A method for joining graphite and transparent material using ultrafast laser

Abstract

The application relates to a method for connecting graphite and transparent material by using superfast laser, and relates to a method for connecting graphite and transparent material. The method aims to solve the problems of great difficulty in connecting graphite and transparent material, and inability to realize large size and light weight. The method comprises the following steps: pretreatment of graphite and transparent material; fixation and placement of graphite and transparent material; determination of focus position; and superfast laser connection. The application is used for superfast laser connection of graphite and transparent material. The graphite and transparent material are connected and used for devices such as fast mirrors, which are first proposed in the application and have originality. The superfast laser connection of graphite and transparent material meets the production demand of light weight, satisfies the production demand of large size components, and does not damage the light transmittance of the transparent material.

Description

TECHNICAL FIELD

[0001] The present application relates to a method for connecting graphite and transparent material. BACKGROUND

[0002] With the rapid development of space science and space technology in China, the production demand of "large size and light weight" is proposed for key space optical equipment such as fast reflecting mirror. Glass, transparent ceramic and other transparent materials are ideal materials for optical lenses due to their good light transmission and stable chemical properties. Graphite is an ideal material for auxiliary structures such as supports due to its low density, light weight, high temperature resistance and corrosion resistance. Therefore, the connection of graphite and transparent material is the prerequisite for fully utilizing the performance advantages of both, and has great potential value in the fields of space optics, astronomy and other fields.

[0003] For the connection of graphite and transparent material, among the existing methods at home and abroad, mechanical connection does not meet the production demand of "light weight". The surface activity of graphite, glass, transparent ceramic and other materials is poor, which is not suitable for glue joint and diffusion welding. The transparent material may lose its light transmission after melting and solidification, so fusion welding is not suitable for the connection of graphite and transparent material system. Because glass, transparent ceramic and other transparent materials are chemically stable, it is difficult to have metallurgical reaction, so active elements need to be added for brazing of graphite and transparent material, which increases the welding temperature, resulting in a large stress in the brazed joint, especially for the connection of large size components, the stress problem is more prominent, so the brazing of graphite and transparent material is basically impossible to realize, which cannot meet the production demand of "large size and light weight" of optical equipment, so the connection of graphite and transparent material is difficult. SUMMARY

[0004] The purpose of the present application is to solve the problem of difficulty in connecting graphite and transparent material and the problem of being unable to realize large size and light weight, and a method for connecting graphite and transparent material by using ultrafast laser is proposed.

[0005] The method for connecting graphite and transparent material by using ultrafast laser is carried out in the following steps:

[0006] Step one: pretreatment of graphite and transparent material: polishing and polishing the surface to be connected of graphite, polishing and polishing the transparent material on both sides, and then cleaning the graphite and transparent material;

[0007] Step two: drop acetone or anhydrous ethanol on the surface to be welded of graphite, then place the transparent material and clamp it with a fixture, so that the acetone or anhydrous ethanol fills the gap between the surface to be welded of graphite and transparent material and there is no air bubble inside, to obtain a connecting piece, and then place the connecting piece on the stage of the ultrafast laser;

[0008] The ultrafast laser is a femtosecond laser or a picosecond laser;

[0009] Step three: adjust the focus of the ultrafast laser and the interface exists -50 μm ~ + 50 μm off-focus amount;

[0010] Step four: set the connection parameters and connect the graphite and transparent material,

[0011] The connection parameters include wavelength, pulse width, beam type, spot diameter, repetition frequency, laser power, scanning speed, scanning times, scanning path, scanning line spacing and scanning area.

[0012] The beneficial effects of the present application are:

[0013] 1. The graphite and transparent material are connected by using the ultrafast laser, and the graphite and transparent material connected are used for fast mirrors and other equipment, which is first proposed in the present application and has originality.

[0014] 2. The graphite and transparent material are connected by using the ultrafast laser without adding auxiliary materials such as bolts and intermediate layers, which meets the production demand of lightweight and does not damage the light transmittance of the transparent material.

[0015] 3. The graphite and transparent material can be reliably connected by the present application, because the ultrafast laser is an ultra-short pulse laser with extremely high instantaneous power. The energy density near the focus of the ultrafast laser focused on the interface of the graphite and transparent material will exceed the ablation threshold of the material, causing the material to ionize and produce plasma. The plasma heats the nearby material and causes melting, and finally realizes the local fusion of the graphite and transparent material.

[0016] 4. The joint stress problem of the graphite and transparent material can be avoided by the present application, because the average power of the ultrafast laser is extremely small, the heat input is extremely small, and it is local heating, so the graphite and transparent material do not have overall expansion and contraction, avoiding the stress problem caused by the difference in thermal expansion coefficient. Therefore, compared with brazing, the present application is suitable for connecting large-size components and meets the production demand of large-size components.

[0017] 5. The graphite and transparent material are effectively connected in the present application under room temperature environment and air atmosphere, without the need for high temperature environment, without the need for applying additional load, etc., saving energy, simple operation, fast connection speed and high connection efficiency.

[0018] 6. The graphite and transparent material with huge physical and chemical performance difference are connected together in the present application, and the joint shear strength can reach 8.3 MPa. BRIEF DESCRIPTION OF DRAWINGS

[0019] Figure 1 The photo of the joint interface structure obtained in Example 1;

[0020] Figure 2Elemental mapping of the interface of the joint obtained in Example 1. DETAILED DESCRIPTION

[0021] The technical solutions of the present application are not limited to the following specific embodiments, but also include any reasonable combination of the specific embodiments.

[0022] Specific embodiment one: the method for connecting graphite and transparent material by using ultrafast laser in this embodiment is carried out in the following steps:

[0023] Step one: pretreatment of graphite and transparent material: polish and polish the surface to be connected of graphite, polish both sides of the transparent material, and then clean the graphite and transparent material;

[0024] Step two: drop acetone or anhydrous ethanol on the surface to be welded of graphite, then place the transparent material and clamp it with a fixture, so that the acetone or anhydrous ethanol fills the gap between the surface to be welded of graphite and transparent material and there is no air bubble inside, obtaining the connecting piece, and then placing the connecting piece on the stage of the ultrafast laser;

[0025] The ultrafast laser is a femtosecond laser or a picosecond laser;

[0026] Step three: adjust the focal point of the ultrafast laser to have a defocusing amount of-50μm~+50μm from the interface;

[0027] Step four: set the connection parameters and connect the graphite and transparent material,

[0028] The connection parameters include wavelength, pulse width, beam type, spot diameter, repetition frequency, laser power, scanning speed, scanning times, scanning path, scanning line spacing and scanning area.

[0029] The beneficial effects of this embodiment are:

[0030] 1. The graphite and transparent material are connected by using ultrafast laser, and the graphite and transparent material connected are used for fast mirrors and other equipment, which is first proposed in this application and has originality.

[0031] 2. The graphite and transparent material are connected by using ultrafast laser in this embodiment without adding auxiliary materials such as bolts and intermediate layers, which meets the production demand of lightweight and does not damage the light transmittance of the transparent material.

[0032] 3. This embodiment can realize reliable connection of graphite and transparent material, because ultrafast laser is a kind of ultra-short pulse laser with extremely high instantaneous power. When the ultrafast laser is focused on the interface of graphite and transparent material, the energy density near the focal point will exceed the ablation threshold of the material, causing the material to ionize and produce plasma. The plasma heats the nearby material and causes it to melt, finally realizing the local fusion of graphite and transparent material.

[0033] 4、The embodiment can avoid the joint stress problem of graphite and transparent material, because the average power of ultrafast laser is very small, the heat input is very small, and it is local heating, so the graphite and transparent material do not have overall expansion and contraction, avoiding the stress problem caused by the difference of thermal expansion coefficient, so compared with brazing, the embodiment is suitable for the connection of large size components, and meets the production needs of large size components.

[0034] 5、The embodiment effectively connects graphite and transparent material in room temperature environment and air atmosphere, without the need for high temperature environment, without the need for additional load, etc., saving energy, simple operation, fast connection speed and high connection efficiency.

[0035] 6、The embodiment connects graphite and transparent material with huge physical and chemical performance difference together, and the joint shear strength can reach 8.3MPa.

[0036] Specific implementation method two: the difference between this embodiment and specific implementation method one is that: the transparent material in step one is transparent glass or transparent ceramic.

[0037] Specific implementation method three: the difference between this embodiment and specific implementation method one or two is that: the transparent glass in step one is quartz glass, silica glass, microcrystalline glass, soda lime glass, aluminum silicate glass or borosilicate glass.

[0038] Specific implementation method four: the difference between this embodiment and any one of specific implementation methods one to three is that: the transparent ceramic in step one is oxide transparent ceramic or non-oxide transparent ceramic.

[0039] Specific implementation method five: the difference between this embodiment and any one of specific implementation methods one to four is that: the oxide transparent ceramic in step one is sapphire, aluminum oxide, magnesium oxide, beryllium oxide, yttrium oxide or spinel.

[0040] Specific implementation method six: the difference between this embodiment and any one of specific implementation methods one to five is that: the non-oxide transparent ceramic in step one is gallium arsenide, zinc sulfide, zinc selenide, magnesium fluoride, calcium fluoride or magnesium aluminate.

[0041] Specific implementation method seven: the difference between this embodiment and any one of specific implementation methods one to six is that: the polishing method of the surface to be connected of the graphite in step one is: using 3000-7000 mesh sandpaper for step-by-step polishing; the polishing method of the transparent material is: using 400-7000 mesh sandpaper for step-by-step polishing.

[0042] Specific embodiment eight: the difference between this embodiment and one of the specific embodiments one to seven is that the polishing method of the graphite and the transparent material in step one is that the diamond polishing agent with the granularity of 0.5-2.5 μm is used for polishing for 2-20 min.

[0043] Specific embodiment nine: the difference between this embodiment and one of the specific embodiments one to eight is that the cleaning method in step one is that the polished surface is first washed with acetone or anhydrous ethanol, then is placed in acetone or anhydrous ethanol for ultrasonic cleaning for 5-30 min, and finally is air dried.

[0044] Specific embodiment ten: the difference between this embodiment and one of the specific embodiments one to nine is that the wavelength is in the infrared band, the pulse width is 1 fs-10 ps, the light beam type is a Gaussian light beam, the spot diameter is 1-50 μm, the repetition frequency is 1 kHz-1 MHz, the laser power is 5 mW-50 W, the scanning speed is 0.1-10 mm / s, the scanning times are 1-10, the scanning path is Z-shaped, S-shaped, parallel line-shaped, cross-shaped, concentric rectangular-shaped, concentric circular-shaped or spiral line-shaped, the scanning line spacing is 10 μm-1 mm, and the scanning area is in the contact area of the graphite and the transparent material.

[0045] Example 1

[0046] This example uses the method for connecting graphite and a transparent material by an ultrafast laser according to the following steps:

[0047] Step one: pretreatment of the graphite and the transparent material: polishing and polishing of the surface to be connected of the graphite, double-sided polishing and polishing of the transparent material, and then cleaning of the graphite and the transparent material;

[0048] The transparent material is quartz glass;

[0049] The polishing method of the surface to be connected of the graphite is that 3000-mesh and 7000-mesh sandpaper is used for step-by-step polishing;

[0050] The polishing method of the surface to be connected of the graphite is that 3000-mesh and 7000-mesh sandpaper is used for step-by-step polishing;

[0051] The polishing method of the graphite and the transparent material is that the diamond polishing agent with the granularity of 0.5 μm is used on the polishing cloth to polish the graphite on one side for 2 min and to polish the quartz glass on both sides for 5 min;

[0052] The cleaning method is that the polished surface is first washed with anhydrous ethanol, then is placed in anhydrous ethanol for ultrasonic cleaning for 5 min, and finally is air dried;

[0053] Step two: drop anhydrous ethanol on the surface to be welded of the graphite, then place the transparent material and clamp it with a fixture, so that the anhydrous ethanol fills the gap between the surface to be welded of the graphite and the transparent material and is free of bubbles inside, to obtain a connecting piece, and then place the connecting piece on the objective table of the ultrafast laser;

[0054] The ultrafast laser is a femtosecond laser;

[0055] Step three: adjust the focal point of the ultrafast laser to have a defocusing amount of 0 μm from the interface;

[0056] Step four: set the connecting parameters and connect the graphite and the transparent material,

[0057] The connecting parameters include: wavelength of 1030 nm, pulse width of 300 fs, beam type of Gaussian beam, spot diameter of 10 μm, repetition frequency of 100 kHz, laser power of 600 mW, scanning speed of 0.5 mm / s, scanning times of 1, scanning path of parallel line, scanning line (parallel line) spacing of 30 μm, and scanning area of a 3*3 square in the contact area between the graphite and the transparent material.

[0058] Figure 1 The photo of the interface structure of the joint obtained in Example 1 is shown in FIG. 1. Figure 1 As shown in FIG. 1, at the position irradiated by the laser, the graphite and the quartz glass are fused, the fusion zone is composed of a large number of particles, and the entire joint is free of defects such as pores and cracks. The gap between the graphite and the quartz glass is hardly visible, indicating that the method of the present embodiment and the clamping method can control the gap of the surface to be welded very well. Figure 2 The element area distribution map of the joint obtained in Example 1 is shown in FIG. 2. Figure 2 As shown in FIG. 2, at the position irradiated by the laser, the fusion zone of the graphite and the quartz glass contains only C element and Si element, indicating that the two materials generate SiC through metallurgical reaction at high temperature, and chemical bonds are formed between the graphite and the fusion zone and between the fusion zone and the quartz glass during the solidification process, so that the graphite and the quartz glass are effectively connected. Through testing, the shear strength of the joint of the graphite and the quartz glass in the present embodiment is 8.3 MPa. For the graphite and the quartz glass which have a large difference in physical and chemical properties, the present embodiment can realize reliable connection of the two materials.

[0059] Example 2

[0060] The method for connecting the graphite and the transparent material by the ultrafast laser in the present embodiment is performed according to the following steps:

[0061] Step one: pretreatment of the graphite and the transparent material: polish and polish the surface to be connected of the graphite, polish both surfaces of the transparent material, and then clean the graphite and the transparent material;

[0062] The transparent material is microcrystalline glass.

[0063] The polishing method of the surface of the graphite to be connected is to polish step by step using 3000-mesh and 7000-mesh sandpaper;

[0064] The polishing method of the transparent material is to polish step by step using 400-mesh, 800-mesh, 1500-mesh, 3000-mesh and 7000-mesh sandpaper;

[0065] The polishing method of the graphite and the transparent material is to polish one side of the graphite for 2 minutes and polish both sides of the transparent material for 5 minutes on the polishing cloth using diamond polishing agent with a particle size of 0.5 pm;

[0066] The cleaning method is to first rinse the polished surface with anhydrous ethanol, then ultrasonically clean it in anhydrous ethanol for 5 minutes, and finally air dry;

[0067] Step two: drop anhydrous ethanol on the surface of the graphite to be welded, then place the transparent material and clamp it using a fixture, so that the anhydrous ethanol fills the gap between the surfaces of the graphite and the transparent material to be welded and is free of bubbles inside, to obtain a connecting piece, and then place the connecting piece on the stage of the ultrafast laser;

[0068] The ultrafast laser is a femtosecond laser;

[0069] Step three: adjust the focal point of the ultrafast laser to have a defocusing amount of 0 pm from the interface;

[0070] Step four: set the connection parameters and connect the graphite and the transparent material,

[0071] The connection parameters include: wavelength of 1030 nm, pulse width of 300 fs, beam type of Gaussian beam, spot diameter of 10 pm, repetition frequency of 100 kHz, laser power of 600 mW, scanning speed of 0.5 mm / s, scanning times of 1, scanning path of parallel lines, scanning line (parallel line) spacing of 30 pm, and scanning area of a 3x3 square within the contact area of the graphite and the transparent material.

[0072] After testing, the graphite and the microcrystalline glass in this embodiment are well combined, and the shear strength of the joint of the graphite and the microcrystalline glass is 6.1 MPa.

[0073] Example 3

[0074] The method for connecting graphite and transparent material by using an ultrafast laser in this embodiment is performed in the following steps:

[0075] Step one: pretreatment of the graphite and the transparent material: polish the surface of the graphite to be connected and polish both sides of the transparent material, and then clean the graphite and the transparent material;

[0076] The transparent material is quartz glass;

[0077] The polishing method of the surface of the graphite to be connected is to polish the surface step by step using 3000-mesh and 7000-mesh sandpaper;

[0078] The polishing method of the transparent material is to polish the surface step by step using 400-mesh, 800-mesh, 1500-mesh, 3000-mesh and 7000-mesh sandpaper;

[0079] The polishing method of the graphite and the transparent material is to polish the surface of the graphite for 2 minutes and polish the surface of the quartz glass for 5 minutes using diamond polishing agent with a particle size of 0.5 μm on a polishing cloth;

[0080] The cleaning method is to first rinse the polished surface with anhydrous ethanol, then place it in anhydrous ethanol for ultrasonic cleaning for 5 minutes, and finally air dry;

[0081] Step two: drop anhydrous ethanol on the surface of the graphite to be welded, then place the transparent material and clamp it with a fixture, so that the anhydrous ethanol fills the gap between the surfaces of the graphite and the transparent material to be welded and there are no air bubbles inside, to obtain a connecting piece, and then place the connecting piece on the stage of the ultrafast laser;

[0082] The ultrafast laser is a femtosecond laser;

[0083] Step three: adjust the focal point of the ultrafast laser to be -25 μm away from the interface;

[0084] Step four: set the connection parameters and connect the graphite and the transparent material,

[0085] The connection parameters include: wavelength 1030 nm, pulse width 300 fs, beam type Gaussian beam, spot diameter 10 μm, repetition frequency 100 kHz, laser power 600 mW, scanning speed 0.5 mm / s, scanning times 1, scanning path parallel line, scanning line (parallel line) spacing 30 μm, and scanning area 3x3 square in the contact area of the graphite and the transparent material.

[0086] After testing, the graphite and the quartz glass in this embodiment are well combined, and the shear strength of the joint of the graphite and the quartz glass is 7.5 MPa.

[0087] Example 4

[0088] The method for connecting the graphite and the transparent material in this embodiment is performed according to the following steps:

[0089] Step one: pretreatment of the graphite and the transparent material: polish the surface of the graphite to be connected and polish the surface of the transparent material, then clean the graphite and the transparent material;

[0090] the transparent material is quartz glass;

[0091] the polishing method of the surface of the graphite to be connected is polishing by using 3000-mesh and 7000-mesh sandpaper step by step;

[0092] the polishing method of the transparent material is polishing by using 400-mesh, 800-mesh, 1500-mesh, 3000-mesh and 7000-mesh sandpaper step by step;

[0093] the polishing method of the graphite and the transparent material is polishing by using diamond polishing agent with a particle size of 0.5 μm on polishing cloth, polishing one surface of the graphite for 2 min and polishing both surfaces of the quartz glass for 5 min;

[0094] the cleaning method is first rinsing the polished surface with anhydrous ethanol, then ultrasonic cleaning in anhydrous ethanol for 5 min, and finally air drying;

[0095] Step two: dropping anhydrous ethanol on the surface of the graphite to be welded, then placing the transparent material and clamping with a fixture, so that the anhydrous ethanol fills the gap between the surfaces of the graphite and the transparent material to be welded and has no air bubbles inside, to obtain a connecting piece, and then placing the connecting piece on the stage of the ultrafast laser;

[0096] the ultrafast laser is a femtosecond laser;

[0097] Step three: adjusting the focal point of the ultrafast laser to have a defocusing amount of 0 μm from the interface;

[0098] Step four: setting the connection parameters and connecting the graphite and the transparent material,

[0099] the connection parameters include: wavelength of 1030 nm, pulse width of 300 fs, beam type of Gaussian beam, spot diameter of 10 μm, repetition frequency of 100 kHz, laser power of 400 mW, scanning speed of 0.25 mm / s, scanning times of 1, scanning path of parallel line, scanning line (parallel line) spacing of 30 μm, and scanning area of a 3x3 square in the contact area between the graphite and the transparent material.

[0100] After testing, the graphite and the quartz glass are well combined in this embodiment, and the shear strength of the joint between the graphite and the quartz glass is 8.0 MPa.

[0101] Example 5

[0102] The method for connecting the graphite and the transparent material by using the ultrafast laser in this embodiment is performed in the following steps:

[0103] Step one: pretreatment of the graphite and the transparent material: polishing and polishing the surface of the graphite to be connected, polishing both surfaces of the transparent material, and then cleaning the graphite and the transparent material;

[0104] The transparent material is quartz glass;

[0105] The polishing method of the surface of the graphite to be connected is polishing by using 3000-mesh and 7000-mesh sandpaper step by step;

[0106] The polishing method of the transparent material is polishing by using 400-mesh, 800-mesh, 1500-mesh, 3000-mesh and 7000-mesh sandpaper step by step;

[0107] The polishing method of the graphite and the transparent material is polishing the single surface of the graphite for 2 min and polishing the double surfaces of the quartz glass for 5 min on the polishing cloth by using diamond polishing agent with a particle size of 0.5 μm;

[0108] The cleaning method is first rinsing the polished surface with anhydrous ethanol, then ultrasonic cleaning in anhydrous ethanol for 5 min, and finally air drying;

[0109] Step two: dropping anhydrous ethanol on the surface of the graphite to be welded, then placing the transparent material and clamping by using a fixture, so that the anhydrous ethanol fills the gap of the surfaces of the graphite and the transparent material to be welded and has no bubbles inside, to obtain a connecting piece, and then placing the connecting piece on the objective table of the ultrafast laser;

[0110] The ultrafast laser is a femtosecond laser;

[0111] Step three: adjusting the focal point of the ultrafast laser to have a defocusing amount of 0 μm from the interface;

[0112] Step four: setting the connecting parameters and connecting the graphite and the transparent material,

[0113] The connecting parameters include: wavelength of 1030 nm, pulse width of 300 fs, light beam type of Gaussian light beam, spot diameter of 10 μm, repetition frequency of 100 kHz, laser power of 1 W, scanning speed of 1 mm / s, scanning times of 1 time, scanning path of parallel line shape, scanning line (parallel line) spacing of 30 μm, and scanning area of a 3x3 square in the contact area of the graphite and the transparent material.

[0114] It is tested that the graphite and the quartz glass are well combined in this embodiment, and the shear strength of the joint of the graphite and the quartz glass is 5.9 MPa.

[0115] Embodiment 6

[0116] The method for connecting the graphite and the transparent material by using the ultrafast laser in this embodiment is performed according to the following steps:

[0117] Step one: Pretreatment of graphite and transparent material: polish and polish the surface to be connected of graphite, polish both sides of the transparent material, and then clean the graphite and the transparent material;

[0118] The transparent material is quartz glass;

[0119] The polishing method of the surface to be connected of the graphite is to polish step by step with 3000 mesh and 7000 mesh sandpaper;

[0120] The polishing method of the transparent material is to polish step by step with 400 mesh, 800 mesh, 1500 mesh, 3000 mesh and 7000 mesh sandpaper;

[0121] The polishing method of the graphite and the transparent material is to polish the graphite single side on the polishing cloth with diamond polishing agent with particle size of 0.5 μm for 2 min, and polish the quartz glass double sides for 5 min;

[0122] The cleaning method is to first rinse the polished surface with anhydrous ethanol, then ultrasonic cleaning in anhydrous ethanol for 5 min, and finally air dry;

[0123] Step two: drop anhydrous ethanol on the surface to be welded of the graphite, then place the transparent material and clamp with the fixture, so that the anhydrous ethanol fills the gap between the surface to be welded of the graphite and the transparent material without air bubbles inside, to obtain the connecting piece, and then place the connecting piece on the stage of the ultrafast laser;

[0124] The ultrafast laser is a femtosecond laser;

[0125] Step three: adjust the focus of the ultrafast laser to have a defocusing amount of 0 μm from the interface;

[0126] Step four: set the connection parameters and connect the graphite and the transparent material,

[0127] The connection parameters include: wavelength of 1030 nm, pulse width of 300 fs, beam type of Gaussian beam, spot diameter of 10 μm, repetition frequency of 100 kHz, laser power of 600 mW, scanning speed of 0.5 mm / s, scanning times of 1, scanning path of concentric circle, scanning line (concentric circle) spacing of 30 μm, and scanning area of a circular area with a diameter of 4 in the contact area between the graphite and the transparent material.

[0128] It is tested that the graphite and the quartz glass are well combined in this embodiment, and the shear strength of the joint between the graphite and the quartz glass is 7.3 MPa.

Claims

1. A method of joining graphite and transparent material with ultrafast laser, characterized in that: The method for connecting graphite and transparent material by using ultrafast laser is carried out in the following steps: Step 1: Pretreatment of graphite and transparent material: polishing and polishing the surface to be connected of graphite, polishing and polishing the double surface of transparent material, and then cleaning the graphite and transparent material; Step 2: Dropping acetone or anhydrous ethanol on the surface to be welded of graphite, then placing the transparent material and clamping by using a fixture, so that the acetone or anhydrous ethanol fills the gap of the surface to be welded of graphite and transparent material and has no air bubbles inside, obtaining the connecting piece, and then placing the connecting piece on the objective table of the ultrafast laser; The ultrafast laser is a femtosecond laser or a picosecond laser; Step 3: Adjusting the focal point of the ultrafast laser to have a defocusing amount of-50 μm~+50 μm with the interface; Step 4: Setting the connecting parameters and connecting the graphite and transparent material, The connecting parameters include wavelength, pulse width, beam type, spot diameter, repetition frequency, laser power, scanning speed, scanning times, scanning path, scanning line spacing and scanning area; the wavelength is in the infrared band, the pulse width is 1 fs~10 ps, the beam type is Gaussian beam, the spot diameter is 1~50 μm, the repetition frequency is 1 kHz~1 MHz, the laser power is 5 mW~50 W, the scanning speed is 0.1~10 mm / s, the scanning times are 1~10, the scanning path is Z-shaped, S-shaped, parallel line-shaped, cross-shaped, concentric rectangular, concentric circular or spiral line-shaped, the scanning line spacing is 10 μm~1 mm, and the scanning area is in the contact area of graphite and transparent material. The transparent material in step 1 is transparent glass or transparent ceramic.

2. The method of claim 1, wherein: The transparent glass in step 1 is quartz glass, silica glass, microcrystalline glass, soda-lime glass, alumino-silicate glass or borosilicate glass.

3. The method of claim 1, wherein: The transparent ceramic in step 1 is oxide transparent ceramic or non-oxide transparent ceramic.

4. The method of claim 1, wherein: The oxide transparent ceramic in step 1 is sapphire, alumina, magnesia, beryllia, yttria or spinel.

5. The method of claim 1, wherein: The non-oxide transparent ceramic in step 1 is gallium arsenide, zinc sulfide, zinc selenide, magnesium fluoride, calcium fluoride or magnesium aluminate.

6. The method of claim 1, wherein: The polishing method of the surface to be connected of graphite in step 1 is: using 3000~7000 mesh sandpaper to polish step by step; the polishing method of the transparent material in step 1 is: using 400~7000 mesh sandpaper to polish step by step.

7. The method of claim 1, wherein: The polishing method of the graphite and transparent material in step 1 is: using diamond polishing agent with a particle size of 0.5~2.5 μm to polish for 2~20 min.

8. The method of claim 1, wherein: The cleaning method in step 1 is: first washing the polished surface with acetone or anhydrous ethanol, then ultrasonic cleaning in acetone or anhydrous ethanol for 5~30 min, and finally air drying.

9. The method of claim 1, wherein: ​

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