Method for monitoring quality of tungsten carbide powder

Abstract

The invention discloses a tungsten carbide powder quality monitoring method, and relates to the technical field of hard alloy detection, tungsten carbide powder is prepared into hard alloy according to a formula process, then sample preparation, corrosion and tungsten carbide grain morphology observation are performed in sequence, and the obtained tungsten carbide grain morphology is used for representing the integrity of tungsten carbide powder raw material grain crystallization. In addition, according to tests, the integrity of tungsten carbide grains can influence the mechanical performance of the hard alloy.

Description

Technical Field

[0001] The invention relates to the technical field of cemented carbide detection, and in particular to a quality monitoring method for tungsten carbide powder. Background Art

[0002] At present, a variety of detection indicators are usually established from three aspects, such as impurity content, particle size and particle size composition, and carbon content, as quality monitoring of WC powder, such as chemical methods to detect impurity elements; Fisher particle size analyzer to detect powder particle size; scanning electron microscope to observe particle surface morphology and grain size; argon ion cross-section polishing to observe the internal structure of particles; X-ray diffractometer to detect incompletely carbonized W2C; carbon analyzer to detect free carbon and total carbon to control carbon content. However, it was found in the production process that the performance of cemented carbide produced by powders with similar indicators from different batches in the same equipment and under the same process conditions is still different. It can be seen that the current indicators for monitoring the quality of WC powder are not comprehensive, and it is necessary to characterize them more accurately.

[0003] The complete crystallization of tungsten carbide grains is crucial to the performance of cemented carbide. Incomplete crystallization of tungsten carbide will lead to reduced toughness of the alloy and low comprehensive performance. At present, there is no good way to characterize the completeness of tungsten carbide grains. The quality of tungsten carbide can only be judged by the service life of cemented carbide. Summary of the invention

[0004] The purpose of the present invention is to solve at least one of the technical problems existing in the prior art and to provide a method for monitoring the quality of tungsten carbide powder.

[0005] The technical solution of the present invention is as follows:

[0006] A method for monitoring the quality of tungsten carbide powder comprises preparing the tungsten carbide powder into a cemented carbide according to a formula process, and then sequentially performing sample preparation, corrosion, and observing the tungsten carbide grain morphology. The obtained tungsten carbide grain morphology is used to characterize the integrity of the tungsten carbide powder raw material grain crystallization, thereby judging the quality of the tungsten carbide powder.

[0007] As a preferred embodiment of the present invention, the complete tungsten carbide grains include at least one of triangular prisms, truncated triangular prisms and plate-like grains.

[0008] As a preferred embodiment of the present invention, the integrity of the raw material grains can improve the fracture toughness of the cemented carbide.

[0009] As a preferred embodiment of the present invention, the method of preparing tungsten carbide powder into cemented carbide according to the formulation process is:

[0010] Tungsten carbide powder with a Fsss particle size of 0.6-0.8μm and Co powder with a Fsss particle size of less than 0.8μm are used as raw materials, the cobalt content accounts for 10-12wt% of the tungsten carbide content, an inhibitor is added, and cemented carbide is obtained through batching, ball milling, spray drying, pressing and pressure sintering. The magnetic saturation of the cemented carbide is controlled at 80-90%.

[0011] As a preferred embodiment of the present invention, the inhibitor comprises chromium carbide and vanadium carbide in a mass ratio of 1:1-3, and the added amount of the inhibitor accounts for 0.5-1% of the mass of the tungsten carbide powder.

[0012] As a preferred embodiment of the present invention, the ball milling time is 40-60h.

[0013] As a preferred embodiment of the present invention, the pressure sintering temperature is 1400-1420° C., and the sintering pressure is 6-9 MPa.

[0014] As a preferred embodiment of the present invention, the corrosion comprises the following steps:

[0015] S1: Clean the sample using ultrasound;

[0016] S2: Use a mixture of potassium hydroxide and potassium ferrocyanide to corrode tungsten carbide for 3-5 minutes;

[0017] S3: Use ferric chloride hydrochloric acid solution to corrode the cobalt phase in the sample for 15-20 minutes;

[0018] S4: Use the mixed solution of potassium hydroxide and potassium ferrocyanide to corrode the tungsten carbide again for 20-60 seconds.

[0019] The beneficial effects of the present invention are as follows: the present invention prepares tungsten carbide powder into cemented carbide, and characterizes the integrity of the crystallization of the tungsten carbide powder raw material grains through sample preparation, corrosion, and observation of the complete tungsten carbide grain morphology, so as to determine the quality of the tungsten carbide powder raw material; and it can be known through experiments that the integrity of the tungsten carbide grains will affect the mechanical strength of the cemented carbide. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 This is a microscopic image of the cemented carbide of Example 1;

[0021] Figure 2 This is a microscopic image of the cemented carbide of Example 2. DETAILED DESCRIPTION

[0022] The technical solution of the present invention is a method for monitoring the quality of tungsten carbide powder. The tungsten carbide powder is prepared into a cemented carbide according to a formula process, and then sample preparation, corrosion, and observation of the tungsten carbide grain morphology are carried out in sequence. The obtained tungsten carbide grain morphology is used to characterize the integrity of the crystallization of the tungsten carbide powder raw material grains, thereby judging the quality of the tungsten carbide powder.

[0023] Specifically, the complete tungsten carbide grains include at least one of triangular prisms, truncated triangular prisms and plate-shaped grains.

[0024] Specifically, the integrity of the raw material grains can improve the fracture toughness of cemented carbide.

[0025] Specifically, the method of preparing tungsten carbide powder into cemented carbide according to the formulation process is:

[0026] Tungsten carbide powder with a Fsss particle size of 0.6-0.8μm and Co powder with a Fsss particle size of less than 0.8μm are used as raw materials, the cobalt content accounts for 10-12wt% of the tungsten carbide content, an inhibitor is added, and cemented carbide is obtained through batching, ball milling, spray drying, pressing and pressure sintering. The magnetic saturation of the cemented carbide is controlled at 80-90%.

[0027] Furthermore, the inhibitor comprises chromium carbide and vanadium carbide in a mass ratio of 1:1-3, and the added amount of the inhibitor accounts for 0.5-1% of the mass of the tungsten carbide powder.

[0028] Furthermore, the ball milling time is 40-60 hours, specifically 40 hours, 50 hours or 60 hours.

[0029] Preferably, the pressure sintering temperature is 1400-1420°C, which may be 1400°C, 1410°C or 1420°C, and the sintering pressure is 6-9Mpa, which may be 6Mpa, 7Mpa, 8Mpa or 9Mpa.

[0030] As a preferred embodiment of the present invention, the corrosion comprises the following steps:

[0031] S1: Clean the sample using ultrasound;

[0032] S2: using a mixture of potassium hydroxide and potassium ferrocyanide to corrode tungsten carbide for 3-5 minutes, specifically 3 minutes, 4 minutes or 5 minutes;

[0033] S3: Use ferric chloride hydrochloric acid solution to corrode the cobalt phase in the sample for 15-20 minutes. The time is adjusted appropriately according to the particle size of tungsten carbide. The finer the particle size, the longer the corrosion time.

[0034] S4: Use the mixed solution of potassium hydroxide and potassium ferrocyanide to corrode tungsten carbide again for 20-60s, 20s, 30s, 40s, 50s or 60s in specific departments.

[0035] Specifically, the concentrations of potassium hydroxide and potassium ferrocyanide can be 10 wt%, 15 wt%, 20 wt%, 25 wt%, or 30 wt% respectively.

[0036] The present invention prepares tungsten carbide powder into cemented carbide, characterizes the integrity of the crystallization of the tungsten carbide powder raw material grains through sample preparation, corrosion, and observation of the complete tungsten carbide grain morphology, and determines the quality of the tungsten carbide powder raw material.

[0037] The embodiments of the present invention are described in detail below. The embodiments described below are exemplary and are only used to explain the present invention, and should not be construed as limiting the present invention. If no specific techniques or conditions are specified in the embodiments, the techniques or conditions described in the literature in this area or the product specifications are used. The reagents or instruments used that do not specify the manufacturer are all conventional products that can be obtained commercially.

[0038] Example 1

[0039] Tungsten carbide powder, Co powder with Fsss particle size <0.8μm is used as raw material, the cobalt content accounts for 12wt% of the tungsten carbide content, an inhibitor is added, and the mixture is batched, ball milled for 50 hours, spray dried, pressed and pressure sintered. Specifically: the spray-dried mixture is made into a 24.3mm×6.6mm×8.1mm compact under a pressing pressure of 120MPa, and the compact is sintered at a sintering temperature of 1410℃ and a low pressure of 8Mpa for 60min to obtain a cemented carbide.

[0040] The inhibitor includes chromium carbide and vanadium carbide in a mass ratio of 1:1, and the added amount of the inhibitor accounts for 0.7% of the mass of the tungsten carbide powder.

[0041] The pressure sintering temperature is 1415° C., and the sintering pressure is 8 MPa.

[0042] Tungsten carbide powders are A and B WC006 powder raw materials, with specific surface area of ​​1.9-2.1m 2 / g, average particle size 0.6μm, total carbon (Ct) content of 6.10-6.14%, combined carbon Cf content greater than 6.07%, oxygen content less than 0.3% and does not contain grain growth inhibitor.

[0043] The cemented carbides made from the two raw materials are numbered 1# and 2# respectively.

[0044] Example 2

[0045] Different from Example 1, the tungsten carbide powders are two kinds of WC008 powder raw materials A and B, with a Fisher particle size of 0.7-0.9 μm, a total carbon (Ct) content of 6.10-6.14%, a combined carbon Cf content of more than 6.07%, an oxygen content of less than 0.2% and no grain growth inhibitor.

[0046] The cemented carbides made from the two raw materials are numbered 3# and 4# respectively.

[0047] The cemented carbide samples of the above examples were prepared, corroded and the morphology of tungsten carbide grains was observed using a scanning electron microscope. Figure 1 and Figure 2 The obtained tungsten carbide grain morphology is used to characterize the integrity of the tungsten carbide powder raw material grain crystallization, thereby judging the quality of the tungsten carbide powder.

[0048] The corrosion method is as follows: (1) Use ultrasound to clean the sample; (2) Use a mixture of 20wt% potassium hydroxide and 20wt% potassium ferrocyanide in a mass ratio of 1:1 to corrode WC for 5 minutes; (3) Use ferric chloride hydrochloric acid to corrode the cobalt phase for 15 minutes; (4) Use a mixture of 20wt% potassium hydroxide and 20wt% potassium ferrocyanide in a mass ratio of 1:1 to corrode WC for 50s.

[0049] At the same time, the properties of the cemented carbides of Examples 1 and 2 were tested, and the test results are shown in Tables 1 and 2, respectively.

[0050] Table 1 Physical and mechanical properties test results of cemented carbide in Example 1

[0051]

[0052] Table 2 Physical and mechanical properties test results of cemented carbide in Example 2

[0053]

[0054] from Figure 1 As shown in Table 1, in Example 1, WC006 powder raw materials (A, B) with the same raw material indicators and the same preparation process are used to prepare the cemented carbide. From the microscopic scanning diagram, it can be seen that incomplete tungsten carbide grains appear in the 2# sample (B raw material), and it is found that the fracture toughness of the physical properties of the 2# sample in Table 1 is affected, that is, the incomplete tungsten carbide grains will reduce the fracture toughness of the cemented carbide, that is, in Example 1, the quality of A raw material is better than that of B raw material.

[0055] from Figure 2As shown in Table 2, in Example 2, WC008 powder raw materials (A, B) with the same raw material indicators and the same preparation process are used to prepare the cemented carbide. From the microscopic scanning diagram, it can be seen that incomplete tungsten carbide grains appear in the 2# sample (A raw material), and it is found that the fracture toughness and bending strength of the physical properties of the 3# sample in Table 1 are affected, that is, the incomplete tungsten carbide grains will reduce the fracture toughness of the cemented carbide, that is, in Example 2, the quality of the B raw material is better than that of the A raw material.

[0056] Therefore, it can be known that the present invention prepares tungsten carbide powder into cemented carbide, characterizes the integrity of the tungsten carbide powder raw material grain crystallization by sampling, corrosion, and observation of the complete tungsten carbide grain morphology to determine the quality of the tungsten carbide powder raw material.

[0057] The above-mentioned embodiments only express the preferred implementation modes of the present invention, and the description thereof is relatively specific and detailed, but it cannot be understood as limiting the scope of the present invention. It should be pointed out that, for ordinary technicians in this field, various other corresponding changes and deformations can be made according to the technical solutions and concepts described above, and all these changes and deformations should fall within the scope of protection of the claims of the present invention.

Claims

1. A method for monitoring the quality of tungsten carbide powder, characterized in that: The tungsten carbide powder is prepared into cemented carbide according to the formula process, and then the sample is prepared, corroded, and the tungsten carbide grain morphology is observed in sequence. The obtained tungsten carbide grain morphology is used to characterize the integrity of the tungsten carbide powder raw material grain crystallization, thereby judging the quality of the tungsten carbide powder.

2. The quality monitoring method of tungsten carbide powder according to claim 1, characterized in that: The complete tungsten carbide grains include at least one of triangular prisms, truncated triangular prisms and plate-shaped grains.

3. The quality monitoring method of tungsten carbide powder according to claim 1, characterized in that: The integrity of raw material grains can improve the fracture toughness of cemented carbide.

4. The method for quality monitoring of tungsten carbide powder according to claim 1, characterized in that: The method for preparing tungsten carbide powder into cemented carbide according to the formula process is: Tungsten carbide powder with a Fsss particle size of 0.6-0.8μm and Co powder with a Fsss particle size of less than 0.8μm are used as raw materials, the cobalt content accounts for 10-12wt% of the tungsten carbide content, an inhibitor is added, and cemented carbide is obtained through batching, ball milling, spray drying, pressing and pressure sintering. The magnetic saturation of the cemented carbide is controlled at 80-90%.

5. The method for quality monitoring of tungsten carbide powder according to claim 4, characterized in that: The inhibitor comprises chromium carbide and vanadium carbide in a mass ratio of 1:1-3, and the added amount of the inhibitor accounts for 0.5-1% of the mass of the tungsten carbide powder.

6. The method for monitoring the quality of tungsten carbide powder according to claim 4, characterized in that: The ball milling time is 40-60h.

7. The method for monitoring the quality of tungsten carbide powder according to claim 4, characterized in that: The pressure sintering temperature is 1400-1420° C., and the sintering pressure is 6-9 MPa.

8. The method for quality monitoring of tungsten carbide powder according to claim 1, characterized in that: The corrosion comprises the following steps: S1: Use ultrasonic waves to clean the sample; S2: Use a mixture of potassium hydroxide and potassium ferrocyanide to corrode tungsten carbide for 3-5 minutes; S3: Use ferric chloride hydrochloric acid solution to corrode the cobalt phase in the sample for 15-20 minutes; S4: Use the mixed solution of potassium hydroxide and potassium ferrocyanide to corrode the tungsten carbide again for 20-60 seconds.

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