阅读说明：本技术 一种应用于陶瓷的超快激光焊接方法 (Ultrafast laser welding method applied to ceramics ) 是由 李晓鹏 支新涛 冯靖 彭勇 王克鸿 周琦 王大森 袁松梅 于 2020-04-29 设计创作，主要内容包括：本发明涉及陶瓷连接技术领域,具体地说是一种陶瓷的超快激光焊接方法。该方法通过超快激光对陶瓷工件结合处进行辐照,陶瓷吸收光子能量,在高功率密度下诱导出非线性吸收现象,焦点处的陶瓷发生瞬时熔融,原子活性大大提高,进而陶瓷工件结合处的元素发生扩散现象,形成焊点。由于超快激光作用时间极短,热量来不及散失,热影响区极小。通过改变超快激光相关参数,既可以实现陶瓷的可靠连接,又可以大大降低有热应力导致焊缝开裂的现象。本发明采用上述方法,可降低焊缝的焊接应力,避免焊缝处裂纹产生,在不出现烧蚀的情况下实现陶瓷的熔融焊接。(The invention relates to the technical field of ceramic connection, in particular to an ultrafast laser welding method for ceramics. According to the method, the ceramic workpiece joint is irradiated by ultrafast laser, photon energy is absorbed by the ceramic, a nonlinear absorption phenomenon is induced under high power density, the ceramic at the focus is instantaneously melted, atomic activity is greatly improved, and then elements at the ceramic workpiece joint are diffused to form a welding spot. Because the ultra-fast laser has extremely short acting time, the heat can not be dissipated in time, and the heat affected zone is extremely small. By changing relevant parameters of the ultrafast laser, not only can reliable connection of ceramics be realized, but also the phenomenon of welding seam cracking caused by thermal stress can be greatly reduced. By adopting the method, the welding stress of the welding seam can be reduced, the generation of cracks at the welding seam is avoided, and the melting welding of ceramics is realized under the condition of no ablation.)

1. An ultrafast laser welding method applied to ceramics is characterized in that a ceramic material welding interface is cleaned, ultrafast laser welding is utilized, a nonlinear absorption phenomenon is induced under high power density, ceramics at a focus are instantaneously melted, atomic activity is greatly improved, elements at a joint of a ceramic workpiece are diffused, and a welding spot is formed.

2. The welding method applied to ceramic materials according to claim 1, wherein the ceramic material is alumina ceramic, zirconia ceramic, silicon carbide ceramic or silicon nitride ceramic put into structural ceramic; dielectric ceramics of barium titanate ceramics and titanium dioxide ceramics; transparent ceramic of magnesium aluminate ceramic and magnesium oxide ceramic; the thickness of one of the semiconductor ceramics of vanadium oxide ceramics or zinc oxide ceramics is 0.1 mm-1 mm.

3. The ultrafast laser welding method for ceramics according to claim 1, wherein the ultrafast laser has a pulse width of 300 fs-10 ps.

4. The ultrafast laser welding method applied to ceramics according to claim 1, wherein the laser light source may be a single path or multiple paths in parallel, and the laser light path may be a general light path or a light path subjected to time domain shaping, specifically: when the welding area is less than 20mm, a common light path and a single-path light source are adopted; when the welding area is larger than 20mm, a space-time shaping light path and a plurality of paths of parallel light sources are adopted.

5. Welding method applied to ceramic materials according to claim 1, characterized in that it comprises the following steps:

step 1: sequentially adopting acetone, absolute ethyl alcohol and deionized water to ultrasonically clean the part to be welded, and then drying;

step 2: fixing the ceramic material to be welded on an ultrafast laser working platform according to welding requirements, and preparing for welding;

and step 3: opening the ultrafast laser, and adjusting laser power, scanning speed, laser frequency, defocusing amount and scanning times of the ultrafast laser;

and 4, step 4: focusing a laser focus at a welding seam, drawing a motion track graph required by scanning, determining a scanning starting point, and starting scanning;

and 5: and taking out the workpiece after the laser processing is finished.

6. The ultrafast laser welding method applied to ceramic materials as claimed in claim 5, wherein in the step 4, the ultrafast laser welding process parameters range: the laser power is 2W-40W, the scanning speed is 1 mm/s-20 mm/s, the defocusing amount is-1.5 mm, the repetition frequency is 0.2 MHz-1 MHz, and the scanning frequency is 1-50 times.

7. The ultrafast laser welding method applied to ceramic materials as claimed in claim 5, wherein, in the step 4, when the ultrafast laser welding process is repeated for the number of scanning times, the repetition manner includes four types: firstly, scanning one point for multiple times, and then scanning the next point for multiple times; secondly, scribing and scanning, and then returning to the starting point for repeated scanning; thirdly, reciprocating scanning after scribing scanning; fourthly, the method comprises the following steps: a very narrow face scan is performed centered on the weld.

Technical Field

The invention relates to the technical field of ceramic material connection, in particular to an ultrafast laser welding method for ceramics.

Background

Compared with metal materials and high polymer materials, the ceramic material has the excellent characteristics of high melting point, high hardness, high temperature resistance, corrosion resistance, wear resistance and the like, has wide and difficult-to-replace application in the industrial fields of national defense industry, electronic information, mechanical manufacturing, nuclear energy, new energy and the like, and the application of the ceramic material keeps about 10 percent of growth year by year in the last two decades. However, the ceramic material has poor welding performance due to its characteristics of high hardness, high melting point, and large brittleness, and the like, and the ceramic material has low processability, and cannot meet the requirements for manufacturing complex parts. The conventional joining methods for ceramic materials include brazing, diffusion welding, mechanical joining, laser welding, and the like, and most of them are brazing and diffusion welding. However, as brazing and diffusion welding are difficult to meet the requirements under the condition of high temperature, laser is always explored for welding ceramics at home and abroad in recent years, but the traditional continuous laser has large thermal shock effect, cracks always exist in the welded ceramic weld joint, and further wide application of ceramic materials is severely restricted. How to reduce or eliminate the problem of thermal cracks in ceramic laser welding becomes a great problem for limiting ceramic welding at present.

Disclosure of Invention

The invention aims to solve the defects of the prior art, and the ceramic material is melted by using the ultrahigh instantaneous power of the ultrafast laser, and meanwhile, the crack problem occurring in the ceramic material welding process is reduced by using the characteristics of discontinuous pulse and cold processing of the ultrafast laser and matching with proper technological parameters and processing modes.

The technical scheme adopted by the invention for solving the technical problems is as follows:

an ultrafast laser welding method applied to ceramics comprises the steps of cleaning a welding surface of a ceramic material and ultrafast laser welding, so that the ceramic material is welded, and cracks caused by thermal stress in the welding process are reduced.

The method comprises the following specific process steps:

step 1: before ultrafast laser welding, the ceramic welding surface is sequentially cleaned by acetone, absolute ethyl alcohol and deionized ultrasonic, and then is dried.

Step 2: after the ceramic is fixed according to welding requirements, the ceramic is placed on an ultrafast laser welding workbench, a welding line is opposite to the direction of laser transmission, and the ceramic is fixed by a pressing plate, so that the spatial position of the ceramic is not changed in the welding process.

And step 3: and opening the laser, drawing a welding track graph according to the welding requirement, setting corresponding laser parameters, moving the laser focus to the track starting point, and starting laser scanning welding.

The principle and basis of the invention are as follows: the ultrafast laser has an extremely narrow single pulse width, and can realize high pulse energy density at low pulse power due to extremely short action time and small action area under the single pulse. The focusing action area of the ultrafast laser is controlled to induce the nonlinear absorption process of the area, and the interaction of the laser and the ceramic crystal lattice is utilized, so that the ceramic element is locally and rapidly diffused, the melting but not the ablation at the focus is realized, meanwhile, the action time of the ultrafast laser is extremely short, and the accumulation of heat at the welding position can be ignored. The ultrafast laser can achieve high quality fusion welding between ceramics.

Compared with the prior art, the invention has the following remarkable advantages:

1. the ultrafast laser has an extremely short pulse width, and the thermal diffusion phenomenon is not obvious, so that the ultrafast laser hardly generates a thermal influence effect on the periphery of a ceramic welding seam.

2. Compared with continuous laser, the ultrafast laser has low damage threshold of welding ceramic materials, small thermal shock and few cracks.

3. The ultrafast laser welding ceramic does not need brazing filler metal and is environment-friendly.

4. The ultrafast laser welding ceramic has no special requirements on environment and wide application occasions.

5. The ultrafast laser welding ceramic can be operated in special environments such as water, vacuum and the like only by being carried out in a light transmitting environment.

6. The ultrafast laser welding ceramic has no special requirement on the shape of the welding seam, and is easy to realize automation.

7. The ultrafast laser welding ceramic welding seam can be repeated, and the welding seam quality can be controlled.

Drawings

FIG. 1 is a schematic illustration of ultra-fast laser welding.

FIG. 2 is a weld profile of ultrafast laser welding of ceramic materials.

Detailed Description

The invention is further described below with reference to the accompanying drawings:

as shown in figure 1. An ultrafast laser welding method applied to ceramics comprises cleaning of a welding surface of a ceramic material and ultrafast laser welding, so that efficient welding of the ceramic material is achieved, and cracks caused by thermal stress in a welding process are reduced.

The ceramic material is alumina ceramic, zirconia ceramic, silicon carbide ceramic, silicon nitride ceramic and other structural ceramics, barium titanate ceramic, titanium dioxide ceramic and other dielectric ceramics, magnesium aluminate ceramic, magnesium oxide ceramic and other transparent ceramics, vanadium oxide ceramic, zinc oxide ceramic and other semiconductor ceramics.

The laser light source can be a single path or a plurality of paths in parallel, and the laser light path can be a common light path or a light path subjected to time domain shaping. When the welding area is not large, a common light path and a single-path light source are adopted; when the welding area is large, a space-time shaping light path and a plurality of paths of parallel light sources are adopted.

The method comprises the following steps:

the first step is as follows: before ultrafast laser welding, the ceramic welding surface is sequentially cleaned by acetone, absolute ethyl alcohol and deionized ultrasonic, and then is dried.

The second step is that: after the ceramic is fixed according to welding requirements, the ceramic is placed on an ultrafast laser welding workbench, a welding line is opposite to the direction of laser transmission, and the ceramic is fixed by a pressing plate, so that the spatial position of the ceramic is not changed in the welding process.

The third step: and opening the laser, drawing a welding track graph according to the welding requirement, setting corresponding laser parameters, moving the laser focus to the track starting point, and starting laser scanning welding.

The pulse width of the ultrafast laser is in the order of femtoseconds and picoseconds. The optical path is shaped to accommodate the size of the footprint area. The adjustable parameters of the ultrafast laser include power, defocusing amount, repetition frequency, pulse width, scanning mode, scanning speed and scanning times.