CN110776330A - Brazing method of ceramic and metal - Google Patents

Abstract

The present disclosure provides a brazing method for ceramics and metals, comprising: preparing ceramics to be welded and metals to be welded, and surface-treating the ceramics to be welded, so that the surface of the ceramics to be welded is formed into a smooth surface; The surface is metallized to form an intermediate metal layer combined with the ceramic to be welded, and the thermal expansion coefficient of the ceramic to be welded matches the thermal expansion coefficient of the intermediate metal layer; Soldering, the metal brazing filler metal is placed between the intermediate metal layer and the metal to be welded. During brazing, the metal brazing filler metal is melted by heating, and the molten metal brazing filler metal infiltrates the intermediate metal layer and maintains the molten state for a predetermined time, so that the metal brazing filler metal is melted. The interface with the ceramic to be welded with the intermediate metal layer forms the welding surface, and is annealed and cured. According to the present disclosure, it is possible to provide a ceramic-to-metal brazing method capable of reducing thermal stress of an interface layer and improving airtightness and shear strength of the interface layer.

Description

Brazing method of ceramics and metals

technical field

In particular, the present disclosure relates to a brazing method of ceramics and metals.

Background technique

Ceramics, as high-temperature structural materials, are widely used in various fields due to their good biocompatibility, heat resistance, corrosion resistance and electrical insulation properties. However, in practical applications, in order to solve the problem of poor workability caused by the excessive hardness of the ceramic itself, it is necessary to connect the ceramic and the metal by a certain method to form a metal-ceramic composite structure.

Currently, the most common method for joining ceramic and metallic materials is brazing. Brazing has the advantages of small heat affected zone and reliable joints, and is very suitable for the connection between dissimilar materials. However, due to the poor wettability of ceramics, it is difficult to form a good connection between ceramics and metal materials. Moreover, the thermal expansion coefficients of ceramics and metals are quite different from each other, which will lead to excessive thermal stress in the joint and affect the strength and air tightness of the joint.

SUMMARY OF THE INVENTION

The present disclosure has been made in view of the above-mentioned state of the art, and an object of the present disclosure is to provide a ceramic-metal brazing method capable of reducing the thermal stress of the interface layer and improving the airtightness and shear strength of the interface layer.

To this end, the present disclosure provides a method for brazing a ceramic and a metal, including: preparing a ceramic to be welded and a metal to be welded, and performing surface treatment on the ceramic to be welded, so that the surface of the ceramic to be welded is formed as smooth surface; metallization is performed on the surface of the ceramic to be welded to form an intermediate metal layer combined with the ceramic to be welded, the thermal expansion coefficient of the ceramic to be welded matches the thermal expansion coefficient of the intermediate metal layer; and the The ceramic to be welded, the metal brazing filler metal and the metal to be welded are stacked and brazed in sequence, and the metal brazing filler metal is located between the intermediate metal layer and the metal to be welded. Heating to melt the metal brazing filler metal, the molten metal brazing filler metal infiltrates the intermediate metal layer, and maintains the molten state for a predetermined time, so that the interface between the metal brazing filler metal and the ceramic to be welded with the intermediate metal layer is formed. Weld faces are formed, annealed and cured.

In the present disclosure, the brazing method of ceramics and metals includes surface treatment of the ceramics to be welded, and the surface of the ceramics to be welded is metallized to form an intermediate metal layer with a matching thermal expansion coefficient, and the metal brazing filler metal can be melted and melted during brazing. Wetting the intermediate metal layer, in this case, the molten metal brazing filler metal can well infiltrate the ceramic to be welded whose surface has been metallized, and the intermediate metal layer can make the thermal expansion coefficient of the brazing interface between the ceramic to be welded and the metal to be welded. It presents a gradient transition, which can reduce the difference in thermal expansion coefficient between the interfaces due to different materials, reduce the thermal stress of the interface layer and improve the air tightness.

In addition, in the brazing method involved in the present disclosure, the roughness of the surface of the ceramic to be welded may be less than 0.05 μm. In this case, the surface of the ceramic to be welded can be made smooth and flat, which is beneficial to the subsequent brazing between the ceramic and the metal.

In addition, in the brazing method involved in the present disclosure, the metallization treatment method may be sputtering, vapor deposition, PVD, CVD, plating, and high-temperature sintering. Thereby, a tightly bonded intermediate metal layer can be formed on the surface of the ceramic to be welded.

In addition, in the brazing method according to the present disclosure, the intermediate metal layer may be composed of at least one selected from the group consisting of Nb, Au, Ti, and alloys thereof. In this way, the metal brazing filler metal can well wet the ceramic to be soldered with the intermediate metal layer on the surface.

In addition, in the brazing method according to the present disclosure, the metal brazing filler metal may be at least one selected from Au, Ag, Ti, Nb and alloys thereof. In this case, the wettability of the brazing filler metal to the ceramic to be soldered and the metal to be soldered can be improved.

In addition, in the brazing method involved in the present disclosure, optionally, the size of the ceramic to be welded, the metal to be welded, and the metal brazing filler metal are matched. Therefore, the brazing of the ceramic to be welded and the metal to be welded can be facilitated.

In addition, in the brazing method involved in the present disclosure, optionally, pressure is applied to the to-be-welded member formed by stacking the ceramic to be welded, the metal brazing filler metal, and the metal to be welded in sequence. Thereby, the workpiece to be welded can be fixed during brazing, and the uniformity of the width of the brazing seam and its edge can be controlled. In addition, in the brazing method involved in the present disclosure, optionally, before brazing, the metal to be welded is surface-treated. Thereby, the surface wettability of the metal to be welded can be increased.

In addition, in the brazing method involved in the present disclosure, optionally, in the brazing, the temperature is raised to 1060° C. to 1150° C. at a heating rate of 1° C. 1 mi 1 to 50° C. 1 mi 1 , maintained for 1 mi 1 to 30 mi 1 , and then The cooling rate of 2°C 1mi1 to 20°C 1mi1 is cooled to 200°C to 400°C, and then cooled to below 150°C with the furnace. In this case, it is possible to improve the generation and distribution of brittle phases between the interfaces, increase the strength, reduce thermal stress and thermal deformation of the base metal, eliminate cracks in the weld, and improve the interface layer between the ceramic to be welded and the metal to be welded. air tightness and shear strength.

In addition, in the brazing method involved in the present disclosure, the ceramic to be welded may be made of aluminum oxide, zirconium oxide, silicon oxide, carbon material, silicon nitride, silicon carbide, titanium oxide, aluminosilicate or At least one kind of calcium-aluminum-based composition. In this case, a biocompatible ceramic to be welded can be obtained.

According to the present disclosure, it is possible to provide a ceramic-metal brazing method capable of reducing the thermal stress of the interface layer and improving the airtightness and shear strength of the interface layer.

Description of drawings

FIG. 1 shows a schematic flowchart of a brazing method for ceramics and metals involved in an example of the present disclosure.

FIG. 2 shows a perspective view of a jig according to an example of the present disclosure.

FIG. 3 shows a cross-sectional view of the fixture shown in FIG. 2 along line AA'.

4 shows a cross-sectional view of a jig fitted with a piece to be welded according to an example of the present disclosure.

FIG. 5 shows an assembly structure diagram of a to-be-welded part involved in an example of the present disclosure.

6 shows a cross-sectional view of a workpiece to be welded according to an example of the present disclosure.

7 shows a slice view of a brazed joint of Al ₂ O ₃ ceramic and pure Ti metal involved in an embodiment of the present disclosure.

Detailed ways

Hereinafter, preferred embodiments of the present disclosure will be described in detail with reference to the accompanying drawings. In the following description, the same reference numerals are assigned to the same components, and overlapping descriptions are omitted. In addition, the drawings are only schematic diagrams, and the ratios of the dimensions of the members, the shapes of the members, and the like may be different from the actual ones.

FIG. 1 shows a schematic flowchart of a brazing method for ceramics and metals involved in an example of the present disclosure.

The brazing method for ceramics and metals involved in this embodiment includes: preparing the ceramics 31 to be welded and the metals 33 to be welded, and performing surface treatment on the ceramics 31 to be welded, so that the surfaces of the ceramics 31 to be welded are formed into a smooth surface (step S10 ). ); metallization is performed on the surface of the ceramic to be welded 31 to form an intermediate metal layer combined with the ceramic to be welded 31, and the thermal expansion coefficient of the ceramic to be welded 31 matches the thermal expansion coefficient of the intermediate metal layer (step S20); 31. The metal brazing filler metal 32 and the metal to be welded 33 are sequentially stacked and brazed (step S30). In this embodiment, the member to be welded 30 may include a ceramic to be welded 31 , a metal brazing filler metal 32 and a metal to be welded 33 . The shape of the to-be-welded member 30 is not particularly limited, and in some examples, the to-be-welded member 30 may be cylindrical.

In some examples, the brazing filler metal 32 may be located between the intermediate metal layer and the metal to be soldered 33 . In addition, in some examples, optionally, during the brazing process, the metal brazing filler metal 32 is melted by heating, the molten metal brazing filler metal 32 infiltrates the intermediate metal layer, and is kept in a molten state for a predetermined time, so that the metal brazing filler metal 32 is melted. The interface with the ceramic to be welded 31 having the intermediate metal layer forms a welding surface, and is annealed and cured.

In the brazing method for ceramics and metals according to the present embodiment, the brazing method for ceramics and metals includes surface treatment of the ceramics 31 to be welded, and the surface of the ceramics 31 to be welded is metallized to form a In the middle metal layer, the metal brazing filler metal 32 can melt and infiltrate the intermediate metal layer during brazing. The layer can make the thermal expansion coefficient of the brazing interface between the ceramic 31 to be welded and the metal to be welded 33 present a gradient transition, thereby reducing the thermal expansion coefficient difference between the interfaces due to different materials, reducing the thermal stress of the interface layer and improving the air tightness.

In addition, in this embodiment, the generation and distribution of brittle phases (brittle compounds) between interfaces can be improved by selecting appropriate brazing temperature and holding time during brazing, increasing strength, reducing thermal stress and base metal ( The thermal deformation of the ceramic to be welded 31 and the metal to be welded 33) eliminates cracks in the weld and improves the air tightness and shear strength of the interface layer between the ceramic to be welded 31 and the metal to be welded 33 .

In some examples, in step S10 , the surface of the ceramic to be welded 31 may be ground and polished until the surface roughness is less than 0.05 μm. In this case, the surface of the ceramic 31 to be welded is smooth and flat, which is beneficial to the subsequent brazing between the ceramic and the metal. In some examples, in step S10, the surface of the ceramic to be welded 31 may be ground to form a ground surface.

In some examples, the ceramic to be welded 31 may include upper and lower surfaces. Thereby, a polished surface obtained by grinding at least one of the upper and lower surfaces of the ceramic to be welded 31 can be obtained. In this case, since the object to be ground is at least one of the upper and lower surfaces of the ceramics 31 to be welded, the difficulty of the grinding process can be reduced, and the surface of the ceramics to be welded 31 can be ground to a smooth surface, thereby improving the efficiency of the welding process. Surface wetting properties of ceramic 31.

In addition, in some examples, the roughness of at least one of the upper and lower surfaces of the ceramic to be welded 31 may be less than 0.05 μm. In this case, the surface of the ceramic 31 to be welded can be made smooth and flat, which is beneficial to the subsequent brazing between the ceramic and the metal. In some examples, the roughness of the surface of the ceramic to be welded 31 may be 0.04 μm, 0.03 μm, 0.02 μm, 0.01 μm, or the like.

In some examples, the ceramic to be welded 31 may be biocompatible. Thereby, damage to the human body can be reduced, and compatibility with human tissue can be achieved. Additionally, in some examples, the ceramic to be welded 31 may be an oxide ceramic. Thereby, the ceramic to be welded 31 with stable chemical properties can be obtained.

In some examples, the ceramic to be welded 31 may be made of a material selected from the group consisting of aluminum oxide (Al ₂ O ₃ ), zirconium oxide (ZrO ₂ ), silicon oxide (SiO 2 ), titanium oxide (TiO ₂ ), aluminosilicate (Na ₂ O ·Al ₂ O ₃ ·SiO ₂ ) or at least one of calcium-aluminum-based (CaO·Al ₂ O ₃ ). Thereby, the ceramic to be welded 31 having biocompatibility can be obtained.

In this embodiment, the ceramic to be welded 31 may be an alumina (Al ₂ O ₃ ) ceramic. In some examples, the ceramic to be welded 31 is preferably composed of alumina (Al ₂ O ₃ ) with a mass fraction of 96% or more. More preferably, the ceramic to be welded 31 is composed of alumina (Al ₂ O ₃ ) with a mass fraction of 99% or more, and most preferably, the ceramic to be welded 31 is composed of alumina (Al ₂ O ₃ ) with a mass fraction of 99.99% or more constitute. Generally speaking, in the ceramic 31 to be welded, the increase in the mass fraction of alumina (Al ₂ O ₃ ) can increase its main crystalline phase, and the physical properties of the ceramic to be welded 31 can also be improved, such as compressive strength, resistance The flexural strength and elastic modulus are also increased accordingly, so it can be considered that alumina (Al ₂ O ₃ ) with a higher mass fraction will exhibit better biocompatibility and long-term reliability. In other examples, the ceramic to be welded 31 may also be a zirconia (ZrO ₂ ) ceramic.

In some examples, the ceramic to be welded 31 may be a non-oxidizing ceramic. For example, the ceramic to be welded 31 may be made of at least one of carbon material (C), silicon nitride (Si ₃ N ₄ ), and silicon carbide (SiC).

In some examples, the ceramic to be welded 31 can also be made of silicon oxide (SiO ₂ ), potassium oxide (K ₂ O), sodium oxide (Na ₂ O), calcium oxide (CaO), magnesium oxide ( At least one of MgO) and iron oxide (Fe ₂ O ₃ ).

In some examples, the ceramic to be welded 31 may be disk-shaped. However, the example of the present invention is not limited thereto, for example, the ceramic to be welded 31 may be square.

In this embodiment, the metal to be welded 33 may have biocompatibility. Thereby, damage to the human body can be reduced, and compatibility with human tissue can be achieved. In some examples, in step S10, the metal to be welded 33 may be selected from at least one of Ti (titanium), Nb (niobium), Ni (nickel), Zr (zirconium), Ta (tantalum) and alloys thereof . Thereby, the metal to be welded 33 having biocompatibility can be obtained. Additionally, in one example, the metal to be welded 33 may be pure Ti. In another example, the metal to be welded 33 may be a Ti alloy. In addition, in yet another example, the metal to be welded 33 may be an iron-nickel alloy.

In some examples, the metal to be welded 33 may be a non-biocompatible metal. For example, the metal to be welded 33 may be made of at least one selected from copper (Cu), iron (Fe), magnesium (Mg), lead (Pb), aluminum (Al), and alloys thereof, or the like.

FIG. 6 shows a cross-sectional view of a workpiece 30 to be welded according to an example of the present disclosure.

In some examples, as shown in FIG. 6 , the metal to be welded 33 may have an annular protrusion 331 . In this case, the subsequent matching of the workpiece 30 to be welded with other components (not shown) is facilitated. In some examples, the metal to be welded 33 may be integrally formed.

In some examples, the annular protrusion 331 may extend along the inner diameter direction. Additionally, in some examples, the inner diameter of the annular protrusion 331 may be smaller than the inner diameter of the brazing filler metal 32 (described later), ie, the inner diameter of the annular protrusion 331 may be smaller than the inner diameter of the brazing filler metal 32 . Thereby, it can be matched with the metal brazing filler metal 32, thereby facilitating brazing.

In this embodiment, before step S20, surface treatment of the metal to be welded 33 may also be included. Thereby, the surface wettability of the metal to be welded 33 can be increased.

In some examples, the metal to be welded 33 may be surface treated by sanding in stages using sandpaper. In this way, the surface of the metal to be welded 33 can be better polished to a suitable roughness, thereby increasing the wettability of the metal to be welded 33 . For example, in one example, the metal 33 to be welded may be graded with #200, #400, #600, #1200, #2000, and #4000 sandpapers. In another example, the metal to be welded 33 may be graded with #100, #300, #500, #1000, #1500, #2500, and #4000 sandpapers. Additionally, in yet another example, the metal 33 to be welded may be graded with #280, #400, #800, #1600, #2500, #3500, and #5000 sandpapers.

In some examples, the surface-treated flatness of the metal to be welded 33 may be 8-10 μm. In this case, it can better adhere to the metal brazing filler metal 32, which is beneficial to brazing. For example, the surface-treated flatness of the metal 33 to be welded may be 8 μm, 8.2 μm, 8.5 μm, 8.8 μm, 9 μm, 9.2 μm, 9.5 μm, 9.8 μm or 10 μm.

Additionally, in some examples, the flatness of the metal 33 to be soldered may factor into the thickness of the brazing metal 32 . In some examples, the thicker the metal brazing filler metal 32 is, the greater the flatness that the metal to be welded 33 can tolerate, and the smaller the flatness that the metal to be welded 33 can tolerate.

In addition, in this embodiment, before step S20, cleaning the polished metal 33 to be welded may be included. In some examples, the polished metal 33 to be welded may be cleaned with ethanol for 10 to 20 mi, and then cleaned with isopropyl alcohol for 10 to 20 mi. For example, the polished metal 33 to be welded can be cleaned with ethanol for 15mi1 and then with isopropanol for 15mi1. Thereby, foreign matter on the surface of the technology to be welded can be removed, which is beneficial to subsequent brazing.

In some examples, in step S20, the method of metallization may be sputtering, evaporation, plating or high temperature sintering. Thereby, an intermediate metal layer combined with the ceramic 31 to be welded can be formed on the surface. In other examples, the method of metallization is preferably sputtering.

In some examples, the method of metallization may be PVD (Physical Vapor Deposition) or CVD (Chemical Vapor Deposition). In other examples, the method of metallization may be magnetron sputtering. Additionally, in some examples, the method of metallization may be a low temperature processing method. For example, the temperature of magnetron sputtering may not exceed 300°C.

In some examples, in step S20, the intermediate metal layer may be composed of at least one selected from the group consisting of Nb, Au, Ti and alloys thereof. Thereby, the ceramic to be welded 31 having the intermediate metal layer on the surface can be well wetted. Additionally, in some examples, the intermediate metal layer may be composed of Nb, in other words, the intermediate metal layer may be a niobium layer formed of Nb. In addition, the intermediate metal layer composed of Nb has good bonding ability with the alumina ceramics, thereby helping to improve the reliability of the brazing of the ceramics to be welded 31 and the metals to be welded 33 .

In some examples, the ground surface of the ceramic to be welded 31 may be metallized to form an intermediate metal layer. That is, the intermediate metal layer may be formed on the ground surface of the ceramic to be welded 31 . In other examples, the surface of the ceramic to be welded 31 may be surface ground and metallized to form a brazing surface.

In addition, in this embodiment, in step S20, the thermal expansion coefficient of the ceramic to be welded 31 matches the thermal expansion coefficient of the intermediate metal layer, that is, the thermal expansion coefficient of the intermediate metal layer may be between the thermal expansion coefficient of the ceramic to be welded 31 and the metal to be welded. 33, so that the thermal expansion coefficient between the interface of the ceramic to be welded 31 and the metal to be welded 33 presents a gradient transition, reducing the difference in the thermal expansion coefficient between the interfaces due to different materials, thereby reducing the thermal stress of the interface , to improve performance.

In some examples, metallization may be limited to the edge locations of the brazed face. In other words, metallization can be performed at the edge of the ground surface to form a metallized brazing surface that matches the metal brazing filler metal 32 . In this case, the intermediate metal layer can be formed at the position of the ceramic to be welded 31 to be brazed with the metal to be welded 33. In other examples, metallization may be performed on the entire abrasive surface. In other examples, metallization may be performed only in the middle of the ground surface.

In some examples, an intermediate metal layer may be formed at the edge locations of the brazing surface. Thus, the welding between the ceramic to be welded 31 and the metal to be welded 33 can be facilitated.

In some examples, the shape of the intermediate metal layer may be selected based on the shape of the metal 33 to be welded. For example, the metal to be welded 33 is annular, and the intermediate metal layer can be annular. Additionally, in some examples, the intermediate metal layer may have a ring width equal to the metal to be welded 33 . Therefore, the welding between the ceramic to be welded 31 and the metal to be welded 33 can be more favorable.

In some examples, the intermediate metal layer can be placed under a microscope to magnify 500 times to 1000 times to observe the quality of the intermediate metal layer. For example, observe whether the intermediate metal layer is tight, whether the appearance is smooth, etc.

In some examples, in step S20, magnetron sputtering can be used to sputter Nb onto the to-be-brazed position of the ceramic 31 to be brazed, and the sputtered Nb can become a flat intermediate metal layer at the to-be-brazed position. For example, the position to be brazed may be the edge position of the ceramic to be welded 31 covered by the metal brazing filler metal 32 in FIG. 6 .

In addition, in this embodiment, step S20 may include cleaning the ceramic to be welded 31 having the intermediate metal layer. Thus, foreign matter on the surface of the ceramic to be welded 31 can be removed, which is beneficial for subsequent brazing. In some examples, the ceramic to be welded 31 with the intermediate metal layer may be cleaned with ethanol for 3 to 5 mi, and then cleaned with isopropanol for 3 to 5 mi. For example, in one example, the ceramic 31 to be welded with the intermediate metal layer may be cleaned with ethanol for 4mi1, and then cleaned with isopropanol for 4mi1.

In some examples, before step S30, preparing metal brazing filler metal 32 may also be included. In other examples, the brazing filler metal 32 may be in the form of a thin sheet. In this case, it can help the metal brazing filler metal 32 to melt and wet the material to be welded (ceramic 31 to be welded, metal 33 to be welded, etc.). For example, as shown in FIG. 6 , the brazing filler metal 32 may be in the shape of a ring-shaped sheet. However, the present embodiment is not limited thereto, and in some examples, the metal brazing filler metal 32 may be in the form of powder, paste, wire, strip, or the like.

In some examples, the brazing metal 32 may be biocompatible. The metal brazing filler metal 32 may be selected from at least one of Au, Ag, Ti, Nb and alloys thereof. In this case, a biosafety brazing layer can be formed. For example, the metal brazing filler metal 32 may be pure Au. In addition, in some examples, the molten pure Au has good wettability to the niobium layer, which can help to improve the reliability of the brazing of the ceramic to be welded 31 and the metal to be welded 33 .

In addition, metal brazing filler metal 32 may be arranged on the brazing surface. In some examples, metal brazing filler metal 32 may be placed on the intermediate metal layer.

In some examples, as shown in FIG. 2 , the brazing filler metal 32 may be disposed at edge locations. In this case, brazing can be performed on the intermediate metal layer of the ceramic to be soldered 31 . In other examples, the metal brazing filler metal 32 may be disposed over the entire brazing surface. In some examples, the metal brazing filler metal 32 may be disposed in the middle of the brazing surface.

In addition, in this embodiment, in step S30 , pretreatment of the metal brazing filler metal 32 may be included. In some examples, the metal brazing filler metal 32 may be surface treated using sandpaper in stages. Thereby, the oxide film on the surface can be removed. For example, in one example, the brazing filler metal 32 may be graded with #200, #400, #600, #1200, #2000, and #4000 sandpapers. In another example, the brazing filler metal 32 may be graded with #100, #300, #500, #1000, #1500, #2500, and #4000 sandpapers. Additionally, in yet another example, the brazing metal 32 may be graded with #280, #400, #800, #1600, #2500, #3500, and #5000 sandpapers.

In some examples, the sizes of the ceramic to be welded 31 , the metal to be welded 33 and the metal brazing filler metal 32 may be matched. Thus, the brazing of the ceramic to be welded 31 and the metal to be welded 33 can be facilitated. For example, the outer diameter of the metal brazing filler metal 32 may be smaller than the outer diameter of the ceramics 31 to be welded, and the outer diameter of the metal 33 to be welded may be equal to the outer diameter of the ceramics 31 to be welded.

In some examples, the outer diameter of the brazing filler metal 32 may be smaller than the outer diameter of the ceramic 31 to be soldered. In other examples, the difference between the outer diameter of the ceramic to be soldered 31 and the outer diameter of the metal brazing filler metal 32 may not exceed 0.05mm. For example, the difference between the outer diameter of the ceramic to be soldered 31 and the outer diameter of the metal brazing filler metal 32 may be 0.01 mm, 0.02 mm, 0.03 mm, 0.04 mm, 0.05 mm, or the like.

In some examples, the inner diameter of the metal to be welded 33 may be smaller than the diameter of the ceramic to be welded 31 . In addition, the metal to be welded 33 may have the same outer diameter as the ceramic to be welded 31 .

In some examples, the outer diameter of the metal to be welded 33 may be larger than the outer diameter of the ceramic to be welded 31 . In other examples, the outer diameter of the metal to be welded 33 may be smaller than the outer diameter of the ceramic to be welded 31 .

In some examples, the inner diameter of the brazing filler metal 32 may be smaller than the inner diameter of the metal to be soldered 33 . In other words, the ring width of the metal brazing filler metal 32 may be smaller than the ring width of the metal 33 to be welded. In other examples, the difference between the inner diameter of the brazing filler metal 32 and the inner diameter of the metal to be welded 33 may not exceed 0.05 mm. For example, the difference between the inner diameter of the metal brazing filler metal 32 and the inner diameter of the metal to be welded 33 may be 0.01 mm, 0.02 mm, 0.03 mm, 0.04 mm, 0.05 mm, or the like. In addition, the inner diameter of the metal to be welded 33 may refer to the inner diameter of the annular protrusion 331 .

In some examples, the intermediate metal layer may match the metal to be welded 33 . Additionally, in some examples, the inner diameter of the intermediate metal layer may be equal to the inner diameter of the metal to be welded 33 . In other examples, the outer diameter of the intermediate metal layer may be equal to the outer diameter of the metal to be welded 33 .

In some examples, the ring width of the intermediate metal layer may be equal to the ring width of the metal to be welded 33 . In some examples, the ring width of the intermediate metal layer may be greater than the ring width of the metal to be welded 33 .

In some examples, the outer diameter of the ceramic to be welded 31 may be 10 mm to 9.9 mm. For example, the outer diameter of the ceramic to be welded 31 may be 9.9 mm, 9.91 mm, 9.92 mm, 9.93 mm, 9.94 mm, 9.95 mm, 9.96 mm, 9.97 mm, 9.98 mm, 9.99 mm or 10 mm.

In some examples, the outer diameter of the metal to be welded 33 may be 10.1 mm to 9.9 mm. For example, the outer diameter of the metal to be welded 33 may be 9.9 mm, 9.92 mm, 9.95 mm, 9.98 mm, 10 mm, 10.02 mm, 10.05 mm, 10.08 mm or 10.1 mm.

In some examples, the inner diameter of the metal to be welded 33 may be 8.9 mm to 8.7 mm. For example, the inner diameter of the metal to be welded 33 may be 8.7mm, 8.72mm, 8.75mm, 8.78mm, 8.8mm, 8.82mm, 8.85mm, 8.88mm or 8.9mm.

In some examples, the ring width of the metal to be welded 33 may be 0.5 mm to 0.7 mm. For example, the ring width of the metal to be welded 33 may be 0.5mm, 0.52mm, 0.55mm, 0.58mm, 0.6mm, 0.62mm, 0.65mm, 0.68mm or 0.7mm.

In other examples, the thickness of the metal brazing filler metal 32 may be 80 μm to 120 μm. For example, the thickness of the metal brazing filler metal 32 may be 80 μm, 85 μm, 90 μm, 95 μm, 100 μm, 105 μm, 110 μm, 115 μm, or 120 μm.

In some examples, optionally, pressure is applied to the workpiece to be welded 30 formed by stacking the ceramic to be welded 31 , the metal brazing filler metal 32 and the metal to be welded 33 in sequence. Thereby, the workpiece 30 to be welded can be fixed during brazing, and the uniformity of the width of the brazing seam and its edge can be controlled.

Hereinafter, the jig 1 for soldering used in step 30 according to the present embodiment will be described in detail with reference to the drawings.

FIG. 2 shows a perspective view of the jig 1 according to the example of the present disclosure. FIG. 3 shows a cross-sectional view of the jig 1 shown in FIG. 2 along the line AA'. In FIG. 3 , for the convenience of showing the structure of the stage 10 , the cover which is fitted with the stage 10 is omitted.

In the present embodiment, a jig for soldering (hereinafter sometimes referred to as a “jig”) 1 may include a stage 10 and a pressure block 20 fitted with the stage 10 . In step S30, the workpieces 30 to be welded (the ceramics 31 to be welded, the brazing filler metals 32 and the metals 33 to be welded) are sequentially placed on the stage 10, and the pressing blocks 20 matched with the stage 10 are arranged on the stage to be welded. on the weldment 30, so that the to-be-welded 30 can be brazed.

Additionally, in some examples, stage 10 may be semi-cylindrical. In this case, better brazing can be performed. For example, the semi-cylindrical stage 10 may be placed in a brazing tube furnace (not shown) having a cylindrical furnace tube for brazing. In addition, the shape of the stage 10 may match the shape of the furnace tube of the brazed tube furnace. In this case, it is beneficial to fix the fixture 1 in the brazing tube furnace, and the brazing can be better performed. For example, the furnace tube of the brazed tube furnace may have a prismatic shape, and the stage 10 may also have a prismatic shape.

In addition, in this embodiment, a vacuum pump (not shown) may be connected to the brazing tube furnace. In some examples, the vacuum level within the brazed tube furnace (not shown) may be 10 ⁻⁴ pa. In other examples, the vacuum level in the brazed tube furnace (not shown) may be 10 ⁻³ pa. In addition, in yet another example, the degree of vacuum in the brazed tube furnace (not shown) may be 10 ⁻² pa.

In addition, in some examples, according to the selected brazing filler metal (metal brazing filler metal 32 ), the vacuum degree in the brazing tube furnace (not shown) can also be 8×10 ^-3 Pa, 5×10 ^-3 Pa, 3×10-3pa, 7× ^10-2pa , 5× ^10-2pa , ² × ^10-2pa or 1pa.

Additionally, in some examples, stage 10 may have through holes 12 (see FIG. 4 ). In addition, the through hole 12 may penetrate through the bottom portion 11 a of the groove 11 . In some examples, the stage 10 may have at least one groove (eg, groove 11 in FIG. 3 , which shows an example of four grooves 11 ), and a base from the groove (groove 11 ) 11a penetrates the through hole (through hole 12 ) of the stage 10 .

In some examples, the groove 11 can be used to place the workpiece to be welded 30 (including the ceramic to be welded 31 , the metal brazing filler metal 32 and the metal to be welded 33 ), and can cooperate with the pressing block 20 . Additionally, in some examples, the pressure block 20 may have vent holes 21 .

In addition, when the stage 10 is provided with a plurality of grooves 11 , batch brazing can be performed on a plurality of workpieces to be welded 30 at the same time, thereby improving work efficiency. For example, the stage 10 may have 2, 8, 12, 16 or 20 grooves 11 therein in addition to the illustration of FIG. 3 .

In some examples, the pressure block 20 can fix the workpiece 30 to be welded during the brazing process, so as to avoid displacement of the workpiece 30 during the brazing process. In addition, gas flow can be formed in the through hole 12 and the vent hole 21 of the fixture 1, so the temperature distribution of the fixture 1 can be uniform during the brazing process, so that the workpiece 30 to be welded is heated evenly, and the vent hole 21 can discharge the brazing Impurities such as metal vapors generated in the process are avoided, so as to avoid the contamination of the workpiece 30 to be welded.

In some examples, the bottom 11a of the groove 11 may be flat (see FIG. 3 ). Thus, the workpiece 30 to be welded can be stably placed on the bottom 11 a of the groove 11 .

In some examples, the groove 11 may be cylindrical. In this case, it can be particularly suitable for the workpiece 30 to be welded which is also cylindrical. However, the present embodiment is not limited thereto, and in some examples, the grooves 11 may also have a prismatic shape or the like. For example, in one example, the groove 11 may also be in the shape of a rectangular parallelepiped. In another example, the groove 11 can also be in the shape of a cube.

In addition, in some examples, the inner diameter of the groove 11 may be equal to the expansion dimension of the workpiece 30 at the brazing temperature plus the expansion dimension of the fixture 1 at the brazing temperature plus the reserved dimension. In some examples, the reserved size may be 0.02mm-0.03mm. For example, the reserved size may be 0.02mm, 0.022mm, 0.025mm, 0.028mm, 0.03mm, and the like.

In addition, in some examples, the through hole 12 can have hot gas flow, so that the temperature distribution in the stage 10 can be uniform during the brazing process, and thus the workpiece 30 to be welded can be uniformly heated. In addition, the existence of the through hole 12 can also make it easier to clean the groove 11 . In addition, since the through hole 12 can penetrate through the bottom 11a of the groove 11, the groove 11 can be used to place the workpiece 30 to be welded, so the through hole 12 can facilitate the removal of the workpiece.

In addition, in some examples, the jig 1 may further include a cover (not shown) covering the stage 10 . In this case, the atmosphere during brazing can be protected, and the degree of vacuum can be well maintained.

Additionally, in some examples, the stage 10 may have a groove 13 surrounding the groove 11 , and the edge of the cover (not shown) may fit into the groove 13 . Thereby, the cover body (not shown) can cover the stage 10 . In some examples, the edge of the cover body can be engaged with the groove 13 .

In addition, in some examples, as shown in FIG. 4 , the pressing block 20 may be a combination of two cylinders with different inner diameters. In this compact 20, a cylinder with a small inner diameter has a small diameter so that it can fit into the groove 11, and a cylinder with a large inner diameter has a large diameter so that it can cover the groove 11. In this case, the pressing of the workpiece 30 to be welded can be achieved by the pressing block 20 .

In some examples, in the compact 20 , the diameter of the cylinder with a small inner diameter may be smaller than the inner diameter of the groove 11 . Additionally, in some examples, in the compact 20 , the diameter of the cylinder having a small inner diameter may be larger than the inner diameter of the metal to be welded 33 . In other examples, in the compact 20 , the diameter of the cylinder with a large inner diameter may be larger than the inner diameter of the groove 11 .

In other examples, the compact 20 may be a prism. Additionally, in some examples, the pressure block 20 may be a circular frustum. Additionally, in some examples, the compact 20 is integrally formed. Additionally, in some examples, the pressure block 20 may be used to apply pressure to the ceramic to be welded 31 and the metal to be welded 33 .

In some examples, vent holes 21 may be provided in the compact 20 . In addition, in some examples, the pressure block 20 may have a plurality of ventilation holes 21 , for example, the pressure block 20 may have 2 or 3 ventilation holes 21 . In this case, since gas flow can be formed in the vent hole 21 , the temperature distribution in the stage 10 can be uniform during the brazing process, and the workpiece 30 to be welded can be heated uniformly. In addition, the vent holes 21 can also help to discharge impurities such as metal vapors generated during the brazing process, so as to avoid the contamination of the workpiece 30 to be welded.

In some examples, among the plurality of ventilation holes 21 , there may be ventilation holes 21 penetrating in the longitudinal direction. In this case, the uniformity of heating of the parts to be welded 30 can be further improved, and the contamination of the parts to be welded 30 can be better avoided.

In some examples, the compact 20 may be used to separately apply pressure to the ceramic to be welded 31 and the metal to be welded 33 . In this case, the uniformity of the width of the brazing seam and its edges can be better controlled and the workpiece 30 to be welded can be fixed during brazing.

In addition, in some examples, the part to be welded 30 may be located between the bottom 11 a of the groove 11 and the pressing block 20 . Thereby, the workpiece 30 to be welded can be well fixed in the groove 11 .

In addition, in this embodiment, the material of the stage 10 may be selected from at least one of graphite, silicon, synthetic stone, boron carbide, silicon carbide, boron nitride, silicon nitride, boron phosphide, and silicon phosphide constitute. In one example, the material of the stage 10 may be graphite. In another example, the material of the stage 10 may be synthetic stone.

In addition, in the present embodiment, the material of the compact 20 may be composed of at least one selected from the group consisting of graphite, silicon, synthetic stone, boron carbide, silicon carbide, boron nitride, silicon nitride, boron phosphide, and silicon phosphide. . In one example, the material of the compact 20 may be graphite. In another example, the material of the compact 20 may be synthetic stone.

Additionally, in some examples, the length of the fixture 1 and the grooves 11 may be distributed in a temperature zone of the brazing tube furnace with a uniform temperature. Thereby, a plurality of workpieces 30 to be welded can be well brazed at the same time.

In addition, in this embodiment, as shown in FIG. 4 , in step S30, the workpiece 30 to be welded can be placed in the groove 11 on the stage 10, and then the workpiece 30 to be welded can be pressed by the pressing block 20, Assembly is complete. Next, the assembled stage 10, the compacts 20 and the parts to be welded 30 are sent to, for example, a brazing tube furnace for brazing. In some examples, the assembled stage 10, compacts 20, and parts to be welded 30 are fed into a uniform temperature zone of a brazing tube furnace. Thereby, a plurality of workpieces 30 to be welded can be well brazed at the same time.

In addition, in some examples, the order of stacking the components of the workpiece 30 to be welded in the groove 11 from bottom to top in FIG. 2 and Figure 6). For example, the order of stacking the parts of the workpiece 30 in the groove 11 from bottom to top may be a disc-shaped Al ₂ O ₃ ceramic, a pure Au solder ring and a pure Ti metal ring, and a disc-shaped Al ₂ O ₃ The center of the ceramic, pure Au solder ring and the pure Ti metal ring can be at the same point. The outer diameter of the disc-shaped Al ₂ O ₃ ceramic and the pure Ti metal ring is roughly the same, and the outer diameter of the pure Au solder ring is larger than that of the circle. The outer diameter of disk-shaped Al ₂ O ₃ ceramics is at most 0.05 mm smaller.

In some examples, a gap may exist between the pressure block 20 and the sidewall of the groove 11 of the stage 10 . In addition, in some examples, the gap H between the pressing block 20 and the side wall of the groove 11 of the stage 10 may be 0.05 mm to 0.06 mm (see FIG. 6 ), in this case, the gap H can be reserved It has the expansion dimensions of 1 and the workpiece 30 to be welded, and the device can be taken out smoothly when the brazing is completed. In addition, there is a gap between the pressing block 20 and the side wall of the groove 11, so that impurities such as metal vapor generated during the brazing process can be further discharged.

In some examples, the jig 1 may also have a collar. In other examples, a collar may be placed within groove 11 and may surround workpiece 30 to be welded. In this case, it is possible to reduce the flow of the metal brazing filler metal 32 after melting.

In some examples, the inner diameter of the groove 11 may be equal to the expansion dimension of the workpiece 30 at the brazing temperature plus the expansion dimension of the fixture 1 at the brazing temperature plus the thickness and reserved dimension of the collar.

In addition, in some examples, in order to prevent the metal brazing filler metal 32 in the workpiece to be welded 30 from dripping during the brazing process, the amount of metal brazing filler metal 32 can be calculated, the holding time and the surface state of the base metal can be controlled. accomplish.

FIG. 4 shows a cross-sectional view of a jig 1 equipped with a to-be-welded piece 30 according to an example of the present disclosure.

FIG. 5 shows an assembly structure diagram of the to-be-welded part 30 involved in the example of the present disclosure.

In addition, in this embodiment, in step S30 , as shown in FIG. 4 , the workpiece 30 to be welded can be placed in the groove 11 on the stage 10 , and then the workpiece 30 to be welded can be pressed by the pressing block 20 to complete the assembly. Next, the assembled stage 10, the compacts 20 and the parts to be welded 30 are sent to, for example, a brazing tube furnace for brazing. In some examples, the assembled stage 10, compacts 20, and parts to be welded 30 are fed into a uniform temperature zone of a brazing tube furnace. Thereby, a plurality of workpieces 30 to be welded can be well brazed at the same time.

In addition, in some examples, the gap H between the pressing block 20 and the side wall of the groove 11 of the stage 10 may be 0.05 mm to 0.06 mm (see FIG. 4 ), in this case, it can be soldered The weldment is removed smoothly when finished. In addition, as described above, the stage 10 may have a plurality of grooves 11 , whereby a plurality of workpieces to be welded 30 can be brazed at the same time. For example, the stage 10 may have 4, 12, 16 or 20 grooves 11 therein in addition to the illustrations of FIGS. 2 and 3 .

In addition, in some examples, the order of stacking the components of the workpiece 30 in the groove 11 from bottom to top may be the ceramic to be welded 31 , the metal brazing filler metal 32 and the metal to be welded 33 (see FIG. 5 ). For example, the order of stacking the parts of the workpiece 30 in the groove 11 from bottom to top can be a circular Al ₂ O ₃ ceramic base, a pure Au solder ring and a pure Ti metal ring, and a circular Al ₂ O ₃ The outer diameter of the ceramic base, pure Au solder ring and pure Ti metal ring is approximately the same.

In addition, in this embodiment, in step S30, the workpiece 30 to be welded can be heated to 1060°C to 1150°C at a heating rate of 1°C 1mi1 to 50°C 1mi1, kept at a temperature of 1mi1 to 30mi1, and then heated at 2°C 1mi1 to 20°C The cooling rate of 1mi1 is cooled to 200°C to 400°C, and then cooled to below 150°C with the furnace. Among them, 1060°C to 1150°C can be used as the brazing temperature. In this case, it is possible to improve the generation and distribution of the brittle phase between the interfaces, increase the strength, reduce the thermal stress and thermal deformation of the base metal, eliminate cracks in the weld, and improve the gap between the ceramic 31 to be welded and the metal to be welded 33 . Air tightness and shear strength of interfacial layers.

In addition, in some examples, in step S30, the temperature may be raised to 1060°C at a heating rate of 20°C 1mi1, maintained for 1mi1, then cooled to 400°C at a cooling rate of 10°C 1mi1, and then cooled to 150°C with the furnace. In other examples, the temperature can be raised to 1065°C at a heating rate of 15°C 1mi1, maintained for 3mi1, then cooled to 250°C at a cooling rate of 12°C 1mi1, and then cooled to 140°C with the furnace. In addition, in another example, the temperature can be raised to 1100°C at a heating rate of 30°C 1mi1, maintained for 5mi1, then cooled to 300°C at a cooling rate of 8°C 1mi1, and then cooled to 120°C with the furnace.

In addition, the brazing temperature may be 850°C, 900°C, 950°C, 1000°C, 1050°C, 1150°C, 1200°C, etc. depending on the selected brazing filler metal (metal brazing filler metal 32 ).

In some examples, after brazing, an interface layer may be formed between the interface of the ceramic to be welded 31 and the metal to be welded 33 . Additionally, in some examples, the interfacial layer may include the brazing metal 32 and the IMC layer. In other examples, the IMC layer may be a contiguous IMC layer. In some examples, the IMC layer may be a discontinuous IMC layer.

In some examples, the IMC layer may be located between the metal to be soldered 33 and the metal brazing filler metal 32 . Additionally, in some examples, the interface layer may include multiple layers of IMC layers. For example, the interface layer may have 2, 3, 4 or 5 IMC layers. Additionally, in some examples, multiple IMC layers may each be located between the metal to be soldered 33 and the brazing filler metal 32 .

In some examples, the multilayered IMC layer may include a brittle phase layer. In addition, in some examples, the brittle phase layer may refer to an alloy layer with a high content of brittle phase (brittle compound). In other examples, the thickness of the brittle phase layer may not exceed 2 μm. For example, the thickness of the brittle phase layer may be 0.5 μm, 0.8 μm, 1 μm, 1.1 μm, 1.2 μm, 1.3 μm, 1.4 μm, 1.5 μm, 1.6 μm, 1.7 μm, 1.8 μm or 2 μm.

According to the present disclosure, it is possible to provide a ceramic-metal brazing method capable of reducing the thermal stress of the interface layer and improving the airtightness and shear strength of the interface layer.

In order to further illustrate the present disclosure, the brazing method for ceramics and metals provided by the present disclosure will be described in detail below with reference to the embodiments, and the beneficial effects achieved by the present disclosure will be fully explained.

7 shows a slice view of a brazed joint of Al ₂ O ₃ ceramic and pure Ti metal involved in an embodiment of the present disclosure.

【Example】

(1) Surface grinding and polishing the upper surface of the disc-shaped Al ₂ O ₃ ceramic to a surface roughness of 0.02 μm;

(2) Metallization is performed on the upper surface of the polished Al ₂ O ₃ ceramic, and the treatment method is to sputter Nb onto the surface to be welded of the Al ₂ O ₃ ceramic by using a magnetron sputtering method to obtain the to-be-welded metallized ceramic ;

(3) cleaning the metallized ceramics to be welded with ethanol for 4ml, and then cleaning 4ml of isopropyl alcohol to obtain clean metallized ceramics to be welded;

(4) Grind the ring-shaped pure Ti metal and the ring-shaped pure Au foil-shaped brazing filler metal with #200, #400, #600, #1200, #2000, #4000 sandpaper step by step, and then clean it with ethanol for 10mi1, Then use isopropanol to clean 15mi1 to get clean pure Ti metal and pure Au foil brazing filler metal;

(5) The clean metallized ceramics to be welded, pure Au foil brazing filler metal and pure Ti metal are stacked in the jig in order from bottom to top, and the parts to be welded are obtained after fixing;

(6) Place the fixture with the parts to be welded in a vacuum brazing furnace, heat it up to 1060°C at a heating rate of 20°C 1mi1, keep the temperature for 1mi1, and then cool it down to 400°C at a cooling rate of 10°C 1mi1, and finally follow the furnace. After cooling to 150°C, the brazing is completed.

Finally, open the furnace and take out the brazed joint of Al ₂ O ₃ ceramic and pure Ti metal, then carry out the air tightness test and room temperature shear strength test of the brazed joint, and slice the brazed joint to observe the microstructure of the brazed joint .

The test results of the air tightness test and the room temperature shear strength test of the brazed joint in this embodiment are: the air tightness is 1E-10*m ³ 1s, and the room temperature shear strength is 20Mpa.

In addition, the slicing results of the brazed joint are shown in Figure 7. From Figure 7, it can be observed that the pure Au solder fills the brazing joint completely, and there are no defects such as pores and unwelded joints in the solder joint. The solder and the base metal on both sides ( Al ₂ O ₃ ceramics and pure Ti metal) interface reaction is sufficient, forming a good metallurgical bond, and no cracks appear on the Al ₂ O ₃ ceramic side and in the brazing seam, and the brittle phase is only distributed on the pure Ti metal side. In addition, most of the brazing seam is pure Au solder, which can effectively relieve the thermal stress of the brazed joint and improve the strength of the brazed joint.

To sum up, the brazed joints obtained in the examples have small thermal stress, and have good air tightness and shear strength.

Although the present disclosure has been specifically described above with reference to the accompanying drawings and embodiments, it should be understood that the above description does not limit the present disclosure in any form. Those skilled in the art can make modifications and changes of the present disclosure as required without departing from the essential spirit and scope of the present disclosure, and these modifications and changes all fall within the scope of the present disclosure.

Claims (10)

1. A method for brazing ceramic and metal, characterized in that:

the method comprises the following steps:

preparing ceramics to be welded and metals to be welded, and performing surface treatment on the ceramics to be welded to form the surface of the ceramics to be welded into a smooth surface;

carrying out metallization treatment on the surface of the ceramic to be welded to form an intermediate metal layer combined with the ceramic to be welded, wherein the thermal expansion coefficient of the ceramic to be welded is matched with that of the intermediate metal layer; and is

Sequentially stacking the ceramics to be welded, the metal solder and the metal to be welded and brazing, wherein the metal solder is positioned between the middle metal layer and the metal to be welded,

in the brazing process, the metal brazing filler metal is melted through heating, the melted metal brazing filler metal infiltrates the middle metal layer and is kept in a molten state for a preset time, so that a welding surface is formed on an interface between the metal brazing filler metal and the ceramic to be welded with the middle metal layer, and annealing and solidification are carried out.

2. The brazing method according to claim 1, wherein:

the roughness of the surface of the ceramic to be welded is less than 0.05 μm.

3. The brazing method according to claim 1, wherein:

the metallization treatment method is sputtering, evaporation, plating or high-temperature sintering.

4. The brazing method according to claim 1, wherein:

the intermediate metal layer is composed of at least one selected from Nb, Au, Ti and alloys thereof.

5. The brazing method according to claim 1, wherein:

the metal solder is at least one selected from Au, Ag, Ti, Nb and alloys thereof.

6. The brazing method according to claim 1, wherein:

the sizes of the ceramic to be welded and the metal to be welded are matched with the size of the metal brazing filler metal.

7. The brazing method according to claim 1 or 6, wherein:

and applying pressure to the to-be-welded piece formed by sequentially stacking the to-be-welded ceramic, the metal solder and the to-be-welded metal.

8. The brazing method according to claim 1, wherein:

before brazing, the metal to be welded is subjected to surface treatment.

9. The brazing method according to claim 1, wherein:

in the brazing, the temperature is raised to 1060 ℃ to 1150 ℃ at the heating rate of 1 ℃ 1mi1 to 50 ℃ 1mi1, the temperature is kept between 1mi1 and 30mi1, then the temperature is lowered to 200 ℃ to 400 ℃ at the cooling rate of 2 ℃ 1mi1 to 20 ℃ 1mi1, and then the temperature is cooled to below 150 ℃ along with a furnace.

10. The brazing method according to claim 1, wherein:

the ceramic to be welded is composed of at least one selected from alumina, zirconia, silica, titania, aluminosilicate or calcium-aluminum series.

Images