CN115595585A - A kind of preparation method of special metallographic polishing agent for easily oxidized metal - Google Patents

Abstract

A preparation method of a special metallographic polishing agent for easily oxidized metals comprises nano cerium oxide or lanthanum oxide abrasive particles, a dispersing agent, a PH regulator and an alcohol group or oil-based/alcohol-based mixed liquid. The preparation method comprises the following steps: adding a precipitator into the cerium salt or lanthanum salt solution, aging to generate precipitates, washing, drying and roasting to obtain the cerium oxide or lanthanum oxide abrasive particles. Grinding the abrasive particles into nano-grade abrasive particles by ball milling; adding a dispersing agent, a pH regulator and an alcohol group or oil-based/alcohol-based mixed liquid, and uniformly mixing in a high-speed cutting dispersion machine to obtain the special metallographic polishing agent for the easily-oxidized metal. The invention adopts oil base or oil base/alcohol base mixed liquid as a dispersion system, which can prevent the oxidation of the easily oxidized metal in the polishing process; in a weakly alkaline environment, the polishing agent abrasive particles can effectively remove stress layers and oxide films on the surface layers of easily oxidized metal samples.

Description

A kind of preparation method of special metallographic polishing agent for easily oxidized metal

technical field

The invention relates to a polishing agent and a preparation method thereof, in particular to a preparation method of a special metallographic polishing agent for easily oxidized metals, which belongs to the technical field of polishing agents.

Background technique

With the rapid development of science and technology and industry, magnesium alloys are currently being used more and more in aerospace, textile, instrumentation and other fields. Compared with other metal materials, magnesium alloys have low density, radiation resistance, high specific strength and specific stiffness. , and good vibration damping, it has broad application prospects in the fields of electronics, automobiles and aerospace. Magnesium alloys will form a texture during processing, and the grains will have a preferred orientation.

Electron Backscatter Diffraction (EBSD) technology is a research and analysis method installed in a scanning electron microscope to determine the crystal structure orientation and related information. It plays an extremely important role in the study of the microstructure of materials and their performance control, and is known as a "new weapon" for the study of material microstructure. However, EBSD analysis has relatively high requirements on the surface quality of the sample, requiring no residual stress layer, no oxide film, no pollution, good electrical conductivity and suitable size on the sample surface. The preparation of EBSD samples is the basis and difficulty of EBSD detection. Chemical-mechanical polishing is an efficient, safe, economical and widely applicable method for preparing EBSD samples. However, there is currently no production and sales of chemical-mechanical polishing agents for easily oxidized metals such as magnesium alloys and copper alloys in China. At present, electrolytic polishing is mainly used to prepare magnesium alloy and copper alloy EBSD samples. Electrolytic polishing has disadvantages such as complicated process, narrow application range, toxic and dangerous electrolyte, and low safety.

There are few types of metallographic polishing agents prepared for EBSD analysis samples in China, and there are problems that they are not suitable for polishing easily oxidized metals such as magnesium alloys and copper alloys. Severe oxidation occurs when polishing magnesium alloys and copper alloys. General metallographic polishing agents cannot remove the stress layer and oxide film on the surface of magnesium alloy and copper alloy samples, and there is a problem of low polishing efficiency.

Contents of the invention

The purpose of the present invention is, aim at the problem that the metallographic polishing agent that EBSD analysis sample prepares exists, especially can't solve the polishing problem of easily oxidized metals such as magnesium alloy, copper alloy, proposes the preparation of a kind of special metallographic polishing agent for easily oxidizable metal method.

The technical scheme realized by the present invention is as follows, a preparation method of a special metallographic polishing agent for easily oxidized metals. Alcohol-based/alcohol-based mixed liquid; among them, the dispersant is 1.5%, the pH regulator is 0.7%-0.8%, the abrasive grain is 5%-20%, and the balance is alcohol-based or oil-based alcohol-based mixed liquid.

The preparation method is as follows:

Mix Ce ⁴⁺ salt or La ³⁺ salt with polyvinylpyrrolidone (PVP K30) solution or hydrochloric acid solution to make cerium salt or lanthanum salt solution, then add precipitant, and stand and age at 50°C-100°C until it forms The precipitate is washed with deionized water or ethanol, and then vacuum-dried to obtain a cerium oxide precursor or a lanthanum oxide precursor. Abrasive particles are ball milled into nano-sized cerium oxide particles; add dispersant, PH regulator, alcohol-based or oil-based/alcohol-based mixed liquid, mix in a high-speed cutting disperser, and disperse evenly to obtain easily oxidizable metals Metallographic polish.

The method uses a planetary ball mill to mill the abrasive grains for 1-3 hours, 3-5 hours and 5-10 hours; respectively obtain polishing agent abrasive grains with particle diameters of 0.06 μm, 0.05 μm and 0.02 μm; Nano-sized cerium oxide particles can be used alone as polishing agent abrasive particles, or mixed with different particle sizes of cerium oxide particles as polishing agent abrasive particles; :1 mix, as mixed abrasive grains.

The oil base is glycerin or silicone oil, and the alcohol base is ethanol or methanol; for the oil base/alcohol base mixed liquid, the ratio of oil to alcohol is 1:2-1:3.

The dispersant is polyvinylpyrrolidone (PVP K30), sodium polyacrylate (PAAS) or magnesium aluminum silicate.

The pH regulator is ethanolamine, sodium hydroxide or sodium methylate.

The calcination temperature of the cerium oxide particles or lanthanum oxide particles with a certain crystallinity is 800°C-950°C.

The beneficial effect of the present invention is as follows, the polishing agent of the present invention compares with the chemical-mechanical polishing agent on the market at present, the present invention adopts oil base or oil base/alcohol base mixed liquid, replaces water as dispersion system, can prevent easily oxidized metal Oxidation in the polishing process; in addition, in the weak alkaline environment of the present invention, the polishing agent abrasive grains of the present invention can effectively remove the stress layer and oxide film on the surface of easily oxidized metal samples; the present invention uses cerium oxide and lanthanum oxide nano-scale particles as polishing agents Abrasive grains have the advantages of high polishing efficiency, low sample surface roughness, and high flatness.

Compared with the commonly used electrolytic polishing method for preparing EBSD samples of easily oxidized metals such as magnesium alloys and copper alloys, the preparation of EBSD samples by using special metallographic polishing agents for easily oxidized metals has the advantages of simple process, wide application range, non-toxic, harmless and safe. Good performance and other advantages.

Description of drawings

Fig. 1 is a block diagram of the preparation process of metallographic polishing agent of the present invention;

Fig. 2 is the magnesium alloy after adopting the polishing agent of the embodiment of the present invention to polish;

Fig. 3 is the magnesium alloy after adopting common chemical-mechanical polishing agent polishing;

Fig. 4 adopts the pure copper after polishing agent polishing of the embodiment of the present invention;

Figure 5 shows pure copper polished with common chemical-mechanical polishing agents.

detailed description

The specific embodiment of the present invention is shown in Fig. 1 as a flow chart of the preparation process of the metallographic polishing agent of the present invention.

Example 1

1. Preparation of nano cerium oxide abrasive grains:

(1) Preparation of raw materials: Mix Ce ⁴⁺ salt with polyvinylpyrrolidone (PVP K30) solution to prepare a cerium salt solution;

(2) Precipitation: Add the precipitating agent sodium carbonate, and let it stand and age at 80°C until the precipitation is formed;

(3) Cleaning: Clean the sediment with deionized water or ethanol;

(4) Drying: the precipitate was dried in a vacuum oven at 200°C for 2 hours to obtain a cerium oxide precursor;

(5) Roasting: The cerium oxide precursor is placed in a muffle furnace and heated to 900°C, kept for 2 hours, and then calcined to generate cerium oxide particles with a certain degree of crystallinity;

(6) Ball milling: put the cerium oxide particles in an agate ball mill jar, mill them with a planetary ball mill for 5 hours to obtain cerium oxide particles with a particle size of 0.05 μm, and ball mill them for 10 hours to obtain cerium oxide particles with a particle size of 0.02 μm.

2. Polishing liquid preparation:

Mix cerium oxide particles of 0.02 μm and 0.05 μm at a ratio of 5:1; mix 1.5% of the total mass of the dispersant polyvinylpyrrolidone, 0.8% of the total mass of the pH regulator ethanolamine, and 10% of the total mass of cerium oxide particles, and the rest Glycerin/ethanol mixed liquid (the ratio of glycerin and ethanol is 1:2), high-cut dispersion in a high-speed cutting disperser, mixed evenly, to obtain a special metallographic polishing agent for easily oxidized metals.

Example 2

1. Preparation of nano cerium oxide abrasive grains:

(1) Prepare raw materials: mix Ce ⁴⁺ salt with hydrochloric acid solution to prepare cerium salt solution;

(2) Precipitation: add the precipitant ammonium bicarbonate, and let it stand and age at 70°C until the precipitate is formed;

(3) Cleaning: Clean the sediment with deionized water or ethanol;

(4) Drying: the precipitate was dried in a vacuum oven at 80°C for 10 hours to obtain a cerium oxide precursor;

(5) Roasting: the cerium oxide precursor is placed in a muffle furnace and heated to 850°C, kept for 3 hours, and then calcined to generate cerium oxide particles with a certain degree of crystallinity;

(6) Ball milling: the cerium oxide particles were placed in an agate ball mill jar, and ball milled with a planetary ball mill for 5 hours to obtain cerium oxide particles with a particle size of 0.05 μm.

2. Preparation of polishing solution:

The dispersant polyvinylpyrrolidone with a total mass of 1.0%, the pH regulator ethanolamine with a total mass of 0.9%, and the cerium oxide particles with a total mass of 15% are mixed with the remaining glycerin/ethanol mixed liquid (the ratio of glycerin and ethanol is 1:3 ), high-cut dispersion in a high-speed cutting disperser, and uniform mixing to obtain metallographic polishing agents for easily oxidized metals.

Example 3

1. Preparation of nano-lanthanum oxide abrasive grains:

(1) Raw material preparation: mix La ³⁺ salt with polyvinylpyrrolidone (PVP K30) solution to make lanthanum salt solution;

(2) Formation of precipitates: Add the precipitant ammonium bicarbonate, and let it stand and age at 90°C until the precipitates are formed;

(3) Cleaning: Clean the sediment with deionized water or ethanol;

(4) Drying: the precipitate was dried in a vacuum oven at 120°C for 6 hours to obtain a precursor of lanthanum oxide;

(5) Roasting: The lanthanum oxide precursor is placed in a muffle furnace and heated to 920°C, kept for 2 hours, and then roasted to form lanthanum oxide particles with a certain degree of crystallinity;

(6) Ball milling: Put the lanthanum oxide particles in an agate ball mill jar, mill them with a planetary ball mill for 3 hours to obtain lanthanum oxide particles with a particle size of 0.06 μm, and mill them for 7 hours to obtain lanthanum oxide particles with a particle size of 0.02 μm.

2. Preparation of polishing solution:

Mix lanthanum oxide particles of 0.02 μm and 0.06 μm at a ratio of 3:1; mix 1.0% of the total mass of the dispersant polyvinylpyrrolidone, 1.0% of the total mass of the pH regulator ethanolamine, and 10% of the total mass of lanthanum oxide particles, and the rest Glycerin/methanol mixed liquid (the ratio of glycerol to methanol is 1:3), high-cut dispersion in a high-speed cutting disperser, mixed evenly, to obtain a special metallographic polishing agent for easily oxidized metals.

Example 4

1. Preparation of nano-lanthanum oxide abrasive grains:

(1) Prepare raw materials: mix La ³⁺ salt with hydrochloric acid solution to make lanthanum salt solution;

(2) Precipitation: Add the precipitant oxalic acid, and let it stand and age at 80°C until the precipitate is formed;

(3) Cleaning: Clean the sediment with deionized water or ethanol;

(4) Drying: the precipitate was dried in a vacuum oven at 90°C for 10 hours to obtain a precursor of lanthanum oxide;

(5) Roasting: Put the lanthanum oxide precursor in a muffle furnace and heat it up to 900°C, keep it warm for 5 hours, and generate lanthanum oxide particles with a certain degree of crystallinity after roasting;

(6) Ball milling: the lanthanum oxide particles were placed in an agate ball mill jar and milled for 5 hours with a planetary ball mill to obtain lanthanum oxide particles with a particle size of 0.05 μm.

2. Preparation of polishing solution:

The total mass of 1.0% of the dispersant sodium polyacrylate, the total mass of 1.0% of the pH regulator sodium methoxide, the total mass of 5% of the lanthanum oxide particles, and the rest of the ethanol liquid are high-shear dispersed in a high-speed cutting disperser and mixed evenly. Get metallographic polishes for easily oxidized metals.

Embodiment 5 (test example)

Using the above-mentioned polishing agents and common chemical-mechanical polishing agents, the magnesium alloy was chemical-mechanical polished with a VibroMet® 2 vibration polishing machine, and the polished material was tested by SEM. The results are shown in Figure 2 and Figure 3.

As can be seen from the test results, compared with the commonly used chemical-mechanical polishing agent, the material surface has no scratches and oxide layers after being polished by the polishing agent of the present invention, and the polishing quality is obviously better than the general chemical-mechanical polishing agent commonly used at present.

Embodiment 6 (test example)

The above-mentioned polishing agents and common chemical-mechanical polishing agents were used to perform chemical-mechanical polishing on pure copper with a VibroMet® 2 vibration polishing machine, and the polished materials were tested by SEM. The results are shown in Figure 4 and Figure 5.

As can be seen from the test results, compared with the commonly used chemical-mechanical polishing agent, the material surface has no scratches and oxide layers after being polished by the polishing agent of the present invention, and the polishing quality is obviously better than the general chemical-mechanical polishing agent commonly used at present.

Claims (9)

1. The preparation method of the special metallographic polishing agent for the easily oxidized metal is characterized in that the metallographic polishing agent comprises nano cerium oxide or lanthanum oxide abrasive particles, a dispersing agent, a pH regulator and an alcohol group or oil-based/alcohol-based mixed liquid; wherein, the dispersant is 0.1 to 1.5 percent, the PH regulator is 0.1 to 1.0 percent, the abrasive particles are 5 to 20 percent, and the balance is alcohol group or oil-based alcohol group mixed liquid;

the preparation method comprises the following steps:

(1) Preparing abrasive particles:

adding Ce ⁴⁺ Salt or La ³⁺ Mixing a salt with a polyvinylpyrrolidone solution or a hydrochloric acid solution to prepare a cerium salt or lanthanum salt solution, adding a precipitator, standing and aging at a certain temperature until precipitates are generated, cleaning the precipitates with deionized water or ethanol, then drying in vacuum to obtain a cerium oxide precursor or a lanthanum oxide precursor, and roasting the cerium oxide precursor or the lanthanum oxide precursor to generate cerium oxide or lanthanum oxide abrasive particles with certain crystallinity;

(2) Preparing a polishing agent:

grinding the cerium oxide or lanthanum oxide abrasive particles into nano cerium oxide or lanthanum oxide particles by a ball mill; adding a dispersing agent, a pH regulator and an alcohol group or an oil-based/alcohol-based mixed liquid, performing high-shear dispersion in a high-speed cutting dispersion machine, and uniformly mixing to obtain the special metallographic polishing agent for the easily-oxidized metal.

2. The preparation method of the easy-to-oxidize metal dedicated metallographic polishing agent according to claim 1, wherein the oil base is glycerol or silicone oil, and the alcohol base is ethanol or methanol; the oil-based/alcohol-based mixed liquid comprises the following components in percentage by weight of 1.

3. The method for preparing the special metallographic polishing agent for the easily-oxidizable metal according to claim 1, wherein the dispersing agent is polyvinylpyrrolidone, sodium polyacrylate or magnesium aluminum silicate.

4. The method for preparing the special metallographic polishing agent for the easily-oxidizable metal according to claim 1, wherein the pH regulator is ethanolamine, sodium hydroxide or sodium methoxide.

5. The preparation method of the special metallographic polishing agent for the easily-oxidized metal according to claim 1, wherein the method is characterized in that a planetary ball mill is adopted to perform ball milling on the abrasive particles for 1-3 hours, 3-5 hours and 5-10 hours; respectively obtaining polishing agent abrasive particles with the particle sizes of 0.06 mu m, 0.05 mu m and 0.02 mu m; the nano cerium oxide particles with different particle sizes can be independently used as polishing agent abrasive particles, and the cerium oxide particles with different particle sizes can be mixed to be used as the polishing agent abrasive particles; 0.02 μm and 0.05 μm/0.06 μm of particle size cerium oxide were mixed in accordance with 2.

6. The method for preparing the special metallographic polishing agent for the oxidizable metal according to claim 1, wherein the temperature of the aging is 50 ℃ to 100 ℃ during standing.

7. The method for preparing the special metallographic polishing agent for the easily-oxidizable metal according to claim 1, wherein the roasting temperature of the cerium oxide particles with a certain degree of crystallinity is 800 ℃ to 950 ℃.

8. The method for preparing the special metallographic polishing agent for the easily-oxidizable metal according to claim 1, wherein the metallographic polishing agent has a weak alkalinity with a pH value of 9-10.

9. The method for preparing the special metallographic polishing agent for the easily-oxidizable metal according to claim 1, wherein the precipitating agent is sodium carbonate, ammonium bicarbonate or oxalic acid.

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