A Michelson interferometer is commonly used for evaluating the morphology of a cell. However, the interference imaging with reference and object beams is easily affected by external vibrations and environmental disturbances, leading to unstable interference patterns. In this paper, the three-dimensional surface morphology of the biological cell is evaluated by a new quantitative phase imaging method, which couples Michelson-like lateral shear interferometric microscopy with self-referencing numerical phase calibration. The Michelson-like lateral shear interferometric microscopy is constructed by replacing the two plane mirrors of the traditional Michelson interferometer with two common right-angle prisms and generates interference fringe patterns. The lateral shear is created and freely adjustable by simply translating/or rotating one right-angle prism. To calculate the phase information of the biological cells quantitatively, the classical Fourier transform method is used to process the recorded interferogram, and then the self-referencing numerical phase calibration method is utilized for acquiring accurate phase information. Successfully achieving quantitative phase imaging of a cell verifies the feasibility and practicability of the proposed method.
{"title":"Coupling Michelson-like lateral shear interferometric microscopy with self-referencing numerical phase calibration for quantitative measurement of 3D surface morphology of biological cells","authors":"Tengfei Sun, Shaoying Ke, Wentao Sui, Wenhao Zhang, Peng Lu, Dongfeng Qi, Bing Yang, Juan Wei, Wei Zhang, Hongyu Zheng","doi":"10.2351/7.0001360","DOIUrl":"https://doi.org/10.2351/7.0001360","url":null,"abstract":"A Michelson interferometer is commonly used for evaluating the morphology of a cell. However, the interference imaging with reference and object beams is easily affected by external vibrations and environmental disturbances, leading to unstable interference patterns. In this paper, the three-dimensional surface morphology of the biological cell is evaluated by a new quantitative phase imaging method, which couples Michelson-like lateral shear interferometric microscopy with self-referencing numerical phase calibration. The Michelson-like lateral shear interferometric microscopy is constructed by replacing the two plane mirrors of the traditional Michelson interferometer with two common right-angle prisms and generates interference fringe patterns. The lateral shear is created and freely adjustable by simply translating/or rotating one right-angle prism. To calculate the phase information of the biological cells quantitatively, the classical Fourier transform method is used to process the recorded interferogram, and then the self-referencing numerical phase calibration method is utilized for acquiring accurate phase information. Successfully achieving quantitative phase imaging of a cell verifies the feasibility and practicability of the proposed method.","PeriodicalId":508142,"journal":{"name":"Journal of Laser Applications","volume":"31 13","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-04-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140696878","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Zhu Ming, Hanlin Yan, Zongzhi Zhang, Yang Qian, Shi Yu, Fan Ding
The purpose of this study was to investigate the thermal interaction between coaxially fed powder and diode laser, which is extremely complex and difficult to be detected in thermal real-time monitoring by the infrared camera system. In order to analyze the dynamic melting behavior of the powder, a high-speed camera system was established to capture the melting behavior of a single powder coaxially fed into the laser, which can reflect the entire melting process. There is a transition of “solid → solid-liquid two-phase state → liquid state” after a single powder enters the laser, and the duration and thermophysical behavior in different transition stages are not the same. Different states and duration determine distinct heat absorption effects. Based on high-speed camera detection results, the thermophysical behavior in different characteristic stages of the melting process in single powder was studied to develop a mathematical model, which is able to simulate and predict the temperature and state of the powder about to enter the melting pool. The experimental and simulation results show that (1) for a well-tested powder melting process, where the laser power ranges from 100 to 1500 W, the duration of the powder particle's absorption stage is between 4.41 and 18 ms, the duration of the solid-liquid two-phase state is between 0.52 and 2.63 ms, and the duration of the liquid state is between 4.67 and 13.48 ms. (2) The laser power ranges from 100 to 1500 W, and the temperature of the powder particles as they enter the melt pool ranges from 745 to 3200 °C.
{"title":"Research on melting behavior of coaxially fed powder in diode laser cladding process","authors":"Zhu Ming, Hanlin Yan, Zongzhi Zhang, Yang Qian, Shi Yu, Fan Ding","doi":"10.2351/7.0001047","DOIUrl":"https://doi.org/10.2351/7.0001047","url":null,"abstract":"The purpose of this study was to investigate the thermal interaction between coaxially fed powder and diode laser, which is extremely complex and difficult to be detected in thermal real-time monitoring by the infrared camera system. In order to analyze the dynamic melting behavior of the powder, a high-speed camera system was established to capture the melting behavior of a single powder coaxially fed into the laser, which can reflect the entire melting process. There is a transition of “solid → solid-liquid two-phase state → liquid state” after a single powder enters the laser, and the duration and thermophysical behavior in different transition stages are not the same. Different states and duration determine distinct heat absorption effects. Based on high-speed camera detection results, the thermophysical behavior in different characteristic stages of the melting process in single powder was studied to develop a mathematical model, which is able to simulate and predict the temperature and state of the powder about to enter the melting pool. The experimental and simulation results show that (1) for a well-tested powder melting process, where the laser power ranges from 100 to 1500 W, the duration of the powder particle's absorption stage is between 4.41 and 18 ms, the duration of the solid-liquid two-phase state is between 0.52 and 2.63 ms, and the duration of the liquid state is between 4.67 and 13.48 ms. (2) The laser power ranges from 100 to 1500 W, and the temperature of the powder particles as they enter the melt pool ranges from 745 to 3200 °C.","PeriodicalId":508142,"journal":{"name":"Journal of Laser Applications","volume":"15 4","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-04-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140715436","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Memristor-based logic circuits are gaining a lot of attention due to the potential for high logic density hardware and novel in-memory computing applications. Readily available methods for fabricating of memristor logic structures that are suitable for integration with conventional computer hardware are a growing need. This work presents a direct laser writing process capable of rapidly fabricating memristor logic circuits by laser irradiation of metal salt precursor solutions. Planar memristor patterns are fabricated, and their I–V response is characterized. Boolean logic gates are fabricated from planar memristor pairs that exhibit low programming voltages and rapid switching. Cu/Cu2O/Cu and Ag/Cu2O/Cu memristors are also fabricated in crossbar arrays, showing the ability to be programmed to multiple resistance states through ultrashort voltage pulses. The devices also show the potential to have high endurance and nonvolatile resistance state retention.
{"title":"Laser writing of memristive logic gates and crossbar arrays","authors":"Joshua Jones, Ningyue Mao, Peng Peng","doi":"10.2351/7.0001345","DOIUrl":"https://doi.org/10.2351/7.0001345","url":null,"abstract":"Memristor-based logic circuits are gaining a lot of attention due to the potential for high logic density hardware and novel in-memory computing applications. Readily available methods for fabricating of memristor logic structures that are suitable for integration with conventional computer hardware are a growing need. This work presents a direct laser writing process capable of rapidly fabricating memristor logic circuits by laser irradiation of metal salt precursor solutions. Planar memristor patterns are fabricated, and their I–V response is characterized. Boolean logic gates are fabricated from planar memristor pairs that exhibit low programming voltages and rapid switching. Cu/Cu2O/Cu and Ag/Cu2O/Cu memristors are also fabricated in crossbar arrays, showing the ability to be programmed to multiple resistance states through ultrashort voltage pulses. The devices also show the potential to have high endurance and nonvolatile resistance state retention.","PeriodicalId":508142,"journal":{"name":"Journal of Laser Applications","volume":"9 11","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-04-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140716656","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
A new plastic processing method for laser bending of TC4 titanium alloy heavy plates was developed in this work. Different from previous studies, the thickness of the plates in this work reached 6 and 12 mm. High-energy laser beam was applied on the surface of the TC4 titanium alloy heavy plate, resulting in thermal stress on the surface of the plate and causing bending deformation. The microstructure and mechanical properties of the bended plates were investigated. A finite element model was also developed to simulate the laser-assisted bending process of the TC4 titanium alloy heavy plate. The microstructure observation indicates that the original α + β worm-like microstructure changed to basket-weave microstructure composed of α′ phase of acicular martensite after laser bending. This microstructure with high densities of dislocation and twinning played an important role in grain boundary strengthening. Therefore, the hardness of the center of the heat-affected zone > the hardness of the base metal > the hardness of the edge of the heat-affected zone after bending. The tensile strength of the heat-affected zone is not significantly different from that of the base metal, but the tensile elongation is slightly lower than that of the base metal and its plasticity is lower. The simulation implies that temperature gradients in the normal direction caused by laser scanning can stimulate a horizontal partial stress σx. The variation of σx causes the plate form a bending angle after laser scanning.
{"title":"Characterization of the deformation behavior and microstructure evolution in laser bending of TC4 titanium alloy heavy plate","authors":"Yulin Shao, Zhanzhou Liu, Haochen Ding, Chi Zhang, Zhiwen Shao, Liwen Zhang","doi":"10.2351/7.0001303","DOIUrl":"https://doi.org/10.2351/7.0001303","url":null,"abstract":"A new plastic processing method for laser bending of TC4 titanium alloy heavy plates was developed in this work. Different from previous studies, the thickness of the plates in this work reached 6 and 12 mm. High-energy laser beam was applied on the surface of the TC4 titanium alloy heavy plate, resulting in thermal stress on the surface of the plate and causing bending deformation. The microstructure and mechanical properties of the bended plates were investigated. A finite element model was also developed to simulate the laser-assisted bending process of the TC4 titanium alloy heavy plate. The microstructure observation indicates that the original α + β worm-like microstructure changed to basket-weave microstructure composed of α′ phase of acicular martensite after laser bending. This microstructure with high densities of dislocation and twinning played an important role in grain boundary strengthening. Therefore, the hardness of the center of the heat-affected zone > the hardness of the base metal > the hardness of the edge of the heat-affected zone after bending. The tensile strength of the heat-affected zone is not significantly different from that of the base metal, but the tensile elongation is slightly lower than that of the base metal and its plasticity is lower. The simulation implies that temperature gradients in the normal direction caused by laser scanning can stimulate a horizontal partial stress σx. The variation of σx causes the plate form a bending angle after laser scanning.","PeriodicalId":508142,"journal":{"name":"Journal of Laser Applications","volume":"118 25","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-03-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140089320","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Biplab Kumar Dash, S. Bhatnagar, Hari Srinivasa Rao Magham, Shubham Rao, Gopinath Muvvala, S. Mullick
Laser direct energy deposition (DED) has some accompanying issues, such as existence of micropores, elemental segregation at grain boundaries, intergranular corrosion, etc. Therefore, the current work aims for a reduction in clad defects and enhancement in surface properties for laser direct deposition of Inconel 625 by implementing ultrasonic vibration. The acoustic streaming and cavitation effect induced by ultrasonic vibration results in the breaking of columnar grains, along with grain refinement and better elemental distribution in the matrix during the solidification process. The investigation is carried out for deposition using a 240 W Yb-fiber laser under the application of ultrasonic vibration with a variable amplitude of 6–13 μm (frequency: 33–28 kHz). A relatively higher vibration amplitude was found more efficient in converting long columnar grains into finer and uniformly distributed equiaxed grains, with a significant reduction in micropores. Further, it resulted in a shorter molten pool lifetime because of the generation of more nucleation centers, leading to better cooling. The above effects resulted in higher microhardness of the deposited layer. Further, the wear and corrosion resistance showed an improvement with the application of vibration, which may be due to the finer equiaxed grains, less porosity, and better elemental distribution at a higher vibration amplitude.
{"title":"Effect of ultrasonic vibration on microstructural evolution, clad defects, and surface properties in laser direct energy deposition of Inconel 625","authors":"Biplab Kumar Dash, S. Bhatnagar, Hari Srinivasa Rao Magham, Shubham Rao, Gopinath Muvvala, S. Mullick","doi":"10.2351/7.0001258","DOIUrl":"https://doi.org/10.2351/7.0001258","url":null,"abstract":"Laser direct energy deposition (DED) has some accompanying issues, such as existence of micropores, elemental segregation at grain boundaries, intergranular corrosion, etc. Therefore, the current work aims for a reduction in clad defects and enhancement in surface properties for laser direct deposition of Inconel 625 by implementing ultrasonic vibration. The acoustic streaming and cavitation effect induced by ultrasonic vibration results in the breaking of columnar grains, along with grain refinement and better elemental distribution in the matrix during the solidification process. The investigation is carried out for deposition using a 240 W Yb-fiber laser under the application of ultrasonic vibration with a variable amplitude of 6–13 μm (frequency: 33–28 kHz). A relatively higher vibration amplitude was found more efficient in converting long columnar grains into finer and uniformly distributed equiaxed grains, with a significant reduction in micropores. Further, it resulted in a shorter molten pool lifetime because of the generation of more nucleation centers, leading to better cooling. The above effects resulted in higher microhardness of the deposited layer. Further, the wear and corrosion resistance showed an improvement with the application of vibration, which may be due to the finer equiaxed grains, less porosity, and better elemental distribution at a higher vibration amplitude.","PeriodicalId":508142,"journal":{"name":"Journal of Laser Applications","volume":" 7","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-03-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140091498","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
In this paper, laser cleaning of thermal barrier coatings is investigated by finite element simulation and experiments. The effect of different parameters on the maximum temperature of the substrate surface during the cleaning process is studied. The results show that the repetition frequency and pulse width have little effect on the maximum temperature of the substrate surface, and the maximum temperature of the substrate surface has an approximately linear relationship with the laser power and an exponential decay relationship with the scanning speed. From the perspective of cleaning efficiency and damage to the substrate, the parameter windows for laser cleaning of thermal barrier coatings were obtained. The highest cleaning efficiency for the top ceramic layer is about 3.02 mm3/s. The highest cleaning efficiency for the bond layer is about 2.17 mm3/s.
{"title":"Study on the processing parameter window for laser cleaning thermal barrier coating","authors":"Guoqiang Dai, Yunxia Ye, Yinqun Hua","doi":"10.2351/7.0001202","DOIUrl":"https://doi.org/10.2351/7.0001202","url":null,"abstract":"In this paper, laser cleaning of thermal barrier coatings is investigated by finite element simulation and experiments. The effect of different parameters on the maximum temperature of the substrate surface during the cleaning process is studied. The results show that the repetition frequency and pulse width have little effect on the maximum temperature of the substrate surface, and the maximum temperature of the substrate surface has an approximately linear relationship with the laser power and an exponential decay relationship with the scanning speed. From the perspective of cleaning efficiency and damage to the substrate, the parameter windows for laser cleaning of thermal barrier coatings were obtained. The highest cleaning efficiency for the top ceramic layer is about 3.02 mm3/s. The highest cleaning efficiency for the bond layer is about 2.17 mm3/s.","PeriodicalId":508142,"journal":{"name":"Journal of Laser Applications","volume":"202 3","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139821507","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
David Abookasis, Daniel Malchi, Dror Robinson, Mustafa Yassin
Continuous measurement of pressure is vital in many fields of industry, medicine, and science. Of particular interest is the ability to measure pressure in a noninvasive and contact-free manner. This work presents the potential of oblique incident reflectometry (OIR) to monitor variation in pressure via the reduced scattering parameter (μs′). Pressure deforms the geometry of the medium and causes distortion of its internal structure and the spatial distribution of optical properties. Light scattering is related to the morphology (size, density, distribution, etc.) and refractive index distributions of the medium, and applied pressure will influence directly these parameters. Therefore, we assume that pressure can be quantitatively assessed through monitoring the reduced scattering coefficient. For this purpose, the technique of OIR to evaluate the scattering parameter during pressure variations was utilized. OIR is a simple noninvasive and contact-free imaging technique able to quantify both absorption and scattering properties of a sample. In our setup, the medium is illuminated obliquely by a narrow laser beam, and the diffuse reflectance light is captured by a CCD camera. In offline processing, the shift (δ) of the diffuse light center from the incident point is mathematically analyzed and μs′ coefficient (μs′∼δ−1) is extracted. We present here confirmation of the validity of this assumption through results of a series of experiments performed on turbid liquid and artery occlusion of a human subject under different pressure levels. Thus, μs′ has the potential to serve as a good indicator for the monitoring of pressure.
{"title":"Pressure estimation via measurement of reduced light scattering coefficient by oblique laser incident reflectometry","authors":"David Abookasis, Daniel Malchi, Dror Robinson, Mustafa Yassin","doi":"10.2351/7.0001263","DOIUrl":"https://doi.org/10.2351/7.0001263","url":null,"abstract":"Continuous measurement of pressure is vital in many fields of industry, medicine, and science. Of particular interest is the ability to measure pressure in a noninvasive and contact-free manner. This work presents the potential of oblique incident reflectometry (OIR) to monitor variation in pressure via the reduced scattering parameter (μs′). Pressure deforms the geometry of the medium and causes distortion of its internal structure and the spatial distribution of optical properties. Light scattering is related to the morphology (size, density, distribution, etc.) and refractive index distributions of the medium, and applied pressure will influence directly these parameters. Therefore, we assume that pressure can be quantitatively assessed through monitoring the reduced scattering coefficient. For this purpose, the technique of OIR to evaluate the scattering parameter during pressure variations was utilized. OIR is a simple noninvasive and contact-free imaging technique able to quantify both absorption and scattering properties of a sample. In our setup, the medium is illuminated obliquely by a narrow laser beam, and the diffuse reflectance light is captured by a CCD camera. In offline processing, the shift (δ) of the diffuse light center from the incident point is mathematically analyzed and μs′ coefficient (μs′∼δ−1) is extracted. We present here confirmation of the validity of this assumption through results of a series of experiments performed on turbid liquid and artery occlusion of a human subject under different pressure levels. Thus, μs′ has the potential to serve as a good indicator for the monitoring of pressure.","PeriodicalId":508142,"journal":{"name":"Journal of Laser Applications","volume":"40 16","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139686312","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
In this paper, laser cleaning of thermal barrier coatings is investigated by finite element simulation and experiments. The effect of different parameters on the maximum temperature of the substrate surface during the cleaning process is studied. The results show that the repetition frequency and pulse width have little effect on the maximum temperature of the substrate surface, and the maximum temperature of the substrate surface has an approximately linear relationship with the laser power and an exponential decay relationship with the scanning speed. From the perspective of cleaning efficiency and damage to the substrate, the parameter windows for laser cleaning of thermal barrier coatings were obtained. The highest cleaning efficiency for the top ceramic layer is about 3.02 mm3/s. The highest cleaning efficiency for the bond layer is about 2.17 mm3/s.
{"title":"Study on the processing parameter window for laser cleaning thermal barrier coating","authors":"Guoqiang Dai, Yunxia Ye, Yinqun Hua","doi":"10.2351/7.0001202","DOIUrl":"https://doi.org/10.2351/7.0001202","url":null,"abstract":"In this paper, laser cleaning of thermal barrier coatings is investigated by finite element simulation and experiments. The effect of different parameters on the maximum temperature of the substrate surface during the cleaning process is studied. The results show that the repetition frequency and pulse width have little effect on the maximum temperature of the substrate surface, and the maximum temperature of the substrate surface has an approximately linear relationship with the laser power and an exponential decay relationship with the scanning speed. From the perspective of cleaning efficiency and damage to the substrate, the parameter windows for laser cleaning of thermal barrier coatings were obtained. The highest cleaning efficiency for the top ceramic layer is about 3.02 mm3/s. The highest cleaning efficiency for the bond layer is about 2.17 mm3/s.","PeriodicalId":508142,"journal":{"name":"Journal of Laser Applications","volume":"20 3","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139881237","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Qi Cheng, Ning Guo, Yunlong Fu, Junhui Tong, Xin Zhang, Hao Chen, Jinlong He
Underwater local dry laser welding of the tube-plate structure was performed first. The effects of laser power and welding speed on welding quality were studied. With the increase in the laser power or decrease in the welding speed, the melting zone (MZ) area and depth-width ratio of the welded joint increased, and metallurgical porosity also increased. When the laser power was 2 kW and the welding speed was 12 mm/s, a better metallurgical bond could be formed between the tube and plate, and there were fewer metallurgical pores in the welded joint. Due to a large amount of evaporation and ionization of water in the gap between the tube and plate, metallurgical pores formed in the welded joint. By adding a waterproof layer on the back of the substrate, the metallurgical porosity decreased from 2.1% to 0%. In order to investigate the influence of a water environment on welding quality, the in-air laser welding was performed. Compared to in-air welded joint, the MZ area, depth to width ratio, and grain size were smaller. The average microhardness of underwater welded joint was higher than that of in-air welded joint due to the refined crystalline strengthening. In addition, because the magnesium burning loss in an underwater environment was less than that in an in-air environment, the microhardness values at the top of the underwater MZ were similar to those at the bottom, while the microhardness values at the top and bottom of the in-air MZ were much different.
{"title":"Underwater laser welding of tube-plate structure of aluminum alloy","authors":"Qi Cheng, Ning Guo, Yunlong Fu, Junhui Tong, Xin Zhang, Hao Chen, Jinlong He","doi":"10.2351/7.0001193","DOIUrl":"https://doi.org/10.2351/7.0001193","url":null,"abstract":"Underwater local dry laser welding of the tube-plate structure was performed first. The effects of laser power and welding speed on welding quality were studied. With the increase in the laser power or decrease in the welding speed, the melting zone (MZ) area and depth-width ratio of the welded joint increased, and metallurgical porosity also increased. When the laser power was 2 kW and the welding speed was 12 mm/s, a better metallurgical bond could be formed between the tube and plate, and there were fewer metallurgical pores in the welded joint. Due to a large amount of evaporation and ionization of water in the gap between the tube and plate, metallurgical pores formed in the welded joint. By adding a waterproof layer on the back of the substrate, the metallurgical porosity decreased from 2.1% to 0%. In order to investigate the influence of a water environment on welding quality, the in-air laser welding was performed. Compared to in-air welded joint, the MZ area, depth to width ratio, and grain size were smaller. The average microhardness of underwater welded joint was higher than that of in-air welded joint due to the refined crystalline strengthening. In addition, because the magnesium burning loss in an underwater environment was less than that in an in-air environment, the microhardness values at the top of the underwater MZ were similar to those at the bottom, while the microhardness values at the top and bottom of the in-air MZ were much different.","PeriodicalId":508142,"journal":{"name":"Journal of Laser Applications","volume":"15 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-01-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139439177","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Ming Zhu, Hao Zhang, Kun Shi, Xiaofei Hou, Yu Shi, Ding Fan, Wenzhu Zhang
When using pulsed laser to remove a thick paint layer from a 2024 aluminum alloy substrate, the paint layer should be removed layer by layer, and the substrate should remain intact after the paint layer is completely removed. In this process, the formation of a rough surface on the paint increases laser absorption, changing the removal mechanism, which becomes an unstable factor for nondestructive paint removal. This study investigated the laser paint removal mechanism of fluorocarbon paint and found that when the laser fluence was 0.91 J/cm2, the main removal mechanisms were thermal stress and combustion-decomposition removal, while at 94.36 J/cm2, the main mechanism was sputtering removal. The study also investigated the relationship between surface roughness and the number of laser scans, which showed a positive linear correlation. Additionally, an equivalent model of a rough surface was established to analyze the changes in absorption, though this model has yet to be verified and further research and validation is required to confirm our findings.
{"title":"Formation and effect of rough surface in pulsed laser removal of thick paint layer on 2024 aluminum","authors":"Ming Zhu, Hao Zhang, Kun Shi, Xiaofei Hou, Yu Shi, Ding Fan, Wenzhu Zhang","doi":"10.2351/7.0001010","DOIUrl":"https://doi.org/10.2351/7.0001010","url":null,"abstract":"When using pulsed laser to remove a thick paint layer from a 2024 aluminum alloy substrate, the paint layer should be removed layer by layer, and the substrate should remain intact after the paint layer is completely removed. In this process, the formation of a rough surface on the paint increases laser absorption, changing the removal mechanism, which becomes an unstable factor for nondestructive paint removal. This study investigated the laser paint removal mechanism of fluorocarbon paint and found that when the laser fluence was 0.91 J/cm2, the main removal mechanisms were thermal stress and combustion-decomposition removal, while at 94.36 J/cm2, the main mechanism was sputtering removal. The study also investigated the relationship between surface roughness and the number of laser scans, which showed a positive linear correlation. Additionally, an equivalent model of a rough surface was established to analyze the changes in absorption, though this model has yet to be verified and further research and validation is required to confirm our findings.","PeriodicalId":508142,"journal":{"name":"Journal of Laser Applications","volume":"13 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-01-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139443371","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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