CN103056553B - A kind of solder and preparation method thereof and the method utilizing solder to be connected sapphire and niobium or niobium alloy - Google Patents

Abstract

The invention relates to a brazing filler metal, a preparation method thereof, and a method for connecting sapphire and niobium or a niobium alloy by using the brazing filler metal, and relates to the field of the brazing filler metal and its preparation and connection methods. The invention aims to solve the problems that the existing brazing method for connecting sapphire and metal has relatively large residual stress in the joint, is not resistant to high temperature, has a relatively complicated process, and has low joint strength. A brazing material: prepared from Ag powder, CuO powder, TiH ₂ powder, Si ₃ N ₄ nanometer ceramic particles and a binder. Preparation method: 1. preparation of Ag-CuO-TiH ₂ powder; 2. preparation of solder mixed powder; 3. uniform mixing of solder mixed powder and binder. The method of using solder to connect sapphire and niobium or niobium alloy: 1. Prepare the sapphire sample to be welded and the niobium or niobium alloy sample to be welded; 2. Coat the solder on the surface to be welded; 3. Heat the form to complete the connection. The invention is applicable to the field of welding.

Description

A kind of brazing filler metal and its preparation method and the method for using brazing filler metal to connect sapphire and niobium or niobium alloy

technical field

The present invention relates to the field of brazing filler metals and methods for their preparation and joining.

Background technique

Sapphire is α-Al ₂ O ₃ single crystal, which is an excellent crystal material with excellent physical, mechanical and chemical properties such as high strength, high thermal shock resistance, high corrosion resistance and high wave transmittance. It is an ideal material for satellite optical windows. However, because it is a single crystal material of alumina, the price is relatively expensive, and its application needs to be inevitably connected with metals, such as niobium, Kovar alloy and carbon steel. At present, the connection methods of sapphire and metal mainly include brazing, diffusion welding, glass welding, adhesive bonding and mechanical connection. Diffusion welding joints have relatively high strength, but the connection time is long and the cost is high, and the pores in the weld will seriously affect the airtightness of the seal. Large residual stress will be generated in the glass welding seam, and defects such as cracks, pores, and cavities will easily form. The glass layer itself is also susceptible to corrosion, and the high temperature stability of the joint is poor. The adhesive joint has low strength, cannot withstand high temperature, and is easy to age, which seriously affects the service life and reliability of the connecting parts. The airtightness of the mechanical connection components is insufficient, the sapphire screw hole is difficult to process, and it is prone to stress concentration and cracking. The brazing method to connect sapphire and metal is mainly active brazing and indirect brazing. The active brazing method joint has relatively large residual stress and is not resistant to high temperature, while the indirect brazing method is more complicated and the joint strength is not high.

CN102699572A discloses a solder prepared from Ag powder, Cu powder, Ti powder and Si ₃ N ₄ nano ceramic particles.

Contents of the invention

The present invention aims to solve the problems that the existing brazing method for connecting sapphire and metal has relatively large residual stress, high temperature resistance, complicated process and low joint strength, and provides a brazing filler metal and its preparation method and A method of connecting sapphire and niobium or niobium alloys with solder.

A kind of solder is prepared from Ag powder, CuO powder, TiH ₂ powder, Si ₃ N ₄ nanometer ceramic particles and binding agent; Wherein, the mass ratio of described Ag powder and CuO powder is 1:( 0.06～0.17), the mass ratio of described Ag powder and TiH powder is ₁ :(0.01～0.11), the mass ratio of described Ag powder and Si ₃ N ₄ nano ceramic particles is 1:(0.012～0.12) , the mass ratio of the Ag powder to the binder is 1:(0.05-0.07).

Described binding agent is formed by mixing glycerol, hydroxyethyl cellulose and water; Wherein, the mass ratio of described glycerol and hydroxyethyl cellulose is 1:(3～7), The mass ratio of the glycerol to water is 1:(90-92).

A kind of preparation method of brazing filler metal is specifically finished according to the following steps:

1. Mix Ag powder, _CuO powder and TiH2 powder, add acetone to it, and then, under the protection of argon, ball mill at a rate of 200r/min-300r/min for 1h-3h to obtain Ag- _CuO -TiH2 powder ; Wherein, the mass ratio of described Ag powder and CuO powder is 1:(0.06～0.17), the mass ratio of described Ag powder and TiH ₂ powder is 1:(0.01～0.11), the mixing of grinding ball and adding The mass ratio of powder is (4～6):1, and the ratio of the mass sum of Ag powder, _CuO powder and TiH2 powder to the volume of acetone is 1g:(0.45mL～0.72mL);

2. Add Si ₃ N ₄ nano-ceramic particles and acetone to the Ag-CuO-TiH ₂ powder obtained in step 1, mix them, and then ball mill at 200r/min to 300r/min under the condition that the degree of vacuum is less than 5Pa Speed, ball milling for 2h-5h, to obtain solder mixed powder; wherein, the mass ratio of Ag in Ag-CuO-TiH ₂ powder to Si ₃ N ₄ nano-ceramic particles is 1:(0.012-0.12), and the grinding ball and the added The mass ratio of the sum of the powder is (15～25):1, the ratio of the sum of the mass of Ag-CuO-TiH ₂ powder and Si ₃ N ₄ nano ceramic particles to the volume of acetone is 1g:(0.5mL～0.8mL );

Three, the brazing filler metal mixed powder that step 2 obtains is mixed evenly with binding agent, obtains paste solder, promptly has finished the preparation of brazing filler metal; Wherein, the quality of Ag and binding agent in described brazing filler metal mixed powder The ratio is 1:(0.05～0.07).

The method of connecting sapphire and niobium or niobium alloy with brazing filler metal is specifically completed according to the following steps:

1. Prepare sapphire samples, polish the sapphire surface to be welded to a surface roughness of 0.1 μm to 0.3 μm, prepare niobium or niobium alloy samples, and polish to the surface roughness of the surface to be welded to 0.1 μm to 0.2 μm; clean and polish After the surface of the sapphire sample and niobium or niobium alloy sample is obtained, the sapphire sample to be welded and the niobium or niobium alloy sample to be welded are obtained;

Two, the brazing material of the present invention is evenly coated on the surface to be welded of the sapphire sample to be welded and the surface to be welded of the niobium or niobium alloy sample to be welded in step one, the sapphire sample to be welded and the niobium alloy sample to be welded or the coated surface of the niobium alloy sample is connected and compacted to obtain the pretreated sample; wherein, the pressure between the surface to be welded of the sapphire sample to be welded and the surface to be welded of the niobium or niobium alloy sample to be welded is 9.8× 10 ³ Pa～10×10 ³ Pa;

3. Under the condition of vacuum degree of 0.6×10 ^-3 Pa～1.5×10 ^-3 Pa, heat the pretreated sample obtained in step 2 from room temperature to 410 °C at a heating rate of 15 °C/min～20 °C/min ℃～480℃, keep warm for 10min～20min, then heat to 700℃～750℃ at a heating rate of 5℃/min～15℃/min, keep warm for 15min～25min, and then heat at a heating rate of 7℃/min～15℃/min Heating rate to 1050°C-1150°C, keeping warm for 20min-30min, finally, cooling down to 350°C-450°C at a cooling rate of 5°C/min-10°C/min, after that, naturally cooling to room temperature, that is, the use of brazing is completed. A method of connecting sapphire to niobium or niobium alloys.

Advantages of the present invention: when the solder provided by the present invention is used to connect sapphire and niobium or niobium alloy, since the nano-ceramic phase particles are added to the solder, the residual stress caused by the mismatch of expansion coefficients is greatly relieved, X-ray test The residual stress at the interface of the joint is only 5MPa, while the conventional Ag-Cu-Ti solder is brazed under the same process parameters, the residual stress in the joint after welding is as high as 65Mpa, and the obtained weld interface does not have cracks or pores; At the same time, the process of connecting sapphire and niobium or niobium alloy with the solder of the present invention is simple, the average shear strength of the joint is as high as 200MPa, and the joint components can withstand high temperatures above 1000°C.

Description of drawings

Fig. 1 is a scanning electron micrograph of the solder mixed powder obtained in step 2 of test 1.

Detailed ways

Specific embodiment one: present embodiment is a kind of brazing filler metal, and it is prepared by Ag powder, CuO powder, TiH ₂ powder, Si ₃ N ₄ nano-ceramic particles and binding agent; Wherein, described Ag powder and The mass ratio of CuO powder is 1:(0.06～0.17), the mass ratio of described Ag powder and TiH ₂ powder is 1:(0.01～0.11), the mass ratio of described Ag powder and Si ₃ N ₄ nano ceramic particles The ratio is 1:(0.012-0.12), and the mass ratio of the Ag powder to the binder is 1:(0.05-0.07).

In this embodiment, TiH ₂ is selected as the addition form of active Ti. TiH ₂ can be completely decomposed by vacuum heating and dehydrogenation to obtain activated Ti, which effectively prevents active Ti from being oxidized.

This embodiment has the following advantages: when the brazing filler metal provided by this embodiment is used to connect sapphire and niobium or niobium alloy, since nano-ceramic phase particles are added to the brazing filler metal, the residual stress caused by the mismatch of expansion coefficients is greatly relieved, X-ray test shows that the residual stress at the interface of the joint is only 5MPa, while the conventional Ag-Cu-Ti solder is brazed under the same process parameters, the residual stress in the joint after welding is as high as 65Mpa, and there is no crack or air hole in the weld interface obtained At the same time, the process of connecting sapphire and niobium or niobium alloy with the solder of this embodiment is simple, the average shear strength of the joint is as high as 200MPa, and the joint components can withstand high temperatures above 1000°C.

Specific embodiment 2: The difference between this embodiment and specific embodiment 1 is that the binder is formed by mixing glycerol, hydroxyethyl cellulose and water; wherein, the glycerin The mass ratio to hydroxyethyl cellulose is 1:(3-7), and the mass ratio of glycerol to water is 1:(90-92). Others are the same as in the first embodiment.

Embodiment 3: The difference between this embodiment and Embodiment 1 or 2 is that the mass ratio of the Ag powder to the binder is 1:0.06. Others are the same as in the first or second embodiment.

Specific embodiment four: This embodiment provides a kind of preparation method of brazing filler metal, specifically is finished according to the following steps:

1. Mix Ag powder, _CuO powder and TiH2 powder, add acetone to it, and then, under the protection of argon, ball mill at a rate of 200r/min-300r/min for 1h-3h to obtain Ag- _CuO -TiH2 powder ; Wherein, the mass ratio of described Ag powder and CuO powder is 1:(0.06～0.17), the mass ratio of described Ag powder and TiH ₂ powder is 1:(0.01～0.11), the mixing of grinding ball and adding The mass ratio of the powder is (4~6):1, and the ratio of the mass sum of Ag powder, _CuO powder and TiH2 powder to the volume of acetone is 1g:(0.45mL~0.72mL)

2. Add Si ₃ N ₄ nano-ceramic particles and acetone to the Ag-CuO-TiH ₂ powder obtained in step 1, mix them, and then use a ball mill of 200r/min to 300r/min under the condition that the degree of vacuum is less than 5Pa Speed, ball milling for 2h-5h, to obtain solder mixed powder; wherein, the mass ratio of Ag in Ag-CuO-TiH ₂ powder to Si ₃ N ₄ nano-ceramic particles is 1:(0.012-0.12), and the grinding ball and the added The mass ratio of the sum of the powders is (15-25):1, and the ratio of the sum of the mass of Ag-CuO-TiH ₂ powder and Si ₃ N ₄ nano-ceramic particles to the volume of acetone is 1g:(0.5mL-0.8mL) ;

Three, the brazing filler metal mixed powder that step 2 obtains is mixed evenly with binding agent, obtains paste solder, promptly has finished the preparation of brazing filler metal; Wherein, the quality of Ag and binding agent in described brazing filler metal mixed powder The ratio is 1:(0.05～0.07).

In this embodiment, the use of acetone grinding media can accelerate the ball milling process, reduce the surface energy of the powder, prevent the powder from agglomerating, reduce the effect of cold welding, and improve the powder yield.

In this embodiment, TiH ₂ is selected as the addition form of active Ti. TiH ₂ can be completely decomposed by vacuum heating and dehydrogenation to obtain activated Ti, which effectively prevents active Ti from being oxidized.

This embodiment has the following advantages: when the brazing filler metal provided by this embodiment is used to connect sapphire and niobium or niobium alloy, since nano-ceramic phase particles are added to the brazing filler metal, the residual stress caused by the mismatch of expansion coefficients is greatly alleviated. The residual stress of the joint interface is only 5MPa according to the ray test, but the residual stress in the joint after welding is as high as 65Mpa when the conventional Ag-Cu-Ti solder is used for brazing under the same process parameters. , the obtained weld interface does not have defects of cracks or pores; at the same time, the process of connecting sapphire and niobium or niobium alloy with the solder of this embodiment is simple, the average shear strength of the joint is as high as 200 MPa, and the joint components can withstand more than 1000 ° C high temperature.

Embodiment 5: The difference between this embodiment and Embodiment 4 is that the binder in the step 3 is mixed with glycerol, hydroxyethyl cellulose and water; wherein, the The mass ratio of glycerol to hydroxyethyl cellulose is 1:(3-7), and the mass ratio of glycerol to water is 1:(90-92). Others are the same as in Embodiment 4.

Embodiment 6: The difference between this embodiment and Embodiment 4 or 5 is that the mass ratio of Ag and binder in the solder mixed powder in Step 3 is 1:0.06. Others are the same as in Embodiment 4 or 5.

Specific Embodiment Seven: This embodiment provides a method for connecting sapphire and niobium or niobium alloy using brazing material, which is specifically completed according to the following steps:

1. Prepare sapphire samples, polish the sapphire surface to be welded to a surface roughness of 0.1 μm to 0.3 μm, prepare niobium or niobium alloy samples, and polish to the surface roughness of the surface to be welded to 0.1 μm to 0.2 μm; clean and polish After the surface of the sapphire sample and niobium or niobium alloy sample is obtained, the sapphire sample to be welded and the niobium or niobium alloy sample to be welded are obtained;

Two, the brazing material described in the specific embodiment one is evenly coated on the surface to be welded of the sapphire sample to be welded and the surface to be welded of the niobium or niobium alloy sample to be welded in step one, and the sapphire sample to be welded and the surface to be welded The coated surfaces of the niobium or niobium alloy samples to be welded are connected and compacted to obtain pretreated samples; wherein, the distance between the surface to be welded of the sapphire sample to be welded and the surface to be welded of the niobium or niobium alloy sample to be welded The pressure is 9.8×10 ³ Pa～10×10 ³ Pa;

3. Under the condition of vacuum degree of 0.6×10 ^-3 Pa～1.5×10 ^-3 Pa, heat the pretreated sample obtained in step 2 from room temperature to 410 °C at a heating rate of 15 °C/min～20 °C/min ℃～480℃, keep warm for 10min～20min, then heat up to 700℃～750℃ at a heating rate of 5℃/min～15℃/min, keep warm for 15min～25min, and then heat at a heating rate of 7℃/min～15℃/min Heating at a heating rate of 1050°C to 1150°C, holding for 20min to 30min, and finally cooling down to 350°C to 450°C at a cooling rate of 5°C/min to 10°C/min. A method of connecting sapphire to niobium or niobium alloys.

In the second step of this embodiment, the pressure between the sapphire sample to be welded and the niobium or niobium alloy sample to be welded is 9.8×10 ³ Pa to 10×10 ³ Pa, which is to ensure that the sapphire and niobium or niobium alloy of close contact.

In the third step of this embodiment, the segmented heating method is adopted to ensure that the binder can be fully decomposed and volatilized at a temperature of 410°C to 480°C, and then the TiH ₂ can be completely decomposed into active Ti at a temperature of 700°C to 750°C, and finally the Raise the temperature to 1050℃～1150℃ at a slow rate, which ensures the sufficient wetting and spreading of the composite solder on the base metal. After 20min～30min of heat preservation, the brazing material and the base metal will have a proper metallurgical reaction and the brazing joint will Uniform structure, improve joint strength, post-weld cooling with a cooling rate of 5°C/min to 10°C/min is to minimize the residual stress of the post-weld joint and ensure the reliability of the joint.

This embodiment has the following advantages: when the brazing filler metal provided by this embodiment is used to connect sapphire and niobium or niobium alloy, since nano-ceramic phase particles are added to the brazing filler metal, the residual stress caused by the mismatch of expansion coefficients is greatly alleviated. The residual stress of the joint interface is only 5MPa in the ray test, but the residual stress in the joint after welding is as high as 65MPa when the conventional Ag-Cu-Ti solder is brazed under the same process parameters. , the obtained weld interface does not have defects of cracks or pores; at the same time, the process of connecting sapphire and niobium or niobium alloy with the solder of this embodiment is simple, the average shear strength of the joint is as high as 200 MPa, and the joint components can withstand more than 1000 ° C high temperature.

Embodiment eight: the difference between this embodiment and embodiment seven is: the grinding method in the step one is: the sapphire sample is roughly ground with a grinder, and then successively use #240, #360, #600, Grind with #800, #1000, #1200 water sandpaper, and then use diamond spray polishing agent with a particle size of 0.5μm～1.5μm to polish the sapphire for 0.3h～0.7h; use #240, #360, #600 for niobium or niobium alloy in turn , #800, #1000, #1200 water sandpaper grinding. Others are the same as in the seventh embodiment.

Specific embodiment nine: the difference between this embodiment and specific embodiment seven or eight is: the cleaning method in the step one is: soak the polished sapphire sample and niobium or niobium alloy sample with acetone, ultrasonically Clean for 20min to 30min at a temperature of 30°C to 40°C, then wipe with absolute ethanol, then clean the surface of the sample to be welded with flowing distilled water, and finally dry it. Others are the same as the seventh or eighth specific embodiment.

This embodiment chooses 30℃～40℃ heating ultrasonic cleaning method because the cavitation effect of ultrasonic wave is the best at 30℃～40℃, which can fully remove the dirt on the surface of the sample. The purpose of cleaning with flowing distilled water instead of tap water is to prevent tap water Impurities contaminate the cleaned sample surface.

Specific embodiment ten: The difference between this embodiment and one of specific embodiments seven to nine is that the brazing filler metal in the described step 2 is evenly coated in the step 1 to obtain the thickness of the surface to be welded of the sapphire sample to be welded to be 0.5 mm ~ 0.8mm, the brazing material is uniformly coated in step 1 to obtain the thickness of the surface to be welded of the niobium or niobium alloy sample to be welded is 0.5mm ~ 0.8mm. Others are the same as one of the seventh to ninth specific embodiments.

Adopt following test to verify effect of the present invention:

Test one: a kind of preparation method of brazing filler metal, specifically finish according to the following steps:

1. Mix Ag powder, _CuO powder and TiH powder, add acetone thereto, and then, under argon protection, ball mill at a speed of 220r/min for 2h to obtain Ag- _CuO -TiH powder; wherein, the The mass ratio of Ag powder and CuO powder is 1:0.1, and described Ag powder and TiH _The mass ratio of powder is 1:0.05, and the mass ratio of milling ball and the mixed powder that adds is 5:1, and Ag powder, CuO powder and TiH _The ratio of the mass sum of powder to the volume of acetone is 1g:0.5mL;

2. Add Si ₃ N ₄ nano-ceramic particles and acetone to the Ag-CuO-TiH ₂ powder obtained in step 1, mix them, and then, under the condition that the vacuum degree is less than 5Pa, ball mill with a ball milling speed of 250r/min 5h, obtain solder mixed powder; Wherein, Ag- _CuO -TiH The mass ratio of Ag and Si ₃ N ₄ nano-ceramic particles in the powder is 1:0.1, and the mass ratio of the sum of the grinding balls and the added powder is 20 : 1, the ratio of Ag-CuO-TiH ₂ powder and the sum of the quality of Si ₃ N ₄ nano ceramic particles to the volume of acetone is 1g:0.7mL;

3. Mix the solder mixed powder and binder obtained in step 2 evenly to obtain paste solder, which completes the preparation of solder; wherein, the binder is made of glycerol, hydroxyethyl Cellulose and water are mixed; The mass ratio of described glycerol and hydroxyethyl cellulose is 1:4, and the mass ratio of described glycerol and water is 1:91, and described brazing filler metal is mixed The mass ratio of Ag in the powder to the binder is 1:0.06.

The solder mixed powder obtained in step 2 of test 1 was tested by scanning electron microscope, and Figure 1 can be obtained. From Fig. 1, it can be observed that nanoscale Si3N4 is adsorbed _on the surface of pristine Ag- _CuO -Ti powder.

Test 2: The method of connecting sapphire and niobium or niobium alloy with brazing filler metal is completed according to the following steps:

1. Prepare the sapphire sample, roughly grind the sapphire sample with a grinder, then grind it with #240, #360, #600, #800, #1000, #1200 water sandpaper in turn, and then use diamond spray polishing with a particle size of 1 μm Polish the sapphire for 0.5h to obtain a polished sapphire with a surface roughness of 0.2 μm; prepare niobium samples and grind them with #240, #360, #600, #800, #1000, #1200 water sandpaper in turn until the surface roughness of the surface to be welded is 0.1 μm; soak the polished sapphire sample and niobium or niobium alloy sample in acetone, ultrasonically clean it for 30 minutes at a cleaning temperature of 35°C, then wipe it with absolute ethanol, and then use a flow Distilled water to clean the surface of the sample to be welded, and finally dry;

2. Apply the brazing material of test one evenly on the surface to be welded of the sapphire sample to be welded and the surface to be welded of the niobium or niobium alloy sample to be welded obtained in step one, and the sapphire sample to be welded and the niobium alloy sample to be welded or niobium alloy samples with the coated surfaces connected and compacted to obtain pretreated samples; wherein, the thickness of the solder on the surface of the sapphire sample to be welded is 0.5 mm, and the thickness of the solder on the surface of the niobium or niobium alloy sample to be welded is 0.5 mm. The thickness of the material is 0.5mm, and the pressure between the surface to be welded of the sapphire sample to be welded and the surface to be welded of the niobium or niobium alloy sample to be welded is 10×10 ³ Pa;

3. Under the condition of vacuum degree of 1×10 ^-3 Pa, heat the pretreated sample obtained in step 2 from room temperature to 450°C at a heating rate of 15°C/min, keep it warm for 15min, and then heat it at 10°C/min Heating at a heating rate of 730°C, holding for 20 minutes, heating at a heating rate of 8°C/min to 1100°C, holding for 25 minutes, and finally, cooling at a cooling rate of 9°C/minn to 400°C, and then cooling to room temperature naturally. That is to say, the method of connecting sapphire and niobium or niobium alloy by solder is completed.

The joints of the connecting components obtained in the second test are adopted to detect the residual stress of the joint interface by X-ray, and the residual stress is 5MPa. The existing Ag-Cu-Ti solder that adopts the conventional method is under the same process parameters as the second test. After brazing, the residual stress in the welded joint is as high as 65MPa. In comparison, the residual stress at the joint of the connected components obtained in Test 2 is greatly reduced.

The shear strength test is carried out on the joints of the connected components obtained in the second test, and the average shear strength of the joints can be obtained as 200MPa.

The high temperature resistance test of the connecting components obtained in the second test shows that the service temperature of the joint can reach above 1000°C.

Claims (5)

1. a kind of brazing filler metal, it is by Ag powder, CuO powder, TiH ₂ powder, Si ₃ N ₄ nano ceramic particles and binding agent are prepared from; Wherein, the mass ratio of described Ag powder and CuO powder is 1:(0.06～0.17), the mass ratio of described Ag powder and TiH powder is ₁ :(0.01～0.11), the mass ratio of described Ag powder and Si ₃ N ₄ nano ceramic particles is 1:(0.012 ～0.12), the mass ratio of described Ag powder and binder is 1:(0.05～0.07); Described binding agent is formed by mixing glycerol, hydroxyethyl cellulose and water; Wherein, the mass ratio of described glycerol and hydroxyethyl cellulose is 1:(3～7), The mass ratio of described glycerol and water is 1:(90～92); The preparation method of described a kind of brazing filler metal is specifically finished according to the following steps: 1. Mix Ag powder, _CuO powder and TiH2 powder, add acetone to it, and then, under the protection of argon, ball mill at a rate of 200r/min-300r/min for 1h-3h to obtain Ag- _CuO -TiH2 powder ; Wherein, the mass ratio of described Ag powder and CuO powder is 1:(0.06～0.17), the mass ratio of described Ag powder and TiH ₂ powder is 1:(0.01～0.11), the mixing of grinding ball and adding The mass ratio of powder is (4～6):1, and the ratio of the mass sum of Ag powder, _CuO powder and TiH2 powder to the volume of acetone is 1g:(0.45mL～0.72mL); 2. Add Si ₃ N ₄ nano-ceramic particles and acetone to the Ag-CuO-TiH ₂ powder obtained in step 1, mix them, and then use a ball mill of 200r/min to 300r/min under the condition that the degree of vacuum is less than 5Pa speed, ball milling for 2h to 5h, to obtain solder mixed powder; wherein, the mass ratio of Ag to Si ₃ N ₄ nano ceramic particles in the Ag-CuO-TiH ₂ powder is 1: (0.012 to 0.12), and the grinding ball and the added powder The mass ratio of the sum of the materials is (15-25):1, and the ratio of the sum of the mass of Ag-CuO-TiH ₂ powder and Si ₃ N ₄ nano-ceramic particles to the volume of acetone is 1g:(0.5mL-0.8mL) ; Three, the brazing filler metal mixed powder that step 2 obtains is mixed evenly with binding agent, obtains paste solder, promptly has finished the preparation of brazing filler metal; Wherein, the quality of Ag and binding agent in described brazing filler metal mixed powder The ratio is 1:(0.05～0.07). 2. utilize the method for connecting sapphire and niobium or niobium alloy with brazing material as claimed in claim 1, it is characterized in that: method is specifically finished according to the following steps: 1. Prepare sapphire samples, polish the sapphire surface to be welded to a surface roughness of 0.1 μm to 0.3 μm, prepare niobium or niobium alloy samples, and polish to the surface roughness of the surface to be welded to 0.1 μm to 0.2 μm; clean and polish After the surface of the sapphire sample and niobium or niobium alloy sample is obtained, the sapphire sample to be welded and the niobium or niobium alloy sample to be welded are obtained; Two, the brazing material described in claim 1 is evenly coated on the surface to be welded of the sapphire sample to be welded and the surface to be welded of the niobium or niobium alloy sample to be welded in step 1, the sapphire sample to be welded and the surface to be welded The coated surface of the niobium or niobium alloy sample to be welded is connected and compacted to obtain a pretreated sample; wherein, the pressure between the surface to be welded of the sapphire sample to be welded and the surface to be welded of the niobium or niobium alloy sample to be welded 9.8×10 ³ Pa～10×10 ³ Pa; 3. Under the condition of vacuum degree of 0.6×10 ^-3 Pa～1.5×10 ^-3 Pa, heat the pretreated sample obtained in step 2 from room temperature to 410 °C at a heating rate of 15 °C/min～20 °C/min ℃～480℃, keep warm for 10min～20min, then heat up to 700℃～750℃ at a heating rate of 5℃/min～15℃/min, keep warm for 15min～25min, and then heat at a heating rate of 7℃/min～15℃/min Heating at a heating rate of 1050°C to 1150°C, holding for 20min to 30min, and finally cooling down to 350°C to 450°C at a cooling rate of 5°C/min to 10°C/min. A method of connecting sapphire to niobium or niobium alloys. 3. The method for connecting sapphire and niobium or niobium alloy with brazing material according to claim 2, characterized in that: the grinding method in the described step 1 is: the sapphire sample is roughly ground with a grinder, and then sequentially with #240 , #360, #600, #800, #1000, #1200 water sandpaper, and then polish the sapphire with a diamond spray polishing agent with a particle size of 0.5μm-1.5μm for 0.3h-0.7h; 240, #360, #600, #800, #1000, #1200 water sandpaper grinding. 4. The method for connecting sapphire with niobium or niobium alloy with brazing material according to claim 2 or 3, characterized in that: the cleaning method in the described step 1 is: the polished sapphire sample and niobium or niobium alloy Soak the sample in acetone, ultrasonically clean it for 20min to 30min at a temperature of 30°C to 40°C, then wipe it with absolute ethanol, then clean the surface of the sample to be welded with flowing distilled water, and finally dry it. 5. the method for connecting sapphire and niobium or niobium alloy according to claim 2 or 3, is characterized in that: the brazing filler metal in the described step 2 is evenly coated in step 1 to obtain the sapphire sample to be welded. The thickness of the surface is 0.5mm-0.8mm, and the brazing filler metal is evenly applied in step 1 to obtain the thickness of the surface to be welded of the niobium or niobium alloy sample to be welded is 0.5mm-0.8mm.