Visible light transparent high-strength connection method for sapphire single crystal joints

Abstract

The invention relates to the technical field of sapphire single crystal welding, in particular to a sapphire single crystal connector visible light transparent high-strength connecting method which comprises the steps that high-refractive-index full-transparent glass brazing filler metal is cut into brazing filler metal pieces, and grinding and polishing treatment is conducted; placing the grinded and polished brazing sheet on the to-be-welded surface of the sapphire single crystal base metal, heating and pre-cladding at a first set temperature, and keeping the temperature for a first set time to form a transparent glass cladding layer on the to-be-welded surface so as to obtain a to-be-welded sapphire single crystal; the two sapphire single crystals to be welded are assembled, so that the transparent glass cladding layers are oppositely contacted and aligned, and a test piece to be welded is obtained; the to-be-welded test piece is heated to a second set temperature and subjected to heat preservation for a second set time, and sapphire single crystal connection is completed; wherein the second set temperature is lower than the first set temperature. The sapphire single crystal connector visible light transparent high-strength connecting method aims at solving the problems that a metal brazing filler metal or glass powder connecting process is tedious, a connector is prone to pollution, air holes are generated, and connector optics is affected.

Description

Technical Field

[0001] The invention relates to the technical field of sapphire single crystal welding, and in particular to a visible light transparent high-strength connection method for sapphire single crystal joints. Background Art

[0002] Sapphire single crystal, also known as Al2O3 single crystal, is an optical material with a visible light transmittance of up to 80%, a hardness second only to diamond, and stable chemical properties. It has been used more and more widely, but due to the insufficient size of single sapphire crystals and the high processing cost of large-size single sapphire crystals, the engineering application of sapphire crystals as optical windows is still limited.

[0003] The difficulty of growing meter-sized sapphire single crystals has increased exponentially, and it has been difficult to break through the relevant technical bottlenecks in recent years. Traditional connection methods such as solid-phase reaction connection and active brazing have two major drawbacks: First, it is difficult to make the joint transparent, which may be because the connecting middle layer is opaque or has a large difference in refractive index with the sapphire single crystal; second, the connection requires high temperature and long time, and often requires connection in a vacuum, which has a long production cycle and high cost. Compared with traditional methods, glass and sapphire single crystals have the same covalent bond structure, good chemical compatibility, and similar and adjustable thermal expansion coefficients. Therefore, connecting sapphire single crystals through glass brazing has certain advantages, but the refractive index of ordinary glass is quite different from that of sapphire single crystals, which reduces the transmittance of the joint and cannot meet the optical performance requirements of sapphire single crystal devices during service.

[0004] Traditional sapphire single crystal connection materials have shortcomings such as high welding temperature, cumbersome process due to powdery state, easy to produce pores and affect optical properties. In order to achieve visible light transparent welding of sapphire single crystal, the number and size of the interface reaction products between the intermediate layer connection material and the base material must be controlled within a certain range. Therefore, the intermediate layer material with similar composition to the base material is usually selected. However, the welding process temperature is high, which not only requires high welding equipment and environmental control, but also contradicts the sustainable development concept of energy conservation. When the intermediate layer material is in powder form, the powder and organic solvent mixing, coating and drying processes must be completed in sequence before welding; in order to control the size of the gap, it is often necessary to place a gasket in the weld, and the process operation is cumbersome and the error rate is high; in addition, the adhesive used when the powder solder is formed is easy to cause contamination to the joint; and the gas impurity content in the powder solder is high, and defects such as pores are easy to be produced during the welding process, resulting in low transparency and high haze of the joint.

[0005] Therefore, the inventor provides a visible light transparent high-strength connection method for sapphire single crystal joints. Summary of the invention

[0006] (1) Technical issues to be solved

[0007] The embodiment of the present invention provides a visible light transparent high-strength connection method for sapphire single crystal joints, which solves the technical problems of cumbersome metal solder or glass powder connection process, easy contamination of the joint and generation of pores that affect the optics of the joint.

[0008] (2) Technical solution

[0009] The present invention provides a visible light transparent high-strength connection method for sapphire single crystal joints, comprising the following steps:

[0010] Cutting the high-refractive-index fully transparent glass solder into solder sheets, and performing surface grinding and polishing treatment on the solder sheets;

[0011] Placing the polished solder sheet on the pre-treated sapphire single crystal base material surface to be welded, heating at a first set temperature for pre-cladding and keeping the temperature for a first set time, forming a transparent glass cladding layer on the surface to be welded, and obtaining a sapphire single crystal to be welded;

[0012] Assembling the two sapphire single crystals to be welded relative to each other so that the transparent glass cladding layers are in relative contact and aligned, thereby obtaining a welded test piece;

[0013] The welded specimen is heated to a second set temperature and kept at the temperature for a second set time, so that the transparent glass melt layer softens and melts, thereby completing the sapphire single crystal connection; wherein the second set temperature is lower than the first set temperature.

[0014] Furthermore, the surface grinding and polishing of the solder sheet is specifically performed as follows:

[0015] The solder sheet is polished with sandpaper of different mesh sizes in turn, and then polished with a diamond polishing agent at a rotation speed of 500-600 r / min.

[0016] Furthermore, the first set temperature is 900-1000°C.

[0017] Furthermore, the first set time is 15 to 30 minutes.

[0018] Furthermore, the step of heating the welded specimen to a second set temperature and keeping the temperature for a second set time is specifically as follows:

[0019] The welded specimen is placed in a resistance furnace, heated to the second set temperature at a set rate in an air atmosphere, and kept at the second set temperature for the second set time.

[0020] Furthermore, the set rate is 6-10°C / min.

[0021] Furthermore, the second set temperature is 800-900°C.

[0022] Furthermore, the second set time is 15 to 30 minutes.

[0023] Furthermore, the high refractive index fully transparent glass solder is LaK6 glass solder.

[0024] Furthermore, the strength of the prepared sapphire single crystal joint is greater than 20 MPa, and the transmittance is greater than 85%.

[0025] (3) Beneficial effects

[0026] In summary, the present invention connects sapphire single crystals by adopting a high-refractive-index fully transparent glass solder sheet high-temperature pre-melting and low-temperature connection method, thereby achieving the matching of the refractive index of the sapphire single crystal joint and the base material, so that the joint has good light transmittance while having certain mechanical properties and service reliability, and solves the shortcomings of metal solder or glass powder connection process being cumbersome, easy to cause pollution to the joint and produce pores that affect the optics of the joint, etc., and has important application value for the connection of sapphire single crystals and even the processing of sapphire single crystal optical products. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings required for use in the embodiments of the present invention are briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work.

[0028] Figure 1 It is a schematic flow chart of a visible light transparent high-strength connection method for a sapphire single crystal joint provided by an embodiment of the present invention;

[0029] Figure 2 This is a diagram of the joint transmittance at different holding times at 900° C. provided in Example 2 of the present invention;

[0030] Figure 3 is a shear strength curve diagram of a sapphire single crystal joint at different connection temperatures provided by an embodiment of the present invention;

[0031] Figure 4 This is a microstructure morphology of a sapphire single crystal joint brazed with a glass solder sheet at a magnification of 200 times provided in Example 2 of the present invention;

[0032] Figure 5 This is a microstructure morphology diagram of a sapphire single crystal joint brazed with a glass solder sheet at a magnification of 400 times provided in Example 2 of the present invention. DETAILED DESCRIPTION

[0033] The following detailed description of the embodiments of the present invention is provided in conjunction with the accompanying drawings and examples. The following detailed description of the embodiments and the accompanying drawings are used to illustrate the principles of the present invention, but cannot be used to limit the scope of the present invention, that is, the present invention is not limited to the described embodiments.

[0034] It should be noted that, in the absence of conflict, the embodiments and features in the embodiments of the present application can be combined with each other. The present application will be described in detail below with reference to the accompanying drawings and in combination with the embodiments.

[0035] Figure 1 FIG. 1 is a flow chart of a method for connecting a sapphire single crystal joint with visible light transparency and high strength provided by an embodiment of the present invention. Figure 1 , the method may include the following steps:

[0036] S100, cutting the high refractive index fully transparent glass solder into solder sheets, and performing surface grinding and polishing treatment on the solder sheets.

[0037] Specifically, high-refractive-index fully transparent glass is used for connection. The refractive index of the glass itself is close to that of sapphire single crystal. Sapphire single crystal connectors are expected to be used in the field of large-size aviation transparent armor and can be expanded to the field of optical devices. The 1mm thick solder sheet is polished with #400, #800, #1200, and #1500 sandpaper in turn, and then polished with a diamond polishing agent with a particle size of 1μm at a speed of 500-600r / min to obtain a solder sheet with a thickness of 500μm.

[0038] S200, placing the ground and polished solder sheet on the pre-treated sapphire single crystal base material surface to be welded, heating it at a first set temperature for pre-cladding and keeping it warm for a first set time, forming a transparent glass cladding layer on the surface to be welded, and obtaining a sapphire single crystal to be welded.

[0039] Specifically, the method of connecting sapphire single crystals by glass cladding does not require a vacuum environment and excessively high connection temperature, which effectively reduces the process cost of connecting sapphire single crystals. The specific operation process of pre-treatment of sapphire single crystals is: polishing with #400, #800, #1200, and #1500 sandpaper in sequence, and then polishing with diamond polishing agents with a particle size of 1μm and 0.5μm in sequence on an automatic grinding and polishing machine with a rotation speed of 500-600r / min. Furthermore, the first set temperature is 900-1000°C, and the first set time is 15-30min.

[0040] S300, assembling two sapphire single crystals to be welded relative to each other so that the transparent glass cladding layers are in relative contact and aligned, thereby obtaining a welded test piece.

[0041] Specifically, a special connection tool is used to relatively assemble the two sapphire single crystals to be welded after the processing in step S200, with the pre-cladding surfaces relatively contacting and aligned, to obtain a test piece to be welded.

[0042] S400, heating the test piece to be welded to a second set temperature and keeping it warm for a second set time, so that the transparent glass melt layer softens and melts, and the sapphire single crystal connection is completed; wherein the second set temperature is lower than the first set temperature.

[0043] Specifically, the test piece to be welded is placed in a resistance furnace, heated to a second set temperature at a set rate in an air atmosphere and kept warm for a second set time, wherein the set rate is 6-10°C / min, the second set temperature is 800-900°C, and the second set time is 15-30min.

[0044] In the above embodiment, compared with metal active solder, glass solder welding sapphire single crystal has two shortcomings. On the one hand, the glass soldering temperature is relatively high and the high refractive index glass solder usually contains volatile components, which easily produces defects such as pores and unwelded joints during the welding process; on the other hand, the glass solder and the sapphire single crystal react at the interface to generate a precipitate phase, which will cause the transparency of the joint to decrease after the precipitate phase reaches a certain size. Furthermore, the strength of the prepared sapphire single crystal joint is greater than 20MPa and the transmittance is greater than 85%.

[0045] As an optional implementation, the high refractive index fully transparent glass solder is LaK6 glass solder. LaK6 high refractive index fully transparent glass used for sapphire single crystal connection can be well combined with the sapphire single crystal mother material to ensure the service stability of the weld.

[0046] The inventors have found through a large number of experiments that the shear strength curves of sapphire single crystal joints at different connection temperatures are as follows: Figure 3 As shown, from Figure 3 It can be found that in the temperature range of 800-900℃, the shear strength is positively correlated with the temperature (the curve shows an upward trend); in the temperature range of 900-950℃, the shear strength is independent of the temperature (the curve shows a stable trend, which is a horizontal line); in the temperature range of 900-1000℃, the shear strength is inversely correlated with the temperature (the curve shows a downward trend).

[0047] Example 1

[0048] 1. Cut the LaK6 high refractive index transparent glass solder into 1mm thick solder sheets with a diamond wire saw, and then cut the 1mm thick solder sheets with #400, #800, #1200, #

[0049] The solder sheet was polished with 1500 g sandpaper and then polished with a diamond polishing agent with a particle size of 1 μm at a rotation speed of 500 to 600 r / min to obtain a solder sheet with a thickness of 500 μm.

[0050] 2. The surface of the sapphire single crystal to be welded is polished with #400, #800, #1200, and #1500 sandpaper in turn, and then polished with diamond polishing agents with particle sizes of 1μm and 0.5μm at a rotation speed of 500-600r / min, and then the surface of the base material to be welded is pre-clad. The specific operation process is: place the polished high-refractive-index transparent LaK6 glass solder sheet on the surface of the sapphire single crystal to be welded, keep it at 975℃ for 15 minutes, and then cool it with the furnace to obtain a high-refractive-index transparent glass cladding layer.

[0051] 3. Assemble the two processed sapphire single crystals to be welded relative to each other, with the pre-cladding surfaces in relative contact and aligned, to obtain a welded test piece.

[0052] 4. Place the test piece to be welded in a resistance furnace, heat it at a rate of 8℃ / min in an air atmosphere, and keep it at 850℃ for 15 minutes to soften and fuse the glass to form a ferrite joint with good electromagnetic and mechanical properties of the weld.

[0053] The sapphire single crystal joint obtained in this embodiment 1 can have a strength of up to 23 MPa and a transmittance of up to 85%.

[0054] Example 2

[0055] 1. Cut the LaK6 high refractive index transparent glass solder into 1mm thick solder sheets with a diamond wire saw, and then grind the 1mm thick solder sheets with #400, #800, #1200, and #1500 sandpapers in turn, and then polish with a diamond polishing agent with a particle size of 1μm at a rotation speed of 500-600r / min to obtain a solder sheet with a thickness of 500μm.

[0056] 2. The surface of the sapphire single crystal to be welded is polished with #400, #800, #1200, and #1500 sandpaper in turn, and then polished with diamond polishing agents with particle sizes of 1μm and 0.5μm at a rotation speed of 500-600r / min, and then the surface of the base material to be welded is pre-clad. The specific operation process is: place the polished high-refractive index transparent LaK6 glass solder sheet on the surface of the sapphire single crystal to be welded, keep it at 975℃ for 15 minutes, and then cool it with the furnace to obtain a high-refractive index transparent glass cladding layer.

[0057] 3. Assemble the two processed sapphire single crystals to be welded relative to each other, with the pre-cladding surfaces in relative contact and aligned, to obtain a welded test piece.

[0058] Fourth, place the specimen to be welded in a resistance furnace, heat it at a rate of 8°C / min in an air atmosphere, and keep it at 900°C for 15 minutes to soften and fuse the glass to form a transparent sapphire single crystal connection joint.

[0059] The strength of the sapphire single crystal joint obtained in Example 2 can reach 45MPa, and the transmittance can reach 2%. The transmittance curve of the sapphire single crystal joint obtained in Example 2 is as follows: Figure 2 As shown by Figure 2 It can be seen that the joint transmittance can reach 85% when the insulation time is 60 minutes at 900℃.

[0060] The sapphire single crystal joint prepared in Example 2 was characterized by microstructure and morphology. Figure 4 and Figure 5 As shown in the figure, it can be seen that the weld width is about 50μm, and a certain number of whiskers are generated at the interface between glass and sapphire single crystal. A certain number of whiskers can improve the mechanical properties of the joint without affecting the optical properties of the joint, and can meet the comprehensive requirements of transparent armor for the mechanical and optical functions of sapphire single crystal joints, and has potential application value for the structural and functional integration of sapphire single crystal connectors.

[0061] It should be clear that the various embodiments in this specification are described in a progressive manner, and the same or similar parts between the various embodiments can be referred to each other, and each embodiment focuses on the differences from other embodiments. The present invention is not limited to the specific steps and structures described above and shown in the figures. In addition, for the sake of brevity, a detailed description of known methods and technologies is omitted here.

[0062] The above are only embodiments of the present application and are not limited to the present application. For those skilled in the art, the present application may have various changes and variations without departing from the scope of the present invention. Any modification, equivalent substitution, improvement, etc. made within the spirit and principle of the present application should be included in the scope of the claims of the present application.

Claims

1. A visible light transparent high-strength connection method for sapphire single crystal joints, characterized in that: The method comprises the following steps: Cutting the high-refractive-index fully transparent glass solder into solder sheets, and performing surface grinding and polishing treatment on the solder sheets; Placing the polished solder sheet on the pre-treated sapphire single crystal base material surface to be welded, heating at a first set temperature for pre-cladding and keeping the temperature for a first set time, forming a transparent glass cladding layer on the surface to be welded, and obtaining a sapphire single crystal to be welded; Assembling the two sapphire single crystals to be welded relative to each other so that the transparent glass cladding layers are in relative contact and aligned, thereby obtaining a welded test piece; The welded specimen is heated to a second set temperature and kept at the temperature for a second set time, so that the transparent glass melt layer softens and melts, thereby completing the sapphire single crystal connection; wherein the second set temperature is lower than the first set temperature.

2. The visible light transparent high-strength connection method for sapphire single crystal joints according to claim 1 is characterized in that: The surface grinding and polishing treatment of the solder sheet is specifically: The solder sheet is polished with sandpaper of different mesh sizes in turn, and then polished with a diamond polishing agent at a rotation speed of 500-600 r / min.

3. The visible light transparent high-strength connection method for sapphire single crystal joints according to claim 1 is characterized in that: The first set temperature is 900-1000°C.

4. The visible light transparent high-strength connection method for sapphire single crystal joints according to claim 3 is characterized in that: The first set time is 15 to 30 minutes.

5. The visible light transparent high-strength connection method for sapphire single crystal joints according to claim 1 is characterized in that: The step of heating the welded specimen to a second set temperature and keeping the temperature for a second set time is specifically as follows: The welded specimen is placed in a resistance furnace, heated to the second set temperature at a set rate in an air atmosphere, and kept at the second set temperature for the second set time.

6. The visible light transparent high-strength connection method for sapphire single crystal joints according to claim 5 is characterized in that: The set rate is 6-10°C / min.

7. The visible light transparent high-strength connection method for sapphire single crystal joints according to claim 1 or 5 is characterized in that: The second set temperature is 800-900°C.

8. The visible light transparent high-strength connection method for sapphire single crystal joints according to claim 6 is characterized in that: The second set time is 15 to 30 minutes.

9. The visible light transparent high-strength connection method for sapphire single crystal joints according to claim 1 is characterized in that: The high refractive index fully transparent glass solder is LaK6 glass solder.

10. The visible light transparent high-strength connection method for sapphire single crystal joints according to claim 1 is characterized in that: The strength of the prepared sapphire single crystal joint is greater than 20MPa and the light transmittance is greater than 85%.

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