CN114261100A

CN114261100A - A method for ultrafast laser welding of transparent hard and brittle materials and metals

Info

Publication number: CN114261100A
Application number: CN202111556814.XA
Authority: CN
Inventors: 杨胶溪; 刘哲; 张伟
Original assignee: Beijing University of Technology; AVIC Beijing Aeronautical Manufacturing Technology Research Institute
Current assignee: Beijing University of Technology; AVIC Beijing Aeronautical Manufacturing Technology Research Institute
Priority date: 2021-12-17
Filing date: 2021-12-17
Publication date: 2022-04-01
Anticipated expiration: 2041-12-17
Also published as: CN114261100B

Abstract

The invention discloses a method for welding transparent hard and brittle materials and metals by ultrafast laser, wherein two ultrafast laser beam energies with different wavelengths are applied simultaneously in the welding process. The transparent hard and brittle material is tightly attached above the metal material during welding, the focus of the laser beam (lambda 1) is adjusted to be positioned above the metal-nonmetal interface, the focus of the laser beam (lambda 2) is adjusted to be positioned below the metal-nonmetal interface, the lambda 1 laser beam is positioned in front, the lambda 2 laser beam is positioned behind, and the two beams are separated by a certain distance and welded in the same path.

Description

Method for welding transparent hard and brittle material and metal by ultrafast laser

Technical Field

The invention relates to the field of laser processing, in particular to a method for welding a transparent material and metal by using ultrafast lasers with different wavelengths.

Background

The transparent materials such as glass and the like have the characteristics of high strength, small specific gravity, high anti-seismic strength and chemical stability, excellent optical and electromagnetic wave performance and the like, and are widely applied to the high-end technical fields such as aerospace, weaponry, microelectronics, biomedicine and the like at present. However, the glass material has the characteristics of low plasticity, easy fracture, easy surface damage and the like, so that the traditional processing methods such as mechanical connection, adhesion, anodic bonding and the like have obstacles to processing the glass material, and particularly, a high-quality processed piece meeting the requirements is difficult to obtain aiming at the problem of large difference between the thermal expansion coefficients of the glass material and the metal.

Ultrafast laser has characteristics such as short pulse width, high peak value, high repetition frequency, has obtained extensive recognition and use in transparent material processing field. Compared with long pulse, the ultra-fast laser pulse width is less than the time of heat conduction to crystal lattice, extremely high temperature is achieved in extremely short time, and meanwhile, the generation of a heat affected zone can be effectively avoided. The ultrafast laser welding technology based on nonlinear absorption is expected to greatly improve the connection performance of the transparent and the metal, and the ultrahigh peak power density of the femtosecond laser can induce extremely high local temperature, so that the transparent material with high melting point is directly melted, and the local fusion between the materials is realized. The ultrafast laser micro-welding technology has unique advantages in the aspect of welding, realizes the space selective welding of micron and even nanometer scale in a non-contact mode, reduces the complexity of the structure, increases the reliability, and simultaneously avoids the generation of larger heat distortion and heat stress. The existing ultrafast laser welding methods all use laser beams with the same wavelength, so that glass materials and metals cannot achieve good welding effect at the same time, and the phenomenon that the glass materials are not fully melted or the metal is over-burnt during welding occurs.

The Chinese patent proposes that the fusion of glass materials is carried out by utilizing multi-laser beam combination, the method can carry out fusion connection on two materials which do not meet optical contact conditions, the fusion connection efficiency is improved, and engineering application is convenient to realize, but the following problems exist: (1) when the laser is closed and welded, the energy of the welding seam is too high, so that the instantaneous temperature of the material is too high, and the glass material is cracked due to too large thermal stress, so that a high-energy laser beam cannot be applied to the mode; (2) the method can only realize the welding of two same materials with the maximum gap of about 12 mu m, and cannot perform the welding on the welding seam with larger gap. (3) The laser beams used by the laser beam combination welding are respectively ultrafast laser and continuous laser, the brittle materials processed by the continuous laser are easy to generate brittle fracture, and the heat effect is still high.

Disclosure of Invention

Aiming at the defects in the prior art, the invention provides a method for welding transparent hard and brittle materials and metals by ultrafast laser, which can effectively improve the weld quality and welding efficiency and realize the firm welding of the transparent materials and the metals with large gaps by utilizing the difference of the absorption rates and the processing qualities of different materials to different wavelengths. Meanwhile, the laser beams with two wavelengths are ultrafast lasers, the lambda 1 wavelength laser beam can effectively improve the defect of low absorptivity of the transparent material, the lambda 2 wavelength laser beam is used for enhancing the strength of the welding seam, heat accumulation which causes brittle fracture of the glass material due to accumulation at the welding seam is avoided, and the problems of heat ablation, brittle fracture and the like can be effectively avoided.

In order to achieve the purpose, the invention provides a method for welding a transparent hard and brittle material and metal by ultrafast laser, which comprises the following steps:

firstly, polishing the metal surface, respectively and lightly sweeping the surfaces of the transparent material and the metal material to be welded by using lens wiping paper dipped with alcohol, and waiting for the alcohol to volatilize. And the material to be welded is stacked on the two-dimensional moving platform in a mode that the transparent material is arranged on the upper part and the metal material is arranged on the lower part. During welding, the transparent hard and brittle material is tightly attached to the upper part of the metal material, the focus of the laser beam (lambda 1) is adjusted to be positioned above the metal-nonmetal interface, the focus of the laser beam (lambda 2) is adjusted to be positioned below the metal-nonmetal interface, the lambda 1 laser beam is in front, the lambda 2 laser beam is behind, and the two beams are welded at a certain distance and in the same path.

λ 1 laser beam is in front and λ 2 laser beam is behind, meaning that with respect to a point on the scan path, the λ 1 laser beam passes through that point first and the λ 2 laser beam passes through that point after a distance (D).

Further, the focal point of the laser beam (. lamda.1) is located in the range of 0.1 to 0.6mm above the metal-nonmetal interface, and the focal point of the laser beam (. lamda.2) having a wavelength of 800nm to 1100nm is located in the range of 0.1 to 1.0mm below the metal-nonmetal interface.

Furthermore, the laser power is 1W-100W, the pulse width is 240fs-10ps, the frequency is 1kHz-1MHz, the focal length of the field lens is 30mm-200mm, the scanning speed is 10mm/s-100mm/s, and the distance between scanning paths is 10 mu m-500 mu m.

Furthermore, the incidence angles of the two laser beams are inclined or not inclined towards the advancing direction, the included angle theta 1 between the incidence angle of the lambda 1 laser beam and the vertical normal is 0-10 degrees, and the included angle theta 2 between the incidence angle of the lambda 2 laser beam and the vertical normal is 0-10 degrees.

Furthermore, the transparent material has high absorptivity to the laser beam with the wavelength 1, the transparent material can reach the threshold value of nonlinear absorption more easily, the laser beam with the wavelength 2 can weld metals more efficiently, and the obtained weld joint has better quality compared with other wavelengths.

Furthermore, the surface of the metal to be welded is polished to be smooth by using 320-mesh or above sand paper, the transparent material needs to be polished, and an intermediate layer does not need to be added in the welding process.

The invention provides a method for welding a transparent hard and brittle material and metal by ultrafast laser, which has the advantages that:

the invention relates to a method for welding a transparent hard and brittle material and metal by ultrafast laser, which considers that different materials have different absorption efficiency to laser beams with different wavelengths, respectively uses two beams of ultrafast laser with different wavelengths to increase the absorption rate of the material to the laser, more easily reaches the nonlinear absorption threshold of the transparent material, and the transparent material and the metal are more fully fused, thereby obtaining a welding seam with better quality and higher strength. Meanwhile, the two used laser beams are ultrafast lasers, the lambda 1 wavelength laser beam can effectively improve the defect of low absorption rate of the transparent material, the lambda 2 wavelength laser beam is used for enhancing the strength of the welding line, the thermal influence can be effectively reduced, and the phenomena of brittle fracture, high residual stress and the like caused by overhigh heat accumulation in the welding process can be avoided while the welding strength is ensured.

Drawings

Fig. 1 is a schematic diagram of the present invention, which uses ultrafast lasers with two different wavelengths to fuse transparent materials and metals.

Detailed Description

In order to make the objects, technical solutions and advantages of the present invention clearer, the technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings, and it is obvious that the described embodiments are some, but not all embodiments of the present invention. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.

Example 1:

the method comprises the steps of welding stacked silicate glass and aluminum alloy by a femtosecond laser with a wavelength lambda 1 of 515nm, a pulse width of 240fs and a pulse repetition frequency of 100kHZ and a wavelength lambda 2 of 1064nm, a pulse width of 240fs and a pulse repetition frequency of 100kHZ, wherein the silicate glass is 15x10mm in size, the aluminum alloy is 30x20mm in size, and the aluminum alloy is 10mm in thickness, starting the laser, focusing the laser beam with the wavelength lambda 1 at a position 0.2mm above metal-nonmetal, adjusting the output power of the laser to 10W, and realizing a scanning path by using a scanning galvanometer, wherein the focal length of a focusing field lens is 110mm, the scanning speed is 80mm/s, and the welding seam interval is 100 mu m. The laser beam with the wavelength of lambda 2 is firstly focused at a position 0.3mm below the metal-nonmetal, the incident angle theta 2 is 1 DEG, the output power of the laser is adjusted to be 20W, the scanning path is realized by using a scanning galvanometer, the focusing field lens is 110mm, the scanning speed is 100mm/s, and the welding seam interval is 100 mu m. The distance between the two laser beams is 4mm in the welding process. The welding results show that: the glass and the metal are both melted to realize the welding effect, the shearing strength is more than 21Mpa, and the glass is not damaged.

Example 2:

the method comprises the steps of welding stacked sapphire glass and titanium alloy by a femtosecond laser with a wavelength lambda 1 of 532nm, a pulse width of 10ps, a pulse repetition frequency of 200kHZ and a wavelength lambda 2 of 1030nm, a pulse width of 10ps and a pulse repetition frequency of 200kHZ, wherein the sapphire glass is 15x10mm in size, the thickness of 3mm, the titanium alloy is 30x20mm in size and 10mm in thickness, starting the laser, focusing the laser with the wavelength lambda 1 at a position 0.1mm above metal-nonmetal, adjusting the output power of the laser by 20W, and realizing a scanning path by using a scanning galvanometer, wherein the focal length of a focusing field lens is 30mm, the scanning speed is 60mm/s, and the space between welding lines is 50 mu m. The laser beam with the wavelength of lambda 2 is firstly focused at a position 0.2mm below the metal-nonmetal, the incident angle theta 2 is 8 degrees, the output power of the laser is adjusted to be 30W, the scanning path is realized by using a scanning galvanometer, the focusing field lens is 30mm, the scanning speed is 80mm/s, and the welding seam interval is 50 mu m. The distance between the two laser beams is 2mm in the welding process. The welding results show that: the glass and the metal are both melted to realize the welding effect, the shearing strength is more than 23Mpa, and the glass is not damaged.

Example 3:

the method comprises the steps of enabling a laser beam with the wavelength lambda 1 to be 343nm, the pulse width to be 500fs, the pulse repetition frequency to be 100kHZ, enabling a femtosecond laser with the wavelength lambda 2 to be 800nm, the pulse width to be 500fs and the pulse repetition frequency to be 100kHZ, welding and stacking silicate glass and a copper alloy, enabling the size of the silicate glass to be 15x10mm, the thickness to be 2mm, the size of the copper alloy to be 30x20mm and the thickness to be 10mm, starting the laser, enabling the laser beam with the wavelength lambda 1 to be focused 0.3mm above metal-nonmetal, enabling the incidence angle theta 1 to be 0 degrees, adjusting the output power of the laser to be 10W, using a scanning galvanometer to realize a scanning path, enabling the focal length of a focusing field lens to be 150mm, enabling the scanning speed to be 50mm/s and enabling the welding seam spacing to be 150 mu m. The laser beam with the wavelength of lambda 2 is firstly focused at a position 0.1mm below the metal-nonmetal, the incident angle theta 2 is 6 degrees, the output power of the laser is adjusted to be 30W, the scanning path is realized by using a scanning galvanometer, the focusing field lens is 150mm, the scanning speed is 60mm/s, and the welding seam interval is 100 mu m. The distance between the two laser beams is 6mm in the welding process. The welding results show that: the glass and the metal are both melted to realize the welding effect, the shearing strength is more than 20Mpa, and the glass is not damaged.

It will be understood by those skilled in the art that the foregoing is only a preferred embodiment of the present invention, and is not intended to limit the invention, and that any modification, equivalent replacement, or improvement made within the spirit and principle of the present invention should be included in the scope of the present invention.

Claims

1. a method for ultrafast laser welding transparent hard and brittle material and metal, it is characterized in that, in the welding process, the ultrafast laser beam energy of two different wavelengths is applied simultaneously; during welding, the transparent hard and brittle material is closely attached above the metal material , the focus of the λ1 laser beam with the wavelength of 300nm-600nm is adjusted to be located above the metal-non-metal interface and the range d1 is 0.1-0.6mm, and the focus of the λ2 laser beam with the wavelength of 800nm-1100nm is adjusted to be located below the metal-non-metal interface. The range d2 is 0.1-1.0mm , the λ1 laser beam is in the front, the λ2 laser beam is behind, the incidence of the two laser beams is inclined or not inclined toward the forward direction, the angle θ1 between the incident angle of the λ1 laser beam and the vertical normal is in the range of 0-10°, and the incident angle of the λ2 laser beam The angle θ2 with the vertical normal is in the range of 0-10°. The distance between the two beams is 0.1-10mm and they are welded in the same path. The welding process parameters are: laser power 1W-100W, pulse width 240fs-10ps, frequency 1kHz-1MHz, field lens focal length 30mm-200mm, scanning speed 10mm/s-100mm/s, scanning path spacing 10μm-500μm.