Continuous laser high-stability welding method for ceramic materials

Abstract

One purpose of the invention is to provide a continuous laser high-stability welding method for a ceramic material. The continuous laser high-stability welding method comprises the following steps: S1, coating a layer of carbon particles of 100-500 nm on a ceramic surface; and S2, under the long-focus condition, continuous laser with specific power is selected to weld the ceramic material. For the aluminum oxide ceramic wafer, aiming at the specific welding depth, under the condition that the welding time and the welding area are fixed, the relation between the melting depth and the laser power is D = 0.17584 * P * T / A, D is the melting depth, and the unit is mm; p is laser power, and the unit is W; t is the welding time, and the unit is s; a is the area of a welding area, and the unit is mm < 2 >. By adopting the design of a long-focus optical system, under the conditions of lower power density, larger light spot size and longer focal depth, focusing conditions and laser power parameters can be accurately regulated and controlled according to the requirements of ceramic samples with different thicknesses, and uniform and stable melting of materials in a specified depth direction is realized; therefore, material vaporization and welding defects caused by material vaporization are avoided.

Description

Technical Field

[0001] The invention belongs to the technical field of laser processing, and in particular relates to a continuous laser high-stability welding method for ceramic materials. Background Art

[0002] Ceramic materials, thanks to their exceptional hardness, superior thermal stability, chemical inertness, and excellent electrical insulation properties, hold a central position in numerous high-end applications, including electronic packaging, integrated circuit substrates, aerospace engine hot-end components, medical implants (such as artificial joints and dental crowns), and precision optical devices. However, these inherent properties—particularly their extremely high hardness (alumina (Al2O3), for example, can reach a Mohs hardness of 9), significant brittleness, and low thermal conductivity—pose significant obstacles to precision processing using traditional machining methods (such as turning, milling, grinding, and drilling). Under intense mechanical loads, the material is prone to numerous unavoidable defects in and around the machining area. These defects manifest themselves at the macro level through edge chipping, crack propagation, and ultimately, complete fracture failure; at the micro level, through microcrack initiation and the formation of subsurface damage layers, significantly reducing the strength, reliability, and service life of ceramic components. For functional ceramic components requiring stringent geometric precision, smooth surface quality, or complex three-dimensional contours, these defects are often the primary cause of substandard performance and the inability to meet the demands of cutting-edge applications. The contradiction between efficiency, precision and surface integrity in traditional machining is difficult to balance, which seriously restricts the scale and cost control of high-performance ceramic component manufacturing.

[0003] In order to overcome the bottleneck of traditional processing, laser technology has been regarded as an important breakthrough in improving ceramic processing capabilities since the late 20th century due to its advantages such as non-contact, high-energy controllability, and easy automation.

[0004] Although the aforementioned pulsed laser technologies (especially ultrafast lasers) have achieved remarkable success in specific scenarios, they still face insurmountable technical barriers in their broader engineering applications, especially in the fields of high efficiency and deep processing: Energy injection instability can lead to localized heating and, consequently, thermal stress. Laser energy is injected into the material in discrete peak pulses. When the local energy density momentarily exceeds the material's vaporization threshold, the intense vaporization recoil pressure and rapid heating and cooling cycles induce significant thermal stresses, particularly in brittle ceramics, which can easily induce microcracks and even macrocracks (which are difficult to completely eliminate even with ultrafast lasers). Furthermore, the process window is narrow, and even slight fluctuations in parameters (power, frequency, and scan speed) can lead to unstable processing results and batch-to-batch variations in quality.

[0005] Average power bottlenecks lead to low processing efficiency: Pulsed laser energy is typically concentrated within a brief pulse peak, resulting in relatively low average power. This means that the total heat deposited on the material per unit time is limited. For applications requiring large amounts of material removal or deep-layer processing (such as thick plate cutting and deep-penetration welding), scanning speeds must be significantly slowed to achieve the desired effect (such as deep penetration), significantly extending processing time and significantly mismatching the industry's needs for large-scale, high-efficiency manufacturing.

[0006] High system complexity and cost: To generate high-frequency, high-stability short / ultrashort pulses (especially in the ps / fs range), lasers and associated control and beam shaping systems (such as regenerative amplifiers, pulse pickers, and complex cooling systems) are extremely sophisticated and complex, resulting in high equipment acquisition and maintenance costs. High-precision motion control platforms further increase overall investment.

[0007] These defects (porosity, cracks, lack of fusion, and uneven penetration depth / morphology) intertwine and reinforce each other, leading to severe strength degradation and extremely poor connection reliability in ceramic laser welded joints, a key obstacle hindering their application in practical engineering structures. A new laser welding method is urgently needed that can effectively improve the ceramic's absorption rate for continuous laser welding, achieve stable and controllable heating at large penetration depths, and suppress keyhole instability and associated defects. This will unlock the potential of continuous laser welding for efficient, high-quality ceramic joining.

[0008] In addition, on the one hand, there are differences in understanding among those skilled in the art; on the other hand, the inventor studied a large number of documents and patents when making the present invention, but due to space limitations, not all details and contents are listed in detail. However, this does not mean that the present invention does not have the characteristics of these prior arts. On the contrary, the present invention already has all the characteristics of the prior art, and the applicant reserves the right to add relevant prior art to the background art. Summary of the Invention

[0009] Continuous-wave (CW) lasers are considered a potential solution for efficient processing (especially deep processing such as welding) due to their stable, high-average power output (providing continuous energy injection). However, many widely used functional ceramics (such as Al2O3 and ZrO2) have extremely low intrinsic absorption rates for common CW lasers (often less than 5%). The laser energy cannot be effectively absorbed by the material and converted into heat energy, resulting in low processing efficiency or the inability to perform melting processing at all. Among existing strategies to improve absorption (such as surface roughening, pre-deposition of a thin metal layer, and modification with pulsed lasers), the "composite laser method" (using an auxiliary pulsed laser for surface modification to enhance its absorption of subsequent CW lasers) is the most common. However, this method requires the precise integration of at least two sets of lasers (pulsed + continuous) and complex beam combining and path calibration (such as coaxial or split beam paths). The optical path stability requirements are high, and the process complexity and system cost are much higher than single-laser processing. Of particular concern is that current research and applications in continuous laser processing of ceramics are highly concentrated in drilling, cutting, or surface modification. Research on laser welding, which also holds immense engineering value (especially joining thick ceramic layers), is relatively scarce, with limited results. The few existing attempts are often limited to joining thin sheets or spot welding tiny components.

[0010] Based on the above technical problems, one of the objectives of the present invention is to provide a method for continuous laser welding of ceramic materials with high stability, which comprises the following steps: S1: Coating a layer of 100-500 nm carbon particles on the ceramic surface; S2: Under long focus conditions, select a specific power continuous laser to weld ceramic materials. For alumina ceramic sheets, for a specific welding depth, under fixed welding time and welding area, the relationship between melting depth and laser power is: D=0.17584×P×T / A, D: Melting depth, unit is mm; P: Laser power, unit is W; T: Welding time, unit is s; A: Welding area, unit is mm 2 .

[0011] According to a preferred embodiment, the wavelength of the continuous laser is 266-2000 nm.

[0012] According to a preferred embodiment, the continuous laser power is 100-500 W.

[0013] According to a preferred embodiment, the telephoto condition is that the focal length is 500 mm or above.

[0014] According to a preferred embodiment, the sample is fixed by a fixture and a stage so that the contact interface of the ceramic material is located at the laser focus.

[0015] According to a preferred embodiment, the carbon particle material increases the absorption rate of the ceramic material to the continuous laser by 4 times or more. Preferably, the carbon particle material is one or more of graphene, porous carbon, and carbon black.

[0016] According to a preferred embodiment, the melting depth of the ceramic material during welding is 0.05-2 mm.

[0017] According to a preferred embodiment, the thickness of the ceramic material is 0.5-20 mm.

[0018] According to a preferred embodiment, the welding area is a rectangle with a side length of 5 mm to 100 mm.

[0019] According to a preferred embodiment, the ceramic material is one of aluminum oxide, aluminum nitride or silicon nitride.

[0020] One of the objectives of the present invention is to provide a ceramic material prepared based on the above-mentioned continuous laser high-stability welding method for ceramic materials, and the strength of the ceramic material after welding is typically 60~100 MPa.

[0021] One of the purposes of the present invention is to provide a continuous laser high-stability welding device for ceramic materials, which includes a continuous laser generating module, an information processing module and a material fixing table. The information processing module is configured to: execute the above-mentioned continuous laser high-stability welding method for ceramic materials, and control the continuous laser generating module to emit continuous laser of specific power to the ceramic material on the material fixing table.

[0022] The beneficial effects of this technical solution are as follows: This patent proposes a high-stability continuous laser welding method for ceramic materials. This method significantly enhances the absorption efficiency of continuous laser light on the ceramic surface through the aid of carbon particles, enabling stable and efficient coupling of laser energy into the material, effectively avoiding the formation of pore defects caused by fluctuations in absorption rates during traditional welding. Using a telephoto optical system design, the focusing conditions and laser power parameters can be precisely controlled to meet the needs of ceramic samples of varying thicknesses, under conditions of low power density, large spot size, and long depth of focus, achieving uniform and stable melting of the material at a specified depth, thereby avoiding material vaporization and the resulting welding defects caused by local overheating.

[0023] By establishing a precise correspondence between melting depth and laser power, this method can achieve high-quality and stable welding of ceramic materials of different thicknesses under long focal depth conditions using specifically optimized continuous laser power parameters.

[0024] Compared with existing technologies, traditional welding methods often require a significant increase in laser power to achieve deep penetration welding effects. This high power density will induce a pinhole effect. Although it improves the laser absorption rate to a certain extent, it is also prone to typical welding defects such as pores and cracks. In addition, in the depth direction, due to the significant laser defocus phenomenon, in order to meet the heating and melting requirements of deep areas, it is often necessary to further increase the energy input, which not only aggravates the formation of welding defects, but also reduces the process stability. This application effectively solves the above problems through carbon particle assisted absorption and long focal depth optimization design, significantly improving the welding quality and process reliability while ensuring the welding depth. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 A schematic diagram of the technical solution of the continuous laser high-stability welding method for ceramic materials provided by the present invention; Figure 2 This is a cross-sectional view of the ceramic sample after continuous laser welding with different powers. The depth of the recast layer can be used to analyze and study the melting depth of continuous laser welding with different powers.

[0026] Reference numerals 1: Continuous laser; 2: Focusing lens; 3: Laser beam; 4: Ceramic material sample; 5: Carbon particles. DETAILED DESCRIPTION

[0027] In the description of the present invention, terms are used for descriptive purposes only and should not be understood to indicate or imply relative importance or implicitly indicate the number of technical features indicated. In the description of the present invention, "plurality" means two or more, unless otherwise specifically defined.

[0028] The present invention is further described below with reference to specific examples. Experimental methods in the following examples, where specific conditions are not specified, generally follow conventional conditions or the conditions recommended by the manufacturer. Unless otherwise defined, all professional and scientific terms used herein have the same meanings as those familiar to professionals in the field. In addition, any methods and materials similar or equivalent to those described herein can be applied to the present invention. The preferred embodiments and materials described herein are for illustrative purposes only.

[0029] It should be noted that, in the absence of conflict, the embodiments of the present invention and the features in the embodiments may be combined with each other.

[0030] The core difficulty in achieving reliable connection of thick layers (millimeter or even centimeter level) of ceramic materials lies in how to ensure a high enough laser energy density to melt the deep materials while avoiding destructive defects caused by process runaway.

[0031] Specifically, achieving deep penetration welding (deep penetration welding) requires maintaining extremely high power density at the focal point. However, once the actual injected power exceeds a critical threshold (which is closely related to the material's melting point, latent heat of vaporization, and thermal diffusion rate), the material's surface layer will violently vaporize, generating recoil pressure similar to that experienced during deep penetration laser welding of metals, which can force the molten metal downward and laterally. For brittle ceramics, this process is accompanied by high levels of uneven heat input and mechanical disturbances.

[0032] Furthermore, ceramic melts have high viscosity, poor fluidity, and high surface tension, making the keyhole walls susceptible to melt flow, vapor pressure fluctuations, and plasma shielding, leading to instability. Once the keyhole walls collapse and are refilled with melt, pores or holes are formed. Molten pool solidification shrinkage (especially in thick joints) exacerbates the tendency toward holes. Porosity is a critical weakness in welded joint strength and a source of cracking.

[0033] Furthermore, when welding thick ceramic layers, the weld depth (penetration) can reach several millimeters or even deeper. This increased depth leads to an expansion of the spot area (defocusing) and a significant decrease in power density. When the depth falls below the threshold for maintaining deep penetration welding, the welding mode suddenly switches from keyhole mode to heat conduction mode, with penetration sharply decreasing or even interrupted, resulting in unfused or uneven penetration within the joint. In a defocused state, the keyhole morphology is unstable, making spatter and voids more likely to occur. Excessive differences in energy input at different depths can cause weld deformation and induce cracks at the boundary of the fusion zone or at the interface between the fusion line and the base material.

[0034] In response to the above problems, this patent proposes a method for continuous laser welding of ceramic materials with high stability. Specifically, a layer of carbon particles 5 is coated on the surface of the ceramic material to regulate the absorption of the laser, and then a specific laser power is set under long-focus conditions to weld the ceramic material. With the assistance of the carbon particles 5, the continuous laser enhances absorption, avoiding porosity defects caused by changes in absorption rate during welding; under long-focus conditions, the laser power density is low, the spot size is large, and the focal depth is long. Specific focusing conditions and continuous power can be selected according to the thickness of the sample to achieve stable melting of the ceramic in a specified depth direction, avoiding welding defects caused by overheating and vaporization. Under the action of long focal depth and specific continuous laser power, high-stability welding of ceramic materials of specified thickness can be achieved.

[0035] The relative position relationship between the continuous laser generating module and the material fixing platform is as follows: Figure 1 As shown, the laser emitting side of the continuous laser generating module is arranged toward the material fixing platform. The material fixing platform is provided with a fixing component for fixing ceramics.

[0036] Preferably, the information processing module is a component disposed within the continuous laser generating module. The information processing module can also be disposed outside the continuous laser generating module and be wirelessly connected to the continuous laser generating module.

[0037] The information processing module proposed in this patent is a highly integrated data processing system that can realize data collection, storage, processing and interaction functions. The module includes data storage functions, which can store real-time collected data, historical data, processing models and historical processing results, and supports multiple storage methods such as blockchain storage, cloud storage services, in-memory databases, local storage devices and data warehouses. At the same time, the information processing module has data processing functions, which can analyze, calculate and model the collected data to generate corresponding evaluation results, support real-time processing and batch processing, and can run various machine learning models and statistical analysis algorithms. The information processing module also integrates data collection functions, can connect with various sensors and monitoring equipment to realize real-time data collection, and supports multiple communication protocols to adapt to different application scenarios. In addition, the information processing module has information interaction functions, can receive external instructions and output processing results, and supports interaction with various terminals such as smartphones, personal computers, tablets, smart wearable devices, industrial control terminals and in-vehicle information terminals.

[0038] In practical applications, the information processing module can adopt a cloud-based data processing model, uploading real-time data acquired by the data acquisition module to cloud storage, where the cloud server performs AI analysis and returns the results to the terminal device. Alternatively, a local edge computing model can be adopted, integrating the information processing module into a portable device in a confidentiality scenario to achieve local data processing and storage backup.

[0039] Example 1 A 30 mm × 30 mm × 3 mm alumina ceramic sheet was selected as the sample. Carbon black particles (5) were pre-coated to a thickness of 300 nm on the surface of the ceramic material. Two identical ceramic sheets were placed on top of each other and fixed using a fixture and a stage.

[0040] The relationship between melting depth and laser power is: D=0.17584×P×T / A, D: Melting depth, unit is mm; P: Laser power, unit is W; T: Welding time, unit is s; A: Welding area, unit is mm 2 .

[0041] Adjust the laser power and welding time of the equipment based on the requirements of the melting depth and welding area of ​​products composed of ceramic sheets of different materials during welding.

[0042] For example: the laser is controlled to output continuous laser light, and the average laser power of the continuous laser light is 300 W; the wavelength of the continuous laser light is 632.8 nm, and the light beam is focused on the contact interface of the two ceramic sheets after passing through a telephoto focusing lens, wherein the focal length of the focusing lens is 500 mm, and the diameter of the focused spot is 170 µm. The laser is controlled to scan the welding area, and the size of the welding area is 5 mm × 5 mm. The continuous laser light causes the material to melt at the contact interface of the two ceramic sheets, and the melting depth is 1.055 nm, and the welding is finally completed. Example 2 and Comparative Example 1 also limit the material, wavelength, and melting depth.

[0043] The tensile test showed that the typical strength of the welded sample was 75 MPa.

[0044] Example 2 A 30 mm × 30 mm × 3 mm alumina ceramic sheet was selected as the sample, and carbon particles 5 were coated on the surface of the ceramic material through pretreatment. Two identical ceramic sheets were placed on top of each other and fixed using a fixture and a stage.

[0045] The laser was controlled to output continuous laser light with an average power of 150 W. The beam was focused on the contact interface between the two ceramic sheets after passing through a telephoto focusing lens with a focal length of 500 mm and a focused spot diameter of 170 μm. The laser was controlled to scan the weld area with a welding time of 0.5 s and a weld area of ​​5 mm × 5 mm. The continuous laser light caused material melting at the interface between the two ceramic sheets. At this power, the material melted to a depth of approximately 0.528 mm, completing the weld.

[0046] The tensile test showed that the typical strength of the welded sample was 70 MPa.

[0047] Comparative Example 1 This embodiment is based on Figure 1 Welding operation method.

[0048] The laser was controlled to output continuous laser light with an average power of 150 W. The beam was focused on the contact interface between the two ceramic sheets after passing through a telephoto focusing lens with a focal length of 500 mm and a focused spot diameter of 170 μm. The laser was controlled to scan the weld area with a welding time of 0.59 s and a weld area of ​​5 mm × 5 mm. The continuous laser light caused material melting at the contact interface between the two ceramic sheets, with a melting power of approximately 0.528 mm, ultimately completing the weld.

[0049] The tensile test showed that the typical strength of the welded sample was 55 MPa.

[0050] Comparative Example 2 This embodiment is based on Figure 1 Welding operation method.

[0051] The laser was controlled to output continuous laser light with an average power of 150 W. The beam was focused on the contact interface between the two ceramic sheets after passing through a telephoto focusing lens with a focal length of 500 mm and a focused spot diameter of 170 μm. The laser was controlled to scan the weld area with a welding time of 0.48 s and a weld area of ​​5 mm × 5 mm. The continuous laser light caused melting of the material at the contact interface between the two ceramic sheets, with a melting power of approximately 0.528 mm, ultimately completing the weld.

[0052] The tensile test showed that the typical strength of the welded sample was 65 MPa.

[0053] Comparative Example 3 This embodiment is based on Figure 1 Welding operation method.

[0054] The laser was controlled to output continuous laser light with an average power of 150 W. The beam was focused on the contact interface between the two ceramic sheets after passing through a telephoto focusing lens with a focal length of 500 mm and a focused spot diameter of 170 μm. The laser was controlled to scan the weld area for a welding time of 0.3 s over a weld area of ​​5 mm × 5 mm. The continuous laser light caused melting of the material at the interface between the two ceramic sheets, ultimately completing the weld.

[0055] The tensile test showed that the typical strength of the welded sample was 40 MPa.

[0056] Through experimental research under different welding conditions, the inventor found that the typical strength value of the welded sample can be significantly improved by operating the welding procedure proposed in the present invention. This phenomenon shows that improper handling of the welding position can lead to bubbles and cracks in the weld that affect the strength. These defects not only reduce the effective bearing area of ​​the weld, but also introduce stress concentration points. Under stress, these stress concentration points will become weak links, making the weld joint more prone to local damage, thereby seriously affecting the overall performance and reliability of the welded structure. The welding procedure proposed based on the present invention can effectively avoid these problems and ensure welding quality and structural strength.

[0057] Comparative Example 4 The difference between this comparative example and Example 1 is that the alumina ceramic sheet is not pretreated for coating with carbon particles 5, and a short focal depth condition of 50 mm is adopted. Other experimental methods and selected parameters remain the same.

[0058] The tensile test showed that the typical strength of the welded sample was 30 MPa.

[0059] Figure 2 The cross-sectional view of the sample after welding with power adjusted shows that welding with only power adjusted will result in a relatively higher melting depth (a non-formula adjustment based on working experience), and with the increase, more obvious cracks will appear, resulting in different degrees of strength reduction, hardness reduction and porosity defects in the ceramic material centered on the welding position after welding.

[0060] The welding technology formed based on the procedure provided by the present invention and the carbon particle coating reduces cracks and pores at the welding position (the cracks and pores at some welding positions basically do not affect their connection relationship), and there is basically no problem of reduced strength and hardness at the welding position and its surrounding areas.

[0061] It should be noted that the above-described specific embodiments are illustrative only. Those skilled in the art may devise various solutions based on the disclosure of the present invention, and such solutions fall within the scope of the present invention and are intended to be protected by the present invention. Those skilled in the art should understand that the present description and its accompanying drawings are intended to be illustrative only and are not intended to limit the scope of the claims. The scope of protection of the present invention is defined by the claims and their equivalents.

Claims

1. A method for continuous laser high-stability welding of ceramic materials, characterized in that: The following steps are involved: S1: Coating a layer of 100-500 nm carbon particles (5) on the ceramic surface; S2: Under long focus conditions, select a specific power continuous laser to weld ceramic materials. For alumina ceramic sheets, for a specific welding depth, under fixed welding time and welding area, the relationship between melting depth and laser power is: D=0.17584×P×T / A, D: melting depth, unit is mm; P: laser power, unit is W; T: welding time, unit is s; A: welding area, unit is mm 2 .

2. The method for continuous laser welding of ceramic materials with high stability according to claim 1, characterized in that: The wavelength of the continuous laser is 266-2000 nm.

3. The method for continuous laser welding of ceramic materials with high stability according to claim 1, characterized in that: The continuous laser power is 100-500 W.

4. The method for continuous laser welding of ceramic materials with high stability according to claim 1, wherein: The telephoto condition is that the focal length is 500 mm or above.

5. The method for continuous laser welding of ceramic materials with high stability according to claim 1, characterized in that: The sample is fixed by a fixture and a stage so that the contact interface of the ceramic material is at the laser focus.

6. The method for continuous laser welding of ceramic materials with high stability according to claim 1, wherein: The melting depth of the ceramic material during welding is 0.05-2 mm.

7. The method for continuous laser welding of ceramic materials with high stability according to claim 1, wherein: The thickness of the ceramic material is 0.5-20 mm.

8. The method for continuous laser welding of ceramic materials with high stability according to claim 1, characterized in that: The ceramic material is one of aluminum oxide, aluminum nitride or silicon nitride.

9. The ceramic material prepared by the continuous laser high-stability welding method for ceramic materials according to any one of claims 1 to 8, characterized in that: The strength of the ceramic material after welding is typically 60-100 MPa.

10. A continuous laser high-stability welding device for ceramic materials, characterized in that: It includes continuous laser generating module, information processing module and material fixing platform. The information processing module is configured to: execute the continuous laser high-stability welding method for ceramic materials according to any one of claims 1 to 8, and control the continuous laser generating module to emit a continuous laser of a specific power to the ceramic material on the material fixing table.

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