Method and connector for connecting spherical cover-shaped light window and metal by brazing

Abstract

The present invention discloses a method and connector for brazing a spherical light window to a metal. The method comprises the following steps: a metallization treatment, in which a metallization paste is applied to the welding surface of the spherical light window for metallization; and a brazing treatment, in which the metallized spherical light window is brazed to the metal. This application specifically adjusts the temperature rise procedure of the metallization step based on the properties of the spherical light window material, thereby improving the welding effect between the spherical light window material and the metal, resolving the problem of thermal expansion coefficient mismatch between the spherical light window and the connecting metal, and preventing loosening between the window and the metal assembly as the assembly temperature rises, thereby better protecting precision components such as sensors within the light window.

Description

Technical Field

[0001] The present invention relates to the technical field of optoelectronic airtight packaging equipment, and in particular to a method for brazing a spherical cover-shaped light window to a metal and a connector. Background Art

[0002] Currently, the main ways to connect the spherical light window to the metal are: ① adhesive connection; ② various mechanical connection structures, such as screw connection, clamping connection structure, etc., but all of them have great disadvantages.

[0003] The adhesive used for bonding is a high-molecular-weight polymer, which has low temperature resistance and generally operates at temperatures not exceeding 300°C. However, dome-shaped windows are subject to operating temperatures of 500-600°C or even higher. Under these operating conditions, the adhesive will soften, resulting in a loss of window connection strength. Furthermore, high-molecular-weight polymers inevitably age, which inevitably reduces their lifespan and reliability.

[0004] Mechanical connection structures, such as "screw connection," use a number of screws evenly spaced along the circumference to connect the housing to the metal shell; "clamp connection," clamp the housing in a metal hoop tightened by screws and lined with a low-elastic modulus backing plate. Because the spherical light window material is very brittle, hole machining is difficult, and drilling easily creates corners. Stress concentration is also significant at the hole edges, significantly reducing load-bearing capacity. This, to some extent, limits the scope of application of mechanical connection methods.

[0005] In view of this, the present invention is proposed. Summary of the Invention

[0006] The object of the present invention is to provide a method for connecting a spherical cover-shaped light window to a metal by brazing and a connecting piece.

[0007] The present invention is achieved in that:

[0008] In a first aspect, the present invention provides a method for brazing a spherical light window to a metal, comprising the following steps:

[0009] Metallization treatment: apply metallization paste on the welding surface of the dome-shaped light window, heat the dome-shaped light window to 1250-1450°C at a rate of 3-5°C / min, keep the temperature constant for 0.5h-1h, and then cool it down to below 280°C at a rate of 1-3°C / min;

[0010] Brazing is to connect the metallized spherical light window to the metal by brazing.

[0011] In an optional embodiment, the brazing step satisfies at least one of the following ①-③:

[0012] ① The coating thickness of the metallization paste on the welding surface of the spherical cover light window is 50-300 μm;

[0013] ② The average particle size of the metallized paste is below 300 μm

[0014] ③ When the spherical cover-shaped light window is made of ceramic, the ratio of the average particle size of the ceramic raw material to the average particle size of the metallization paste is 5-12:1.

[0015] In an optional embodiment, the metallization treatment step is performed under a flowing reducing atmosphere with a flow rate of 40-120 ml / min.

[0016] In an optional embodiment, the brazing step satisfies at least one of the following ①-④:

[0017] ①The solder is silver-copper solder;

[0018] ②The thickness of solder paste applied on the welding surface is 50um-400um

[0019] ③Maintain vacuum degree 10 -3 the following;

[0020] ④ First increase the temperature to 700-900℃ at a rate of 3-5℃ / min, keep constant temperature for 5-25min, and then cool down to below 280℃ at a rate of 0.5-2℃ / min.

[0021] In an optional embodiment, in the metallization treatment step, the metallization paste includes metallization powder and organic matter, and the metallization powder includes 45-47 parts by weight of molybdenum powder, 22-24 parts by weight of manganese monoxide powder or manganese powder, 16-20 parts by weight of aluminum oxide powder and 8-10 parts by weight of silicon dioxide powder.

[0022] In an optional embodiment, the metallized powder further includes an activator, and the activator includes at least one of calcium oxide powder, magnesium oxide powder, barium oxide powder, and titanium oxide powder. The metallized powder further includes 1-2 parts by weight of the activator.

[0023] In an optional embodiment, the volume ratio of the metallized powder to the organic matter is 11-27:9.

[0024] In an optional embodiment, the organic matter includes at least one of niter cotton solution, diethyl oxalate, terpineol, polyvinyl alcohol and ethyl cellulose.

[0025] In an optional embodiment, the spherical cover-shaped light window is made of sapphire, yttrium oxide ceramic, composite ceramic or K9 glass.

[0026] In a second aspect, the present application provides a spherical cover-shaped light window and a metal brazing connection obtained by any of the methods described above.

[0027] The present invention has the following beneficial effects:

[0028] The spherical cover light window is different from the flat light window. The existence of the curvature will lead to a smaller contact area between the light window and the metal, and uneven stress distribution after the light window is subjected to external force. The present application targets the properties of the spherical cover light window and makes targeted adjustments to the heating program of the metallization step, thereby improving the welding effect between the spherical cover light window and the metal, solving the problem of mismatch in thermal expansion coefficients between the spherical cover light window and the connected metal, and avoiding relaxation between the spherical cover light window and the metal assembly as the temperature rises, thereby better protecting precision components such as sensors in the light window.

[0029] The solder between the light window and the metal shell is melted at high temperature, and a chemical metallurgical bond is generated at the interface between the solder and the single crystal to form a stable reaction bonding layer, thereby combining the light window and the metal together, with high welding strength and good airtightness. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the following briefly introduces the drawings required for use in the embodiments. It should be understood that the following drawings only illustrate certain embodiments of the present invention and therefore should not be regarded as limiting the scope. For ordinary technicians in this field, other relevant drawings can be obtained based on these drawings without paying any creative work.

[0031] Figure 1 It is a structural diagram of the spherical cover light window and the titanium alloy brazing connection;

[0032] Figure 2 Schematic diagram of welding surface;

[0033] Figure 3 is the relationship between the ratio of ceramic raw material particle size to metallized powder particle size and welding strength;

[0034] Figure 4 is the relationship between metallization powder particle size, welding strength and metallization temperature.

[0035] In the figure: 1-spherical light window, 2-welding surface, 3-titanium alloy shell DETAILED DESCRIPTION

[0036] To make the purpose, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention are described clearly and completely below. Where specific conditions are not specified in the embodiments, conventional conditions or conditions recommended by the manufacturer are used. Where the manufacturer of the reagents or instruments is not specified, all are conventional products that can be purchased commercially.

[0037] An embodiment of the present invention provides a method for brazing a spherical light window to a metal, comprising the following steps:

[0038] Metallization treatment: apply metallization paste on the welding surface of the dome-shaped light window, heat the dome-shaped light window to 1250-1450°C at a rate of 3-5°C / min, keep the temperature constant for 0.5h-1h, and then cool it down to below 280°C at a rate of 1-3°C / min;

[0039] Brazing is to connect the metallized spherical light window to the metal by brazing.

[0040] In this embodiment, a higher metallization temperature is used to improve the bonding strength between the sapphire and the metal. For dome-shaped light windows, the structure is more complex than that of flat light windows, and the stress release process during welding is more stringent. The basic stress release is in the structural design of the dome and the metal base, while the release of thermal stress depends on the temperature uniformity of the metallization and brazing processes. Therefore, during metallization and brazing, the equipment temperature must be uniform, and the heating and cooling speeds must be slow, especially during the cooling process. However, blindly extending the heating and holding time will cause mottling on the weld surface, and heating too quickly will cause the weld surface to bulge or even peel.

[0041] In this embodiment, before metallization, the welding surface of the sapphire is first cleaned, generally using acetone as a solvent and ultrasonic cleaning, and then dried with hot air; before welding, the welding surface of the metal needs to be acid-washed, washed with water, washed with ammonia water and deionized water in sequence, and then cleaned with acetone as a solvent and ultrasonic cleaning, and then dried with hot air to ensure the cleanliness of the welding surface.

[0042] In some optional embodiments, the spherical light window is made of sapphire, yttrium oxide ceramic, composite ceramic or K9 glass.

[0043] In some optional embodiments, the metallization treatment step is carried out under a flowing reducing atmosphere with a reducing atmosphere flow rate of 40-120 ml / min to avoid reaction between the spherical light window or the metallization paste and oxygen, etc. The reducing atmosphere can be one or more of H2, H2+N2, H2+Ar, H2+other inert or neutral atmospheres, preferably H2+N2.

[0044] In some optional embodiments, the coating thickness of the metallized paste on the welding surface of the spherical cover-shaped light window is 50-300um, specifically, it can be 50um, 100um, 150um, 200um, 250um or 300um, preferably 50-150um, and the coating method can be screen printing, scraping, manual pen coating and other methods.

[0045] The thickness and uniformity of the paste applied during metallization and brazing also affect the stress release during the heat treatment process. Therefore, the thickness uniformity of the paste is also crucial. Otherwise, the welding may fail at best, and the dome-shaped light window may even crack.

[0046] In some optional embodiments, when the spherical cover-shaped light window is made of ceramic, the ratio of the average particle size of the ceramic raw material to the average particle size of the metallization paste is 5-12:1.

[0047] For ceramic dome-shaped light windows such as yttria ceramics and composite ceramics, the particle size of the metallized powder needs to match the particle size of the ceramic material. 陶瓷 / D 粉体 As the ratio of D increases, the welding strength increases first and then decreases. 陶瓷 / D 粉体 =8:1, the maximum welding strength is 144MPa. Figure 3 As shown, the welding strength unit is MPa, where D 陶瓷 and D 粉体 All refer to the average particle size.

[0048] In some optional embodiments, the average particle size of the metallization paste is less than 300 μm.

[0049] For sapphire dome-shaped light windows, the introduction of nanopowders can increase the density of the metallization layer, improve the sealing strength, and reduce the metallization temperature. Figure 4 As shown, the unit of temperature is °C and the unit of welding strength is MPa. However, considering the corresponding relationship between the cost of nano powder and welding strength, metallized powders below 50 nanometers are generally not used unless special strength requirements are required.

[0050] For brazing steps:

[0051] In some optional embodiments, the solder is a silver-copper solder. The silver-copper solder combined with the metallization paste in the present application can further enhance the welding strength between sapphire and metal, especially between sapphire and titanium alloy. Specifically, the solder can be silver-copper solder such as Ag28Cu, AgCuTi or AgCuInTi, or silver-copper-titanium, silver-copper-indium-titanium, etc. with added active ingredients. The active ingredients enhance the mutual solubility and mutual penetration ability between the solder and the brazing metal.

[0052] In some optional embodiments, the thickness of the solder paste applied on the welding surface is 50um-400um, specifically, it can be 50um, 100um, 150um, 200um, 250um, 300um, 350um or 400um, preferably 300-400um, and the coating method can be screen printing, scraping, manual pen coating and other methods.

[0053] In some optional embodiments, the vacuum level is maintained at 10 -3 Below, avoid the influence of air;

[0054] In some optional embodiments, also considering the complexity of the spherical light window structure, the temperature is first raised to 700-900°C at a rate of 3-5°C / min, kept constant for 5-25 minutes, and then cooled to below 280°C at a rate of 0.5-2°C / min.

[0055] In some optional embodiments, the metallization paste includes metallization powder and organic matter, and the metallization powder includes 45-47 parts by weight of molybdenum powder, 22-24 parts by weight of manganese monoxide powder or manganese powder, 16-20 parts by weight of aluminum oxide powder and 8-10 parts by weight of silicon dioxide powder.

[0056] The metallization paste in this application includes Mo, Mn or MnO, aluminum oxide, and silicon dioxide, wherein MnO (Mn can be oxidized to MnO at 800°C in 0.001% water) reduces the viscosity of the glass phase, aluminum oxide increases the strength of the metallization, and silicon dioxide improves wetting.

[0057] In some optional embodiments, the metallized powder further includes an activator, and the activator includes at least one of calcium oxide powder, magnesium oxide powder, barium oxide powder, and titanium oxide powder. The metallized powder further includes 1-2 parts by weight of the activator.

[0058] The activator can dissolve and diffuse with MnO to generate a melt with a relatively low melting point and viscosity. On the one hand, it has a good wetting effect on Mo and fills into the porous sintered Mo; on the other hand, it undergoes mutual melting and combination with a small amount of glass phase in the window material.

[0059] In some optional embodiments, the volume ratio of the metallized powder to the organic matter is 11-27:9, specifically 11:9, 15:9, 19:9, 24:9, or 27:9. Too much or too little metallized powder will reduce the metallization effect. When the metallized powder is mixed with the organic solvent to prepare the metallized paste, the metallized powder and the organic solvent need to be thoroughly and evenly mixed. If necessary, ball milling can be used.

[0060] In some optional embodiments, the organic matter includes at least one of nitre-cotton solution, diethyl oxalate, terpineol, polyvinyl alcohol and ethyl cellulose, and nitre-cotton solution is usually selected.

[0061] In a second aspect, the present invention provides a spherical cover-shaped light window and a metal brazing connection part prepared by the method described in any one of the aforementioned embodiments.

[0062] The structural diagram of the spherical cover light window and the titanium alloy after brazing is shown in the figure below. Figure 1-2 As shown, the welding surface 2 is located between the spherical light window 1 and the titanium alloy shell 3. Compared with flat light windows, the welding of spherical light windows requires consideration of the special properties of sapphire. On the other hand, the welding surface is smaller and the thermal stress generated after heating is greater. Therefore, maintaining the airtightness between the light window and the metal is more difficult. It requires a stronger chemical metallurgical bond between the solder and the single crystal interface and a more stable reaction bonding layer.

[0063] The features and performance of the present invention are further described in detail below with reference to the embodiments.

[0064] Example 1:

[0065] For 0.5 micron metallized powder, brazing sapphire + TC4 titanium alloy, the ratio of metallized powder molybdenum powder, manganese monoxide, aluminum oxide, and silicon dioxide is 47:23:20:10, the metallized powder is mixed with terpineol in a ratio of 19:9, the coating thickness is 150μm, the metallizing gas is H2+N2 (1:1), the flow rate is 80ml / min, the metallizing process is: heating rate 5℃ / min, temperature 1350℃, constant temperature 0.5h, cooling 3℃ / min, cooling to below 280℃ and then cooling to below 50℃ with the furnace; brazing solder Ag28Cu, coating thickness 300μm, brazing furnace vacuum degree 10 -3 Brazing process: heating rate 3℃ / min, temperature 780℃, constant temperature 10min, cooling rate 0.5℃ / min, cooling to below 280℃ and then cooling to below 50℃ with the furnace, the best welding strength is 122MPa.

[0066] Example 2:

[0067] For 0.5 micron metallized powder, brazing sapphire + TC4 titanium alloy, the metallized powder molybdenum powder, manganese monoxide, aluminum oxide, silicon dioxide ratio is 47:23:20:10, the metallized powder and pine alcohol are mixed in a ratio of 19:9, the coating thickness is 150μm, the metallizing gas is H2+N2 (1:1), the flow rate is 80ml / min, the metallizing process is: heating rate 10℃ / min, temperature 1500℃, constant temperature 15min, cooling 5℃ / min, cooling to below 280℃ and then cooling to below 50℃ with the furnace, the metallization is abnormal, the surface is convex and peeling; brazing solder Ag28Cu, coating thickness 300μm, brazing furnace vacuum degree 10 -3 Brazing process: heating rate 10℃ / min, temperature 1000℃, constant temperature 2min, cooling rate 5℃ / min, cooling to below 280℃ and then cooling to below 50℃ with the furnace, welding failed, and the welding surface of the spherical sapphire window cracked.

[0068] Example 3:

[0069] For 0.5 micron metallized powder, brazing sapphire + TC4 titanium alloy, the metallized powder molybdenum powder, manganese monoxide, aluminum oxide, silicon dioxide ratio is 47:23:20:10, the metallized powder and terpineol are mixed in a ratio of 19:9, the coating thickness is 150μm, the metallizing gas is H2+N2 (1:1), the flow rate is 80ml / min, the metallizing process is: heating rate 2℃ / min, temperature 1200℃, constant temperature 2h, cooling 0.5℃ / min, cooling to below 280℃ and then cooling to below 50℃ with the furnace, the metallization is abnormal, the surface is spotted; brazing solder Ag28Cu, coating thickness 300μm, brazing furnace vacuum degree 10 -3 Brazing process: heating rate 2℃ / min, temperature 650℃, constant temperature 1h, cooling rate 0.2℃ / min, cooling to below 280℃ and then cooling to below 50℃ with the furnace. The welding was successful, but the weld width was 0.8mm, which did not meet the requirement of ≤0.6mm, and the strength was only 87MPa.

[0070] Example 4:

[0071] The optimal mass ratio of molybdenum powder, manganese monoxide powder, aluminum oxide powder and silicon dioxide powder is 47:23:20:10. The metallized layer has a small proportion of metal phase Mo and a large amount of glass phase filler, which increases its thermal expansion coefficient and facilitates welding. The welding strength reaches 140MPa.

[0072] The ratio of metallized powder molybdenum powder, manganese monoxide, aluminum oxide, and silicon dioxide is 47:23:20:10, the average particle size of the metallized powder is 50nm, the metallized powder is mixed with terpineol in a ratio of 15:9, the coating thickness is 150μm, the metallizing gas is H2+N2 (1:1), the flow rate is 80ml / min, the metallizing process is: heating rate 5℃ / min, temperature 1350℃, constant temperature 0.5h, cooling 3℃ / min, cooling to below 280℃ and then cooling to below 50℃ with the furnace; brazing solder Ag28Cu, coating thickness 300μm, brazing furnace vacuum degree 10 -3 Brazing process: heating rate 3℃ / min, temperature 780℃, constant temperature 10min, cooling rate 0.5℃ / min, cooling to below 280℃ and then cooling to below 50℃. Under this condition, the welding strength is 140MPa.

[0073] Example 5:

[0074] The mass ratio of molybdenum powder, manganese monoxide powder, aluminum oxide powder and silicon dioxide powder is 35:25:25:15. Too little molybdenum and too much glass phase filler will reduce the sealing strength and the welding strength will be reduced to 101MPa.

[0075] The ratio of metallized powder molybdenum powder, manganese monoxide, aluminum oxide, and silicon dioxide is 35:25:25:15, the average particle size of the metallized powder is 50nm, the metallized powder is mixed with terpineol in a ratio of 15:9, the coating thickness is 150μm, the metallizing gas is H2+N2 (1:1), the flow rate is 80ml / min, the metallizing process is: heating rate 5℃ / min, temperature 1350℃, constant temperature 0.5h, cooling 3℃ / min, cooling to below 280℃ and then cooling to below 50℃ with the furnace; brazing solder Ag28Cu, coating thickness 300μm, brazing furnace vacuum degree 10 -3 Brazing process: heating rate 3℃ / min, temperature 780℃, constant temperature 10min, cooling rate 0.5℃ / min, cooling to below 280℃ and then cooling to below 50℃. Under this condition, the welding strength is 101MPa.

[0076] Example 6:

[0077] If the ratio of molybdenum powder, manganese monoxide, aluminum oxide, and silicon dioxide in the metallization powder is 60:15:15:10, the amount of molybdenum increases, while MnO, aluminum oxide, and silicon dioxide decrease relatively. The viscosity of the glass phase is high, which affects the diffusion and thus the metallization result, and the welding strength is reduced to 120MPa.

[0078] The ratio of metallized powder molybdenum powder, manganese monoxide, aluminum oxide, and silicon dioxide is 60:15:15:10, the average particle size of the metallized powder is 50nm, the metallized powder is mixed with terpineol in a ratio of 15:9, the coating thickness is 150μm, the metallizing gas is H2+N2 (1:1), the flow rate is 80ml / min, the metallizing process is: heating rate 5℃ / min, temperature 1350℃, constant temperature 0.5h, cooling 3℃ / min, cooling to below 280℃ and then cooling to below 50℃ with the furnace; brazing solder Ag28Cu, coating thickness 300μm, brazing furnace vacuum degree 10 -3 Brazing process: heating rate 3℃ / min, temperature 780℃, constant temperature 10min, cooling rate 0.5℃ / min, cooling to below 280℃ and then cooling to below 50℃. Under this condition, the welding strength is 120MPa.

[0079] Example 7:

[0080] By adding one or more of CaO, MgO, TiO2, and BaO to the optimal formula (molybdenum powder, manganese monoxide powder, aluminum oxide powder, and silicon dioxide powder, in a mass ratio of 47:23:20:10), with the total proportion of components being 1-2 parts, the welding strength can be increased, up to 156MPa.

[0081] The mass ratio of metallized powder molybdenum powder, manganese monoxide, aluminum oxide, silicon dioxide, and calcium oxide is 47:23:20:10:2, the average particle size of the metallized powder is 50nm, the metallized powder is mixed with terpineol in a ratio of 15:9, the coating thickness is 150μm, the metallizing gas is H2+N2 (1:1), the flow rate is 80ml / min, the metallizing process is: heating rate 5℃ / min, temperature 1350℃, constant temperature 0.5h, cooling 3℃ / min, cooling to below 280℃ and then cooling to below 50℃ with the furnace; brazing solder Ag28Cu, coating thickness 300μm, brazing furnace vacuum degree 10 -3 Brazing process: heating rate 3℃ / min, temperature 780℃, constant temperature 10min, cooling rate 0.5℃ / min, cooling to below 280℃ and then cooling to below 50℃. Under this condition, the welding strength is 156MPa.

[0082] Example 8: Yttrium oxide ceramic spherical light window is selected, the ceramic material particle size is 5μm, the metallized powder molybdenum powder, manganese monoxide, aluminum oxide, silicon dioxide ratio is 47:23:20:10, the average particle size of the metallized powder is D 陶瓷 / D 粉体 The ratios of 5, 6, 7.8, 9, 10, 11, and 12 are respectively prepared, and the average particle sizes of the metallized powders are 1 μm, 800 nm, 700 nm, 600 nm, 550 nm, 500 nm, 450 nm, and 400 nm. The metallized powders are mixed with terpineol in a ratio of 15:9, and the coating thickness is 150 μm. The metallizing gas is H2+N2 (1:1) with a flow rate of 80 ml / min. The metallizing process is as follows: a heating rate of 5°C / min, a temperature of 1350°C, constant temperature for 0.5 h, a cooling rate of 3°C / min, cooling to below 280°C and then cooling with the furnace to below 50°C; the brazing solder is Ag28Cu, the coating thickness is 300 μm, and the vacuum degree of the brazing furnace is 10 -3 Brazing process: heating rate 3℃ / min, temperature 780℃, constant temperature 10min, cooling rate 0.5℃ / min, cooling to below 280℃ and then cooling to below 50℃ with the furnace, the welding strength of the product was tested and obtained. Figure 3 .

[0083] Example 9:

[0084] A sapphire dome-shaped light window was selected, and the ratio of metallized powders, molybdenum powder, manganese monoxide, aluminum oxide, and silicon dioxide was 47:23:20:10. The average particle sizes of the metallized powders were 50 nm, 200 nm, 0.5 μm, and 300 μm, respectively. The metallized powders were mixed with terpineol in a ratio of 15:9, with a coating thickness of 300 μm. The metallizing gas was H2+N2 (1:1) with a flow rate of 80 ml / min. The metallizing process was as follows: a heating rate of 5°C / min, a temperature of 1350°C, a constant temperature of 0.5 h, a cooling rate of 3°C / min, a temperature drop of below 280°C, and then a furnace cooling to below 50°C. The brazing solder was Ag28Cu, with a coating thickness of 300 μm. The vacuum degree of the brazing furnace was 10 -3 Brazing process: heating rate 3℃ / min, temperature 780℃, constant temperature 10min, cooling rate 0.5℃ / min, cooling to below 280℃ and then cooling to below 50℃ with the furnace, the welding strength of the product was tested and obtained. Figure 4 .

[0085] Example 10:

[0086] The only difference from Example 1 is that the metallization process is: heating rate 3°C / min, temperature 1450°C, constant temperature 1h, cooling 1°C / min, cooling to below 280°C and then cooling to below 50°C with the furnace. Under this condition, the welding strength obtained is 110MPa.

[0087] Example 11:

[0088] The only difference from Example 1 is that the metallization process is: heating rate 4°C / min, temperature 1250°C, constant temperature 0.75h, cooling 2°C / min, cooling to below 280°C and then cooling to below 50°C with the furnace. Under this condition, the welding strength obtained is 116MPa.

[0089] Example 12:

[0090] The only difference from Example 1 is that the brazing process is: heating rate 5°C / min, temperature 900°C, constant temperature 25min, cooling rate 2°C / min, cooling to below 280°C and then cooling to below 50°C with the furnace. Under these conditions, the welding strength obtained is 112 MPa.

[0091] Example 13:

[0092] The only difference from Example 1 is that the brazing process is: heating rate 4°C / min, temperature 700°C, constant temperature 5min, cooling rate 0.5°C / min, cooling to below 280°C and then cooling to below 50°C with the furnace. Under these conditions, the welding strength obtained is 108 MPa.

[0093] The foregoing description is merely a preferred embodiment of the present invention and is not intended to limit the present invention. Those skilled in the art will readily appreciate that various modifications and variations of the present invention are possible. Any modifications, equivalent substitutions, or improvements made within the spirit and principles of the present invention are intended to be within the scope of protection of the present invention.

Claims

1. A method for connecting a spherical light window to a metal by brazing, characterized in that: The steps include: A metallization treatment comprises applying a metallization paste to the welding surface of the dome-shaped light window, heating the dome-shaped light window to 1250-1450°C at a rate of 3-5°C / min, maintaining the temperature for 0.5-1 hour, and then cooling the temperature to below 280°C at a rate of 1-3°C / min. The metallization paste comprises a metallization powder and an organic matter, wherein the metallization powder comprises 45-47 parts by weight of molybdenum powder, 22-24 parts by weight of manganese monoxide powder or manganese powder, 16-20 parts by weight of aluminum oxide powder, and 8-10 parts by weight of silicon dioxide powder. The dome-shaped light window is made of sapphire, yttrium oxide ceramic, composite ceramic, or K9 glass. Brazing is to connect the metallized spherical light window to the metal by brazing. In the brazing step, the temperature is first raised to 700-900°C at a rate of 3-5°C / min, kept constant for 5-25 minutes, and then cooled to below 280°C at a rate of 0.5-2°C / min. The brazing material used is silver-copper solder.

2. The method for connecting a spherical light window to a metal by brazing according to claim 1, characterized in that: The metallization treatment step is carried out under a flowing reducing atmosphere with a flow rate of 40-120 ml / min.

3. The method for connecting a spherical light window to a metal by brazing according to claim 1, wherein: The metallization paste satisfies at least one of the following ①-③: ① The coating thickness of the metallization paste on the welding surface of the spherical cover light window is 50-300 μm; ② The average particle size of the metallization paste is less than 300 μm; ③ When the spherical cover-shaped light window is made of ceramic, the ratio of the average particle size of the ceramic raw material to the average particle size of the metallization paste is 5-12:

1.

4. The method for connecting a spherical light window to a metal by brazing according to claim 1, wherein: The brazing step satisfies at least one of the following ①-②: ①The thickness of solder paste applied on the welding surface is 50um-400um; ②Maintain vacuum degree 10 -3 the following.

5. The method for connecting a spherical light window to a metal by brazing according to claim 1, wherein: The metallized powder further includes an activator, which includes at least one of calcium oxide powder, magnesium oxide powder, barium oxide powder, and titanium oxide powder. The metallized powder further includes 1-2 parts by weight of the activator.

6. The method for connecting a spherical light window to a metal by brazing according to claim 1, wherein: The volume ratio of the metallized powder to the organic matter is 11-27:

9.

7. The method for connecting a spherical light window to a metal by brazing according to claim 1, wherein: The organic matter includes at least one of niter cotton solution, diethyl oxalate, terpineol, polyvinyl alcohol and ethyl cellulose.

8. A spherical cover-shaped light window and metal brazing connection obtained by the method according to any one of claims 1 to 7.

Images