CN113385679A

CN113385679A - Method for preparing cobalt powder with high apparent density

Info

Publication number: CN113385679A
Application number: CN202110670029.0A
Authority: CN
Inventors: 董贵有; 张志平; 王朝安
Original assignee: Anhui Hanrui New Material Co ltd
Current assignee: Anhui Hanrui New Material Co ltd
Priority date: 2021-06-17
Filing date: 2021-06-17
Publication date: 2021-09-14
Anticipated expiration: 2041-06-17
Also published as: CN113385679B

Abstract

The invention discloses a method for preparing cobalt powder with high apparent density, which comprises the following steps: (1) filling the sponge cobalt prepared by the reduction process into a cold pressing die, and pressing to obtain a pressed blank; (2) crushing the obtained pressed blank by a crusher and sieving to obtain the product with the apparent density of 1.7g/cm³The above soft agglomerated cobalt powder; (3) putting the obtained soft agglomerated cobalt powder into a boat, placing the boat in a single-tube furnace, and carrying out low-temperature reduction sintering under hydrogen atmosphere; (4) crushing the reduced and sintered cobalt powder by a jet mill crusher to obtain the cobalt powder with the apparent density of 1.5g/cm³The above hard agglomerated cobalt powder. The cobalt powder prepared by the method has the advantages of over 50 percent of improved apparent density, uniform particle size distribution, low oxygen content and good fluidity.

Description

Method for preparing cobalt powder with high apparent density

Technical Field

The invention relates to the technical field of metal particle preparation, in particular to a method for preparing cobalt powder with high apparent density.

Background

Cobalt (Co) has excellent physical, chemical and mechanical properties and is the best overall binder in diamond tool applications. The cobalt powder produced by the reduction method is in a sponge shape after being discharged from a furnace, generally called sponge cobalt, the sponge cobalt is directly crushed to prepare the cobalt powder, and the apparent density of the cobalt powder is generally 1.0g/cm³About, the apparent density is less, has increased downstream customer to a great extent and has used the degree of difficulty in the application link, because less apparent density means have great volume under certain quality, need have great die cavity of charging when cold pressing is loaded, this design degree of difficulty and the system that has increased the cold pressing mouldManufacturing cost; therefore, under special conditions, the cobalt powder needs to be granulated, a granulating agent needs to be added in the granulating process, and the existence of the granulating agent can influence the processing technology of diamond tool products, the holding force of diamond, the wear resistance of tire bodies and the like, so that the application of the cobalt powder in the field of diamond tools is further limited.

Disclosure of Invention

In order to solve the technical problem of small apparent density of cobalt powder in the prior art, the invention provides a method for preparing cobalt powder with high apparent density.

The technical scheme adopted by the invention is as follows:

a method for preparing high apparent density cobalt powder comprises the following steps:

(1) filling the sponge cobalt prepared by the reduction process into a cold pressing die, and pressing to obtain a pressed blank;

(2) crushing the pressed blank obtained in the step (1) by a crusher and then sieving to obtain the product with the apparent density of 1.7g/cm³The above soft agglomerated cobalt powder;

(3) putting the soft agglomerated cobalt powder obtained in the step (2) into a boat, placing the boat in a single-tube furnace, and carrying out low-temperature reduction sintering in a hydrogen atmosphere;

(4) crushing the reduced and sintered cobalt powder by a jet mill crusher to obtain the cobalt powder with the apparent density of 1.5g/cm³The above hard agglomerated cobalt powder.

Preferably, the pressing pressure in the step (1) is 250-300 MPa, and the pressure is maintained for 2-5 seconds.

Preferably, the mesh number of the screen in the step (2) is 40-60 meshes.

Preferably, the boat loading amount in the step (3) is 2-3 kg/boat, the reduction temperature is 300-380 ℃, the reduction time is 150-200 min, and the hydrogen flow is 10-15 m³/h。

Preferably, the crushing frequency of the jet mill crusher in the step (4) is 30-36 HZ.

The invention has the beneficial effects that: according to the invention, soft agglomerated cobalt powder with a dendritic shape is obtained by pressing, crushing and sieving, and is subjected to low-temperature reduction sintering in a hydrogen atmosphere, so that sintering necks are generated inside the soft agglomerated cobalt powder to be connected to form thicker dendritic hard agglomerated cobalt powder, and the dendritic hard agglomerated cobalt powder is crushed by an airflow mill to obtain hard agglomerated cobalt powder with consistent size and shape and solid sphere shape of whole particles, so that the loose packing density of the cobalt powder is effectively improved, meanwhile, the fluidity of the cobalt powder is improved, and the oxygen content of the cobalt powder is reduced.

After the apparent density of the cobalt powder is improved, the apparent density of the cobalt powder is closer to that of metal powder such as copper, iron, nickel and the like commonly used by diamond tools, so that the design of a cold-pressing die is more convenient, and the designed die has higher universality; in addition, the cobalt powder is not required to be granulated, so that the method can be applied to more diamond tool products, and the application range of the cobalt powder is expanded.

After the fluidity of the cobalt powder is improved, the cobalt powder is distributed more uniformly in the manufacturing process of the diamond tool, so that the quality of the diamond tool product is more stable.

Because the cobalt powder is reduced at low temperature in the hydrogen atmosphere, the oxygen content of the cobalt powder is further reduced, the cobalt powder with low oxygen content is beneficial to stabilizing the sintering process of the diamond tool product, and the holding force of the cobalt-based matrix to diamond is improved.

Drawings

FIG. 1 is an electron micrograph of the soft agglomerated cobalt powder prepared in example 1.

FIG. 2 is an electron micrograph of a sintered hard agglomerated cobalt powder prepared in example 1.

FIG. 3 is an electron microscope image of the hard agglomerated cobalt powder prepared in example 1 after being pulverized by a jet mill pulverizer.

Detailed Description

In order to better understand the present invention, the following examples are further provided to illustrate the present invention, but the present invention is not limited to the following examples.

The quality detection standard of cobalt powder adopted in the following examples is as follows: GB/T26285-2010 superfine cobalt powder.

Example 1

(1) Taking 1kg of sponge cobalt obtained by a reduction method, and filling the sponge cobalt with the inner diameter of

Pressing the round cold pressing die into a pressing blank, controlling the pressure to be 300MPa, and maintaining the pressure for 5 seconds;

(2) pulverizing the pressed embryo in a pulverizer, and sieving with 60 mesh sieve to obtain product with apparent density of 1.75g/cm³The soft agglomerated cobalt powder;

(3) the prepared apparent density is 1.75g/cm³The soft agglomerated cobalt powder is put into a boat and put into a single tube furnace to be reduced and sintered under hydrogen atmosphere, and the soft agglomerated cobalt powder is changed into hard agglomerated cobalt powder; the loading amount is 2 kg/boat, the hydrogen flow is 12m³The reduction temperature is 380 ℃, and the reduction sintering time is 180 min;

(4) loading the reduced and sintered cobalt powder into a jet mill pulverizer, setting the pulverizing frequency to be 36HZ, and obtaining the apparent density of 1.66g/cm³Hard agglomerated cobalt powder.

The quality indexes of the prepared cobalt powder are shown in table 1:

TABLE 1

Serial number	Inspection item	Unit of	Actual measurement result
				1	Bulk density	g/cm³	1.66
2	Oxygen content	％	0.16
				3	Angle of repose	°	42.66

The prepared cobalt powder was observed microscopically, and the specific appearance shape is shown in fig. 1, fig. 2 and fig. 3.

As shown in fig. 1, the morphology of the soft agglomerated cobalt powder is dendritic; as shown in fig. 2, after sintering, the small branches become coarse, and more solidly connected dendritic hard agglomerated cobalt powder is formed; as shown in FIG. 3, the branched hard agglomerated cobalt powder was pulverized by a jet mill pulverizer to obtain a hard agglomerated cobalt powder having a uniform size and a solid particle.

Example 2

Pressing the round cold pressing die into a pressing blank, controlling the pressure to be 250MPa, and maintaining the pressure for 3 seconds;

(2) the pressed embryo is put into a pulverizer to be pulverized and sieved by a 40-mesh sieve to obtain the product with the apparent density of 1.7g/cm³The soft agglomerated cobalt powder;

(3) the apparent density is 1.7g/cm³The soft agglomerated cobalt powder is put into a boat and put into a single tube furnace to be reduced and sintered under hydrogen atmosphere, and the soft agglomerated cobalt powder is changed into hard agglomerated cobalt powder; the loading amount is 3 kg/boat, the hydrogen flow is 15m³H, the reduction temperature is 350 ℃, and the reduction sintering time is 150 min;

(4) loading the reduced and sintered cobalt powder into a jet mill pulverizer, setting the pulverizing frequency to be 32HZ, and obtaining the apparent density of 1.6g/cm³Hard agglomerated cobalt powder.

The quality indexes of the prepared cobalt powder are shown in the table 2:

TABLE 2

Serial number	Inspection item	Unit of	Actual measurement result
				1	Bulk density	g/cm³	1.6
2	Oxygen content	％	0.2
				3	Angle of repose	°	45.73

Example 3

(2) the pressed embryo is put into a pulverizer to be pulverized and is sieved by a 60-mesh sieve to obtain the product with the apparent density of 1.6g/cm³The soft agglomerated cobalt powder;

(3) the apparent density is 1.6g/cm³The soft agglomerated cobalt powder is put into a boat and put into a single tube furnace to be reduced and sintered under hydrogen atmosphere, and the soft agglomerated cobalt powder is changed into hard agglomerated cobalt powder; the loading amount is 3 kg/boat, the hydrogen flow is 15m³H, the reduction temperature is 300 ℃, and the reduction sintering is carried out for 150 min;

(4) loading the reduced and sintered cobalt powder into a jet mill pulverizer, setting the pulverizing frequency to be 30HZ, and obtaining the apparent density of 1.54g/cm³Hard agglomerated cobalt powder.

The quality indexes of the prepared cobalt powder are shown in table 3:

TABLE 3

Serial number	Inspection item	Unit of	Actual measurement result
				1	Bulk density	g/cm³	1.54
2	Oxygen content	％	0.14
				3	Angle of repose	°	44.58

As can be seen from tables 1 to 3, the bulk density of the cobalt powder prepared by the invention is 1.5g/cm³Above, the apparent density is far more than 1.0g/cm of the prior cobalt powder³The prepared cobalt powder has small repose angle, good fluidity and low oxygen content.

The foregoing is only a preferred embodiment of the present invention, and it should be noted that, for those skilled in the art, various modifications and decorations can be made without departing from the principle of the present invention, and these modifications and decorations should also be regarded as the protection scope of the present invention.

Claims

1. A method for preparing cobalt powder with high apparent density is characterized by comprising the following steps:

2. The method according to claim 1, wherein the pressing pressure in step (1) is 250 to 300MPa, and the dwell time is 2 to 5 seconds.

3. The method according to claim 1, wherein the mesh number of the screen in the step (2) is 40 to 60 meshes.

4. The method of claim 1, wherein the loading amount of the boat in the step (3) is 2-3 kg/boat, the reduction temperature is 300-380 ℃, the reduction time is 150-200 min, and the hydrogen flow rate is 10-15 m³/h。

5. The method according to claim 1, wherein the jet mill pulverizer of the step (4) has a pulverizing frequency of 30 to 36 Hz.