In the past decade, nanoporous metals have been a point of interest in the scientific community because they exhibit chemical, optical, and mechanical properties that are unique from their bulk counterparts. One of the most prominent method for its synthesis is chemical dealloying. While, under electrolytic conditions, dealloying can use process-inputs such as current density and electrical potential to control the ligament size during its synthesis with excellent reproducibility, electroless methods are plagued by the lack of local control of dealloying rates which introduces batch-to-batch variations in ligament size. Given that powder is a format incompatible with electrolysis, this study shows an approach to safely scale fabrication of spherical porous copper powders containing oxides from gas atomized Cu-Al powders. Additionally, the agglomeration that is commonly associated with porous powder fabrication was addressed by its functionalization with an anionic surfactant and powder washing in both deionized water (polar) and anhydrous ethanol (nonpolar). Additionally, hazards associated with its production scaling such as excessive hydrogen evolution, heat generation due to its high-reactivity and exothermic reaction and pyrophoricity are discussed and addressed. As a result of this study, a robust and scalable approach was developed to produce 100 of grams of porous metal powders.
{"title":"Robust and Scalable Synthesis of High Surface Area Porous Copper Spheriodized Powders by Electroless Chemical Dealloying","authors":"S. Niauzorau, N. Kublik, A. Hasib, B. Azeredo","doi":"10.1115/msec2022-85894","DOIUrl":"https://doi.org/10.1115/msec2022-85894","url":null,"abstract":"\u0000 In the past decade, nanoporous metals have been a point of interest in the scientific community because they exhibit chemical, optical, and mechanical properties that are unique from their bulk counterparts. One of the most prominent method for its synthesis is chemical dealloying. While, under electrolytic conditions, dealloying can use process-inputs such as current density and electrical potential to control the ligament size during its synthesis with excellent reproducibility, electroless methods are plagued by the lack of local control of dealloying rates which introduces batch-to-batch variations in ligament size. Given that powder is a format incompatible with electrolysis, this study shows an approach to safely scale fabrication of spherical porous copper powders containing oxides from gas atomized Cu-Al powders. Additionally, the agglomeration that is commonly associated with porous powder fabrication was addressed by its functionalization with an anionic surfactant and powder washing in both deionized water (polar) and anhydrous ethanol (nonpolar). Additionally, hazards associated with its production scaling such as excessive hydrogen evolution, heat generation due to its high-reactivity and exothermic reaction and pyrophoricity are discussed and addressed. As a result of this study, a robust and scalable approach was developed to produce 100 of grams of porous metal powders.","PeriodicalId":45459,"journal":{"name":"Journal of Micro and Nano-Manufacturing","volume":"40 5 1","pages":""},"PeriodicalIF":1.0,"publicationDate":"2022-06-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"82821180","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}
This paper introduces the fabrication of wafer-long nanowires using glancing angle deposition (GLAD). GLAD is an advanced physical vapor deposition technique, and it has the unique advantage of creating three-dimensional nanofeature arrays, compared to conventional top-down nanofabrication techniques. Various nanofeatures created by GLAD have been reported, including pillars, springs, chevrons, ribbons, and those structures as templates for creating nanoporous membranes; this paper fills the gap by presenting the creation of nanowires by GLAD. This paper describes the fabrication process by introducing the seeding scheme of corrals. The seed design for GLAD adopts the design rules of corrals of line seeds, and the GLAD parameters are determined by the design of the corrals of line seeds. In the experiment, conventional photolithography is used for creating micro-level widths and heights and wafer-length of line seed corrals. Two GLAD sessions with the target material for the nanowires and the mask material are deposited on the substrate in sequence with different azimuth angles; the nanowires are obtainable by anisotropic etching and removal of the sacrificial layer of corrals of line seeds. The design of the corrals of line seeds and the control of the size of the nanowires are discussed. The nanowires created are potentially applied in sensing applications, for example, the palladium or platinum nanowires can be used for hydrogen sensing.
{"title":"Fabrication of Nanowires Using Glancing Angle Deposition","authors":"C. Qu, S. Mcnamara, K. Walsh","doi":"10.1115/msec2022-83719","DOIUrl":"https://doi.org/10.1115/msec2022-83719","url":null,"abstract":"\u0000 This paper introduces the fabrication of wafer-long nanowires using glancing angle deposition (GLAD). GLAD is an advanced physical vapor deposition technique, and it has the unique advantage of creating three-dimensional nanofeature arrays, compared to conventional top-down nanofabrication techniques. Various nanofeatures created by GLAD have been reported, including pillars, springs, chevrons, ribbons, and those structures as templates for creating nanoporous membranes; this paper fills the gap by presenting the creation of nanowires by GLAD. This paper describes the fabrication process by introducing the seeding scheme of corrals. The seed design for GLAD adopts the design rules of corrals of line seeds, and the GLAD parameters are determined by the design of the corrals of line seeds. In the experiment, conventional photolithography is used for creating micro-level widths and heights and wafer-length of line seed corrals. Two GLAD sessions with the target material for the nanowires and the mask material are deposited on the substrate in sequence with different azimuth angles; the nanowires are obtainable by anisotropic etching and removal of the sacrificial layer of corrals of line seeds. The design of the corrals of line seeds and the control of the size of the nanowires are discussed. The nanowires created are potentially applied in sensing applications, for example, the palladium or platinum nanowires can be used for hydrogen sensing.","PeriodicalId":45459,"journal":{"name":"Journal of Micro and Nano-Manufacturing","volume":"15 1","pages":""},"PeriodicalIF":1.0,"publicationDate":"2022-06-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"73427599","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}
Qingqing He, Brandon Bethers, Brian Tran, Yang Yang
Certain types of Salvinia water ferns present a highly water-repellent upper surface along their floating leaves. This is accomplished through the use of structured trichomes, which create hydrophobic and superhydrophobic surfaces. Particularly, there are four different types of trichomes found in Salvinia plants that present these characteristics. They are known as Cucullata type, Oblongifolia type, Natans type and Molesta type. However, these structures are characterized by very small sizes, along with complex shapes. With the advantages of high-efficiency, low-cost, fast-fabrication, and ability of producing microstructures, additive manufacturing (AM), known as 3D printing method, has brought lots of attentions to various academic fields. Herein, we apply a 3D printing method to create biomimetic structures designed after the trichomes on Salvinia. In this work, the hydrophobic properties of the four biomimetic structures were tested through the use of optical contact angle measurements after initial modeling through the CAD program Solidworks. Finally, an Optical Contact Angle measurement device was used to determine the hydrophobic properties of each structure. This study concludes that each of the four biomimetic structures based on the different types of trichomes of Salvinia have hydrophobic performance. In particular, the Natans type and Molesta type show superhydrophobic properties, with the Molesta inspired structure displaying the highest contact angle among the four types. These results suggest that future research into the trichome structures of Salvinia water ferns could produce biomimetic structures with enhanced hydrophobic properties and applications.
{"title":"3D Printing of Salvinia Water Fern-Inspired Superhydrophobic Structures","authors":"Qingqing He, Brandon Bethers, Brian Tran, Yang Yang","doi":"10.1115/msec2022-85646","DOIUrl":"https://doi.org/10.1115/msec2022-85646","url":null,"abstract":"\u0000 Certain types of Salvinia water ferns present a highly water-repellent upper surface along their floating leaves. This is accomplished through the use of structured trichomes, which create hydrophobic and superhydrophobic surfaces. Particularly, there are four different types of trichomes found in Salvinia plants that present these characteristics. They are known as Cucullata type, Oblongifolia type, Natans type and Molesta type. However, these structures are characterized by very small sizes, along with complex shapes. With the advantages of high-efficiency, low-cost, fast-fabrication, and ability of producing microstructures, additive manufacturing (AM), known as 3D printing method, has brought lots of attentions to various academic fields. Herein, we apply a 3D printing method to create biomimetic structures designed after the trichomes on Salvinia. In this work, the hydrophobic properties of the four biomimetic structures were tested through the use of optical contact angle measurements after initial modeling through the CAD program Solidworks. Finally, an Optical Contact Angle measurement device was used to determine the hydrophobic properties of each structure. This study concludes that each of the four biomimetic structures based on the different types of trichomes of Salvinia have hydrophobic performance. In particular, the Natans type and Molesta type show superhydrophobic properties, with the Molesta inspired structure displaying the highest contact angle among the four types. These results suggest that future research into the trichome structures of Salvinia water ferns could produce biomimetic structures with enhanced hydrophobic properties and applications.","PeriodicalId":45459,"journal":{"name":"Journal of Micro and Nano-Manufacturing","volume":"3 1","pages":""},"PeriodicalIF":1.0,"publicationDate":"2022-06-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"78228110","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. Alafaghani, Majed Ali, Abdalmageed Almotari, Jian-Qiao Sun, A. Qattawi
Due to the layering nature of additive manufacturing, additively manufactured parts exhibit a unique microstructure and are more susceptible to defects. Post-processing heat treatments of additively manufactured parts have shown great promise in improving their quality and reliability. However, the previous studies presented here demonstrated that additively manufactured parts respond to heat treatments differently compared to their traditional counterparts. This demonstrates a need for models that can predict the influence of different heat treatments on the mechanical behavior of additively manufactured parts. A hybrid approach between data-driven and physically informed models was adopted to model the influence of post-processing heat treatments on the strengthening mechanisms of additively manufactured Inconel 718. This work focuses on Inconel 718 for its common use in additive manufacturing and because it is one of the most studied additively manufactured alloys which resulted in producing more data that can be used to model its behavior.
{"title":"Hybrid Modeling the Influence of Post Processing Heat Treatments on the Strengthening Mechanisms of Additively Manufactured Inconel 718","authors":"A. Alafaghani, Majed Ali, Abdalmageed Almotari, Jian-Qiao Sun, A. Qattawi","doi":"10.1115/msec2022-86354","DOIUrl":"https://doi.org/10.1115/msec2022-86354","url":null,"abstract":"\u0000 Due to the layering nature of additive manufacturing, additively manufactured parts exhibit a unique microstructure and are more susceptible to defects. Post-processing heat treatments of additively manufactured parts have shown great promise in improving their quality and reliability. However, the previous studies presented here demonstrated that additively manufactured parts respond to heat treatments differently compared to their traditional counterparts. This demonstrates a need for models that can predict the influence of different heat treatments on the mechanical behavior of additively manufactured parts. A hybrid approach between data-driven and physically informed models was adopted to model the influence of post-processing heat treatments on the strengthening mechanisms of additively manufactured Inconel 718. This work focuses on Inconel 718 for its common use in additive manufacturing and because it is one of the most studied additively manufactured alloys which resulted in producing more data that can be used to model its behavior.","PeriodicalId":45459,"journal":{"name":"Journal of Micro and Nano-Manufacturing","volume":"314 1","pages":""},"PeriodicalIF":1.0,"publicationDate":"2022-06-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"78606718","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}
Disassembly is an integral part of maintenance, upgrade, and remanufacturing operations to recover end-of-use products. Optimization of disassembly sequences and the capability of robotic technology are crucial for managing the resource-intensive nature of dismantling operations. This study proposes an optimization framework for disassembly sequence planning under uncertainty considering human-robot collaboration. The proposed model combines three attributes: disassembly cost, disassembleability, and safety, to find the optimal path for dismantling a product and assigning each disassembly operation among humans and robots. The multi-attribute utility function has been employed to address uncertainty and make a tradeoff among multiple attributes. The disassembly time reflects the cost of disassembly and is assumed to be an uncertain parameter with a Beta probability density function; the disassembleability evaluates the feasibility of conducting operations by robot; finally, the safety index ensures the safety of human workers in the work environment. The optimization model identifies the best disassembly sequence and makes tradeoffs among multi-attributes. An example of a computer desktop illustrates how the proposed model works. The model identifies the optimal disassembly sequence with less disassembly cost, high disassembleability, and increased safety index while allocating disassembly operations between human and robot. A sensitivity analysis is conducted to show the model’s performance when changing the disassembly cost for the robot.
{"title":"Optimization-Based Disassembly Sequence Planning Under Uncertainty for Human-Robot Collaboration","authors":"Hao-yu Liao, Yuhao Chen, Boyi Hu, S. Behdad","doi":"10.1115/msec2022-85383","DOIUrl":"https://doi.org/10.1115/msec2022-85383","url":null,"abstract":"\u0000 Disassembly is an integral part of maintenance, upgrade, and remanufacturing operations to recover end-of-use products. Optimization of disassembly sequences and the capability of robotic technology are crucial for managing the resource-intensive nature of dismantling operations. This study proposes an optimization framework for disassembly sequence planning under uncertainty considering human-robot collaboration. The proposed model combines three attributes: disassembly cost, disassembleability, and safety, to find the optimal path for dismantling a product and assigning each disassembly operation among humans and robots. The multi-attribute utility function has been employed to address uncertainty and make a tradeoff among multiple attributes. The disassembly time reflects the cost of disassembly and is assumed to be an uncertain parameter with a Beta probability density function; the disassembleability evaluates the feasibility of conducting operations by robot; finally, the safety index ensures the safety of human workers in the work environment. The optimization model identifies the best disassembly sequence and makes tradeoffs among multi-attributes. An example of a computer desktop illustrates how the proposed model works. The model identifies the optimal disassembly sequence with less disassembly cost, high disassembleability, and increased safety index while allocating disassembly operations between human and robot. A sensitivity analysis is conducted to show the model’s performance when changing the disassembly cost for the robot.","PeriodicalId":45459,"journal":{"name":"Journal of Micro and Nano-Manufacturing","volume":"100 1","pages":""},"PeriodicalIF":1.0,"publicationDate":"2022-06-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"80822451","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}
Implantable microelectrode arrays are an effective method for understanding neurotransmitter dynamics with high spatial resolution. In particular, carbon-based electrodes are efficient for electrochemical detection of dopamine, a neurotransmitter studied for its role in motor movement and reward-seeking behavior. However, very few options exist for arrayed carbon microelectrodes, specifically on flexible polymeric probes. We demonstrate fabrication of polyimide probes featuring single walled carbon nanotube (SWCNT) microelectrode arrays and characterize their dopamine detection performance. First, SWCNT synthesis parameters were optimized to grow high density SWCNT “forests” that have uniform height with electrode diameters ranging from 15 μm to 100 μm, as these dimensions are spatially relevant to chemical sensing in an animal model. These SWCNT microelectrodes were then incorporated into a microfabrication process involving deposition and patterning of polyimide substrate and metal traces. The process flow was designed such that the polyimide was not exposed to the high temperatures required to grow SWCNTs. Instead, a bottom-up approach was utilized, in which the SWCNT catalyst was first patterned, the SWCNTs were synthesized on a silicon substrate, then polyimide and trace metal layers were deposited and patterned. Prototype probes were fabricated containing the same range of electrode diameters as those used for SWCNT synthesis development to determine the effect of electrode diameter on ease of microfabrication. Microelectrodes ranging from 15 μm to 50 μm in diameter were found to release from the carrier wafer more easily, while larger electrodes demonstrated poor release. These probes demonstrate a concentration-dependent response to dopamine, with high sensitivity compared to microelectrode arrays consisting of bare metal. Further development of this electrode material will enable neuroscientists to study dopamine at higher spatial resolution, with the benefit of utilizing flexible probes.
{"title":"Synthesis and Fabrication of Single Walled Carbon Nanotube Microelectrode Arrays on Flexible Probes for Neurotransmitter Detection","authors":"Sei Jin Park, Anna N. Ivanovskaya, A. Yorita","doi":"10.1115/msec2022-85273","DOIUrl":"https://doi.org/10.1115/msec2022-85273","url":null,"abstract":"\u0000 Implantable microelectrode arrays are an effective method for understanding neurotransmitter dynamics with high spatial resolution. In particular, carbon-based electrodes are efficient for electrochemical detection of dopamine, a neurotransmitter studied for its role in motor movement and reward-seeking behavior. However, very few options exist for arrayed carbon microelectrodes, specifically on flexible polymeric probes. We demonstrate fabrication of polyimide probes featuring single walled carbon nanotube (SWCNT) microelectrode arrays and characterize their dopamine detection performance. First, SWCNT synthesis parameters were optimized to grow high density SWCNT “forests” that have uniform height with electrode diameters ranging from 15 μm to 100 μm, as these dimensions are spatially relevant to chemical sensing in an animal model. These SWCNT microelectrodes were then incorporated into a microfabrication process involving deposition and patterning of polyimide substrate and metal traces. The process flow was designed such that the polyimide was not exposed to the high temperatures required to grow SWCNTs. Instead, a bottom-up approach was utilized, in which the SWCNT catalyst was first patterned, the SWCNTs were synthesized on a silicon substrate, then polyimide and trace metal layers were deposited and patterned. Prototype probes were fabricated containing the same range of electrode diameters as those used for SWCNT synthesis development to determine the effect of electrode diameter on ease of microfabrication. Microelectrodes ranging from 15 μm to 50 μm in diameter were found to release from the carrier wafer more easily, while larger electrodes demonstrated poor release. These probes demonstrate a concentration-dependent response to dopamine, with high sensitivity compared to microelectrode arrays consisting of bare metal. Further development of this electrode material will enable neuroscientists to study dopamine at higher spatial resolution, with the benefit of utilizing flexible probes.","PeriodicalId":45459,"journal":{"name":"Journal of Micro and Nano-Manufacturing","volume":"39 1","pages":""},"PeriodicalIF":1.0,"publicationDate":"2022-06-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"79873356","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}
Promising developments have shown the untapped potential of additive manufacturing (AM) for fabricating molded fiber molds (MFM), a critical piece for the molded fiber industry. This work builds upon AM implementations, presenting a novel application of micro-architected lattice structure to construct fiber filtering meshes attached to drainage channels, all combined in an “Integrated Mold.” Current AM approaches have failed to build low-cost and high lifespan tools. Instead, their design approach imitates the existing MFM structure, covering a base-shaped structure with a mesh. The main disadvantage of this method is the trade-off between water drainage and stiffness. Lattice materials have shown the capability of building porous structures with high stiffness, strength-to-weight ratio, fatigue tolerance, and the capacity to control the flow of fluids. The methodology presented in this research defines a new approach for MFM design that provides a broader range of porosity and enhances water drainage capabilities without affecting structural performance. As a result, it retrieves enhanced control over the physical properties of MFM. The studies presented in this paper show the functionality of lattice structures as filters for solid particles. Moreover, it offers an immediate application of this technology. The tools developed in this research have validated their capability to withstand more than a hundred cycles as tooling for MFP, proving their functionality for prototyping stages. This result seeks to accelerate the expansion of an industry that capitalizes on locally abundant, biodegradable, and recyclable raw materials.
{"title":"Micro-Architected Lattice-Based Mesh for Fiber Filters: A Novel Additive Manufacturing Architecture for Molded Fiber Tooling","authors":"J. Dominguez, P. González","doi":"10.1115/msec2022-85305","DOIUrl":"https://doi.org/10.1115/msec2022-85305","url":null,"abstract":"\u0000 Promising developments have shown the untapped potential of additive manufacturing (AM) for fabricating molded fiber molds (MFM), a critical piece for the molded fiber industry. This work builds upon AM implementations, presenting a novel application of micro-architected lattice structure to construct fiber filtering meshes attached to drainage channels, all combined in an “Integrated Mold.” Current AM approaches have failed to build low-cost and high lifespan tools. Instead, their design approach imitates the existing MFM structure, covering a base-shaped structure with a mesh. The main disadvantage of this method is the trade-off between water drainage and stiffness.\u0000 Lattice materials have shown the capability of building porous structures with high stiffness, strength-to-weight ratio, fatigue tolerance, and the capacity to control the flow of fluids. The methodology presented in this research defines a new approach for MFM design that provides a broader range of porosity and enhances water drainage capabilities without affecting structural performance. As a result, it retrieves enhanced control over the physical properties of MFM.\u0000 The studies presented in this paper show the functionality of lattice structures as filters for solid particles. Moreover, it offers an immediate application of this technology. The tools developed in this research have validated their capability to withstand more than a hundred cycles as tooling for MFP, proving their functionality for prototyping stages. This result seeks to accelerate the expansion of an industry that capitalizes on locally abundant, biodegradable, and recyclable raw materials.","PeriodicalId":45459,"journal":{"name":"Journal of Micro and Nano-Manufacturing","volume":"17 1","pages":""},"PeriodicalIF":1.0,"publicationDate":"2022-06-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"79891396","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}
N. Khadka, Yucheng Yang, J. Haug, M. Palei, M. Rosenberger, Anthony Hoffman, E. Kinzel
Ultrafast laser processing has been widely studied for surface texturing. The complex interaction between the laser energy, plasma, and surface chemistry produces complex morphologies including Laser-Induced Periodic Surface Structures and random higher aspect ratio geometries. Laser texturing allows engineering of metallic surface’s wettability as well as the reflectance on either broadband or narrowband basis. This paper experimentally maps the laser process parameters to the surface morphology and diffuse reflectance for stainless steel, aluminum, and copper substrates. All experiments are conducted with a 1030 nm wavelength, 230 fs pulse length laser in an ambient environment. The results show how the common morphological regimes shift with material and how the reflectance varies with morphology. To further decrease the reflectance, hierarchical structures are generated by first locally micromachining the surface to form a lattice of trenches using the focused laser beam, before texturing the surface with a rastered, defocused laser beam. The micromachined features interact with laser texturing and increase light trapping on the surface. This is a function of the depth and periodicity of the hierarchical structures as well as the surface topography. This approach provides the ability to lower the surface reflectance and add an extra level of control for directing deep micro-cavities along the surface.
{"title":"Ultrafast Laser Texturing of Metal Surfaces: Effects of Process Parameters on Surface Reflectance and Possibility of Hierarchical Structuring","authors":"N. Khadka, Yucheng Yang, J. Haug, M. Palei, M. Rosenberger, Anthony Hoffman, E. Kinzel","doi":"10.1115/msec2022-85663","DOIUrl":"https://doi.org/10.1115/msec2022-85663","url":null,"abstract":"\u0000 Ultrafast laser processing has been widely studied for surface texturing. The complex interaction between the laser energy, plasma, and surface chemistry produces complex morphologies including Laser-Induced Periodic Surface Structures and random higher aspect ratio geometries. Laser texturing allows engineering of metallic surface’s wettability as well as the reflectance on either broadband or narrowband basis. This paper experimentally maps the laser process parameters to the surface morphology and diffuse reflectance for stainless steel, aluminum, and copper substrates. All experiments are conducted with a 1030 nm wavelength, 230 fs pulse length laser in an ambient environment. The results show how the common morphological regimes shift with material and how the reflectance varies with morphology. To further decrease the reflectance, hierarchical structures are generated by first locally micromachining the surface to form a lattice of trenches using the focused laser beam, before texturing the surface with a rastered, defocused laser beam. The micromachined features interact with laser texturing and increase light trapping on the surface. This is a function of the depth and periodicity of the hierarchical structures as well as the surface topography. This approach provides the ability to lower the surface reflectance and add an extra level of control for directing deep micro-cavities along the surface.","PeriodicalId":45459,"journal":{"name":"Journal of Micro and Nano-Manufacturing","volume":"22 1","pages":""},"PeriodicalIF":1.0,"publicationDate":"2022-06-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"79978799","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}
Ceramic binder jetting processes have inherent limitations in achieving high density due to the low packing density of the powder bed. An emerging route to mitigate the low packing density in ceramic binder jetting entails uniaxial compaction of newly spread powder layers prior to ink deposition. The introduction of layerwise pressure induced a stress shielding effect, i.e., unbalanced stresses between the printed region saturated with ink and the surrounding loose powder, which generates heterogeneous stress in the powder bed and ultimately influences the density of the final part. In this paper, we attempt to better understand the stress shielding effect during the compaction of a selectively ink-jetted powder bed as a function of the printing pattern, i.e., ratio of printed to unprinted sector. Our findings reveal a decreased print area increased the resulting stress shielding effect. Additionally, when pressed without neighboring dry powder, a printed region experienced a much higher stress than the hybrid composition. The dry powder experienced the opposite effect, where when pressed alone, the dry powder had a much lower stress than when pressed with saturated powder. Findings will assist in density prediction and print pattern determination of compacted binder jetted ceramics.
{"title":"Characterization of Stress Shielding in Pressure-Assisted Ceramic Binder Jetting","authors":"L. Kirby, F. Fei, Xuan Song","doi":"10.1115/msec2022-85766","DOIUrl":"https://doi.org/10.1115/msec2022-85766","url":null,"abstract":"\u0000 Ceramic binder jetting processes have inherent limitations in achieving high density due to the low packing density of the powder bed. An emerging route to mitigate the low packing density in ceramic binder jetting entails uniaxial compaction of newly spread powder layers prior to ink deposition. The introduction of layerwise pressure induced a stress shielding effect, i.e., unbalanced stresses between the printed region saturated with ink and the surrounding loose powder, which generates heterogeneous stress in the powder bed and ultimately influences the density of the final part. In this paper, we attempt to better understand the stress shielding effect during the compaction of a selectively ink-jetted powder bed as a function of the printing pattern, i.e., ratio of printed to unprinted sector. Our findings reveal a decreased print area increased the resulting stress shielding effect. Additionally, when pressed without neighboring dry powder, a printed region experienced a much higher stress than the hybrid composition. The dry powder experienced the opposite effect, where when pressed alone, the dry powder had a much lower stress than when pressed with saturated powder. Findings will assist in density prediction and print pattern determination of compacted binder jetted ceramics.","PeriodicalId":45459,"journal":{"name":"Journal of Micro and Nano-Manufacturing","volume":"23 1","pages":""},"PeriodicalIF":1.0,"publicationDate":"2022-06-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"80005189","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}
Joseph Tang, H. Sezer, N. Ahsan, Hossain Ahmed, S. Kaul
In this paper, maximum stresses from the Direct Metal Laser Sintering (DMLS) process are numerically calculated for each layer using a novel computational model that has been developed to capture the layer-by-layer deposition. The computational domain with all layers is modeled numerically with conduction, while using convection and radiation on the model boundaries. The phase change of the material between liquid and solid states is accounted for and the residual thermal stresses are obtained from the temperature gradient data in conjunction with Hooke’s law. The resulting maximum stress versus time behavior and maximum stress distribution patterns on each layer are complex and do not always match the scanning path. However, there is direct correspondence between the stress distribution and the scanning patterns.
{"title":"Modeling Maximum Stresses in Each Layer for Layer-by-Layer Deposition of the Direct Metal Laser Sintering Process for Different Scanning Patterns","authors":"Joseph Tang, H. Sezer, N. Ahsan, Hossain Ahmed, S. Kaul","doi":"10.1115/msec2022-85777","DOIUrl":"https://doi.org/10.1115/msec2022-85777","url":null,"abstract":"\u0000 In this paper, maximum stresses from the Direct Metal Laser Sintering (DMLS) process are numerically calculated for each layer using a novel computational model that has been developed to capture the layer-by-layer deposition. The computational domain with all layers is modeled numerically with conduction, while using convection and radiation on the model boundaries. The phase change of the material between liquid and solid states is accounted for and the residual thermal stresses are obtained from the temperature gradient data in conjunction with Hooke’s law. The resulting maximum stress versus time behavior and maximum stress distribution patterns on each layer are complex and do not always match the scanning path. However, there is direct correspondence between the stress distribution and the scanning patterns.","PeriodicalId":45459,"journal":{"name":"Journal of Micro and Nano-Manufacturing","volume":"9 1","pages":""},"PeriodicalIF":1.0,"publicationDate":"2022-06-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"80328409","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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