials is poor, the combination is not firm, and it is easy to be damaged; ②Diamond single crystal The synthesized polycrystalline layer contains metal cobalt, tungsten and other added substances. When the polycrystalline layer cuts the formation under high pressure and high temperature, the metal material in the polycrystalline layer is heated and expanded. Because its expansion coefficient is different from that of diamond, the diamond single 3. The cobalt, nickel and other iron group elements in the polycrystalline layer will catalyze when heated, so that the diamond single crystal will be rapidly graphitized and lose its wear resistance; 4. The most commonly used is currently Use strong acid to corrode the metal in the polycrystalline layer of the composite sheet, which is also commonly referred to as the decobalt pickling process
Although this process can greatly reduce the metal substances such as cobalt in the polycrystalline layer, it cannot completely remove the cobalt metal contained in the polycrystalline layer, and the remaining cobalt will be destructive under high temperature and high pressure.
After the cobalt metal in the polycrystalline layer is acid-washed, the polycrystalline layer forms a large number of void space structures, which are easy to fall off, and secondly, when cobalt meets the stratum with very fine particles, cuttings accumulate in the polycrystalline layer In the gap, heating and expansion will cause the diamond single crystal to fall off due to heat, which directly affects the firmness and service life of the diamond composite sheet

Method used

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Examples

Experimental program
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Effect test

specific Embodiment 1

[0015] The synthesis process is as follows: (1) After the diamond single crystal is cleaned, it is placed in a vacuum furnace and heated at 10 -2 In a vacuum of Pa, heat to 1350°C to make the surface of the diamond single crystal evenly pre-graphitized: (2) Put the graphitized diamond single crystal and the cemented carbide substrate 1 into the pyrophyllite synthesis chamber of the metal cup, Under the pressure of 5Gpa in the synthesis cavity and the cavity temperature of 1000 degrees Celsius, the pre-graphitized diamond single crystal is converted into diamond again under the action of high temperature and high pressure. (3) After the pre-graphitized diamond single crystal is fully transformed and grown into a polycrystalline layer, the temperature in the cavity is increased to 1400 °C, and the cemented carbide substrate 1 The cobalt metal contained in it melts and diffuses to the surface layer between the diamond single crystal polycrystalline layer 2 and the cemented carbid...

Embodiment 2

[0017] The synthesis process is as follows: (1) After the diamond single crystal is cleaned, it is placed in a vacuum furnace and heated to 1400°C in a vacuum of 0.15 Pa to make the surface of the diamond single crystal evenly pre-graphitized: (2) Graphitize The diamond single crystal and the cemented carbide substrate 1 are put into the pyrophyllite synthesis chamber of the metal cup. Under the pressure of 6Gpa in the synthesis chamber and the chamber temperature of 1100 degrees Celsius, the pre-graphitized diamond single crystal is subjected to high temperature and high pressure. Next, it is converted to diamond again, and the graphite on the surface of the diamond single crystal grows into a diamond polycrystalline layer with a dense structure together with the single crystal graphite at the junction while it is converted into diamond; (3) the diamond single crystal to be pre-graphitized After fully transforming and growing into a polycrystalline layer, the temperature in th...

Embodiment 3

[0019] The synthesis process is as follows: (1) After cleaning the diamond single crystal, place it in a vacuum furnace and heat it to 1450°C in a vacuum of 0.02 Pa to make the surface of the diamond single crystal evenly pre-graphitized: (2) Graphitize The diamond single crystal and the cemented carbide substrate 1 are put into the pyrophyllite synthesis chamber of the metal cup. Under the pressure of 7Gpa in the synthesis chamber and the chamber temperature of 1200 degrees Celsius, the pre-graphitized diamond single crystal is subjected to high temperature and high pressure. Next, it is converted to diamond again, and the graphite on the surface of the diamond single crystal grows into a diamond polycrystalline layer with a dense structure together with the single crystal graphite at the junction while it is converted into diamond; (3) the diamond single crystal to be pre-graphitized After fully transforming and growing into a polycrystalline layer, the temperature in the cha...

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Abstract

The invention provides a pre-graphitized polycrystalline diamond compact. A diamond single crystal polycrystalline layer covers a hard alloy substrate and is synthesized by a diamond single crystal and hard alloy at a high temperature under a high pressure. The process comprises the following steps: putting the diamond single crystal into a vacuum furnace, heating to 1350 to 1450 DEG C in a vacuum of 0.01 to 0.02Pa, and after pre-graphitizing the surface of the diamond single crystal, growing a polycrystalline diamond layer together with contacting single crystal graphite by use of the diamond single crystal and the hard alloy substrate while converting graphite into diamond under a pressure of 5 to 7GPa and at a temperature of 1000 to 1200 DEG C in a metal cup pyrophyllite synthesis cavity; and after growing the polycrystalline diamond layer, raising the temperature in the cavity to 1400 to 1500 DEG C, forming a surface adhesive layer which only has a bonding effect between the polycrystalline layer of the diamond single crystal and the hard alloy substrate, and bonding the polycrystalline diamond layer on the hard alloy substrate, thereby synthesizing the pre-graphitized polycrystalline diamond compact.

Description

technical field [0001] The invention relates to a diamond composite sheet for an oil drilling PDC drill bit, in particular to a pre-graphitized polycrystalline diamond composite sheet. Background technique [0002] At present, PDC drill bits for oil drilling mainly rely on diamond compact (PDC) to cut formations, which are generally cemented carbide, that is, a structure formed by sintering tungsten carbide, cobalt and other trace metals. This kind of diamond composite sheet has made contributions to oil drilling and drilling engineering, but it also has the following disadvantages or shortcomings: ① After the diamond composite sheet is synthesized, the affinity of various materials is poor, the combination is not firm, and it is easy to be damaged; ②Diamond single crystal The synthesized polycrystalline layer contains metal cobalt, tungsten and other added substances. When the polycrystalline layer cuts the formation under high pressure and high temperature, the metal mater...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): E21B10/46B32B9/04B32B15/04B22F7/06
CPCE21B10/46B22F7/06B32B9/04B32B15/04
Inventor 王克行
Owner 莱州市原野科技有限公司
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