A glass welding method using femtosecond laser coupled with low-flux CO2 laser

Abstract

The application belongs to the field of glass welding, and particularly relates to a glass welding method of femtosecond laser coupling low-flux CO2 laser. The method comprises the following steps: (1) selecting two pieces of transparent glass to be welded, clamping the transparent glass after pretreatment by using a clamp, and making the welding surfaces of the transparent glass contact; (2) using a femtosecond laser with a wavelength of 500nm-50000nm and a power of 10-40W to scan and weld the welding surfaces according to a set path and parameters; (3) after the glass welded by the femtosecond laser in step (2) is naturally cooled, using a low-flux CO2 laser with a processing power lower than 1000W and a scanning speed lower than 500mm / min to weld the welding seam welded by the femtosecond laser in step (2) and a range 1-10mm away from the welding seam. The application improves the sealing performance of the welded part, eliminates the cracks generated by the femtosecond laser welding, enhances the welding seam strength, and improves the welding seam quality.

Description

Technical Field

[0001] This invention belongs to the field of glass welding, specifically relating to a glass welding method using a femtosecond laser coupled with a low-flux CO2 laser. Background Technology

[0002] Transparent glass, with its excellent physical and chemical properties, is widely used in new sensors, microelectromechanical systems (MEMS), microfluidic chips, optical communication, and optical sensing. Compared with metal materials, glass has poor plasticity and toughness; when heated unevenly, stress concentration occurs, making it prone to cracking. In recent years, with the continuous development of science and technology, the application fields of glass materials have been expanding, and the demand for high-precision and high-quality glass connections has been increasing. Using traditional adhesives to bond glass materials results in products that are prone to aging, pyrolysis, and thermal expansion, making it difficult to guarantee product reliability. Chinese patent CN217681344U discloses a method for connecting vacuum glass with extremely low gas leakage by using a metal sealing method at the glass material boundary; Chinese patent CN115041863A invented an indium-based composite solder, which achieves effective welding of automotive glass through the metallurgical bonding between a high-indium-based solder layer and a low-indium-based solder layer. Metal fusion and brazing metallurgy can be used to join glass materials, ensuring a certain degree of airtightness of the welding materials. However, the welding strength is not high, the service life of the welded parts is short, and they are prone to failure.

[0003] Currently, ultrashort pulse laser technology, as a novel non-contact processing method, has enabled high-strength glass welding using femtosecond lasers, replacing traditional glass joining processes. The interaction between ultrashort pulse lasers and transparent materials exhibits low thermal effects and nonlinear absorption, making it highly suitable for micro-welding of transparent materials. Welding glass using ultrashort pulse laser technology requires clean glass surfaces, i.e., achieving optical bonding conditions, with the gap between the two pieces of glass to be welded being less than 1 / 4 wavelength. This requirement can be met by applying an external force perpendicular to the welding surface. Chinese Patent Publication No. CN110039177A uses an ultrafast laser glass welding system to weld glass. Although this invention achieves sealed glass welding without optical bonding using ultrafast laser technology, its welding strength needs improvement. Chinese Patent No. CN113387553A proposes a femtosecond laser dual-pulse glass welding strength enhancement system that enhances the intensity of the plasma shock wave in the femtosecond laser irradiation zone, thereby improving the glass welding strength. Glass materials welded using this method show enhanced welding strength. However, it did not solve the problems of poor welding sealing caused by non-optical bonding and glass welding with large gaps in traditional ultrafast lasers; the recovery force generated after applying the pre-set external force and the stress concentration caused by uneven heating are prone to crack defects in the weld boundary area. Summary of the Invention

[0004] An object of the present invention is to provide a high-strength glass welding method coupling femtosecond laser with low-flux CO₂ laser. Based on a femtosecond laser processing system, the present invention couples a low-flux CO₂ laser processing system to perform local remelting treatment on the welded glass material, which improves the sealing performance of the weldment, eliminates cracks generated by femtosecond laser welding, enhances weld strength and improves weld quality.

[0005] The technical solution for achieving the object of the present invention is: a glass welding method coupling femtosecond laser with low-flux CO₂ laser, comprising the following steps:

[0006] Step (1): selecting two pieces of transparent glass to be welded, after pretreating the transparent glass, clamping them with a fixture to bring the to-be-welded surfaces of the transparent glass into contact;

[0007] Step (2): welding the to-be-welded surfaces by scanning along a set path and with set parameters using a femtosecond laser with a wavelength of 500nm to 50000nm and a power of 10 to 40W;

[0008] Step (3): after the glass welded by femtosecond laser in step (2) is naturally cooled, welding the weld obtained by femtosecond laser welding in step (2) and the area within 1 to 10mm from the weld using a low-flux CO₂ laser with a processing power lower than 1000W and a scanning speed lower than 500mm / min.

[0009] Further, in step (1), the dimensions of the two pieces of transparent glass are 2~100mm×2~100mm×0.1~10mm, and the type of the transparent glass is fused silica glass, borosilicate glass or high-silica glass.

[0010] Further, the pretreatment in step (1) specifically comprises: soaking the glass to be welded in anhydrous ethanol for 1 to 100min, then ultrasonically cleaning the same for 1 to 100min, and wiping the same with alcohol.

[0011] Further, during clamping in step (1), the fixture only applies an external force perpendicular to the surface of the glass to be welded, so that the glass to be welded is in a fitting state.

[0012] Further, during femtosecond laser welding in step (2), the galvanometer scanning speed is 10 to 1000mm / s, and the defocus amount is less than 10mm.

[0013] Further, during femtosecond laser welding in step (2), the contact surface of the glass to be welded is parallel to the plane of the femtosecond laser processing platform, and the laser focus is located at the contact interface of the glass to be welded.

[0014] Further, the scanning path of the femtosecond laser is in a continuous "several-shaped" pattern.

[0015] Further, the two "ji"-shaped structures have a width of 0.1 to 100 mm and a height of 0.1 to 100 mm.

[0016] Further, the natural cooling time in step (3) is 0.5 to 3 h.

[0017] A glass is prepared by the above method.

[0018] Compared with the prior art, the present invention has the following remarkable advantages:

[0019] (1) The present invention provides a high-strength glass welding method using femtosecond laser coupled with low-flux CO₂ laser, wherein CO₂ laser remelting treatment is performed on the material after femtosecond laser welding; when welding glass with femtosecond laser, the laser is focused on the glass joint, and by adjusting parameters such as femtosecond laser pulse energy and scanning speed, a melting effect is formed on the glass surface so that the glasses are welded together; glass materials have a high absorptivity for CO₂ far-infrared laser, when the laser focus is on the joint surface of two glasses to be welded, the laser energy can directly act on the joint surface, so the material is heated during glass welding, and with heat transfer, the entire welding area will be remelted and then solidified; when the input CO₂ laser energy is too high, it is easy to generate new defects such as pores and thermal stress concentration; therefore, for problems such as microcracks and poor air tightness generated after femtosecond laser welding, low-flux CO₂ laser can be used to remelt and solidify the weld seam and its surrounding area, thereby improving weld quality; compared with traditional glass welding processes such as gluing, metal edge melting, and intermediate solder welding, the welding strength of glass welded by femtosecond laser coupled with low-flux CO₂ laser is higher and the weld quality is better.

[0020] (2) Compared with traditional single-pulse ultrafast laser glass welding, where welding strength may lead to cracks due to uneven stress on the glasses to be welded, and non-optical fitting and large gaps reduce the sealing performance of the weld, the high-strength glass welding method using femtosecond laser coupled with low-flux CO₂ laser can avoid this problem and improve weld quality.

[0021] (3) The high-strength glass welding method provided by the present invention uses pre-applied external force to reduce the gap between the glasses to be welded, and after welding is completed, the generated elastic restoring force easily causes residual stress in the weld, leading to microcracks at the weld boundary; during processing, the coupled CO₂ laser has low laser power and small heat input, which can meet the heat input requirement for local remelting of the weld area; the residual stress generated is very small, which can avoid crack defects and improve the sealing performance of the weld. Description of Drawings

[0022] Figure 1 is a schematic diagram of femtosecond laser glass welding of the present invention.

[0023] Figure 2 is a schematic diagram of the femtosecond laser welding path of the present invention.

[0024] Figure 3 This is a schematic diagram of the processing path of the CO2 laser of the present invention during the processing process.

[0025] Figure 4 This is a flowchart of the high-strength glass welding method of the present invention.

[0026] Explanation of reference numerals in the attached figures:

[0027] 1 - Femtosecond pulsed laser; 2 - Glass to be welded stacked on top; 3 - Contact surface of the glass material to be welded; 4 - Glass to be welded stacked below; 5 - Weld seam; 6 - Laser propagation direction. Detailed Implementation

[0028] The present invention will now be described in further detail with reference to the accompanying drawings.

[0029] A method for high-strength glass welding using a femtosecond laser coupled with a low-flux CO2 laser, such as... Figure 4 The diagram shows the operation flowchart of this invention. First, the glass material to be welded is selected and pre-treated. External force is applied using a fixture to bring the surfaces of the glass to be welded into contact. The clamped sample is placed on the processing platform of the femtosecond laser. The femtosecond laser is used to weld the glass. Subsequently, the welded glass material is processed on a low-throughput CO2 laser processing platform.

[0030] Specifically, the steps include the following:

[0031] A method for high-strength glass welding using a femtosecond laser coupled with a CO2 laser. The method involves: pre-treating the glass to be welded; applying external force using a clamp to bring the glass into a bonded state; placing the clamped sample on the processing platform of the femtosecond laser; and welding the glass using the femtosecond laser. The welded glass material is then processed on a low-throughput CO2 laser processing platform.

[0032] Specifically, the steps include the following:

[0033] Step (1): Select the two pieces of transparent glass to be welded;

[0034] Step (2): Pre-treat the glass to be welded mentioned in step (1), clean it, and then clamp it with a fixture;

[0035] Step (3): Place the glass to be welded prepared in step (2) on the femtosecond laser processing platform;

[0036] Step (4): Use a femtosecond laser to scan the prepared glass to be welded along a certain path and with certain parameters to achieve glass welding.

[0037] Step (5): After natural cooling, the glass material subjected to femtosecond welding is placed on a low-flux CO₂ laser processing platform;

[0038] Step (6): Scanning the weld formed by femtosecond laser with a low-flux CO₂ laser along a certain path to obtain a glass-welded product with high strength and good air tightness.

[0039] The size of the glass to be welded selected in step (1) is 2 to 100 mm × 2 to 100 mm × 0.1 to 10 mm, and the specific glass types include fused silica glass, borosilicate glass, high-silica glass, etc.

[0040] The pretreatment of the glass to be welded in step (2) is soaking the glass to be welded in absolute ethanol for 1 to 100 min, then cleaning it in an ultrasonic cleaning device for 1 to 100 min, and wiping the surface to be welded with alcohol.

[0041] The fixture in step (2) only provides an external force perpendicular to the surface of the glass to be welded, so as to keep the glasses to be welded in a fitted state.

[0042] The contact surface of the glass to be welded in step (3) is parallel to the plane of the femtosecond laser processing platform.

[0043] In step (4), the wavelength of the femtosecond laser is 1035 nm, the processing power during processing is 15 W, the galvanometer scanning speed is 50 mm / s, and the defocus amount is 0.53 mm.

[0044] During the processing of the femtosecond laser in step (4), the laser focus is located at the contact interface of the glass to be welded; the scanning path of the laser is in an "n" shape, the width of each "n" is 0.1 to 100 mm, and the height is 0.1 to 100 mm.

[0045] After the completion of femtosecond laser welding in step (5), the workpiece is naturally cooled for 0.5 to 3 h.

[0046] The scanning path of the low-flux CO₂ laser in step (6) is as shown in Figure 3 . The scanning covers the weld position and a range of 1 to 10 mm around the weld.

[0047] When processing with the low-flux CO₂ laser in step (6), the processing power is 0.1 to 1000 W, and the scanning speed is 0.1 to 500 mm / s.

[0048] The high-strength glass welding method using femtosecond laser coupled with low-flux CO₂ laser proposed herein successfully achieves high-strength welding of glass.

[0049] Example 1

[0050] High borosilicate glass was selected as the experimental material. Samples of 20mm×20mm×2mm and 10mm×10mm×2mm were prepared for subsequent tensile and shear strength testing. To minimize the gap between the two samples, maintain surface cleanliness, and improve welding performance, the samples were pre-soaked in an alcohol solution for 10 minutes. They were then cleaned in an ultrasonic cleaner for 10 minutes and wiped with alcohol. Finally, the two pieces of glass to be welded were clamped together. The glass was placed on a femtosecond laser processing platform, with the laser focus on the interface between the two pieces of glass. Due to the presence of elastic restoring force, cracks are prone to occur at the corners of the connection area. Therefore, when designing the scanning path, the elastic restoring force of the glass was distributed as evenly as possible around the perimeter of the connection area. Figure 2 As shown, to enable the weld to withstand the elastic recovery force of the clamping force, the laser source moves in a "V" shape during connection to form a specific "V" shaped connection surface. The welding line length b is 10 mm, and the line spacing a is 200 μm. The femtosecond laser has a power of 20 W, a scanning speed of 25 mm / s, and a wavelength of 1035 nm.

[0051] After the femtosecond laser welding is completed, a low-flux CO2 laser is coupled, with a CO2 laser power of 28W, for localized remelting. During scanning, the CO2 laser spot diameter is 448 micrometers; Figure 3 As shown, the distance between the upper and lower paths is 224 μm, and the scanning speed is 120 mm / s.

[0052] In this embodiment, the glass shear strength achieved by femtosecond laser-coupled low-flux CO2 laser welding reached 28 MPa, which is 40% higher than the 20 MPa welding shear strength of traditional ultrashort pulse laser welding of glass materials, and the sealing performance of the glass material was also improved.

Claims

1. A glass welding method using a femtosecond laser coupled with a low-flux CO2 laser, characterized in that, Comprising the following steps: Step (1): Select two pieces of transparent glass to be welded, clamp the transparent glass with a fixture after pretreatment, so that the surfaces to be welded of the transparent glass are in contact; during clamping in step (1), the fixture only provides an external force perpendicular to the surface of the glass to be welded, so that the glass to be welded is in a fitted state; Step (2): Adopt femtosecond laser with a wavelength of 500nm~50000nm and a power of 10~40W to weld the surfaces to be welded by scanning according to the set path and parameters; Step (3): After the glass welded by femtosecond laser in step (2) is naturally cooled, use low-flux CO₂ laser with a processing power lower than 1000W and a scanning speed lower than 500mm / min to weld the weld seam obtained by femtosecond laser welding in step (2) and the area within 1~10mm from the weld seam; During femtosecond laser welding in step (2), the contact surface of the glass to be welded is parallel to the plane of the femtosecond laser processing platform, and the laser focus is located at the contact interface of the glass to be welded.

2. The method according to claim 1, characterized in that, In step (1), the dimensions of the two pieces of transparent glass are 2~100mm×2~100mm×0.1~10mm, and the types of the transparent glass are fused silica glass, borosilicate glass or high-silica glass.

3. The method according to claim 2, characterized in that, The pretreatment in step (1) is specifically: soaking the glass to be welded in absolute ethanol for 1~100min, then ultrasonically cleaning for 1~100min, and wiping with alcohol.

4. The method according to claim 3, characterized in that, During femtosecond laser welding in step (2), the galvanometer scanning speed is 10~1000mm / s, and the defocus amount is less than 10mm.

5. The method according to claim 4, characterized in that, The scanning path of the femtosecond laser is in a continuous "几"-shaped configuration.

6. The method according to claim 5, characterized in that, The width of two "几" shapes is 0.1~100mm, and the height is 0.1~100mm.

7. The method according to claim 1, characterized in that, In step (3), the natural cooling time is 0.5~3h.

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