[ ADLAM LAB ]

레이저가공디자인 연구실

Advanced Design & Laser Aided Manufacturing


INFORMATION

ChanHee Jeong (정찬희)

[Department of mechanical and Automotive Engineering Mechanical Design Major]

Engineering Building I 703, 1223-24 Cheonandaero, Seobuk-gu, Cheonan, 31080, Korea

(31080 충남 천안시 서북구 천안대로 1223-24 기계자동차공학부 1공학관 703호)

H. P  :  010 - 5406 - 3984

Email : hitony3984@gmail.com

  Relevant URL : https://sites.google.com/site/adlamlab2016/home 

EDUCATION

2020-, Kongju National University Mechanical Engineering, Cheonan 

2016 - 2019, Yong-In Arts & Science University


CONFERENCE


AWARDS


‘Start-up Idea Hackathon Competition’ was held in Deoksan Resom Resort. This contest was hosted by the Mobility Headquarters of Daejeon-Sejong-Chungnam Regional Innovation Platform. ADLAM team (Youngjin Seo, Jaegeun Shin, Seungeun Baek, Mincheoul Seong, Chanhee Jeong) won the second prize (1,000,000 KRW).2022.04.08~09

Paper Review

11. A review on dissimilar laser welding of steel-copper, steel-aluminum, aluminum-copper, and steel-nickel for electric vehicle battery manufacturing

Amirhossein Sadeghian, Naveed Iqbal

Keywords: Laser welding, Electric vehicle battery, Steel, Copper, Aluminium, Nickel

The electric vehicle (EV) battery systems are complex assemblies of dissimilar materials in which battery cells are connected using several thousand interconnect joints. Every single joint influences the functionality and efficiency of the whole battery system, making the joining process crucial. Laser welding is considered a desirable choice for EV battery manufacturing due to its non-contact nature, high energy density, precise control over the heat input, and ease of automation. However, incompatible thermos-physical properties of dissimilar materials used in battery tabs and interconnectors pose a significant challenge for achieving complete metallurgical bond. Furthermore, the formation of undesirable weld microstructures such as hard and brittle intermetallic compounds (IMCs) substantially undermines the structural, electrical, and thermal characteristics of battery joints. This paper reviews the fundamental difficulties and latest developments in dissimilar laser welding of steel-copper, steel-aluminum, aluminum-copper, and steel-nickel, some of the potential joint combinations in EV battery pack manufacturing. The weld microstructure and common metallurgical defects, as well as mechanical and electrical properties of joints are discussed. In addition, the effects of laser welding process parameters on the joint properties and the applicability of various interlayers and coatings in laser welding of battery materials are assessed.

10. Automated translating beam profiler for in situ laser beam spot-size and focal position measurements

James Keaveney 

keywords: Electrical properties and parameters, Image processing, Programming languages, Stepper motors, Optical imaging, Geometrical optics, Image sensors, Lenses, Gaussian beam, Covariance and correlation

We present a simple and convenient, high-resolution solution for automated laser-beam profiling with axial translation. The device is based on a Raspberry Pi computer, Pi Noir CMOS camera, stepper motor, and commercial translation stage. We also provide software to run the device. The CMOS sensor is sensitive over a large wavelength range between 300 and 1100 nm and can be translated over 25 mm along the beam axis. The sensor head can be reversed without changing its axial position, allowing for a quantitative estimate of beam overlap with counter-propagating laser beams. Although not limited to this application, the intended use for this device is the automated measurement of the focal position and spot-size of a Gaussian laser beam. We present example data of one such measurement to illustrate device performance.

9. Laser-Induced Ni Foil-Supported NiO@Ni(OH) 2 Hierarchical Structures as Advanced Cathodes for Ultrahigh Performance Nickel−Zinc Batteries

Hui Xiao, Zhen Yang, Yanling Tian*, and Jinglei Yang*

Keywords: femtosecond laser, chemical bath deposition, hierarchical structures, NiO@Ni(OH)2, Ni−Zn battery, stable cycling performance

Laser-Induced Ni Foil.pdf

Aqueous Zn-ion batteries have long been considered as a promising substitute for Li-ion batteries due to their low cost, improved safety, and better environmental sustainability. However, the unsatisfactory energy/power density and inferior cycling ability are the two key obstacles of the aqueous nickel–zinc (Ni–Zn) battery, mainly due to the low capacity and serious irreversibility of its Ni-based cathode. To solve these issues, femtosecond laser texturing along with chemical bath deposition was performed to synthesize a 3D hierarchical NiO@Ni(OH)2 composite structure on a nickel foil as an ultrahigh performance cathode for the Ni–Zn battery. Compared with the nickel foil treated only by chemical bath deposition (denoted as NN@NF), the areal capacity of the Ni foil treated by femtosecond laser texturing and the chemical deposition technique (denoted as NN@LTNF) was substantially improved, achieving 0.593 mA h cm–2 at 10 mA cm–2. Moreover, the as-prepared NN@LTNF//Zn battery demonstrated an ideal peak energy density (0.586 mW h cm–2) and power density (86.7 mW cm–2). Particularly, the NN@LTNF//Zn battery could deliver outstanding reversibility and excellent cycling durability (90.2% capacity retention after 1800 cycles). The prominent improvement of electrochemical performance can be attributed to the NiO@Ni(OH)2 composite structure with 3D network morphology and superhydrophilic property, which can facilitate electrolyte penetration and thus ion mobility to active reaction sites. This research may provide promising vistas for laser-processed advanced Ni-based cathodes in ultrahigh electrochemical performance aqueous Ni–Zn batteries.

8. Optimization of process parameters for reducing warpage in selected laser sintering of polymer parts

Ali Ahmadi Dastjerdi, Mohammad R. Movahhedy, Javad Akbari

Keywords: Selected laser sintering, Warpage, Optimization, FEM

Optimization of process parameters for reducing warpage in selected laser sintering of polymer parts.pdf

Selective Laser Sintering (SLS) is a rapidly growing additive manufacturing process, because it has the capacity to build parts from a variety of materials. However, the dimensional accuracy of the fabricated parts in this process is dependent on the ability to control phenomena such as warpage and shrinkage. This research presents an optimization algorithm to find the best processing parameters for minimizing warpage. The finite element method was used to simulate the sintering of a layer of polymer powder, and the warpage of the layer was calculated. The numerical model was verified through comparison with experimental results. A back-propagation neural network was used to formulate the mapping between the design variables and the objective function. Results of 40 simulation cases with various input parameters such as scanning pattern and speed, laser power, surrounding temperature, and layer thickness were used to train and test the neutral network. Finally, The Genetic Algorithm was employed to optimize the objective function, and the influence of parameters on warpage was investigated. 

7.  Quasi-Continuous Wave Pulsed Laser Welding of Copper Lap Joints Using Spatial Beam Oscillation

Amirhossein Sadeghian 1,*,Subhasisa Nath 1,Yuze Huang 1,*,Ranveer S. Matharu 1,Noppawee Wadee 1,Nicolas Pembrey 2, David G. Waugh 1,*

Keywords: laser beam welding; copper; spatial beam oscillation; oscillation amplitude; oscillation frequency

Laser beam welding of copper (Cu) using near-infrared radiation is extremely challenging due to its high thermal conductivity and large laser reflectivity. In the present study, the challenges and benefits of using spatial beam oscillation during quasi-continuous wave (QCW) pulsed laser beam welding of 0.4 mm Cu to 1 mm Cu in lap joint configuration are presented. This work demonstrates how laser beam oscillating parameters can be used to control the laser weld quality and laser weld dimensions for Cu-Cu joining. Compared to a non-oscillated laser beam, welds made using laser beam oscillation showed fewer spatters, porosities, and better surface quality. Four levels of oscillating amplitudes (0.2 mm, 0.4 mm, 0.6 mm, and 0.8 mm) and oscillating frequencies (100 Hz, 200 Hz, 300 Hz, and 400 Hz) were compared to reveal the effect of beam oscillation parameters. The weld width was mainly controlled by oscillating amplitude, while weld penetration was affected by both oscillating amplitude and frequency. As the oscillating amplitude increased, the weld width increased while the weld penetration decreased. Increasing the oscillating frequency reduced the weld penetration but had a negligible effect on the weld width. The maximum tensile force of approximately 1944 N was achieved for the joint with a high width-to-depth ratio with an oscillating amplitude of 0.8 mm and an oscillating frequency of 200 Hz.

6. Statistical evaluation method to determine the laser welding depth by optical coherence tomography

Meiko Boley, Florian Fetzer, Rudolf Weber, Thomas Graf

Keywords: Laser welding, depth measurement, Optical coherence tomography (OCT), Inline coherent imaging (ICI), Welding depth, Online penetration depth measurement

A statistical filtering method to determine the depth of laser-welded seams from signals recorded by means of optical coherence tomography (OCT) is proposed and discussed. The measured data points are initially classified into noise and significant data by means of a noise probability, which was defined based on the normalized Poisson distribution. A percentile filter is then applied to the significant data to obtain the depth of the weld seam. It is shown that the depth determined by this approach corresponds to the real seam depth, as obtained from longitudinal sections, to within an average error of less than 5%. The method can be applied to different laser welding situations without having to adjust the filter parameters.

5.  Structural and oxide-based colours on laser textured copper

G. Killaire a b, J. Walia a c, S. Rashid a, P. Berini a b c, A. Weck a b d

Keywords: Nanoparticles, Surface Characterization, Structural color, Laser machining, Nanostructured Copper

Laser texturing to create colours has recently attracted significant interest due to the rapid and non-contact nature of the technique. The complex optical response of femtosecond laser-textured copper surfaces, producing a palette of perceived colours with varying amounts of angle dependence, is presented. The colours depend on the line spacing used in the laser raster-scanning process. Grazing angle Fourier transform Infrared spectroscopy (FTIR) and Raman microscopy show increased oxide content with larger total accumulated fluence and increased pulse overlap. The increased oxide content coincides with a greater angle independence of the colours compared to colours obtained at larger line spacings. All samples have a similar sinusoidal periodic microstructure, with amplitudes ranging from 400 nm for the smallest line spacings (∼1 µm) to 100 nm for the largest line spacings (∼20 µm), and are decorated with nanoparticles. The angle dependence of the colours is quantified using reflectance measurements, which show a shift in reflectance peak with observation angle. The overall complex colour of the surfaces is attributed to a combination of copper oxides and structural colours driven by underlying nanoparticles, be they metal or metal-oxide, and sinusoidal gratings with a pitch of approximately 1 µm.

4. Surface ablation efficiency and quality of fs lasers in single-pulse mode, fs lasers in burst mode, and ns lasers

M. Domke a, V. Matylitsky b, S. Stroj a

Keywords: Laser ablation, Ablation efficiency, Burst mode, Silicon, Copper, Steel

Review_Al colour3.pdf

In recent years, the burst-mode caught a lot of attention in the field of ultrashort-pulse laser micro machining. One of the major issues is the influence of the burst pulse number and frequency on ablation efficiency and quality. A recent publication reported of a significant increase in ablation efficiency when processing with ≥25 burst pulses at ≥100 MHz burst frequencies. This raises the question of whether processing with such high pulse densities can be attributed to non-thermal ablation, or whether a quasi-nanosecond laser ablation behavior is achieved. To answer this question, we determined ablation efficiencies as function of fluence for silicon, stainless steel, and copper and compared the ablation quality at the optimal fluence using the following laser systems: femtosecond laser operated in single-pulse mode, fs laser operated in 28-pulse-burst mode with a burst pulse frequency of 148 MHz, and a nanosecond laser with a pulse duration of 175 ns, which is identical with the temporal length of the burst pulse train. The comparison showed that the burst mode used produces similar surface morphologies and melt burrs as the nanosecond laser, but at about 2/3 of its efficiency.

3. Ultrafast laser ablation of indium tin oxide thin films for organic light-emitting diode application

Mira Parka, b) , Byong Hyok Chon a, Hyun Sun Kim a, Sae Chae Jeoung a, Dongho Kim b, Jeoung-Ik Lee c, Hye Yong Chu c, Hyeong Rae Kim d

Keywords: Ultrafast laser,Patterning, ITO, OLED

Ultrafast laser ablation of indium tin oxide thin films for organic light-emitting diode application.pdf

Ultrafast laser ablation of ITO thin film coated on the glass has been investigated as a function of laser fluence as well as the number of laser pulses. The ablation threshold of ITO thin film was found to be 0.07 J/cm2 that is much lower than that of glass substrate (about 1.2–1.6 J/cm2), which leads to a selective ablation of ITO film without damage on glass substrate. The changes in the electrical resistance and morphology of ablated trench of ITO electrode were found to be strongly dependent on the processing conditions. We present the performance of organic light-emitting diodes (OLED) fabricated with ITO electrode patterned by ultrafast laser ablation.

2. Microstructure and properties of Laser Surface Remelting AlCoCrFeNi2.1 HighEntropy Alloy

J. Chen1), J. Zhang1), K. Li2), D. Zhuang2), Q. Zang3), H. Chen3), Y. Lu4), B. Xu4) and Y. Zhang1) 

Keywords: AlCoCrFeNi2.1 high-entropy alloy, laser surface remelting; microstructure, wear resistance properties, corrosion resistance properties

In this study, laser surface remelting of an AlCoCrFeNi2.1 high-entropy alloy was performed using a Yb:YAG laser. The effects of laser surface remelting on the phase structure, microstructure, Vickers hardness, frictional wear properties, and corrosion resistance of the high-entropy alloy were investigated. The remelted layer of the AlCoCrFeNi2.1 high-entropy alloy was produced by remelting at 750 W laser power and formed a good metallurgical bond with the substrate. The X-ray diffraction results showed that the 750 W remelted layer consisted of face-centered cubic and body-centered cubic phases, which were consistent with the phases of the as-cast AlCoCrFeNi2.1 high-entropy alloy, and a new phase was not generated within the remelted layer. Laser surface remelting is very effective in refining the lamellar structure, and the 750 W remelted layer shows a finer lamellar structure compared to the matrix. The surface hardness and wear resistance of the AlCoCrFeNi2.1 high-entropy alloy were substantially improved after laser surface remelting. In a 3.5 wt.% NaCl solution, the laser-remelted surface had a larger self-corrosion potential and smaller self-corrosion current density, and the corrosion resistance was better than that of the as-cast high-entropy alloy. 

For centuries, it had been the dream of alchemists to turn inexpensive metals into gold. Certainly, it is not enough from an alchemist’s point of view to transfer only the appearance of a metal to gold. However, the possibility of rendering a certain metal to a completely different color without coating can be very interesting in its own right. In this work, we demonstrate a femtosecond laser processing technique that allows us to create a variety of colors on a metal that ultimately leads us to control its optical properties from UV to terahertz.