A method for preparing metallographic specimens of high-cobalt cemented carbide

Abstract

The invention relates to the technical field of metallographic sample preparation, in particular to a high-cobalt cemented carbide metallographic sample preparation method, comprising the following steps: mounting, after sampling the metallographic sample, hot mounting the sample with a mounting material, heating for 3-3.5 minutes, and cooling for 2.3-2.6 minutes; pre-grinding, performing pre-grinding operation with a metallographic automatic sample preparation machine, using a 100-mesh grinding disc, automatically adding water for grinding, and a rotation speed of 300 / 150 rpm; coarse grinding, changing to a 200-mesh grinding disc, adding a grinding liquid containing 0.5%-3% of an antioxidant and 0.2%-1% of a degreasing agent, and a grinding and polishing pressure of 190N-200N; fine grinding, changing to a 500-mesh grinding disc, using a grinding liquid containing 3-micron suspension, 0.5%-3% of an antioxidant, and 0.2%-1% of a degreasing agent; and polishing, changing to a 1000-mesh grinding disc, using a grinding liquid containing 1.5-micron suspension, 0.5%-3% of an antioxidant, and 0.2%-1% of a degreasing agent.

Description

Technical Field

[0001] The invention relates to the technical field of metallographic sample preparation, in particular to a method for preparing a high-cobalt cemented carbide metallographic sample. Background Art

[0002] The preparation of metallographic specimens is a very important part of metallographic research, which includes the cutting of specimens, the mounting of specimens, the grinding of specimens, the polishing of specimens, and the display of metallographic microstructures. The inspection of metallographic microstructures requires that the specimens be polished to form metallographic specimens before they can be inspected. The quality of grinding and polishing directly affects the inspection results. The purpose of specimen grinding and polishing is to remove the surface of the specimen and the wear marks left on the grinding surface, to obtain a mirror-like surface, and to prepare for the display of the structure. The existing metallographic specimen preparation methods are complicated, time-consuming, and too expensive. Moreover, for high-cobalt alloys, cobalt is relatively soft in texture, and is easily oxidized to produce black spots during the metallographic specimen preparation and grinding process. The quality of the prepared metallographic specimens is not high. For this reason, we propose a metallographic specimen preparation method. Summary of the Invention

[0003] In order to solve the above problems, the present invention proposes a method for preparing a high-cobalt cemented carbide metallographic sample.

[0004] The present invention adopts the following technical solution: a method for preparing a high-cobalt cemented carbide metallographic sample, comprising the following steps:

[0005] Step 1: Mounting of the sample: After the metallographic sample is sampled, it is hot mounted using mounting materials. First, heat it to 180℃, keep it for 3-3.5 minutes, and then cool it for 2.3-2.6 minutes. The hot mounting pressure is 100-125 Bar.

[0006] Step 2: Pre-grinding of the sample: Use a metallographic automatic sample preparation machine for pre-grinding operation, use a 100-mesh magnetic grinding disc, automatic liquid grinding, pure water as the grinding liquid, the grinding and polishing pressure of the grinding disc is 205N~215N, the grinding disc speed is 300rpm, and the base speed of the metallographic automatic sample preparation machine is 150rpm;

[0007] Step 3: Rough grinding of the sample: Replace the 100-mesh magnetic grinding disc with a 200-mesh magnetic grinding disc, and start grinding with automatic liquid addition. The grinding liquid includes 0.5% to 3% by weight of an antioxidant and 0.2% to 1% by weight of a degreasing agent. The grinding and polishing pressure of the grinding disc is 190N to 200N. The rotation speed of the grinding disc and the base of the metallographic automatic sample preparation machine remains unchanged.

[0008] Step 4: Fine grinding of the sample: Replace the 200-mesh magnetic grinding disc with a 500-mesh magnetic grinding disc, and start grinding with automatic liquid addition. The grinding liquid includes a suspension with a suspended particle diameter of 3 microns, an antioxidant with a mass percentage of 0.5% to 3%, and a degreasing agent with a mass percentage of 0.2% to 1%. The grinding and polishing pressure of the grinding disc remains unchanged, and the rotation speed of the grinding disc and the base of the metallographic automatic sample preparation machine remains unchanged.

[0009] Step 5. Polishing of the sample: Replace the 500-mesh magnetic grinding disc with a 1000-mesh grinding disc, and start grinding with automatic liquid addition. The grinding liquid includes a suspension with a suspended particle diameter of 1.5 microns, an antioxidant with a mass percentage of 0.5% to 3%, and a degreasing agent with a mass percentage of 0.2% to 1%. The grinding and polishing pressure of the grinding disc remains unchanged, and the rotation speed of the grinding disc and the base of the metallographic automatic sample preparation machine remains unchanged.

[0010] Preferably, the antioxidant is a mixture of didodecyl alcohol ester and didetradecyl alcohol ester in a weight ratio of 5:5.

[0011] Preferably, the grinding and polishing time in step 2 is 4 to 7 minutes.

[0012] Preferably, the grinding and polishing time in step three is 1 to 1.5 minutes.

[0013] Preferably, the grinding and polishing time in step 4 is 2 to 2.5 minutes.

[0014] Preferably, the grinding and polishing time in step five is 2 to 2.5 minutes.

[0015] The present invention has at least one of the following beneficial effects:

[0016] In the present invention, pre-grinding is to grind the sample flat, coarse grinding can remove the pre-grinding marks, fine grinding can remove the coarse grinding marks, and polishing can remove the fine grinding marks to achieve the effect of metallographic detection; using grinding wheels of different mesh sizes in each step can effectively improve the grinding and polishing fineness, and controlling a certain grinding wheel speed and grinding and polishing pressure can effectively save grinding and polishing time and improve work efficiency without damaging the sample; adding antioxidants from the beginning of coarse grinding can significantly prevent high cobalt alloys from oxidizing and producing black spots, and degreasing agents can effectively remove residual antioxidants and suspensions to ensure the stable quality of metallographic samples. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 This is a metallographic micrograph of a high-cobalt cemented carbide sample obtained using existing technology;

[0018] Figure 2 This is a metallographic micrograph of a high-cobalt cemented carbide sample obtained in a preferred embodiment of the present invention;

[0019] Figure 3This is a metallographic micrograph of a high-cobalt cemented carbide sample obtained in the second embodiment of the present invention;

[0020] Figure 4 This is a metallographic micrograph of a high-cobalt cemented carbide sample obtained in the third embodiment of the present invention;

[0021] Figure 5 This is a metallographic micrograph of a high-cobalt cemented carbide sample obtained in the fourth embodiment of the present invention. DETAILED DESCRIPTION

[0022] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0023] In the description of the present invention, it should be understood that the terms "center, longitudinal, transverse, length, width, thickness, up, down, front, back, left, right, vertical, horizontal, top, bottom, inside, outside, clockwise, counterclockwise" and the like to indicate orientations or positional relationships are based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as limiting the present invention.

[0024] Example 1

[0025] Reference Figures 1 to 2 A preferred embodiment of the present invention is a method for preparing a metallographic sample of a high-cobalt cemented carbide, comprising the following steps:

[0026] Step 1: Mounting the sample: After the metallographic sample is sampled, it is hot-mounted using a mounting material. It is first heated to 180°C, maintained for 3 to 3.5 minutes, and then cooled for 2.3 to 2.6 minutes. The hot mounting pressure is 100 to 125 bar. In this embodiment, the heating time is 3 minutes, the cooling time is 2.5 minutes, and the hot mounting pressure is 110 bar.

[0027] Step 2: Pre-grinding of the sample: Pre-grinding is performed using a metallographic automatic sample preparation machine, using a 100-mesh magnetic grinding disc, automatic liquid grinding, pure water as the grinding liquid, a grinding and polishing pressure of 205N to 215N, a grinding disc speed of 300rpm, and a metallographic automatic sample preparation machine base speed of 150rpm; pre-grinding is to smooth the sample. In this embodiment, the grinding and polishing pressure is 210N;

[0028] Step 3: Rough grinding of the sample: Replace the 100-mesh magnetic grinding disc with a 200-mesh magnetic grinding disc, and start grinding with automatic liquid addition. The grinding liquid includes 0.5% to 3% by weight of an antioxidant and 0.2% to 1% by weight of a degreasing agent. The grinding and polishing pressure of the grinding disc is 190N to 200N, and the rotation speed of the grinding disc and the base of the metallographic automatic sample preparation machine remains unchanged. The purpose of rough grinding is to remove the wear marks of the pre-grinding process. The degreasing agent can remove the residual antioxidant in the rough grinding process. In this embodiment, the grinding and polishing pressure is 195N.

[0029] Step 4: Fine grinding of the sample: Replace the 200-mesh magnetic grinding disc with a 500-mesh magnetic grinding disc, and start grinding with automatic liquid addition. The grinding liquid includes a solution with a suspended particle diameter of 3 microns, an antioxidant with a mass percentage of 0.5% to 3%, and a degreaser with a mass percentage of 0.2% to 1%. The grinding and polishing pressure of the grinding disc remains unchanged, and the rotation speed of the grinding disc and the metallographic automatic sample preparation machine base remains unchanged. Fine grinding is to remove the wear marks of the rough grinding process, and the degreaser can remove the residues of the suspension and antioxidant in the fine grinding process.

[0030] Step 5. Polishing of the sample: Replace the 500-mesh magnetic grinding disc with a 1000-mesh grinding disc, and automatically add liquid to start grinding. The grinding liquid includes a solution with a suspended particle diameter of 1.5 microns, an antioxidant with a mass percentage of 0.5% to 3%, and a degreaser with a mass percentage of 0.2% to 1%. The grinding and polishing pressure of the grinding disc remains unchanged, and the speed of the grinding disc and the base of the metallographic automatic sample preparation machine remains unchanged. Polishing can make the sample meet the standards of metallographic inspection, and the degreaser can remove the residues of the suspension and antioxidant in the polishing process.

[0031] In the present invention, pre-grinding is to grind the sample flat, coarse grinding can remove the pre-grinding marks, fine grinding can remove the coarse grinding marks, and polishing can remove the fine grinding marks to achieve the effect of metallographic detection; using grinding wheels of different mesh sizes in each step can effectively improve the grinding and polishing fineness, and controlling a certain grinding wheel speed and grinding and polishing pressure can effectively save grinding and polishing time and improve work efficiency without damaging the sample; adding antioxidants from the beginning of coarse grinding can significantly prevent high cobalt alloys from oxidizing and producing black spots, and degreasing agents can effectively remove residual antioxidants and suspensions to ensure the stable quality of metallographic samples.

[0032] like Figure 1 As shown in the metallographic micrograph of the high-cobalt cemented carbide sample obtained by the existing technology, it can be clearly seen that there are many black spots in the cobalt phase, which are caused by oxidation during the grinding and polishing process; Figure 2 As shown, the darker color is the grain, and the gray part between the grains is the cobalt phase. It can be clearly seen that there are basically no oxidized black spots in the cobalt phase. Therefore, it can be known that the high-cobalt cemented carbide metallographic sample obtained by the method of the present invention is of good quality.

[0033] As a preferred embodiment of the present invention, it may also have the following additional technical features:

[0034] The antioxidant is a mixture of didodecyl alcohol ester and didetradecyl alcohol ester in a weight ratio of 5:5; the mixture of didodecyl alcohol ester and didetradecyl alcohol ester with a mass percentage of 0.2% to 1% can effectively prevent cobalt oxidation during the grinding and polishing process. Its solvent is water, so no additional water is needed to cool down during the grinding and polishing process; in this embodiment, the mass percentage of the antioxidant is 1.5%, and the mass percentage of the degreasing agent is 0.6%; in this embodiment, the degreasing agent is the heavy oil cleaning agent ZJ-822B from Taobao's "Zhijing Flagship Store".

[0035] The grinding and polishing time in step 2 is 4 to 7 minutes. In this embodiment, the pre-grinding is carried out with a 100-mesh grinding wheel, a grinding and polishing pressure of 210N, a grinding wheel speed of 300rpm, and a speed of 150rpm for the base of the metallographic automatic sample making machine, which can effectively save the pre-grinding time. In this embodiment, the grinding and polishing time of the pre-grinding process is 5 minutes.

[0036] The grinding and polishing time in step three is 1 to 1.5 minutes. In this embodiment, the rough grinding is carried out with a 200-mesh grinding wheel, a grinding and polishing pressure of 195N, a grinding wheel speed of 300rpm, and a base speed of the metallographic automatic sample making machine of 150rpm, which effectively improves the rough grinding efficiency. In this embodiment, the grinding and polishing time of the rough grinding process is 1.2 minutes.

[0037] The grinding and polishing time in step 4 is 2 to 2.5 minutes. In this embodiment, the fine grinding is carried out with a 500-mesh grinding wheel, a grinding and polishing pressure of 195N, a grinding wheel speed of 300rpm, a metallographic automatic sample preparation machine base speed of 150rpm, and a suspension with a suspended particle diameter of 3 microns. This effectively shortens the fine grinding time while ensuring the quality of the sample; in this embodiment, the grinding and polishing time of the fine grinding process is 2.2 minutes.

[0038] The grinding and polishing time in step five is 2 to 2.5 minutes. In this embodiment, the polishing is carried out with a 1000-mesh grinding wheel, a grinding and polishing pressure of 195N, a grinding wheel speed of 300rpm, a metallographic automatic sample preparation machine base speed of 150rpm, and a suspension with a suspended particle diameter of 1.5 microns to obtain a sample of good quality; in this embodiment, the suspended particles of the suspension are diamonds, and the grinding and polishing time of the polishing process is 2.2 minutes.

[0039] Example 2

[0040] Reference Figure 3In this embodiment, the heating temperature of the sample hot mounting is 180°C, maintained for 3 minutes, and then cooled for 2.5 minutes. The hot mounting pressure is 120 Bar; the grinding and polishing pressure of the sample pre-grinding process is 205N, and the grinding and polishing time is 6 minutes; the grinding and polishing pressure of the rough grinding process is 190N, and the grinding and polishing time is 1.5 minutes. The grinding liquid includes an antioxidant with a mass percentage of 0.5% and a degreaser with a mass percentage of 0.2%; the grinding and polishing pressure of the fine grinding process is 190N, and the grinding and polishing time is 2.4 minutes. The grinding liquid includes a suspension with a suspended particle diameter of 3 microns, an antioxidant with a mass percentage of 0.5%, and a degreaser with a mass percentage of 0.2%; the grinding and polishing pressure of the polishing process is 190N, and the grinding and polishing time is 2.4 minutes. The grinding liquid includes a suspension with a suspended particle diameter of 1.5 microns, an antioxidant with a mass percentage of 0.5%, and a degreaser with a mass percentage of 0.2%. Figure 3 As shown, there are basically no oxidized black spots in the cobalt phase, which shows that the high-cobalt cemented carbide metallographic sample obtained in this embodiment is of good quality.

[0041] Example 3:

[0042] Reference Figure 4 In this embodiment, the heating temperature of the sample hot mounting is 180°C, maintained for 3.2 minutes, and then cooled for 2.6 minutes. The hot mounting pressure is 125 Bar; the grinding and polishing pressure of the sample pre-grinding process is 215N, and the grinding and polishing time is 5 minutes; the grinding and polishing pressure of the rough grinding process is 200N, and the grinding and polishing time is 1.2 minutes. The grinding liquid includes an antioxidant with a mass percentage of 3% and a degreaser with a mass percentage of 1%; the grinding and polishing pressure of the fine grinding process is 200N, and the grinding and polishing time is 2.5 minutes. The grinding liquid includes a suspension with a suspended particle diameter of 3 microns, an antioxidant with a mass percentage of 3%, and a degreaser with a mass percentage of 1%; the grinding and polishing pressure of the polishing process is 200N, and the grinding and polishing time is 2.5 minutes. The grinding liquid includes a suspension with a suspended particle diameter of 1.5 microns, an antioxidant with a mass percentage of 3%, and a degreaser with a mass percentage of 1%. Figure 4 As shown, there are basically no oxidized black spots in the cobalt phase, which shows that the high-cobalt cemented carbide metallographic sample obtained in this embodiment is of good quality.

[0043] Example 4:

[0044] Reference Figure 5In this embodiment, the heating temperature of the sample hot mounting is 180°C, maintained for 3.3 minutes, and then cooled for 2.4 minutes. The hot mounting pressure is 120 Bar; the grinding and polishing pressure of the sample pre-grinding process is 212N, and the grinding and polishing time is 5 minutes; the grinding and polishing pressure of the rough grinding process is 198N, and the grinding and polishing time is 1.2 minutes. The grinding liquid includes an antioxidant with a mass percentage of 2.1% and a degreaser with a mass percentage of 0.4%; the grinding and polishing pressure of the fine grinding process is 198N, and the grinding and polishing time is 2.5 minutes. The grinding liquid includes a suspension with a suspended particle diameter of 3 microns, an antioxidant with a mass percentage of 2.1%, and a degreaser with a mass percentage of 0.4%; the grinding and polishing pressure of the polishing process is 198N, and the grinding and polishing time is 2.5 minutes. The grinding liquid includes a suspension with a suspended particle diameter of 1.5 microns, an antioxidant with a mass percentage of 2.1%, and a degreaser with a mass percentage of 0.4%. Figure 5 As shown, there are basically no oxidized black spots in the cobalt phase, which shows that the high-cobalt cemented carbide metallographic sample obtained in this embodiment is of good quality.

[0045] Under the premise that no conflict occurs, those skilled in the art may freely combine and superimpose the above-mentioned additional technical features.

[0046] The above descriptions are only preferred embodiments of the present invention. Any technical solution that achieves the purpose of the present invention by substantially the same means shall fall within the scope of protection of the present invention.

Claims

1. A method for preparing a metallographic sample of high cobalt cemented carbide, characterized in that: The following steps are involved: Step 1: Mounting of the sample: After the metallographic sample is sampled, it is hot mounted using mounting materials. First, heat it to 180℃, keep it for 3-3.5 minutes, and then cool it for 2.3-2.6 minutes. The hot mounting pressure is 100-125 Bar. Step 2: Pre-grinding of the sample: Use a metallographic automatic sample preparation machine for pre-grinding operation, use a 100-mesh magnetic grinding disc, automatic liquid grinding, pure water as the grinding liquid, the grinding and polishing pressure of the grinding disc is 205N~215N, the grinding disc speed is 300rpm, and the base speed of the metallographic automatic sample preparation machine is 150rpm; Step 3: Rough grinding of the sample: Replace the 100-mesh magnetic grinding disc with a 200-mesh magnetic grinding disc, and start grinding with automatic liquid addition. The grinding liquid includes 0.5% to 3% by weight of an antioxidant and 0.2% to 1% by weight of a degreasing agent. The grinding and polishing pressure of the grinding disc is 190N to 200N. The rotation speed of the grinding disc and the base of the metallographic automatic sample preparation machine remains unchanged. Step 4: Fine grinding of the sample: Replace the 200-mesh magnetic grinding disc with a 500-mesh magnetic grinding disc, and start grinding with automatic liquid addition. The grinding liquid includes a suspension with a suspended particle diameter of 3 microns, an antioxidant with a mass percentage of 0.5% to 3%, and a degreasing agent with a mass percentage of 0.2% to 1%. The grinding and polishing pressure of the grinding disc remains unchanged, and the rotation speed of the grinding disc and the base of the metallographic automatic sample preparation machine remains unchanged. Step 5. Polishing of the sample: Replace the 500-mesh magnetic grinding disc with a 1000-mesh grinding disc, and start grinding with automatic liquid addition. The grinding liquid includes a suspension with a suspended particle diameter of 1.5 microns, an antioxidant with a mass percentage of 0.5% to 3%, and a degreasing agent with a mass percentage of 0.2% to 1%. The grinding and polishing pressure of the grinding disc remains unchanged, and the rotation speed of the grinding disc and the base of the metallographic automatic sample preparation machine remains unchanged. The antioxidant is a mixture of didodecyl alcohol ester and didetradecyl alcohol ester in a weight ratio of 5:

5.

2. The method for preparing a high-cobalt cemented carbide metallographic sample according to claim 1, characterized in that: The grinding and polishing time in the step 2 is 4 to 7 minutes.

3. The method for preparing a high-cobalt cemented carbide metallographic sample according to claim 1, characterized in that: The grinding and polishing time in step 3 is 1 to 1.5 minutes.

4. The method for preparing a high-cobalt cemented carbide metallographic sample according to claim 1, characterized in that: The grinding and polishing time in step 4 is 2 to 2.5 minutes.

5. The method for preparing a high-cobalt cemented carbide metallographic sample according to claim 1, characterized in that: The grinding and polishing time in step 5 is 2 to 2.5 minutes.

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