Porous diamond, and etching method and application thereof

Abstract

A porous diamond, its etching method, and its applications are disclosed, relating to the field of diamond etching technology. The method includes: mixing diamond with calcium carbonate and subjecting it to heat treatment; using the calcium carbonate to etch the diamond surface; after heat treatment, removing residues to obtain the etched diamond. This method uses calcium carbonate as the etchant, has a simple process flow, and can complete etching rapidly at relatively low temperatures, offering advantages such as short production cycles and low energy consumption, which is conducive to mass production. Moreover, the etched diamond retains its original morphology and contour, without graphitization, and does not affect its physicochemical properties such as strength, hardness, wear resistance, and thermal conductivity.

Description

Technical Field

[0001] This invention relates to the field of diamond etching technology, and particularly to a porous diamond, its etching method, and its applications. Background Technology

[0002] Diamond, due to its exceptional hardness, wear resistance, thermal conductivity, and chemical stability, shows broad application prospects in many fields such as processing and manufacturing, tribology, and electronic packaging. However, due to the influence of diamond's surface properties, its chemical inertness becomes a bottleneck in its applications, and diamond surface etching technology is one of the important means to overcome this bottleneck. Therefore, how to precisely control the surface structure and physicochemical properties of diamond has become an important research direction in this field. In recent years, in the processing and manufacturing field, surface etching can form etch pits on the diamond surface, thereby effectively enhancing the interfacial bonding between it and the binder. In the field of tribology, diamond surface etching technology increases the specific surface area of ​​diamond, increasing the contact area with the substrate material, thereby improving the holding force of diamond during the grinding process. In the field of electronic packaging, by constructing micro-nano structures or ordered arrays of specific shapes on the diamond surface through etching technology, phonon scattering at the interface can be effectively reduced, thereby reducing the total interfacial thermal resistance between diamond and the substrate.

[0003] Taking the processing and manufacturing of superhard materials as an example, solid-state etching and vapor-phase etching are commonly used for diamond etching. In solid-state etching, researchers mainly utilize iron-based elements (such as iron, cobalt, and nickel) and their oxides to etch diamond at high temperatures (usually 900-1200℃), thereby roughening the diamond surface to enhance the bonding force with the substrate interface. However, this method has some drawbacks, mainly: firstly, the etchant is expensive and consumed in large quantities; secondly, strong acids or bases are required to remove residual etchant after high-temperature treatment, and many strong acids and bases are controlled reagents, which are expensive, difficult to obtain in large quantities, and easily pollute the environment; thirdly, high temperatures can easily induce graphitization transformation in diamond, reducing its strength, hardness, wear resistance, thermal conductivity, and chemical stability, thus affecting its final performance. Most importantly, this method achieves the etching effect (high degree of etching) by sacrificing the diamond morphology, which significantly alters its original properties. In comparison, vapor phase etching (VPE) technology has advantages such as low cost and no environmental pollution, making it increasingly popular among researchers. However, this method has slow etching speed, long etching time, multiple etching steps, and requires post-processing, making it difficult to promote and apply in industry. Summary of the Invention

[0004] The purpose of this invention is to provide an efficient, economical, and environmentally friendly diamond etching method.

[0005] To achieve the above objectives, the present invention adopts the following technical solution:

[0006] A method for etching diamond includes the following steps:

[0007] Diamond is mixed with calcium carbonate and then heat-treated, with the calcium carbonate used to etch the surface of the diamond.

[0008] After heat treatment, the residues (such as residual calcium carbonate) are removed to obtain the etched diamond.

[0009] This method is the first to use calcium carbonate to etch diamond, and the process is simple with remarkable etching results.

[0010] Furthermore, the diamond is in the form of granules, flakes, or columnar shapes.

[0011] In some embodiments, the diamond is in granular form. Optionally, the diamond granules are synthetic single-crystal diamond granules.

[0012] In some embodiments, the diamond is in the form of a sheet.

[0013] Furthermore, the diamond particles have a particle size of 3–700 μm (e.g., 200 μm).

[0014] Furthermore, the diamond sheet has a size of 3x3x0.5 to 20x20x3 mm, that is, the length and width of the diamond sheet are both 3 to 20 mm, and the thickness is 0.5 to 3 mm (e.g., 3x3x0.5 mm, that is, the length and width are both 3 mm, and the thickness is 0.5 mm).

[0015] Furthermore, the dimensions of the diamond pillar are 0.5x0.5x3 to 5x5x30 mm, that is, the diameter or side length of the diamond pillar is 0.5 to 5 mm, and the height is 3 to 30 mm.

[0016] Furthermore, the calcium carbonate is in powder form.

[0017] Furthermore, the particle size of the calcium carbonate powder is 0.01–0.5 μm; for example, 20–70 nm (i.e., 0.02–0.07 μm).

[0018] Furthermore, the mass ratio of the diamond to the calcium carbonate is 2:1 to 1:2 (e.g., 1:1).

[0019] Furthermore, the heat treatment temperature is 550–950℃ (preferably 550–900℃, such as 550℃, 650℃, 700℃, 800℃, or 900℃), and the holding time does not exceed 60 min (preferably 5–60 min, such as 5 min or 60 min). The heating rate is 5–30℃ / min (such as 5℃ / min, 20℃ / min, or 30℃ / min).

[0020] Optionally, after the heat preservation is completed, cooling treatment can be carried out (e.g., air cooling or furnace cooling).

[0021] Furthermore, the method for removing residues is to soak and clean with deionized water or to clean with ultrasound.

[0022] Optionally, after removing the residue, a drying process can be performed.

[0023] The present invention also provides a porous diamond prepared by the above method.

[0024] The porous diamond can be used in the preparation of electronic packaging materials.

[0025] In addition, the present invention provides a diamond metal matrix composite material, which includes a metal matrix and surface metallized diamond; the surface metallized diamond includes the porous diamond and a metal coating on the surface of the porous diamond.

[0026] Further, the metal substrate is selected from at least one of an aluminum substrate and a copper substrate (e.g., one of them); exemplarily, the metal substrate is an aluminum substrate or a copper substrate.

[0027] Further, the metal coating is a tungsten layer, a tungsten carbide layer, or a tungsten-containing alloy layer. Preferably, the metal coating is a tungsten layer.

[0028] The etching method provided by this invention uses calcium carbonate as the etchant. The process is simple and can be completed rapidly at relatively low temperatures, offering advantages such as short production cycles and low energy consumption, which is beneficial for mass production. Furthermore, the etching residue is mainly calcium carbonate, eliminating the need for strong acid or alkali cleaning; gentle cleaning is sufficient to remove it. This avoids environmental pollution and operational risks, reduces post-processing costs, and meets the requirements of green manufacturing.

[0029] Diamonds prepared using this method exhibit numerous inverted pyramid and triangular pyramid-shaped etching pits on their surface, with uniform etching and clearly visible traces. Simultaneously, due to the moderate degree of etching, the diamonds retain their original morphology and contours, without graphitization, thus preserving their physicochemical properties such as strength, hardness, wear resistance, and thermal conductivity. Attached Figure Description

[0030] Figure 1 This is a process flow diagram for etching diamond according to the present invention;

[0031] Figure 2 The images show a comparison of the surface microstructure of the diamond particles in Example 1; where (a) is an untreated diamond particle; and (b) is a diamond particle after etching at 550°C.

[0032] Figure 3 This is a microscopic image of the surface morphology of diamond particles etched at 650°C for 60 min in Example 2.

[0033] Figure 4 This is a microscopic image of the surface morphology of diamond particles etched at 700°C for 60 min in Example 3.

[0034] Figure 5 This is a microscopic image of the surface morphology of diamond particles etched at 700°C for 5 min in Example 4.

[0035] Figure 6 The images show a comparison of the microstructure of diamond particles etched at 800-900℃ for 5 min in Example 5; the left image shows the 800℃ etching temperature, and the right image shows the 900℃ etching temperature.

[0036] Figure 7 The images show the XRD and Raman spectra of diamond particles etched at 900°C for 5 min in Example 6; where (a) is the XRD pattern and (b) is the Raman pattern.

[0037] Figure 8 The images show a comparison of the microstructure of the diamond sheet surface before and after etching at 800°C for 5 min in Example 7; the left image is before etching, and the right image is after etching.

[0038] Figure 9 The images show a comparison of the microstructure of the diamond surface etched at 800°C with heating rates of 5°C / min and 30°C / min, followed by a holding time of 5 min. The left image shows the temperature at 30°C / min, and the right image shows the temperature at 5°C / min. Detailed Implementation

[0039] In summary, this invention provides a method for rapid low-temperature etching of diamond. The method involves uniformly mixing diamond and calcium carbonate powder in a ratio of 2:1 to 1:2, holding the mixture at 550–900°C for 5–60 minutes, then rinsing with deionized water to remove excess calcium carbonate, and finally drying to obtain the etched diamond. This invention overcomes the shortcomings of existing solid-state diamond etching methods, eliminating the need for large amounts of etching agent, achieving rapid diamond etching at low temperatures, and eliminating the need for subsequent strong acid or alkali cleaning. The method requires simple equipment, operates at low etching temperatures, is rapid, and is environmentally friendly, significantly reducing etching costs and improving etching efficiency. The etched diamond surface exhibits numerous etching pits and obvious etching marks; the etching effect can be improved by adjusting parameters such as temperature and holding time. Furthermore, the aluminum-based and copper-based composite materials made from diamond prepared using this rapid low-temperature etching method, after surface metallization, possess high thermal conductivity and a low coefficient of thermal expansion, showing broad application prospects in the field of electronic packaging.

[0040] To facilitate understanding by those skilled in the art, the present invention will be further described below with reference to embodiments. The content mentioned in the embodiments is not intended to limit the present invention. It should be noted in advance that the following embodiments were completed in a laboratory. Those skilled in the art should understand that the amounts of each component given in the embodiments only represent the ratio between the components, and are not specific limitations.

[0041] Example 1

[0042] Diamond particles of 200 μm and calcium carbonate powder (20-70 nm) were uniformly mixed and placed in a square corundum crucible; the mass ratio of diamond to calcium carbonate powder was 1:1. The crucible was placed in a ceramic fiber box-type resistance furnace, and the temperature was raised to 550°C at a rate of 20°C / min, held for 60 min, and then cooled with the furnace. The product obtained after low-temperature heat treatment was soaked in deionized water to remove the calcium carbonate powder, and then dried to obtain the etched diamond. The morphology after etching is shown in the figure. Figure 2 As shown in (b), compared to the original diamond surface ( Figure 2 Compared to (a), the diamond surface etched at 550°C has only a few etch pits. Despite the lower temperature, slight etching has occurred on the diamond surface due to the action of calcium carbonate.

[0043] Example 2

[0044] The etching temperature was adjusted to 650°C, and other processing parameters were the same as in Example 1. The surface morphology of the diamond particles etched at 650°C is as follows. Figure 3 As shown. Figure 3 As shown in (a), the etching pits on the diamond surface can be observed even at low magnification, but the etching area is relatively small; as Figure 3 As shown in (b) and (c), under high magnification, it can be observed that the etching pits on the {100} crystal plane exhibit an inverted pyramid shape, while the etching pits on the {111} crystal plane exhibit a triangular pyramid shape.

[0045] Example 3

[0046] The etching temperature was further increased to 700°C, while other processing parameters remained the same as in Example 1. The surface morphology of the diamond particles etched at 700°C is as follows. Figure 4 As shown, more and more obvious etching pits can be observed in each crystal facet of the diamond.

[0047] Example 4

[0048] The holding time was reduced from 60 min to 5 min, the etching temperature was 700℃, and other processing parameters were the same as in Example 1. The surface morphology of the diamond particles after holding at 700℃ for 5 min is as follows. Figure 5As shown, compared with Example 3, the etching time was shortened by 1 / 12, but the etching pits on the diamond surface can still be clearly observed. Moreover, the number of etching pits is large and the degree of etching is moderate, indicating that the etching of diamond by this method can be completed at low temperature and in a short time.

[0049] Example 5

[0050] The etching temperature was further increased to 800℃ and 900℃, while other processing parameters remained the same as in Example 4. The surface morphology of the diamond particles after holding at 800℃-900℃ for 5 min is as follows. Figure 6 As shown, compared with Example 4, the etching pits are evenly distributed, the etching marks are obvious and deeper, but the diamond outline and crystal face edges are still distinct, and the original morphology of the diamond particles has not been changed. Therefore, it will not have an adverse effect on its strength, hardness, wear resistance and thermal conductivity.

[0051] Example 6

[0052] The diamond etched in Example 5 at 900°C for 5 min was subjected to XRD and Raman tests. The test results are as follows: Figure 7 As shown, compared with the XRD and Raman spectra of the original diamond particles, no graphite peaks or graphitization transitions were observed in the etched diamond particles, indicating that the method of the present invention does not cause graphitization and oxidation of diamond during the low-temperature rapid etching process.

[0053] Example 7

[0054] The diamond particles in Example 5 were replaced with diamond sheets, the size of which was 3x3x0.5 mm. Other processing parameters remained the same as in Example 5. Figure 8 As can be seen, the original diamond sheet surface is smooth and flat, without any etching pits. After etching at 800℃, very obvious etching pits appeared on the surface of the diamond sheet, indicating that the method of the present invention is not only applicable to the etching of diamond particles, but also to the etching of diamond sheets.

[0055] Example 8

[0056] The heating rate was adjusted to 5℃ / min and 30℃ / min, with other processing parameters the same as in Example 5. The diamond surface morphology etched at 800℃ and held for 5 min under heating rates of 5℃ / min and 30℃ / min is shown below. Figure 9 As shown, at both etching rates, the diamond particle surface exhibited noticeable etching pits, with little difference in the degree of etching. Tungsten was deposited on the surface of diamond particles etched at a heating rate of 30℃ / min, subsequently used to prepare diamond-aluminum matrix composites and diamond-copper matrix composites, achieving thermal conductivity of 608 W·m. -1 ·K -1 and 725 W·m-1 ·K -1 It can meet the application requirements of electronic packaging materials.

[0057] In summary, the etching method provided by this invention requires a low temperature and a short holding time, achieving rapid low-temperature etching. The diamond surface prepared by this method has numerous inverted pyramid and triangular pyramid-shaped etching pits, with uniform etching, clear traces, and moderate etching degree. The etched diamond retains its original morphology and outline, without graphitization, and does not affect its strength, hardness, wear resistance, thermal conductivity, or other physicochemical properties. Applying this diamond to diamond-aluminum matrix composites and diamond-copper matrix composites can significantly improve their thermal conductivity.

[0058] The embodiments described above are merely preferred embodiments of the present invention and are not exhaustive examples of all possible implementations of the present invention. Any obvious modifications made by those skilled in the art without departing from the principles and spirit of the present invention should be considered to be included within the scope of protection of the claims of the present invention.

Claims

1. A method for etching diamond, characterized in that, Includes the following steps: Diamond is mixed with calcium carbonate and then heat-treated, with the calcium carbonate used to etch the surface of the diamond. After heat treatment, the residue is removed to obtain the etched diamond.

2. The method according to claim 1, characterized in that, The diamond is in the form of granules, flakes, or columnar shapes; The calcium carbonate is in powder form.

3. The method according to claim 2, characterized in that, The diamond particles have a particle size of 3–700 μm; The diamond sheet has a length and width of 3-20 mm and a thickness of 0.5-3 mm. The diameter or side length of the diamond column is 0.5-5 mm, and the height is 3-30 mm; The particle size of the calcium carbonate powder is 0.01 to 0.5 μm.

4. The method according to claim 1, characterized in that, The mass ratio of diamond to calcium carbonate is 2:1 to 1:

2.

5. The method according to claim 1, characterized in that, The heat treatment temperature is 550–950°C, and the holding time does not exceed 60 minutes.

6. The method according to claim 1, characterized in that, The method for removing residues is to soak and clean with deionized water or to clean with ultrasound.

7. A porous diamond, characterized in that, Prepared by the method according to any one of claims 1 to 6.

8. The application of the porous diamond according to claim 7 in the preparation of electronic packaging materials.

9. A diamond metal matrix composite material, characterized in that, Including a metal matrix and surface-metallized diamond; The surface-metallized diamond includes the porous diamond of claim 7 and a metal coating on the surface of the porous diamond.

10. The diamond metal matrix composite material according to claim 9, characterized in that, The metal matrix is ​​selected from at least one of aluminum matrix and copper matrix.

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