Markus Wagner, Fabian Günther, Rishabh Rajesh Rao, Uwe Stamm, Dirk Dittrich, Axel Jahn
Laser welding in transmission manufacturing opens up completely new kinds of product solutions with excellent properties in terms of wear, corrosion resistance, and service life. Current welding designs are characterized in particular by difficult-to-weld material combinations (e.g., steel versus cast iron) and a high component stiffness, which is correlated with high residual welding stresses. The major challenge for these mass-produced components remains both their crack-free weldability and their complex cyclic load capacity [U. Stamm, “Rissfreies Laserstrahlschweißen von Mischverbindungen aus Gusseisen und Einsatzstahl, Jahresbericht Fraunhofer IWS 2006” (2006); X. Shu, “Untersuchungen zum Laserstrahlschweißen von Werkstoffkombinationen aus Gußeisen und Stahl,” Dissertation, Shaker, Band 4/94 (1994), ISBN: 3-8265-0098-9; G. Göbel, “Erweiterung der Prozessgrenzen beim Laserstrahlschweißen heißrissgefährdeter Werkstoffe,” Dissertation, Fraunhofer-IRB-Verlag (2007), ISBN: 978-3-8167-7671-0]. Therefore, this contribution presents practical solutions for weld-compatible joint constructions and the reduction of residual stresses on the basis of a representative transmission design. Specifically, a systematic study is being conducted to understand and qualitatively evaluate effective methods for reducing residual weld stresses in circumferential welds. The recommendations developed as part of this study take particular account of the influence of process modifications, material conditions, and geometric aspects on weldability and component distortion. Here, structural welding simulations are performed and verified by experimental welding trials, including metallographic examinations. To ensure the required component fatigue strength, a practical concept for determining Wöhler curves is presented, which is based on structural mechanical simulations and multiaxial fatigue strength tests on simplified test specimens. The adaptations developed in this way facilitate the production of difficult-to-weld and highly stressed transmission components. In particular, time-consuming and cost-intensive iterations of laser welding tests can be significantly reduced or even eliminated [Brenner et al., “Neuere Ergebnisse zum Schweißen von Eisenbasiswerkstoffen mit Faserlasern, 5. Laser-Anwenderforum,” Strahltechnik Band 28 (2006), pp. 139–148, ISBN: 3-933762-18-9, S]. Furthermore, the systematic investigations provide effective recommendations for phenomenological understanding and solving typical welding challenges in practice [J. Standfuß, “Ganzheitliche innovative fügetechnische Konzepte am Beispiel des PKW-Antriebsstranges,” Fraunhofer Verlag (2010), ISBN: 978-3-8396-0125-9]. This applies, in particular, to load-transmitting components in the fields of e-mobility, aerospace, and industrial engineering [Wagner et al., “Entwickeln und Auslegen von lasergeschweißten Getriebe-komponenten für die Luftfahrt,” DVS-Berichte Band 365 (2020), pp. 62–69, ISBN: 978-3-96144
激光焊接在传动制造中开辟了全新的产品解决方案，在耐磨、耐腐蚀和使用寿命方面具有优异的性能。当前的焊接设计尤其以难以焊接的材料组合(例如，钢与铸铁)和高部件刚度为特征，这与高残余焊接应力相关。这些量产部件面临的主要挑战是其无裂纹焊接性和复杂的循环载荷能力。斯塔姆，“激光辐射与激光辐射”，德国劳恩霍夫学会(2006);舒欣，“Untersuchungen zum Laserstrahlschweißen von Werkstoffkombinationen aus Gußeisen und Stahl”，博士论文，振动，第4/94期(1994)，ISBN: 3-8265-0098-9;G. Göbel，“Erweiterung der Prozessgrenzen beim Laserstrahlschweißen heißrissgefährdeter Werkstoffe”，Dissertation, Fraunhofer-IRB-Verlag (2007)， ISBN: 978-3-8167-7671-0]。因此，这一贡献为焊接兼容接头结构和减少残余应力提供了实用的解决方案，并以代表性传动设计为基础。具体来说，正在进行一项系统的研究，以了解和定性评估减少环向焊缝残余应力的有效方法。作为本研究的一部分，提出的建议特别考虑了工艺修改、材料条件和几何方面对可焊性和部件变形的影响。在这里，进行了结构焊接模拟，并通过实验焊接试验进行了验证，包括金相检查。为了保证构件所需的疲劳强度，提出了一种基于结构力学模拟和简化试件多轴疲劳强度试验的Wöhler曲线确定的实用概念。以这种方式开发的适应性有助于生产难以焊接和高应力的传动部件。特别是，激光焊接测试的耗时和成本密集的迭代可以大大减少甚至消除[Brenner等人，“Neuere Ergebnisse zum schweien von Eisenbasiswerkstoffen mit faserlasen, 5]。Laser-Anwenderforum， " Strahltechnik Band 28 (2006)， pp. 139-148, ISBN: 3-933762-18-9, S]。此外，系统的研究为理解现象学和解决实践中的典型焊接挑战提供了有效的建议[J]。斯坦弗斯，“Ganzheitliche innovative f getechnische Konzepte am Beispiel des PKW-Antriebsstranges”，弗劳恩霍夫出版社(2010)，ISBN: 978-3-8396-0125-9。这尤其适用于电动汽车、航空航天和工业工程领域的负载传输组件[Wagner等人，“Entwickeln und Auslegen von lasergeschweißten Getriebe-komponenten f r die Luftfahrt，”DVS-Berichte Band 365 (2020)， pp. 62-69, ISBN: 978-3-96144-098-6]。
{"title":"New possibilities for laser welding of highly loaded transmission components by strategic use of simulation methods","authors":"Markus Wagner, Fabian Günther, Rishabh Rajesh Rao, Uwe Stamm, Dirk Dittrich, Axel Jahn","doi":"10.2351/7.0001189","DOIUrl":"https://doi.org/10.2351/7.0001189","url":null,"abstract":"Laser welding in transmission manufacturing opens up completely new kinds of product solutions with excellent properties in terms of wear, corrosion resistance, and service life. Current welding designs are characterized in particular by difficult-to-weld material combinations (e.g., steel versus cast iron) and a high component stiffness, which is correlated with high residual welding stresses. The major challenge for these mass-produced components remains both their crack-free weldability and their complex cyclic load capacity [U. Stamm, “Rissfreies Laserstrahlschweißen von Mischverbindungen aus Gusseisen und Einsatzstahl, Jahresbericht Fraunhofer IWS 2006” (2006); X. Shu, “Untersuchungen zum Laserstrahlschweißen von Werkstoffkombinationen aus Gußeisen und Stahl,” Dissertation, Shaker, Band 4/94 (1994), ISBN: 3-8265-0098-9; G. Göbel, “Erweiterung der Prozessgrenzen beim Laserstrahlschweißen heißrissgefährdeter Werkstoffe,” Dissertation, Fraunhofer-IRB-Verlag (2007), ISBN: 978-3-8167-7671-0]. Therefore, this contribution presents practical solutions for weld-compatible joint constructions and the reduction of residual stresses on the basis of a representative transmission design. Specifically, a systematic study is being conducted to understand and qualitatively evaluate effective methods for reducing residual weld stresses in circumferential welds. The recommendations developed as part of this study take particular account of the influence of process modifications, material conditions, and geometric aspects on weldability and component distortion. Here, structural welding simulations are performed and verified by experimental welding trials, including metallographic examinations. To ensure the required component fatigue strength, a practical concept for determining Wöhler curves is presented, which is based on structural mechanical simulations and multiaxial fatigue strength tests on simplified test specimens. The adaptations developed in this way facilitate the production of difficult-to-weld and highly stressed transmission components. In particular, time-consuming and cost-intensive iterations of laser welding tests can be significantly reduced or even eliminated [Brenner et al., “Neuere Ergebnisse zum Schweißen von Eisenbasiswerkstoffen mit Faserlasern, 5. Laser-Anwenderforum,” Strahltechnik Band 28 (2006), pp. 139–148, ISBN: 3-933762-18-9, S]. Furthermore, the systematic investigations provide effective recommendations for phenomenological understanding and solving typical welding challenges in practice [J. Standfuß, “Ganzheitliche innovative fügetechnische Konzepte am Beispiel des PKW-Antriebsstranges,” Fraunhofer Verlag (2010), ISBN: 978-3-8396-0125-9]. This applies, in particular, to load-transmitting components in the fields of e-mobility, aerospace, and industrial engineering [Wagner et al., “Entwickeln und Auslegen von lasergeschweißten Getriebe-komponenten für die Luftfahrt,” DVS-Berichte Band 365 (2020), pp. 62–69, ISBN: 978-3-96144","PeriodicalId":50168,"journal":{"name":"Journal of Laser Applications","volume":"50 4","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-11-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135614680","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Timo Rautio, Matias Jaskari, Markku Keskitalo, Joonas Päkkilä, Antti Järvenpää
Additive manufacturing is an enticing way of producing complex geometries and optimized parts for special applications. Even though the achievable static properties for the printed material are usually good when compared to wrought materials, in many cases dynamic properties are known to be much worse. Often, the quality is sacrificed in respect of printing speed. Furthermore, printed materials have usually anisotropic behavior, caused by the remelting and fast cooling of each deposited layer. This means that the mechanical properties need to be measured in several directions in respect of the printing direction for attaining a more holistic approach to the achieved static and dynamic behavior. As a demonstration, this study focuses on determining the properties of 316L stainless steel-manufactured with laser powder bed fusion. A comprehensive set of samples for various testing methods were manufactured to investigate the effect of the layer thickness and printing orientation on the microstructure, mechanical properties, impact strength, and fatigue life. Fatigue performance of the material was evaluated in both axial and flexural bending comparing as-built and polished surface conditions. Bending fatigue testing revealed that a fatigue limit of 100 MPa at best can be achieved with the as-built surface quality, but with a polished surface and lower layer thickness, it could be doubled. Impact toughness and mechanical strength of the material are heavily dependent on the layer thickness, and while the best results were obtained with the lower layer thickness, the printing orientation can have a detrimental effect on it.
{"title":"Fatigue strength and impact toughness dependence of powder bed fusion with laser beam-manufactured 316L stainless steel on orientation and layer thickness","authors":"Timo Rautio, Matias Jaskari, Markku Keskitalo, Joonas Päkkilä, Antti Järvenpää","doi":"10.2351/7.0001113","DOIUrl":"https://doi.org/10.2351/7.0001113","url":null,"abstract":"Additive manufacturing is an enticing way of producing complex geometries and optimized parts for special applications. Even though the achievable static properties for the printed material are usually good when compared to wrought materials, in many cases dynamic properties are known to be much worse. Often, the quality is sacrificed in respect of printing speed. Furthermore, printed materials have usually anisotropic behavior, caused by the remelting and fast cooling of each deposited layer. This means that the mechanical properties need to be measured in several directions in respect of the printing direction for attaining a more holistic approach to the achieved static and dynamic behavior. As a demonstration, this study focuses on determining the properties of 316L stainless steel-manufactured with laser powder bed fusion. A comprehensive set of samples for various testing methods were manufactured to investigate the effect of the layer thickness and printing orientation on the microstructure, mechanical properties, impact strength, and fatigue life. Fatigue performance of the material was evaluated in both axial and flexural bending comparing as-built and polished surface conditions. Bending fatigue testing revealed that a fatigue limit of 100 MPa at best can be achieved with the as-built surface quality, but with a polished surface and lower layer thickness, it could be doubled. Impact toughness and mechanical strength of the material are heavily dependent on the layer thickness, and while the best results were obtained with the lower layer thickness, the printing orientation can have a detrimental effect on it.","PeriodicalId":50168,"journal":{"name":"Journal of Laser Applications","volume":"14 3","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-11-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135410357","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Daniel Koti, John Powell, Himani Naesstroem, Chiara Spaccapaniccia, K. T. Voisey
This paper provides quantitative information about the paths taken by blown powder particles during laser cladding. A proportion of the powder is “wasted” by bouncing off the solid areas surrounding the melt pool. This wastage reduces the productivity and profitability of the process. In this paper, specially developed software was used to analyze high-speed imaging videos of the cladding process, to monitor the directions of powder particle flight toward and away from the melt pool area. This information has been correlated to the geometry and position of the melt pool zone for three different cladding techniques: single track cladding (A tracks), standard overlapping track cladding (AAA cladding), and a recently developed technique called ABA cladding. The results show that the melt pool geometry, and particularly the overlap between the melt pool and the incoming powder stream, has a strong influence on powder catchment efficiency. ABA cladding was found to have considerably better powder catchment efficiency than standard AAA cladding and this improvement can be explained by consideration of the geometries and positions of the melt pools and surrounding solid material in each case. As powder costs are an important factor in industrial laser cladding, the adaption of the ABA technique, and/or control of pool/powder stream overlap (e.g., by making the powder stream not coaxial with the laser beam), could improve the profitability of the process.
{"title":"Laser cladding: A high-speed-imaging examination of powder catchment efficiency as a function of the melt pool geometry and its position under the powder stream","authors":"Daniel Koti, John Powell, Himani Naesstroem, Chiara Spaccapaniccia, K. T. Voisey","doi":"10.2351/7.0001199","DOIUrl":"https://doi.org/10.2351/7.0001199","url":null,"abstract":"This paper provides quantitative information about the paths taken by blown powder particles during laser cladding. A proportion of the powder is “wasted” by bouncing off the solid areas surrounding the melt pool. This wastage reduces the productivity and profitability of the process. In this paper, specially developed software was used to analyze high-speed imaging videos of the cladding process, to monitor the directions of powder particle flight toward and away from the melt pool area. This information has been correlated to the geometry and position of the melt pool zone for three different cladding techniques: single track cladding (A tracks), standard overlapping track cladding (AAA cladding), and a recently developed technique called ABA cladding. The results show that the melt pool geometry, and particularly the overlap between the melt pool and the incoming powder stream, has a strong influence on powder catchment efficiency. ABA cladding was found to have considerably better powder catchment efficiency than standard AAA cladding and this improvement can be explained by consideration of the geometries and positions of the melt pools and surrounding solid material in each case. As powder costs are an important factor in industrial laser cladding, the adaption of the ABA technique, and/or control of pool/powder stream overlap (e.g., by making the powder stream not coaxial with the laser beam), could improve the profitability of the process.","PeriodicalId":50168,"journal":{"name":"Journal of Laser Applications","volume":"28 4","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-11-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135509884","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Daniel Franz, Yongting Yang, Luis Michel, Cemal Esen, Ralf Hellmann
We report for the first time on the realization, characterization and application of an ultrashort pulsed laser robot system for flexible and large-area 2D and 3D laser micromachining with 6 articulated axes. To characterize the dynamic positioning of the laser beam during and after axes movement, CMOS image sensors were integrated into the beam path. A method introduced for the alignment of the optical axes allows a reduction of the deviations in laser beam positioning to less than 141.8 ± 92.9 μm within a 110° rotation range of axis 4. In addition, a high laser beam positioning repeatability of less than 102.2 μm is demonstrated over a total period of 14 h for a movement of axis 5 within a range of 0° to 90°. Initial laser cutting, laser structuring and laser marking applications on automotive dashboards and glass substrates are presented for flexible and large area 2D and 3D manufacturing. By applying a special laser cutting strategy for processing AF 32 eco thin glass, high cutting quality is achieved with a taper of up to 96.3% without the generation of cracks, demonstrating the innovative potential of the high-precision laser robot system. Nonetheless, different identified inherent influences of each axis 1–5 during robot axis movement demand for an innovative beam stabilization concept to achieve high precision in laser beam positioning.
{"title":"Evaluation of an ultrashort pulsed laser robot system for flexible and large-area micromachining","authors":"Daniel Franz, Yongting Yang, Luis Michel, Cemal Esen, Ralf Hellmann","doi":"10.2351/7.0001171","DOIUrl":"https://doi.org/10.2351/7.0001171","url":null,"abstract":"We report for the first time on the realization, characterization and application of an ultrashort pulsed laser robot system for flexible and large-area 2D and 3D laser micromachining with 6 articulated axes. To characterize the dynamic positioning of the laser beam during and after axes movement, CMOS image sensors were integrated into the beam path. A method introduced for the alignment of the optical axes allows a reduction of the deviations in laser beam positioning to less than 141.8 ± 92.9 μm within a 110° rotation range of axis 4. In addition, a high laser beam positioning repeatability of less than 102.2 μm is demonstrated over a total period of 14 h for a movement of axis 5 within a range of 0° to 90°. Initial laser cutting, laser structuring and laser marking applications on automotive dashboards and glass substrates are presented for flexible and large area 2D and 3D manufacturing. By applying a special laser cutting strategy for processing AF 32 eco thin glass, high cutting quality is achieved with a taper of up to 96.3% without the generation of cracks, demonstrating the innovative potential of the high-precision laser robot system. Nonetheless, different identified inherent influences of each axis 1–5 during robot axis movement demand for an innovative beam stabilization concept to achieve high precision in laser beam positioning.","PeriodicalId":50168,"journal":{"name":"Journal of Laser Applications","volume":"125 8","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-10-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"136023536","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Jurandir Marcos Sá de Sousa, Milton Pereira, Juliane Ribeiro da Cruz, Anselmo Thiesen Júnior, Henrique Santos Ferreira, Jhonattan Gutjahr
Additively manufactured martensitic stainless steel components can combine complex geometry with superior mechanical and corrosion performance. In this work, the mechanical performance of AISI 410L processed by laser directed energy deposition (L-DED) additive manufacturing using previously optimized parameters is assessed. Microstructure, hardness, tensile strength, and Charpy impact toughness are evaluated in the as-built and heat-treated conditions. Four heat-treatment routes are investigated: (I) austenitization and water quenched, and austenitization, water quenched, and tempered at (II) 300, (III) 450, and (IV) 600 °C, followed by air cooling. The results show that, for tempering temperatures up to 450 °C, the hardness, yield strength, and ultimate tensile strength show an increasing trend when compared with the as-built condition and reference commercial standard (annealed AISI 410) because of microstructure refinement induced by recrystallization. Tempering at 600 °C, on the other hand, enhances the ductility of the specimens, accounting for an increased deformation until fracture and superior Charpy impact toughness. In summary, this work demonstrates that, for all tested conditions, the tensile strength of the AISI 410L additively manufactured by L-DED outperforms that of the standardized commercial AISI 410 martensitic stainless steel, and that post-processing heat-treatments can be used to further enhance toughness and ductility, making it even more competitive.
{"title":"Influence of post-processing heat-treatment on the mechanical performance of AISI 410L stainless steel manufactured by the L-DED process","authors":"Jurandir Marcos Sá de Sousa, Milton Pereira, Juliane Ribeiro da Cruz, Anselmo Thiesen Júnior, Henrique Santos Ferreira, Jhonattan Gutjahr","doi":"10.2351/7.0001135","DOIUrl":"https://doi.org/10.2351/7.0001135","url":null,"abstract":"Additively manufactured martensitic stainless steel components can combine complex geometry with superior mechanical and corrosion performance. In this work, the mechanical performance of AISI 410L processed by laser directed energy deposition (L-DED) additive manufacturing using previously optimized parameters is assessed. Microstructure, hardness, tensile strength, and Charpy impact toughness are evaluated in the as-built and heat-treated conditions. Four heat-treatment routes are investigated: (I) austenitization and water quenched, and austenitization, water quenched, and tempered at (II) 300, (III) 450, and (IV) 600 °C, followed by air cooling. The results show that, for tempering temperatures up to 450 °C, the hardness, yield strength, and ultimate tensile strength show an increasing trend when compared with the as-built condition and reference commercial standard (annealed AISI 410) because of microstructure refinement induced by recrystallization. Tempering at 600 °C, on the other hand, enhances the ductility of the specimens, accounting for an increased deformation until fracture and superior Charpy impact toughness. In summary, this work demonstrates that, for all tested conditions, the tensile strength of the AISI 410L additively manufactured by L-DED outperforms that of the standardized commercial AISI 410 martensitic stainless steel, and that post-processing heat-treatments can be used to further enhance toughness and ductility, making it even more competitive.","PeriodicalId":50168,"journal":{"name":"Journal of Laser Applications","volume":"179 ","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-10-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"136067819","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Khalaf Ajaj, Mushtaq Abed Al-Jubbori, Abdullah M. Ali
In this study, we synthesized colloidal copper nanoparticles (CuNPs) utilizing Q-switched Nd:YAG laser ablation on a copper plate immersed in double-distilled water at energies of 200 and 400 mJ, respectively, with 100, 200, 300, 400, and 500 pulses. The size and optical properties of nanoparticles were determined using a UV–Vis spectrophotometer, a transmission electron microscope (TEM), and a field emission scanning electron microscope (FE-SEM). The absorption spectra exhibited two surface plasmon resonance peaks (λSPR), one at 217 nm for copper oxide nanoparticles (CuONPs) and the other at 636 nm for CuNPs, with the increase in laser pulses. Consequently, the optical bandgap increased by roughly 3 eV. The TEM and FE-SEM analyses showed nearly spherical Cu nanoparticles with average diameters of 33 and 38 nm for laser energies of 200 and 400 mJ, respectively. An analysis of x-ray diffraction patterns revealed that CuONPs contained the crystallographic planes of a monoclinic and an orthorhombic crystal system. Additionally, the mean crystallite size of laser-ablated nanoparticles increased with increasing pulse energy. Furthermore, the absorption and optical bandgap of CuNPs increased slightly with an increase in ultraviolet irradiation exposure. The results of our study showed an increased inhibitory effect against both Staphylococcus aureus bacteria and Escherichia coli bacteria when CuNPs were irradiated by ultraviolet type C.
{"title":"Influence of ultraviolet irradiation on the optical properties and biological activity of copper nanoparticles prepared by pulsed laser ablation","authors":"Khalaf Ajaj, Mushtaq Abed Al-Jubbori, Abdullah M. Ali","doi":"10.2351/7.0001221","DOIUrl":"https://doi.org/10.2351/7.0001221","url":null,"abstract":"In this study, we synthesized colloidal copper nanoparticles (CuNPs) utilizing Q-switched Nd:YAG laser ablation on a copper plate immersed in double-distilled water at energies of 200 and 400 mJ, respectively, with 100, 200, 300, 400, and 500 pulses. The size and optical properties of nanoparticles were determined using a UV–Vis spectrophotometer, a transmission electron microscope (TEM), and a field emission scanning electron microscope (FE-SEM). The absorption spectra exhibited two surface plasmon resonance peaks (λSPR), one at 217 nm for copper oxide nanoparticles (CuONPs) and the other at 636 nm for CuNPs, with the increase in laser pulses. Consequently, the optical bandgap increased by roughly 3 eV. The TEM and FE-SEM analyses showed nearly spherical Cu nanoparticles with average diameters of 33 and 38 nm for laser energies of 200 and 400 mJ, respectively. An analysis of x-ray diffraction patterns revealed that CuONPs contained the crystallographic planes of a monoclinic and an orthorhombic crystal system. Additionally, the mean crystallite size of laser-ablated nanoparticles increased with increasing pulse energy. Furthermore, the absorption and optical bandgap of CuNPs increased slightly with an increase in ultraviolet irradiation exposure. The results of our study showed an increased inhibitory effect against both Staphylococcus aureus bacteria and Escherichia coli bacteria when CuNPs were irradiated by ultraviolet type C.","PeriodicalId":50168,"journal":{"name":"Journal of Laser Applications","volume":"182 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-10-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"136381576","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Lucas Hille, Johannes Kriegler, Andreas Oehler, Michalina Chaja, Sebastian Wagner, Michael F. Zaeh
Laser structuring of graphite anodes substantially improves the electrochemical performance of lithium-ion batteries by facilitating lithium-ion diffusion through the electrode coatings. However, laser structuring is not yet established in industrial battery production due to limited knowledge of its ablation behavior and a low processing rate. This publication addresses these issues with a combination of experimental and theoretical approaches. In a comprehensive process study with picosecond pulsed laser radiation, the influence of various laser parameters on the obtained structure geometries, i.e., the hole diameters and depths, was examined. Wavelengths of 532 and 355 nm combined with pulse bursts and fluences of approximately 10 J cm−2 eventuated in favorable hole geometries with a high aspect ratio. Compared to singlebeam laser structuring, a nearly tenfold reduction in the processing time was achieved by beam splitting with a diffractive optical element without compromising structure geometries or mechanical electrode integrity. The experimental findings were used to model the scalability of electrode laser structuring, revealing the significant influence of the hole pattern and distance on the potential processing rate. Ultrashort pulsed laser powers in the kilowatt regime were found to be necessary to laser-structure electrodes at industrial processing rates resulting in estimated costs of roughly 1.96 $/kWh. The findings support the industrialization of laser electrode structuring for commercial lithium-ion battery production.
{"title":"Picosecond laser structuring of graphite anodes—Ablation characteristics and process scaling","authors":"Lucas Hille, Johannes Kriegler, Andreas Oehler, Michalina Chaja, Sebastian Wagner, Michael F. Zaeh","doi":"10.2351/7.0001087","DOIUrl":"https://doi.org/10.2351/7.0001087","url":null,"abstract":"Laser structuring of graphite anodes substantially improves the electrochemical performance of lithium-ion batteries by facilitating lithium-ion diffusion through the electrode coatings. However, laser structuring is not yet established in industrial battery production due to limited knowledge of its ablation behavior and a low processing rate. This publication addresses these issues with a combination of experimental and theoretical approaches. In a comprehensive process study with picosecond pulsed laser radiation, the influence of various laser parameters on the obtained structure geometries, i.e., the hole diameters and depths, was examined. Wavelengths of 532 and 355 nm combined with pulse bursts and fluences of approximately 10 J cm−2 eventuated in favorable hole geometries with a high aspect ratio. Compared to singlebeam laser structuring, a nearly tenfold reduction in the processing time was achieved by beam splitting with a diffractive optical element without compromising structure geometries or mechanical electrode integrity. The experimental findings were used to model the scalability of electrode laser structuring, revealing the significant influence of the hole pattern and distance on the potential processing rate. Ultrashort pulsed laser powers in the kilowatt regime were found to be necessary to laser-structure electrodes at industrial processing rates resulting in estimated costs of roughly 1.96 $/kWh. The findings support the industrialization of laser electrode structuring for commercial lithium-ion battery production.","PeriodicalId":50168,"journal":{"name":"Journal of Laser Applications","volume":"IA-13 6","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-10-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135217890","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Jason M. Gross, Seyedeh Reyhaneh Shavandi, Teodora Zagorac, Michael J. Pasterski, Luke Hanley
Laser ablation (LA) using nanosecond (ns) or femtosecond (fs) pulse widths is well-established for the volatilization of a liquid or solid for applications ranging from micromachining to sampling for compositional analysis. Far less work has examined laser ablation in the intermediate picosecond regime (ps-LA), which corresponds to the approximate timescale for the transfer of energy from laser-excited electrons to the lattice. 213 and 355 nm ps-LA of silicon (Si) with Gaussian beam profiles is compared here to 800 nm fs-LA with both Gaussian and flat-top beam profiles, all performed at or above the ablation threshold with 20 000–67 000 laser pulses. The morphology and composition of the ablation spots are examined using scanning electron microscopy and energy dispersive x-ray spectroscopy (EDS), respectively. 213 nm ps-LA yields more visible nanostructures compared to those ablated by 355 nm ps-LA, but both form central craters with surrounding nanostructures due to resolidified material. The flat-top fs beam creates protruding nanostructures isolated near the rim of the crater and an inside-out umbrella-like structure at the center. The Gaussian fs-LA region displays a relatively smooth conical crater, albeit with some nanostructure at the rim of the crater. EDS finds that these nanostructures are at least partly composed of silicon oxide or suboxides. The invisibility of these nanostructures to optical profilometry is consistent with black-silicon. The ablation crater results from optical profilometry for 213 nm ps-LA are close to those for 800 nm flat-top fs-LA, and both are consistent with cylindrical craters.
{"title":"Picosecond versus femtosecond-laser ablation of silicon in atmosphere","authors":"Jason M. Gross, Seyedeh Reyhaneh Shavandi, Teodora Zagorac, Michael J. Pasterski, Luke Hanley","doi":"10.2351/7.0001206","DOIUrl":"https://doi.org/10.2351/7.0001206","url":null,"abstract":"Laser ablation (LA) using nanosecond (ns) or femtosecond (fs) pulse widths is well-established for the volatilization of a liquid or solid for applications ranging from micromachining to sampling for compositional analysis. Far less work has examined laser ablation in the intermediate picosecond regime (ps-LA), which corresponds to the approximate timescale for the transfer of energy from laser-excited electrons to the lattice. 213 and 355 nm ps-LA of silicon (Si) with Gaussian beam profiles is compared here to 800 nm fs-LA with both Gaussian and flat-top beam profiles, all performed at or above the ablation threshold with 20 000–67 000 laser pulses. The morphology and composition of the ablation spots are examined using scanning electron microscopy and energy dispersive x-ray spectroscopy (EDS), respectively. 213 nm ps-LA yields more visible nanostructures compared to those ablated by 355 nm ps-LA, but both form central craters with surrounding nanostructures due to resolidified material. The flat-top fs beam creates protruding nanostructures isolated near the rim of the crater and an inside-out umbrella-like structure at the center. The Gaussian fs-LA region displays a relatively smooth conical crater, albeit with some nanostructure at the rim of the crater. EDS finds that these nanostructures are at least partly composed of silicon oxide or suboxides. The invisibility of these nanostructures to optical profilometry is consistent with black-silicon. The ablation crater results from optical profilometry for 213 nm ps-LA are close to those for 800 nm flat-top fs-LA, and both are consistent with cylindrical craters.","PeriodicalId":50168,"journal":{"name":"Journal of Laser Applications","volume":"7 10","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-10-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135273968","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
In this study, a numerical model of oscillation weld butt joint is developed to investigate the welding of titanium alloy with aluminum alloy. Three oscillation paths, namely, straight, sine, and circular, are used to study the distribution of force in the molten pool, the welding temperature field, and the formation and evolution of porosity within the weld. A 3D Gaussian heat source is used to represent the laser beam. The volume of the fluid method is employed to track the gas-liquid free surface, and the gas-liquid interface force is transformed by using the continuous surface force model. The mechanism of keyhole collapse and pore formation was examined along with the fluid flow, surface tension, and recoil pressure on the molten pool. The results confirmed that the highest welding quality is acquired by using a laser welding circular path. Notably, numerical simulation results are validated through experimental data, and circular oscillating laser welding significantly reduced weld seam porosity in the welding of Ti–Al dissimilar alloys. The circular oscillation path with an offset of 0.6 mm and an oscillation amplitude of 0.6 mm is identified as the optimal approach for suppressing pores in the weld joint. This research provides valuable insights into the fundamental mechanisms of keyhole collapse and pore formation in laser welding, which contributes to the advancement of effective welding strategies for dissimilar alloys.
{"title":"Study of melt pool dynamics and porosity forming mechanism of laser beam oscillation welding of titanium and aluminum","authors":"Jinbo Yu, Jiahao Song, Xigui Xie, Jianxi Zhou","doi":"10.2351/7.0001069","DOIUrl":"https://doi.org/10.2351/7.0001069","url":null,"abstract":"In this study, a numerical model of oscillation weld butt joint is developed to investigate the welding of titanium alloy with aluminum alloy. Three oscillation paths, namely, straight, sine, and circular, are used to study the distribution of force in the molten pool, the welding temperature field, and the formation and evolution of porosity within the weld. A 3D Gaussian heat source is used to represent the laser beam. The volume of the fluid method is employed to track the gas-liquid free surface, and the gas-liquid interface force is transformed by using the continuous surface force model. The mechanism of keyhole collapse and pore formation was examined along with the fluid flow, surface tension, and recoil pressure on the molten pool. The results confirmed that the highest welding quality is acquired by using a laser welding circular path. Notably, numerical simulation results are validated through experimental data, and circular oscillating laser welding significantly reduced weld seam porosity in the welding of Ti–Al dissimilar alloys. The circular oscillation path with an offset of 0.6 mm and an oscillation amplitude of 0.6 mm is identified as the optimal approach for suppressing pores in the weld joint. This research provides valuable insights into the fundamental mechanisms of keyhole collapse and pore formation in laser welding, which contributes to the advancement of effective welding strategies for dissimilar alloys.","PeriodicalId":50168,"journal":{"name":"Journal of Laser Applications","volume":"22 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-10-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135569515","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Fabian Bieg, David Scheider, Christian Kledwig, Clemens Maucher, Hans-Christian Möhring, Martin Reisacher
In today’s manufacturing, additive manufacturing processes enable the production of complicated three-dimensional structures that are hard to be manufactured with traditional manufacturing processes. Due to its high build rate, the laser-based directed energy deposition (DED-LB) process is an attractive and versatile process to manufacture these kinds of components. In addition to the production of components, DED-LB is used for repair or coating applications. The DED-LB process consists of a multitude of complex thermal mechanisms with high heating and cooling rates of 5 × 102 up to 5 × 105 K/s. For materials with high hardness or low thermal conductivity like tool steels, cast iron, or tungsten carbide, these high cooling rates can lead to defects in the microstructure like cracks, pores, or delamination between the substrate and the deposited structures. By preheating the substrate, the cooling rates can be reduced and defects can be eliminated. In this paper, a preheating cycle was developed, which uses the laser of a DMG MORI LT 65 DED hybrid machine as a moving heat source for the substrate preheating. For this cycle, process parameters, a tool path strategy, and a temperature control system were developed. The impact of the elaborated concept was shown by depositing tungsten carbide in a nickel matrix on an S235 steel substrate.
{"title":"Development of a laser preheating concept for directed energy deposition","authors":"Fabian Bieg, David Scheider, Christian Kledwig, Clemens Maucher, Hans-Christian Möhring, Martin Reisacher","doi":"10.2351/7.0001124","DOIUrl":"https://doi.org/10.2351/7.0001124","url":null,"abstract":"In today’s manufacturing, additive manufacturing processes enable the production of complicated three-dimensional structures that are hard to be manufactured with traditional manufacturing processes. Due to its high build rate, the laser-based directed energy deposition (DED-LB) process is an attractive and versatile process to manufacture these kinds of components. In addition to the production of components, DED-LB is used for repair or coating applications. The DED-LB process consists of a multitude of complex thermal mechanisms with high heating and cooling rates of 5 × 102 up to 5 × 105 K/s. For materials with high hardness or low thermal conductivity like tool steels, cast iron, or tungsten carbide, these high cooling rates can lead to defects in the microstructure like cracks, pores, or delamination between the substrate and the deposited structures. By preheating the substrate, the cooling rates can be reduced and defects can be eliminated. In this paper, a preheating cycle was developed, which uses the laser of a DMG MORI LT 65 DED hybrid machine as a moving heat source for the substrate preheating. For this cycle, process parameters, a tool path strategy, and a temperature control system were developed. The impact of the elaborated concept was shown by depositing tungsten carbide in a nickel matrix on an S235 steel substrate.","PeriodicalId":50168,"journal":{"name":"Journal of Laser Applications","volume":"22 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-10-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135569517","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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