Etchant for metallographic erosion of titanium-palladium alloy and metallographic erosion method

Abstract

The invention provides an aggressive agent for titanium-palladium alloy metallographic erosion. The aggressive agent comprises the following components: glycerol, methanol, benzenesulfonic acid, oxalic acid and deionized water. By using the etchant disclosed by the invention, the corrosion of the metallographic structure of the titanium-palladium alloy can be easily controlled, the process is safer, and the metallographic structure which is easy to observe can be more easily obtained; the preparation and erosion processes of the erosion agent are simple and convenient to operate.

Description

Technical Field

[0001] This invention belongs to the field of metallographic analysis, specifically relating to an etchant and etching method for metallographic etching of titanium-palladium alloys. Background Technology

[0002] Titanium alloys (such as TA8, TA9, and TA10) exhibit excellent corrosion resistance and good tolerance to many strong corrosive systems. Their surface oxide film provides excellent corrosion resistance, including systems containing chlorine, alkalis, and certain concentrations of nitric acid and sulfuric acid, as well as most high-temperature organic acid systems. Therefore, their application in chemical plants is becoming increasingly widespread. Titanium-palladium alloys, such as TA9, which incorporate palladium, are even more resistant to low-oxygen, acidic, and high-temperature chloride environments. In 5% boiling sulfuric acid, the corrosion rate of TA9 titanium-palladium alloy is approximately 0.5 mm / a, a significant reduction compared to pure titanium.

[0003] In the field of metal etching technology, especially for high-strength, lightweight, and corrosion-resistant metallic materials such as titanium-palladium alloys, metallographic analysis can quickly assess their application performance. Metallographic etching methods make the microstructure of titanium-palladium alloys clearly visible, facilitating observation and analysis.

[0004] However, due to the strong corrosion resistance of titanium-palladium alloys, etching them is quite difficult. Currently, the main etching agents used are hydrofluoric acid and perchloric acid to reveal surface grain boundaries and microstructure. However, hydrofluoric acid is highly corrosive and can cause irreversible damage to the human body during use; perchloric acid also has an odor and is volatile, potentially causing respiratory injury to laboratory personnel. When using these etching agents, etching is mostly done by wiping or immersion. The etching process is easily affected by the etching time, requiring a reasonable etching time; too long or too short a time can lead to over-etching or insufficient etching effect. Furthermore, the preparation of solutions requires highly corrosive media such as hydrofluoric acid and perchloric acid, and improper operation can cause personal injury, posing a high risk.

[0005] Therefore, there is an urgent need in this field for safe, effective, and controllable erosion agents. Summary of the Invention

[0006] To address the shortcomings of existing technologies, the present invention aims to provide an etchant and etching method for the metallographic etching of titanium-palladium alloys. Using the etchant of the present invention allows for easier control of the metallographic etching of titanium-palladium alloys, a safer process, and the easier acquisition of easily observable metallographic structures. The preparation of the etchant and the etching process are simple and easy to operate.

[0007] To achieve the above-mentioned objectives, the present invention adopts the following technical solution:

[0008] This invention provides an etchant for metallographic etching of titanium-palladium alloys, formulated from the following raw materials:

[0009] 10-20 parts by weight of glycerol, 15-25 parts by weight of methanol, 3-5 parts by weight of benzenesulfonic acid, 3-10 parts by weight of oxalic acid, and 20-30 parts by weight of deionized water.

[0010] The etchant for metallographic etching of titanium-palladium alloys according to the present invention is preferably prepared from the following raw materials:

[0011] 13-18 parts by weight of glycerol, 20-25 parts by weight of methanol, 4-5 parts by weight of benzenesulfonic acid, 8-10 parts by weight of oxalic acid, and 20-25 parts by weight of deionized water.

[0012] The etchant for metallographic etching of titanium-palladium alloys according to the present invention is further preferably formulated from the following raw materials:

[0013] 15 parts by weight of glycerol, 25 parts by weight of methanol, 5 parts by weight of benzenesulfonic acid, 10 parts by weight of oxalic acid, and 20 parts by weight of deionized water.

[0014] This invention also provides a metallographic etching method for titanium-palladium alloys, comprising the following steps:

[0015] 1) Add deionized water, glycerin and methanol to a container in sequence, stir well and let stand, then add benzenesulfonic acid and oxalic acid in sequence, stir until completely dissolved to obtain the etching agent;

[0016] 2) Clean the titanium-palladium alloy sample with deionized water and ethanol to remove surface deposits, dry it, polish it with sandpaper, and then mechanically polish it until the surface is smooth to obtain the titanium-palladium alloy sample.

[0017] 3) Place the etchant prepared in step 1) in a container, select an inert material containing platinum, gold, lead or carbon as the cathode, and the titanium-palladium alloy sample obtained in step 2) as the anode. Place the cathode and anode opposite each other with a distance of 2-4 cm between them; connect the cathode and anode to a DC power supply, apply a voltage of 5-15V, and electrolyze for 20-30 seconds.

[0018] 4) Remove the sample, clean it with deionized water, then clean it with ethanol, and air dry it to complete the metallographic etching.

[0019] According to the metallographic etching method for titanium-palladium alloys of the present invention, in step 1),

[0020] The preparation of the etchant is carried out at room temperature;

[0021] Add deionized water, glycerol and methanol to the container in sequence, stir well and let stand for 10-20 minutes. Then add benzenesulfonic acid and oxalic acid in sequence, stir until completely dissolved and let stand for 20-40 minutes.

[0022] According to the metallographic etching method for titanium-palladium alloys of the present invention, in step 2),

[0023] The ethanol used for cleaning was anhydrous ethanol;

[0024] Use sandpaper with a grit of 200#, 400# and 600# to sand in sequence.

[0025] According to the metallographic etching method for titanium-palladium alloys of the present invention, in step 3),

[0026] The effective working surface area of ​​the cathode and anode is the same, approximately 1 cm². 2 ;

[0027] Inert materials containing platinum, gold, lead, or carbon refer to materials containing platinum, gold, lead, or carbon that can provide a stable potential in a dielectric environment. Preferably, the carbon-containing inert material is graphite. Other inert materials known in the art, such as gold wire or gold sheet, platinum mesh or platinum sheet, lead block, etc., can be selected as needed.

[0028] According to the metallographic etching method for titanium-palladium alloys of the present invention, in step 4), the ethanol used for cleaning is anhydrous ethanol.

[0029] The metallographic etching method for titanium-palladium alloys according to the present invention further includes the following steps:

[0030] After metallographic etching is completed, the grain boundaries and metallographic structure of the etched titanium-palladium alloy sample are observed using a microscope or scanning electron microscope.

[0031] The beneficial effects of the above-mentioned technical solution of the present invention are as follows:

[0032] (1) The raw materials of the electrolyte etchant of the present invention are simple to obtain and prepare. It mainly uses organic acids and alcohols, which have no obvious odor and no harm to the human body. Glycerin and methanol provide a dissolution environment and corrosion inhibition effect on the sample surface. At the same time, the corrosiveness of benzenesulfonic acid and oxalic acid is used to etch the surface of titanium palladium alloy under the action of electrolytic current. The etch rate is relatively slow, which can make good control over the degree of etch and achieve the purpose of metallographic etch, while effectively avoiding the situation of excessive etch or too light etch.

[0033] (2) The chemical composition of the electrolyte erosion agent used is relatively safe and will not produce a large number of substances harmful to the human body during operation, thereby ensuring the personal safety and health of the operators.

[0034] (3) The metallographic etching method of the present invention has good repeatability, and the grain boundaries and phase structures in the obtained metallographic structure are clear, so as to obtain ideal etching results. Attached Figure Description

[0035] Figure 1 The metallographic structure of the sample from Example 1 after treatment with an electrolyte etchant is shown.

[0036] Figure 2 The metallographic structure of the sample from Example 2 after treatment with an electrolyte etchant is shown.

[0037] Figure 3 The metallographic structure of the sample from Example 3 after treatment with an electrolyte etchant is shown.

[0038] Figure 4 The metallographic structure of the sample from Example 4 after treatment with an electrolyte etchant is shown. Detailed Implementation

[0039] The technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are merely a part of the embodiments of the present invention, and not all of them. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention are within the scope of protection of the present invention.

[0040] Unless otherwise defined, all technical terms used herein have the same meaning as commonly understood by those skilled in the art. The technical terms used herein are for the purpose of describing particular embodiments only and are not intended to limit the scope of the invention.

[0041] The main materials used in the following embodiments and application examples are sourced from the following sources:

[0042] Glycerin: Analytical grade, Aladdin

[0043] Methanol: Analytical grade, Comio Chemicals

[0044] Benzenesulfonic acid: analytical grade, Inokai

[0045] oxalic acid: analytical grade, Inokai

[0046] TA9 Alloy: Yantai Huapeng Instrument Equipment Co., Ltd.

[0047] Ethanol: Anhydrous ethanol, analytical grade, Inokai

[0048] Unless otherwise specified, all materials in this invention are commercially available products or products that can be produced by known methods.

[0049] Example

[0050] Example 1: Preparation of Electrolytic Etching Agent

[0051] Prepare a 200mL beaker, take 40g of deionized water through a graduated cylinder and pour it into the beaker. Add 30g of glycerin and 50g of methanol in sequence, stir well and let stand for 15min. Then measure 10g of benzenesulfonic acid and 20g of oxalic acid and add them to the beaker respectively. Stir well and let stand for 30min until they are mixed evenly to obtain the electrolytic etching agent.

[0052] Following the same preparation process as in Example 1, the electrolytic etching agents of Examples 2-4 were prepared according to the raw material composition in Table 1 below.

[0053] Table 1

[0054]

[0055] Application example: Metallographic etching of TA9 alloy

[0056] The TA9 alloy was subjected to metallographic etching using the electrolytic etching agent prepared in Example 1 above. The etching steps are as follows:

[0057] The TA9 alloy sample was ultrasonically treated with anhydrous ethanol, then cleaned with deionized water, and polished step by step with 200#, 400# and 600# sandpaper, and then polished with a polishing machine to obtain the polished TA9 alloy sample.

[0058] Pour the electrolyte etchant into the electrolytic cell. Use a graphite block as the cathode and a polished TA9 alloy as the anode. Place them opposite each other with a distance of 2cm.

[0059] Set the DC power supply voltage to 6V, observe the surface bubbles, and the electrolytic etching time is 25s.

[0060] After electrolytic etching, the TA9 alloy sample was removed, rinsed with deionized water, then rinsed with anhydrous ethanol and air-dried. The metallographic surface was then observed using an optical microscope. Figure 1 As shown.

[0061] Referring to the etching steps described in this application example, the TA9 alloy was metallographically etched using the electrolytic etching agent prepared in Examples 2-4 above. The metallographic surface of the TA9 alloy after electrolytic etching was observed using an optical microscope / scanning electron microscope. The optical microscope image is shown below. Figure 2-4 As shown.

[0062] Figures 1-4 The results show that the obtained metallographic structure has clear grain boundaries and phase structure, is a typical equiaxed α phase structure, with fine grain boundaries, and achieves ideal etching results.

Claims

1. An etchant for metallographic etching of titanium-palladium alloys, prepared from the following raw materials: 10-20 parts by weight of glycerol, 15-25 parts by weight of methanol, 3-5 parts by weight of benzenesulfonic acid, 3-10 parts by weight of oxalic acid, and 20-30 parts by weight of deionized water.

2. The etchant for metallographic etching of titanium-palladium alloys according to claim 1 is prepared from the following raw materials: 13-18 parts by weight of glycerol, 20-25 parts by weight of methanol, 4-5 parts by weight of benzenesulfonic acid, 8-10 parts by weight of oxalic acid, and 20-25 parts by weight of deionized water.

3. The etchant for metallographic etching of titanium-palladium alloys according to claim 1 or 2 is prepared from the following raw materials: 15 parts by weight of glycerol, 25 parts by weight of methanol, 5 parts by weight of benzenesulfonic acid, 10 parts by weight of oxalic acid, and 20 parts by weight of deionized water.

4. A metallographic etching method for titanium-palladium alloys, comprising the following steps: 1) Add deionized water, glycerin and methanol to a container in sequence, stir well and let stand, then add benzenesulfonic acid and oxalic acid in sequence, stir until completely dissolved to obtain the etching agent; 2) Clean the titanium-palladium alloy sample with deionized water and ethanol to remove surface deposits, dry it, polish it with sandpaper, and then mechanically polish it until the surface is smooth to obtain the titanium-palladium alloy sample. 3) Place the etchant prepared in step 1) in a container, select an inert material containing platinum, gold, lead or carbon as the cathode, and the titanium-palladium alloy sample obtained in step 2) as the anode. Place the cathode and anode opposite each other with a distance of 2-4 cm between them; connect the cathode and anode to a DC power supply, apply a voltage of 5-15V, and electrolyze for 20-30 seconds. 4) Remove the sample, clean it with deionized water, then clean it with ethanol, and air dry it to complete the metallographic etching.

5. The metallographic etching method for titanium-palladium alloys according to claim 4, wherein, In step 1), The preparation of the etchant is carried out at room temperature; Add deionized water, glycerol and methanol to the container in sequence, stir well and let stand for 10-20 minutes. Then add benzenesulfonic acid and oxalic acid in sequence, stir until completely dissolved and let stand for 20-40 minutes.

6. The metallographic etching method for titanium-palladium alloys according to claim 4 or 5, wherein, In step 2), The ethanol used for cleaning was anhydrous ethanol; Use sandpaper with a grit of 200#, 400# and 600# to sand in sequence.

7. The metallographic etching method for titanium-palladium alloys according to any one of claims 4-6, wherein, In step 3), the effective working surface areas of the cathode and anode are the same.

8. The metallographic etching method for titanium-palladium alloys according to any one of claims 4-7, wherein, In step 4), the ethanol used for cleaning is anhydrous ethanol.

9. The metallographic etching method for titanium-palladium alloys according to any one of claims 4-8, wherein, Further steps include: After metallographic etching is completed, the grain boundaries and metallographic structure of the etched titanium-palladium alloy sample are observed using a microscope or scanning electron microscope.

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