A Metallographic Corrosion Agent for Nanoparticle-Reinforced Magnesium Matrix Composites and Its Usage Method

Abstract

The present invention relates to a metallographic etchant for nanoparticle-reinforced magnesium matrix composites and a method for using the same. The components and weight percentages of the etchant are as follows: succinic acid: 1-5%, magnesium chloride: 0.5-2%, ethanol: 20-35%, and the balance is water. The method for using the etchant is as follows: samples are taken from the composites and polished successively with coarse-grained, medium-grained, and fine-grained water sandpapers, then polished successively with polishing pastes with particle sizes of 1 μm and 0.5 μm, cleaned with absolute ethanol and dried. At room temperature, a cotton ball is used to dip the metallographic etchant and wipe it on the polished surface for 10-35 s, and then the samples are cleaned successively with distilled water and absolute ethanol and dried. The samples are observed and analyzed with a metallographic microscope. The present invention uses weak acid, salt, and alcohol to prepare the metallographic etchant, and the grain morphology is clearly shown. Compared with the commonly used strong acid etchant, the corrosion is uniform and easy to control, which is beneficial to accurate metallographic analysis, and is harmless to the health of experimental personnel and the environment.

Description

Technical Field

[0001] The present invention relates to a metallographic etchant for nanoparticle-reinforced magnesium matrix composites and a method for using the same, belonging to the technical field of metallographic inspection of magnesium-based materials. Background Art

[0002] Nanoparticle-reinforced magnesium matrix composites are one of the important frontiers in the field of metals. The mechanical properties, physical properties, and corrosion resistance of materials are closely related to their microstructures. In the research and development process, it is essential to observe and analyze their microstructures. Optical microscopy analysis equipment has strong versatility, is easy to operate, and has high working efficiency. Therefore, metallographic analysis is an important means to study the grain structure, morphology, size, and distribution law of the second phase of materials. The composition and processing technology of magnesium-based materials are diverse, and the suitable metallographic etchants also change accordingly. Currently, most commonly used etching solutions contain one or several of nitric acid, hydrofluoric acid, hydrochloric acid, picric acid, etc. Since magnesium has poor corrosion resistance, etching agents containing strong acids are likely to cause over-etching, resulting in inaccurate metallographic analysis, and are also prone to volatilization, causing environmental pollution and endangering the health of operators. Picric acid is highly toxic and explosive, posing a greater safety hazard. Summary of the Invention

[0003] The purpose of the present invention is to provide a metallographic etchant and a method for using the same with relatively weak acidity, strong safety, and more environmental protection for nanoparticle-reinforced magnesium matrix composites. The components and weight percentages of the etchant are as follows: succinic acid: 1-5%, magnesium chloride: 0.5-2%, ethanol: 20-35%, and the balance is water. The method for using the etchant to display the metallographic structure is as follows: sample the magnesium matrix composite and polish it successively with 240#, 600#, 1000#, and 2000# water sandpapers, then polish it successively with polishing pastes with particle sizes of 1 μm and 0.5 μm. After cleaning and drying with absolute ethanol, at room temperature, dip a cotton ball in the metallographic etchant and wipe it on the polished surface for 10-35 s, then wash and dry the sample successively with distilled water and absolute ethanol, and observe and analyze the microstructure with a metallographic microscope.

[0004] The present invention uses weak acid, salt, and alcohol to prepare a metallographic etchant for magnesium matrix composites. The matrix grains are clearly shown and the morphology is distinct. Compared with the existing commonly used strong acid etching agents, the etching is uniform and easy to control, which is beneficial to accurate metallographic analysis and has no harm to the health of experimental personnel and the environment. Brief Description of the Drawings

[0005] Figure 1 It is the microstructure of the SiC nanoparticle (average size 50 nm)-reinforced magnesium matrix composite in Example 1 after being etched with the etchant of the present invention;

[0006] Figure 2It is the microstructure of the SiC nanoparticle (average size 10 nm)-reinforced magnesium matrix composite after being corroded by the etchant of the present invention in Example 2. Detailed implementation manners

[0007] Example 1:

[0008] This example provides a method for revealing the metallographic structure of the SiC nanoparticle (50 nm)-reinforced magnesium matrix composite using the etchant. The components and weight percentages of the etchant are as follows: succinic acid: 2%, magnesium chloride: 1.5%, ethanol: 20%, and the balance is water. The specific steps are as follows:

[0009] Sample the composite material and polish it successively with 240#, 600#, 1000#, and 2000# water sandpapers, and then polish it successively with polishing pastes with particle sizes of 1 μm and 0.5 μm. After cleaning and drying with anhydrous alcohol, at room temperature, dip a cotton ball in the metallographic etchant and wipe it on the polished surface for 15 s. Then, wash the sample successively with distilled water and anhydrous alcohol and dry it. Observe and analyze the microstructure with a metallographic microscope. Figure 1 It is the observed microstructure. The grain boundaries are clear, the grain morphology and size are distinguishable, there are no corrosion pits, and the corrosion effect is good.

[0010] Example 2:

[0011] This example provides a method for revealing the metallographic structure of the SiC nanoparticle (10 nm)-reinforced magnesium matrix composite using the etchant. The components and weight percentages of the etchant are as follows: succinic acid: 4%, magnesium chloride: 0.5%, ethanol: 30%, and the balance is water. The specific steps are as follows:

[0012] Sample the composite material and polish it successively with 240#, 600#, 1000#, and 2000# water sandpapers, and then polish it successively with polishing pastes with particle sizes of 1 μm and 0.5 μm. After cleaning and drying with anhydrous alcohol, at room temperature, dip a cotton ball in the metallographic etchant and wipe it on the polished surface for 30 s. Then, wash the sample successively with distilled water and anhydrous alcohol and dry it. Observe and analyze the microstructure with a metallographic microscope. Figure 2 It is the observed corrosion morphology. The grain morphology is clear, the grain boundaries are distinct, the corrosion is uniform and there are no corrosion pits, and the metallographic corrosion effect is good.

Claims

1. A metallographic etchant for nanoparticle-reinforced magnesium matrix composites, characterized in that, The corrosion agent components and their weight percentages are as follows: succinic acid: 1-5%, magnesium chloride: 0.5-2%, ethanol: 20-35%, and the balance is water; The method for using the metallographic corrosion agent for the nano-particle reinforced magnesium matrix composite material is as follows: sample the composite material and successively polish it with 240#, 600#, 1000#, and 2000# water sandpapers, then polish it successively with polishing pastes with particle sizes of 1μm and 0.5μm. After cleaning and drying with anhydrous alcohol, dip a cotton ball in the metallographic corrosion agent at room temperature and wipe it on the polished surface for 10-35s. Then, clean and dry the sample successively with distilled water and anhydrous alcohol, and observe and analyze the sample with a metallographic microscope; The nano-particle reinforced magnesium matrix composite material is a SiC nano-particle reinforced magnesium matrix composite material.

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