Method for metallizing ceramic by using whisker pinning

Abstract

The invention discloses a method for metallizing ceramic by using whisker pinning, and relates to a method for metallizing ceramic. The technical problems that an existing ceramic metallization process is complex, the application range is small, and cost is high are solved. According to the method, boric acid is adopted to heat the surface of the ceramic containing the Al element, the aluminum borate crystal whiskers in the micro-nano size level can grow, and the crystal whiskers are high in high-temperature strength; then the ceramic with the whisker structure and the metal are subjected to hot pressing at a high temperature, the metal material is softened at a high temperature along with temperature rise, the whiskers can be pressed into the metal, a microcosmic pinning structure is formed, connection between the ceramic and the metal is achieved, and metallized ceramic is obtained; and then in the cooling process, the metal is cooled and shrunk, stress is formed on the crystal whiskers, and the binding force of the ceramic and the metal is improved. According to the method, ceramic metallization is achieved through whisker pinning, operation is simple and effective, and the obtained metallization layer is excellent in performance, good in mechanical stability and wide in application range and has good application prospects.

Description

Technical Field

[0001] This invention relates to a method for metallizing ceramics. Background Technology

[0002] Ceramics possess high hardness, strength, elastic modulus, and excellent high-temperature stability, making ceramic metallization a promising area for both scientific research and industry. However, ceramics and metals typically exhibit significant differences in physical and chemical properties, as well as crystal lattice types, making direct ceramic metallization difficult. Currently, ceramic metallization often requires the construction of intermediate or reaction layers. For example, introducing active elements such as Ti or Zr into the intermediate layer for brazing or diffusion welding can achieve ceramic metallization. Alternatively, it can be achieved through an oxide eutectic reaction in an air reaction atmosphere and under specific heating conditions. Chemical plating can also achieve ceramic metallization, but the adhesion between the plating layer and the ceramic is poor, and the plating solution can cause pollution. Overall, these methods suffer from complex operation processes, pollution, high costs, low production efficiency, limited applicability, complex interfacial reaction products, and restrictions on the types of metallization possible on ceramic surfaces, thus hindering their practical application and development. Summary of the Invention

[0003] The present invention aims to solve the technical problems of existing ceramic metallization processes being complex, having a limited scope of application, and being costly, and provides a method for ceramic metallization using whisker pinning.

[0004] The method for metallizing ceramics using whisker pinning of the present invention is carried out according to the following steps:

[0005] I. Whisker Growth: Both Al-containing ceramics and metals were sanded, then ultrasonically cleaned with anhydrous ethanol, and then air-dried. A layer of boric acid powder or boron oxide powder was spread on one surface of the Al-containing ceramic. The Al-containing ceramic was then heated at 900℃~1200℃ for 30min~360min, and then cooled to room temperature to obtain micro-nano-level whiskers on the surface of the Al-containing ceramic. Then, it was washed with hot water at 90℃~100℃ and air-dried.

[0006] 2. Hot pressing: The metal is brought into close contact with the surface of the Al-containing ceramic whiskers grown in step one, and the metal and the Al-containing ceramic from step one are stacked one on top of the other. Then, the metal is heated to its softening temperature, downward pressure is applied, and the temperature is held at the softening temperature of the metal. Then, the metal is cooled to room temperature in the furnace to achieve the connection between the ceramic and the metal, thus obtaining a metallized ceramic.

[0007] The design principle of the invention:

[0008] The metallization of ceramics essentially requires achieving microscopic connection and interfacial bonding between ceramics and metals. In step one of this invention, boric acid is heated on the surface of an Al-containing ceramic to grow micro / nano-sized aluminum borate whiskers. These whiskers possess ceramic material properties, exhibiting high strength at high temperatures and maintaining good adhesion to the matrix. In step two, the whisker-structured ceramic and metal are hot-pressed at high temperature. As the temperature increases, the strength of the metal decreases while its plasticity increases, resulting in high-temperature softening. At this point, the metal's strength decreases, allowing the whiskers to be pressed into the metal, forming a microscopic pinning structure, thus achieving the connection between the ceramic and metal and obtaining a metallized ceramic. Then, during the cooling process, the metal cools and contracts, creating stress on the whiskers and enhancing the bonding force between the ceramic and metal.

[0009] In addition, since the interface bonding between ceramics and metals can be achieved by relying on whisker pinning, different types and melting points of metals can be selected. There is no need to consider the problem of ceramic-metal interface reaction and the problem of excessively high temperature in conventional brazing methods, which greatly reduces the limitations on ceramic metallization and ceramic-metal connection.

[0010] The ceramic surface whiskers described in step one of this invention can also be replaced with micro-nano structures obtained by methods such as photolithography, etching, or laser processing for further expansion.

[0011] The method of the present invention can also be extended to the cyclic multilayer stacking of ceramic and metal materials to prepare novel composite materials with stacked structures.

[0012] The present invention has the following beneficial effects:

[0013] 1. The process of the present invention is simple and effective. By hot pressing the ceramic with grown whiskers to a metal, ceramic metallization can be achieved.

[0014] 2. In this invention, a large number of whiskers are pinned in the metal, resulting in a strong interfacial bond between the ceramic and the metal.

[0015] 3. This invention uses whiskers pinned in metal to achieve ceramic surface metallization, without considering the interfacial reaction and metallurgical bonding of different phases, and can achieve matching of different ceramics and metals, with a wide range of applications.

[0016] This invention proposes a method for achieving ceramic metallization by whisker pinning. The operation is simple and effective, and the resulting metallized layer has excellent performance, good mechanical stability, and wide applicability, showing great application prospects. Attached Figure Description

[0017] Figure 1 SEM image of the cross-section of the metallized ceramic obtained in step two of Experiment 1;

[0018] Figure 2 The XRD pattern of the product from step one of experiment one. Detailed Implementation

[0019] Specific Implementation Method 1: This implementation method is a method for metallizing ceramics using whisker pinning, specifically carried out according to the following steps:

[0020] I. Whisker Growth: Both Al-containing ceramics and metals were sanded, then ultrasonically cleaned with anhydrous ethanol, and then air-dried. A layer of boric acid powder or boron oxide powder was spread on one surface of the Al-containing ceramic. The Al-containing ceramic was then heated at 900℃~1200℃ for 30min~360min, and then cooled to room temperature to obtain micro-nano-level whiskers on the surface of the Al-containing ceramic. Then, it was washed with hot water at 90℃~100℃ and air-dried.

[0021] 2. Hot pressing: The metal is brought into close contact with the surface of the Al-containing ceramic whiskers grown in step one, and the metal and the Al-containing ceramic from step one are stacked one on top of the other. Then, the metal is heated to its softening temperature, downward pressure is applied, and the temperature is held at the softening temperature of the metal. Then, the metal is cooled to room temperature in the furnace to achieve the connection between the ceramic and the metal, thus obtaining a metallized ceramic.

[0022] Specific Implementation Method Two: This implementation method differs from Specific Implementation Method One in that the Al-containing ceramic mentioned in step one is aluminum nitride, aluminum oxide, sapphire, aluminum nitride, zirconium oxide-toughened alumina, aluminum oxynitride, or Ti3AlC2. Everything else is the same as in Specific Implementation Method One.

[0023] Specific Implementation Method Three: This implementation method differs from Specific Implementation Method One in that the metal mentioned in step one is pure copper, pure aluminum, or pure magnesium. Everything else is the same as in Specific Implementation Method One.

[0024] Specific Implementation Method Four: This implementation method differs from Specific Implementation Method One in that the metal mentioned in step one is pure silver, pure gold, or pure platinum. Everything else is the same as in Specific Implementation Method One.

[0025] Specific Implementation Method Five: This implementation method differs from Specific Implementation Method One in that, in step one, both the Al-containing ceramics and metals are successively polished with 400#, 800#, 1200#, and 2000# sandpaper. Everything else is the same as in Specific Implementation Method One.

[0026] Specific Implementation Method Six: This implementation method differs from Specific Implementation Method Five in that: in step one, anhydrous ethanol is used for ultrasonic cleaning for 5 to 15 minutes. Everything else is the same as in Specific Implementation Method Five.

[0027] Specific Implementation Method Seven: This implementation method differs from Specific Implementation Method Three in that: when the metal mentioned in step one is pure copper, pure aluminum, or pure magnesium, in step two, the metal is heated to its softening temperature under an inert atmosphere or vacuum environment. Everything else is the same as in Specific Implementation Method Three.

[0028] Specific Implementation Method Eight: This implementation method differs from Specific Implementation Method Four in that when the metal mentioned in step one is pure silver, pure gold, or pure platinum, the metal is heated in air to its softening temperature in step two. Everything else is the same as in Specific Implementation Method Four.

[0029] Specific Implementation Method Nine: This implementation method differs from Specific Implementation Method Six in that step two employs constant pressure, pulsed pressure, or periodic cyclic pressure to apply a downward pressure of 0.5 MPa to 5 MPa. Everything else is the same as in Specific Implementation Method Six.

[0030] Specific Implementation Method Ten: This implementation method differs from Specific Implementation Method Nine in that, in step two, the metal is held at its softening temperature for 10 to 60 minutes. Everything else is the same as in Specific Implementation Method Nine.

[0031] The invention was verified using the following experiments:

[0032] Experiment 1: This experiment demonstrates a method for metallizing ceramics using whisker pinning, specifically carried out according to the following steps:

[0033] I. Whisker Growth: AlN ceramic and metallic silver were sequentially polished with 400#, 800#, 1200#, and 2000# sandpaper, respectively, and then ultrasonically cleaned with anhydrous ethanol for 10 min, followed by natural air drying. A layer of boric acid powder was spread on one surface of the AlN ceramic. The AlN ceramic was then heated from room temperature to 950℃ in air at a heating rate of 10℃ / min and held at that temperature for 120 min. It was then cooled to room temperature at a cooling rate of 10℃ / min, resulting in micro-nano-scale whiskers on the surface of the AlN ceramic. The surface was then cleaned with 90℃ hot water and allowed to air dry.

[0034] 2. Hot pressing: The surface of the AlN ceramic whiskers grown in step one is brought into close contact with the metallic silver, and the metallic silver and AlN ceramic are stacked one on top of the other. Then, the mixture is heated in air to the softening temperature of the metallic silver, 850°C. A vertical downward pressure of 1 MPa is then applied using a constant pressure method and the temperature is held at the softening temperature of the metal for 30 minutes. The mixture is then cooled to room temperature in the furnace to achieve the connection between the AlN ceramic and the metallic silver, thus obtaining a metallized ceramic.

[0035] Figure 1The image shows a cross-sectional SEM image of the metallized ceramic obtained in step two of Experiment 1. It can be seen from the image that the whiskers in this experiment are pinned in the metal layer, and the metallic silver forms an interfacial bond with the AlN ceramic, proving that a metallization layer was obtained on the ceramic substrate in this experiment.

[0036] The metallized ceramic obtained in step two of Experiment 1 was subjected to mechanical property testing, and the shear strength reached 55 MPa, proving that the ceramic metallized layer obtained by this method has excellent mechanical stability.

[0037] Figure 2 The XRD pattern of the product from step one of Experiment 1 is shown. The XRD pattern reveals that the main component of the ceramic is AlN, with small amounts of Al4B2O9 (aluminum borate) and AlYO3. Al4B2O9 is the main component of the whiskers growing on the AlN ceramic surface, while AlYO3 is a small amount of impurity in the AlN ceramic. The diffraction peaks of Al4B2O9 and AlYO3 appear between the main diffraction peaks of AlN, and the diffraction peaks of Al4B2O9 and AlYO3 are relatively broad and have low intensity, indicating that their small size leads to low diffraction peak intensity.

Claims

1. A method for metallizing ceramics using whisker pinning, characterized in that... The method is performed according to the following steps: I. Whisker Growth: Both Al-containing ceramics and metals were sanded, then ultrasonically cleaned with anhydrous ethanol, and then air-dried. A layer of boric acid powder or boron oxide powder was spread on one surface of the Al-containing ceramic. The Al-containing ceramic was then heated at 900℃~1200℃ for 30min~360min, and then cooled to room temperature to obtain micro-nano-level whiskers on the surface of the Al-containing ceramic. Then, it was washed with hot water at 90℃~100℃ and air-dried.

2. Hot pressing: The metal is brought into close contact with the surface of the Al-containing ceramic whiskers grown in step one, and the metal and the Al-containing ceramic from step one are stacked one on top of the other. Then, the metal is heated to its softening temperature, downward pressure is applied, and the temperature is held at the softening temperature of the metal. Then, the metal is cooled to room temperature in the furnace to achieve the connection between the ceramic and the metal, thus obtaining a metallized ceramic.

2. The method for metallizing ceramics using whisker pinning according to claim 1, characterized in that... The Al-containing ceramics mentioned in step one are aluminum nitride, aluminum oxide, sapphire, aluminum nitride, zirconium oxide-toughened alumina, aluminum oxynitride, or Ti3AlC2.

3. The method for metallizing ceramics using whisker pinning according to claim 1, characterized in that... The metal mentioned in step one is pure copper, pure aluminum, or pure magnesium.

4. The method for metallizing ceramics using whisker pinning according to claim 1, characterized in that... The metal mentioned in step one is pure silver, pure gold, or pure platinum.

5. The method for metallizing ceramics using whisker pinning according to claim 1, characterized in that... In step one, both the Al-containing ceramics and metals are polished sequentially with 400#, 800#, 1200# and 2000# sandpaper.

6. The method for metallizing ceramics using whisker pinning according to claim 1, characterized in that... In step one, all samples were ultrasonically cleaned with anhydrous ethanol for 5 to 15 minutes.

7. A method for metallizing ceramics using whisker pinning according to claim 3, characterized in that... When the metal mentioned in step one is pure copper, pure aluminum, or pure magnesium, in step two, the metal is heated to its softening temperature in an inert atmosphere or vacuum environment.

8. A method for metallizing ceramics using whisker pinning according to claim 4, characterized in that... When the metal mentioned in step one is pure silver, pure gold, or pure platinum, in step two, it will be heated in air to the softening temperature of the metal.

9. A method for metallizing ceramics using whisker pinning according to claim 1, characterized in that... In step two, a downward pressure of 0.5 MPa to 5 MPa is applied using constant pressure, pulsed pressure, or periodic cyclic pressure.

10. A method for metallizing ceramics using whisker pinning according to claim 1, characterized in that... In step two, the metal is held at its softening temperature for 10 to 60 minutes.

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