阅读说明：本技术 用于去除聚晶金刚石复合片中金属钴的电解方法和装置 (Electrolytic method and device for removing metallic cobalt in polycrystalline diamond compact ) 是由 谭松成 杨颖� 方小红 段隆臣 高辉 潘秉锁 于 2021-06-29 设计创作，主要内容包括：本发明公开了一种用于去除聚晶金刚石复合片中金属钴的电解方法,包括以下步骤：将电解聚晶金刚石脱钴的电解池置于超声波环境中进行电解反应；本发明还公开了一种用于去除聚晶金刚石复合片中金属钴的电解装置,包括：外壳、介质水、超声波发生器和电解池,所述外壳内盛装所述介质水、所述超声波发生器和所述电解池,所述电解池由阳极聚晶金刚石复合片、阴极惰性电极、电解液、电源和内壳组成。本发明通过超声波声强及时清除电极表面附着物,有效增加了腐蚀速率,得到的聚晶金刚石复合片的钴含量小于1.03％,低于普通环境下电解的钴含量。(The invention discloses an electrolysis method for removing metallic cobalt in a polycrystalline diamond compact, which comprises the following steps: placing an electrolytic cell for electrolyzing the polycrystalline diamond to remove cobalt in an ultrasonic environment for electrolytic reaction; the invention also discloses an electrolysis device for removing metallic cobalt in the polycrystalline diamond compact, which comprises: the electrolytic cell comprises an anode polycrystalline diamond compact, a cathode inert electrode, electrolyte, a power supply and an inner shell. According to the invention, the attachments on the surface of the electrode are removed in time through ultrasonic sound intensity, the corrosion rate is effectively increased, and the cobalt content of the obtained polycrystalline diamond compact is less than 1.03 percent and is lower than the electrolytic cobalt content in a common environment.)

1. An electrolytic method for removing metallic cobalt from a polycrystalline diamond compact, comprising the steps of: and placing the electrolytic cell for electrolyzing the polycrystalline diamond to remove cobalt in an ultrasonic environment for electrolytic reaction.

2. The electrolytic method for removing metallic cobalt from a polycrystalline diamond compact of claim 1, wherein the conditions of the electrolytic reaction comprise: the ultrasonic power is 0.1-2.0kW, the working frequency is 20-50kHz, the voltage is 0-8V, the temperature is 20-40 ℃, and the time is 5-40 h.

3. The electrolytic method for removing metallic cobalt from a polycrystalline diamond compact of claim 1, wherein the cemented carbide substrate of the polycrystalline diamond compact is treated with a silica gel insulation pack.

4. The electrolytic method for removing metallic cobalt from a polycrystalline diamond compact of claim 1, wherein the electrolytic cell uses the polycrystalline diamond compact as an anode and an inert electrode as a cathode, the electrolyte in the electrolytic cell is composed of an aqueous solution of sodium chloride and an aqueous solution of potassium chloride, and the cathode and the anode are respectively immersed in the electrolyte after being connected with a power supply.

5. The electrolytic method for removing metallic cobalt from a polycrystalline diamond compact of claim 4, wherein the inert electrode is one of stainless steel, copper, or platinum.

6. The electrolytic method for removing metallic cobalt from a polycrystalline diamond compact of claim 4, wherein the electrolyte solution comprises sodium chloride at a concentration of 1-10g/100mL and potassium chloride at a concentration of 1-20g/100 mL.

7. The electrolytic method according to claim 4, wherein after the electrolysis reaction is completed, the polycrystalline diamond compact is taken out, cleaned with distilled water in an ultrasonic environment, and dried.

8. An electrolytic device for removing metallic cobalt from a polycrystalline diamond compact, comprising: the electrolytic cell comprises an anode polycrystalline diamond compact, a cathode inert electrode, electrolyte, a power supply and an inner shell.

9. The electrolyzer of claim 8 wherein a heater rod is further disposed within the housing, the heater rod being connected to a temperature controller.

Technical Field

The invention relates to the technical field of cobalt removal of diamond compacts. More particularly, the present invention relates to an electrolytic method and apparatus for removing metallic cobalt from polycrystalline diamond compacts.

Background

Polycrystalline Diamond Compacts (PDC) are formed by sintering diamond particles and a sintering catalyst on a cemented carbide substrate at high temperature and high pressure, wherein metallic cobalt is a common sintering catalyst. Because the thermal expansion coefficients of the metal cobalt and the diamond particles are different greatly, the PDC can be damaged by heat in the working process, and the metal cobalt can catalyze the carbon to be converted from the diamond state to the graphite state at high temperature, so that the service life of the PDC is shortened, and therefore, the metal cobalt in the PDC needs to be removed by adopting a necessary means before the PDC is used.

Among the existing cobalt removal methods, the electrolytic cobalt removal method has the advantages of small pollution, mild reaction, low cost and the like. However, in the current electrolytic cobalt removal research, the electrolytic cobalt removal effect is poor, and the wear resistance of the polycrystalline diamond compact cannot be well improved.

Disclosure of Invention

An object of the present invention is to solve at least the above problems and to provide at least the advantages described later.

The invention also aims to provide an electrolysis method for removing metallic cobalt in the polycrystalline diamond compact, the cobalt removal treatment of the polycrystalline diamond compact by adopting the electrolysis method can increase the corrosion efficiency of the metallic cobalt in the diamond layer, remove the attachments on the surface of the anode generated in the electrolysis process in time, and ensure that the cobalt content of the cobalt-removed diamond layer is 1.03%. The invention also provides an electrolysis device for removing the metallic cobalt in the polycrystalline diamond compact.

To achieve these objects and other advantages in accordance with the purpose of the invention, an electrolytic method for removing metallic cobalt from a polycrystalline diamond compact is provided, comprising the steps of: and placing the electrolytic cell for electrolyzing the polycrystalline diamond to remove cobalt in an ultrasonic environment for electrolytic reaction.

Preferably, the conditions of the electrolysis reaction include: the ultrasonic power is 0.1-2.0kW, the working frequency is 20-50kHz, the voltage is 0-8V, the temperature is 20-40 ℃, and the time is 5-40 h.

Preferably, the hard alloy substrate of the polycrystalline diamond compact is treated with a silica gel insulation coating.

Preferably, the polycrystalline diamond compact is used as an anode of the electrolytic cell, the inert electrode is used as a cathode of the electrolytic cell, the electrolyte in the electrolytic cell is composed of a sodium chloride aqueous solution and a potassium chloride aqueous solution, and the cathode and the anode are respectively immersed in the electrolyte after being connected with a power supply.

Preferably, the inert electrode is made of one of stainless steel, copper or platinum.

Preferably, the concentration of sodium chloride in the electrolyte is 1-10g/100mL, and the concentration of potassium chloride is 1-20g/100 mL.

Preferably, after the electrolysis reaction is finished, the polycrystalline diamond compact is taken out, cleaned by using distilled water in an ultrasonic environment, and dried.

The invention also provides an electrolysis device for removing metallic cobalt in the polycrystalline diamond compact, which comprises: the electrolytic cell comprises an anode polycrystalline diamond compact, a cathode inert electrode, electrolyte, a power supply and an inner shell.

Preferably, a heating rod is further arranged in the shell, and the heating rod is connected with a temperature controller.

The invention at least comprises the following beneficial effects:

in the process of carrying out the electrolytic reaction, the invention adopts common inorganic salt as the electrolyte, and has the advantages of environmental protection, safety and good economic benefit compared with other acidic or alkaline electrolytes;

before the electrolytic reaction, the hard alloy substrate is wrapped by silica gel to avoid contacting electrolyte, so that the hard alloy substrate of the polycrystalline diamond composite sheet is prevented from being corroded;

the 'cavity' effect of ultrasonic sound intensity can eliminate uneven local concentration in the electrolytic process, improve the reaction speed, stimulate the formation of new phases and play a role in shearing aggregates;

the ultrasonic wave can play a role in promoting the anode reaction in the electrolytic cobalt removal of the polycrystalline diamond compact;

the ultrasonic wave continuously cleans the surface of the electrode in the electrolytic process, so that the metal cobalt is not covered and shielded by attachments, the dissolving degree of the metal cobalt on the surface is increased, and the reaction rate is accelerated.

Additional advantages, objects, and features of the invention will be set forth in part in the description which follows and in part will become apparent to those having ordinary skill in the art upon examination of the following or may be learned from practice of the invention.

Drawings

FIG. 1 is an as-received scanning electron micrograph of an untreated PDC according to example 1 of the present invention;

FIG. 2 is a diagram of the distribution of elements of FIG. 1;

FIG. 3 is a diagram of the energy spectrum peak and the content of each element in FIG. 1 and FIG. 2;

FIG. 4 is Tafel anode polarization curve of example 2 of the present invention, in which two curves represent the electrolysis effect in the ultrasonic electrolysis environment and the normal electrolysis environment, respectively;

FIG. 5 is a scanning electron microscope image of the PDC after ultrasonic electrolysis in example 3 of the present invention;

FIG. 6 is a diagram of the corresponding elements of FIG. 5;

FIG. 7 is a diagram of the energy spectrum peaks and contents of the elements in FIGS. 5 and 6;

FIG. 8 is a scanning electron micrograph of a PDC after general electrolysis according to example 4 of the present invention;

FIG. 9 is a graph of the corresponding element distribution of FIG. 8;

FIG. 10 is a diagram of the peak energy spectrum and the content of each element in FIGS. 8 and 9;

FIG. 11 is a schematic view of the structure of an ultrasonic electrolyzing apparatus according to the present invention.

Detailed Description

The invention provides an electrolysis method for removing metallic cobalt from a polycrystalline diamond compact, which comprises the step of placing an electrolytic cell for electrolyzing polycrystalline diamond to remove cobalt in an ultrasonic environment for an electrolysis reaction, wherein the ultrasonic electrolysis method is suitable for the acidic, neutral or alkaline environment. Wherein the electrolytic cell is composed of: taking a PCD layer of the polycrystalline diamond compact as an anode; the copper sheet is taken as a cathode, and the cathode and the anode are respectively immersed in the electrolyte after being connected with a power supply.

In the present invention, the conditions of the electrolysis reaction include: the ultrasonic power is 0.1-2.0kW, the working frequency is 20-50kHz, the voltage is 0-8V, the temperature is 20-40 ℃, and the time is 5-40 h.

In the invention, in order to avoid the corrosion of the hard alloy substrate of the polycrystalline diamond compact, the hard alloy substrate is wrapped by silica gel before the electrolytic reaction is carried out so as to avoid the contact with electrolyte. During electrolysis, all metal catalysts in the PDC composite sheet can be electrolyzed, not only cobalt, which is the most commonly used metal catalyst, and thus, the skilled artisan conventionally considers the process of removing the catalyst as a decobalting treatment.

In the invention, the 'cavity' action of ultrasonic sound intensity can eliminate uneven local concentration in the electrolytic process, improve the reaction speed, stimulate the formation of new phases and play a role in shearing aggregates generated in the electrolytic reaction process. The agglomerates refer to hydroxides or chlorides formed by metal cations generated during electrolysis and anions in a solution, and are agglomerated or flocculent to some extent.

According to the invention, an electrochemical workstation is used for measuring a Tafel anode polarization curve in a long potential interval, and the result shows that the electrolytic reaction of the polycrystalline diamond compact is more violent in an ultrasonic environment, and the ultrasonic wave can play a role in promoting the anode reaction in the electrolytic cobalt removal of the polycrystalline diamond compact.

In the invention, after the electrolytic reaction is finished, the polycrystalline diamond compact is taken out, the surface of the polycrystalline diamond compact is cleaned by distilled water in an ultrasonic environment, and the polycrystalline diamond compact is dried. The surface of the polycrystalline diamond compact electrolyzed in the ultrasonic environment is free of attachments, and the ultrasonic wave continuously cleans the surface of the electrode in the electrolysis process, so that the metal cobalt is not covered and shielded by the attachments, the dissolution degree of the metal cobalt on the surface is increased, and the reaction rate is accelerated.

The present invention is further described in detail below with reference to examples so that those skilled in the art can practice the invention with reference to the description.

It is to be noted that the experimental methods described in the following embodiments are all conventional methods unless otherwise specified, and the reagents and materials are commercially available unless otherwise specified.

Evaluating the influence of ultrasonic waves on the removal of metal cobalt from the polycrystalline diamond by using a volt-ampere linear scanning method of an electrochemical workstation; the porosity after cobalt removal is analyzed and calculated by a femaly scanning electron microscope and ImageJ2x software, and the weight percentages of the elements before and after cobalt removal are determined by a field emission scanning electron microscope

< example 1>

Polycrystalline diamond compacts that have not been subjected to an electrolytic decobalting process are polycrystalline diamond compacts that we have purchased commercially.

The polycrystalline diamond compact without electrolytic cobalt removal treatment has the weight percentage of cobalt of 6.13 and the weight percentage of zirconium of 4.16, as shown in figures 1-3.

< example 2>

The polycrystalline diamond compact is used as an anode, copper is used as a cathode, and a saturated calomel electrode is used as a reference electrode. The concentration of sodium chloride in the electrolyte is 1-10g/100mL, and the concentration of potassium chloride is 1-20g/100 mL. The initial potential was set at-8.0V relative to the reference electrode and the final potential was 8.0V. As shown in fig. 4, in a common environment, as the electrode potential increases, the corrosion current density of the polycrystalline diamond compact is basically unchanged and tends to be a horizontal straight line, the electrode reaction is very weak, and the polycrystalline diamond compact is purchased commercially in the common environment. However, when the polycrystalline diamond compact is electrolyzed in an ultrasonic environment, when the electrode potential tends to a positive value, the corrosion current of the anodic polarization curve starts to increase obviously, and the electrode reaction is severe. The higher the current density is, the faster the electrolysis speed is, that is to say, under the ordinary electrolysis condition, the electrolysis speed is almost zero under the tested voltage condition, and under the ultrasonic environment, the electrolysis speed is obviously improved within the voltage range of 0-3V.

< example 3>

The polycrystalline diamond compact is used as an anode, and the copper is used as a cathode. The electrolyte comprises the following components: 3g/100mL of sodium chloride and 5g/100mL of potassium chloride. Electrolyzing under ultrasonic environment, wherein the voltage of the constant voltage source is 3V, and the electrolysis time is 12 h. And cleaning the polycrystalline diamond for 4 hours after electrolysis, and drying for 2 hours. After cobalt removal, the weight percentage of cobalt is 1.03%, the weight percentage of zirconium is 2.14, and no oxide is attached, as shown in fig. 5-7.

< example 4>

The polycrystalline diamond compact is used as an anode, and the copper is used as a cathode. The electrolyte comprises the following components: 3g/100mL of sodium chloride and 5g/100mL of potassium chloride. And electrolyzing under a common environment, wherein the voltage of the constant voltage source is 3.5V, and the electrolysis time is 36 h. And cleaning the polycrystalline diamond for 4 hours after electrolysis, and drying for 2 hours. After cobalt removal, the weight percentage of cobalt is 8.29, the weight percentage of oxygen is 11.04, the cobalt and the zirconium are in cross distribution, the weight percentage of zirconium is 1.44, and the oxide adhesion is obvious, as shown in figures 8-10.

After cobalt removal is completed in examples 3 to 4, the ratio of each element in the polycrystalline diamond compact is shown in table 1.

TABLE 1

As can be seen from fig. 1 to 10 and table 1, the method of the present invention has a good cobalt removal effect on a polycrystalline diamond compact by electrolysis, the corrosion current increase in an ultrasonic environment is significant, the surface porosity is increased, the attachment is reduced, and the cobalt weight percentage is 1.03%, which indicates that the present invention has a good cobalt removal effect.

The invention also provides an electrolysis device for removing metallic cobalt in a polycrystalline diamond compact, as shown in fig. 11, comprising: the electrolytic cell comprises an outer shell 1, medium water 2, an ultrasonic generator 3 and an electrolytic cell, wherein the outer shell 1 is internally filled with the medium water 2, the ultrasonic generator 3 and the electrolytic cell, and the electrolytic cell consists of an anode polycrystalline diamond compact 4, a cathode inert electrode 5, electrolyte 6, a power supply and an inner shell 7. Still be provided with heating rod 8 in the shell 1, heating rod 8 is connected with temperature controller 9.

While embodiments of the invention have been described above, it is not limited to the applications set forth in the description and the embodiments, which are fully applicable to various fields of endeavor for which the invention may be embodied with additional modifications as would be readily apparent to those skilled in the art, and the invention is therefore not limited to the details given herein and to the embodiments shown and described without departing from the generic concept as defined by the claims and their equivalents.