Preparation method of rock mineral sample target capable of realizing pollution-free recovery of sample on target

Abstract

The invention discloses a preparation method of a rock mineral sample target capable of realizing pollution-free recovery of a sample on the target. The preparation method of the rock mineral sample target comprises the following steps: (1) pasting a double faced adhesive tape on the surface of a glass plate, and sequentially pasting samples on the double faced adhesive tape one by one; (2) placing the mold on a glass plate, and enabling the mold and the glass plate to be concentric to prepare a sample target intermediate-1; (3) putting a sample target into the drying oven intermediate-1, adding a hot melt adhesive, vacuumizing, keeping for 0.5-3 hours, naturally cooling to room temperature, and taking out to obtain a sample target intermediate-2; and (4) grinding the sample target intermediate-2 to completely remove the glass plate, then removing the double faced adhesive tape, and grinding and polishing to obtain the sample target capable of realizing pollution-free recovery of the sample on the target. According to the method, the hot melt adhesive is combined with the process of directly polishing to the surface of the sample without demolding, so that the hidden danger of target preparation material residue is effectively eliminated, and the real pollution-free sample target preparation is realized.

Description

Technical Field

[0001] This invention relates to the field of geological sample pretreatment and sample target preparation technology, and in particular to a sample target preparation method suitable for the uncontaminated recovery of the sample to be tested from the sample target after the geological sample has been analyzed on the sample target. Background Technology

[0002] Significant breakthroughs in modern Earth science research have largely benefited from innovations in analytical techniques, particularly the development of microbeam analysis. This method has significantly improved our understanding of the phases, morphology, structure, chemical composition, and isotopic composition of rocks and minerals, and has become an indispensable technique in Earth science research. Before conducting various microbeam analysis experiments, samples need to be embedded according to the testing requirements and prepared into sample targets of specific sizes. Currently, the most common target preparation method is to prepare the sample into a resin target with a diameter of 1 inch. This technique has advantages such as low cost, relatively simple process, high mechanical strength of the sample target, stable performance, and strong adhesion, and has become an important sample target preparation method in various microbeam analyses.

[0003] Furthermore, alloy materials can be used to prepare sample targets for specific testing needs (such as hydrogen isotope analysis). However, existing target preparation methods are generally only suitable for single-piece molded samples. If the sample needs to be removed from the target after microbeam analysis for further testing, existing target materials are often difficult to completely remove from the fine sample particles, potentially interfering with experiments where the introduction of impurities is unacceptable. This is especially true for resin targets made of epoxy resin, where the resin melts and seeps into the gaps between rock particles when the sample is removed by heating, making complete removal difficult. Residual epoxy resin may interfere with the determination of target elements and isotopes in subsequent analyses.

[0004] The most effective method to completely remove the target material is to dissolve it completely. Soluble resin adhesives are important materials for solving the above problems and are one of the commonly used materials in rock thin section preparation. However, these soluble colloids are thick and brittle, and are prone to fragmentation when the adhesive layer thickness reaches 1-5 mm, making it difficult to maintain the flatness of the sample target surface. This not only affects the subsequent grinding and polishing effect but also the microbeam analysis test. In addition, if this material is used for the preparation of fine-grained mineral samples and traditional rock thin section preparation techniques are used, it is not only difficult to ensure that each mineral particle achieves a sufficient degree of grinding and polishing, but also the overall processing efficiency is low when the sample volume is relatively large. Therefore, traditional rock thin section preparation methods cannot solve this problem.

[0005] The quality of single-mineral sample target preparation directly affects the reliability of microbeam analysis data and subsequent test results. Therefore, there is an urgent need to develop a new target preparation method that allows the sample target to be polished to obtain a smooth surface of a single mineral and is suitable for various microbeam analysis tests. After microbeam analysis is completed, the sample can be removed from the target material without any target preparation material remaining, thus enabling sample reuse. Summary of the Invention

[0006] This invention solves the problem of potential sample contamination during sample reuse due to the adhesion of target materials in traditional target preparation processes. It provides a method for preparing rock and mineral sample targets that enables contamination-free recovery of samples from the target. This sample target can not only perform target preparation for rock particles of different sizes and obtain excellent sample target surface smoothness, making it suitable for microbeam analysis of geological samples, but also enables contamination-free recovery of samples from the target after microbeam analysis.

[0007] The first objective of this invention is to provide a method for preparing a rock and mineral sample target that enables contamination-free recovery of samples from the target, comprising the following steps:

[0008] (1) Stick double-sided tape on the surface of the glass plate and stick the samples one by one onto the double-sided tape;

[0009] (2) Place the mold on the glass plate and make the mold concentric with the glass plate to obtain the sample target intermediate-1;

[0010] (3) Place the sample target No. 1 prepared in step (2) into an oven at a temperature of 80℃–140℃, and add hot melt adhesive that can be dissolved in acetone into the sample target intermediate-1. After vacuuming for 0.5–3.0 hours, take it out after naturally cooling to room temperature to obtain sample target intermediate-2.

[0011] (4) Grind the sample target intermediate-2 obtained in step (3), completely remove the glass plate, remove the double-sided adhesive, grind and polish the sample target surface to obtain the sample target that can be recycled without pollution.

[0012] The preparation method proposed in this invention uses a soluble adhesive instead of traditional epoxy resin or alloy materials, effectively avoiding contamination problems introduced by the target-making materials. In traditional resin target fabrication, after the resin is poured and cooled, the plastic mold and sample target are directly removed from a glass plate covered with double-sided tape, and the sample target is ejected directly from the plastic mold to obtain the epoxy resin target. However, this type of hot melt adhesive is extremely brittle, causing the target to break when removed from the glass plate. Therefore, this invention establishes a dedicated target-making process. After the hot melt adhesive is poured and shaped, it is no longer directly removed from the glass plate. Instead, the glass plate is completely ground away by grinding, and the double-sided tape is gently peeled off. This allows the extremely brittle hot melt adhesive to be made into a sample target with a fixed shape and size, and also enables grinding and polishing.

[0013] The hot melt adhesive mentioned in step (3) is a glue stick that can be dissolved in acetone.

[0014] Preferably, the glass plate in step (1) has a diameter of 25 mm and a thickness of 1 mm, and the samples are concentrated in a circular area with a central diameter of 10-12 mm.

[0015] Preferably, the sample in step (1) is a rock or a single mineral, including basalt, feldspar, pyroxene, amphibole and olivine.

[0016] Preferably, the mold in step (2) is a PVC mold with an outer diameter of 25 mm, a wall thickness of 1–5 mm, and a height of 5–50 mm.

[0017] Preferably, step (3) is as follows: the sample target intermediate-1 is placed in an oven at a temperature of 80℃-140℃, and hot melt adhesive that can be dissolved in acetone is added. After vacuuming for 0.5-3.0 hours, it is naturally cooled to room temperature and then taken out to obtain sample target intermediate-2.

[0018] Preferably, step (3) is as follows: the sample target intermediate-1 is placed in an oven at 100°C, and hot melt adhesive that can be dissolved in acetone is added. After vacuuming for 0.5-1.0 hours, it is naturally cooled to room temperature and then taken out to obtain sample target intermediate-2.

[0019] Preferably, the hot melt adhesive has a melting point of 80℃-140℃.

[0020] Preferably, the amount of hot melt adhesive added is 1-2 g.

[0021] A second objective of this invention is to provide a rock and mineral sample target that enables contamination-free recovery of samples from the target, prepared by the aforementioned method. The sample target proposed in this invention allows for grinding and polishing of the sample surface to obtain a smooth plane for a single mineral, and is suitable for various microbeam analysis tests.

[0022] The third objective of this invention is to provide a rock and mineral sample target that enables uncontaminated recovery of samples on the target for geological sample analysis, including microbeam analysis after sample target preparation and single-particle consumption analysis after uncontaminated recovery of the sample.

[0023] Preferably, after the rock and mineral sample target that enables uncontaminated recovery of samples from the target has completed the geological sample microbeam analysis, the post-processing steps of the sample target are as follows: heat the hot melt adhesive near the sample to melt it, then take out the sample to be recovered and the surrounding target material together, add them to a beaker containing acetone, and perform ultrasonic treatment. After the target material is completely dissolved, take out the sample, wash it, dry it, and set it aside for later use.

[0024] Further optimization involves the following post-processing steps: After the rock and mineral sample target, which enables the uncontaminated recovery of samples from the target, completes the corresponding microbeam analysis, a soldering iron is used to heat the area near the sample to melt the hot melt adhesive. The target material in this area, along with the sample, is transferred to a beaker, acetone is added, and the sample is sonicated for 5-10 minutes. Once the target material is completely dissolved, the sample is removed, transferred to another centrifuge tube, washed several times with alcohol, and dried for later use.

[0025] Compared with existing technologies, this invention has the following advantages: The hot melt adhesive used in the preparation method proposed in this invention can be completely dissolved in acetone, fundamentally eliminating the contamination problem caused by the residue of traditional materials such as epoxy resin in the sample; at the same time, the sample preparation process is optimized, so that the cured hot melt adhesive sample target has suitable mechanical strength and can be directly ground and polished, successfully solving the problem that conventional acetone-soluble hot melt adhesives are easily damaged during processing due to their high brittleness, making it impossible to carry out microbeam analysis. In summary, this invention, by using an acetone-soluble hot melt adhesive combined with a new target preparation process of "ground directly from the glass plate to the sample surface without demolding," effectively eliminates the hidden danger of target preparation material residue and achieves truly contamination-free recovery of the sample on the target. Attached Figure Description

[0026] Figure 1 This is a diagram showing the preparation steps of the rock and mineral sample target obtained in Examples 1-4 of the present invention, wherein: (a) represents double-sided tape being pasted on a glass plate; (b) represents sample target intermediate-1; (c) represents sample target intermediate-2; and (d) represents the rock and mineral sample target.

[0027] Figure 2 These are schematic diagrams of the overall structure of the sample targets obtained after casting in Examples 1-4 and Comparative Example 1 of the present invention;

[0028] Figure 3These are magnified distribution images of the sample after polishing the sample target obtained in Example 1, including (a) an overall image of the sample surface; (b & c) magnified images of typical particles to compare and display the flatness between the particles and the sample target; and (d & e) further magnified images of typical particles to display the internal grinding and polishing of the particles. Detailed Implementation

[0029] The following embodiments are further illustrations of the present invention, but not limitations thereof.

[0030] 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. Unless otherwise specified, the experimental materials and reagents used herein are commercially available products conventionally available in this technical field.

[0031] Example 1

[0032] In this embodiment, basalt particles (200-300 micrometers in diameter) were selected as the target sample, and Crystalbond was used. TM #509-3 adhesive was used as the casting material. Figure 1 It showcases the entire manufacturing process and the complete target surface after manufacturing. Figure 2 These are targets obtained under different conditions. Figure 3 This is an enlarged view of the target surface obtained in this embodiment. It can be seen that after grinding and polishing, a very flat particle plane can be obtained.

[0033] The specific operating steps are as follows:

[0034] Apply double-sided tape to a 25 mm diameter, 1 mm thick glass plate. Place each basalt particle flat and adhere it to a 10 mm diameter circle around the center of the glass plate. After the sample is placed, attach a 25 mm outer diameter PVC casting mold to the center of the glass plate, ensuring the mold is concentric with the glass plate. Gently press it down to ensure a seamless connection between the mold and the double-sided tape. Cut approximately 1.3 g of Crystalbond. TM #509-3 adhesive material was placed on the casting mold and heated in a vacuum oven (100℃) until Crystalbond... TMAfter the #509-3 adhesive is completely melted, turn on the vacuum pump to create a vacuum. Maintain this vacuum environment at a constant temperature for 0.5 hours, then turn off the vacuum pump, open the vent valve to bring the vacuum chamber to atmospheric pressure, and start the slow cooling program. Once the chamber has slowly cooled to room temperature, remove the glass plate. Grind the glass plate along with the sample target until it is completely removed. Peel off the double-sided adhesive and continue gently grinding the sample target until a suitable sample surface width is exposed. Polish and clean the sample, then inspect it under a microscope. Once the exposed sample surface is sufficiently wide and thick, the sample target preparation is complete.

[0035] Example 2

[0036] Similar to Example 1, except that the oven temperature was 100°C, and the samples were kept at this temperature in a vacuum environment for 1 hour or 1.5 hours respectively. The sample target surface is as follows... Figure 2 As shown.

[0037] Example 3

[0038] Same as Example 1, except that: the oven temperature was 80°C, and the samples were kept at this temperature in a vacuum environment for 0.5 or 1 hour respectively. The sample target surface is as follows... Figure 2 As shown.

[0039] Example 4

[0040] Same as Example 1, except that: the oven temperature was 120°C, and the samples were kept at a constant temperature in a vacuum environment for 0.5, 1 hour, or 1.5 hours, respectively. The sample target surface is as follows... Figure 2 As shown.

[0041] Comparative Example 1

[0042] Same as Example 1, except that the oven temperature was 80°C, and the temperature was maintained at this level for 0.5 hours under normal pressure. The sample target surface is as follows... Figure 2 As shown.

[0043] Depend on Figure 2 It can be seen that Comparative Example 1, which was not vacuumed, had a large number of pores in the resulting rock and mineral sample target, which affected subsequent analysis.

[0044] Comparative Example 2

[0045] The sample target was prepared using the method disclosed in CN107449648A (a method for preparing a sample target for ore minerals suitable for secondary ion mass spectrometry analysis). When the sample was removed from the sample target again, the target material in the particle gaps could not be completely removed.

[0046] Comparative Example 3

[0047] Common methods for preparing thin sections of rock particles of varying sizes often suffer from drawbacks. Due to height differences between particles, while large particles are polished to optimal results, smaller particles remain embedded in the resin and are not properly ground. Conversely, when small particles are polished to satisfactory results, large particles are excessively worn down. Therefore, traditional methods struggle to simultaneously meet the processing requirements of minerals with different particle sizes. In contrast, this invention effectively processes particles of varying sizes, reducing the amount of valuable samples required while improving sample quality.

[0048] The above description of the embodiments is only for the purpose of helping to understand the technical solution and core idea of ​​the present invention. It should be noted that for those skilled in the art, several improvements and modifications can be made to the present invention without departing from the principle of the present invention, and these improvements and modifications also fall within the protection scope of the claims of the present invention.

Claims

1. A method for preparing a rock and mineral sample target capable of achieving contamination-free recovery of samples from the target, characterized in that, Includes the following steps: (1) Stick double-sided tape on the surface of the glass plate and stick the samples one by one onto the double-sided tape; (2) Place the mold on the glass plate and make the mold concentric with the glass plate to obtain the sample target intermediate-1; (3) Place the sample target intermediate-1 prepared in step (2) into an oven at a temperature of 80℃–140℃, and add hot melt adhesive that can be dissolved in acetone into the sample target intermediate-1. After vacuuming for 0.5–3.0 hours, take it out after naturally cooling to room temperature to obtain sample target intermediate-2. (4) The sample target intermediate-2 obtained in step (3) is directly ground. After the glass plate is completely ground away, the double-sided adhesive is removed. Finally, the sample target surface is ground and polished to obtain the pollution-free mineral sample target.

2. The preparation method according to claim 1, characterized in that, The glass plate in step (1) has a diameter of 25 mm and a thickness of 1 mm, and the samples are concentrated in a circular area with a central diameter of 10–12 mm.

3. The preparation method according to claim 1 or 2, characterized in that, The sample in step (1) is a rock or a single mineral, including basalt, feldspar, pyroxene, amphibole and olivine.

4. The preparation method according to claim 1 or 2, characterized in that, The mold mentioned in step (2) is a PVC mold with an outer diameter of 25 mm, a wall thickness of 1–5 mm, and a height of 5–50 mm.

5. The preparation method according to claim 1, characterized in that, Step (3) is as follows: Place the sample target intermediate-1 in an oven at a temperature of 80℃-140℃, add hot melt adhesive that can be dissolved in acetone, vacuum and maintain for 0.5-3.0 hours, and then take it out after naturally cooling to room temperature to obtain sample target intermediate-2.

6. The preparation method according to claim 1 or 5, characterized in that, The melting point of the hot melt adhesive is 80℃–140℃.

7. The preparation method according to claim 1 or 5, characterized in that, The amount of hot melt adhesive added is 1-2 g.

8. A rock and mineral sample target capable of achieving contamination-free recovery of samples from the target, characterized in that, The rock and mineral sample target is prepared by the preparation method described in claim 1 or 2.

9. The rock and mineral sample target of claim 8, which enables uncontaminated recovery of samples from the target, is applied to geological sample analysis.

10. The application according to claim 9, characterized in that, After the rock and mineral sample target, which enables the uncontaminated recovery of samples from the target, completes the microbeam analysis of the geological sample, the post-processing steps of the sample target are as follows: heat the hot melt adhesive near the sample to melt it, then take out the sample to be recovered and the surrounding target material together, add them to a beaker containing acetone, and perform ultrasonic treatment. After the target material is completely dissolved, take out the sample, wash it, dry it, and set it aside for later use.

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