As a universal casting Mg-RE alloy,Mg-6Gd-3Y-Zr(GW63K,wt.%)alloy exhibits superior strength-ductility synergy and holds significant potential for engineering applications.In this study,the GW63K alloy is produced usin...As a universal casting Mg-RE alloy,Mg-6Gd-3Y-Zr(GW63K,wt.%)alloy exhibits superior strength-ductility synergy and holds significant potential for engineering applications.In this study,the GW63K alloy is produced using the laser powder bed fusion(LPBF)additive manufacturing(AM)process for the first time.The printability,microstructure characteristics,and post-heat treatment conditions of the GW63K alloy are systematically investigated.The as-built GW63K samples demonstrate high relative densities exceeding 99.6%and exhibit no macroscopic and microscopic cracking across a wide range of process parameters,indicating excellent printability.An exceptional heterogeneous microstructure is observed in the as-built GW63K alloy,comprising coarse columnar grains,fine equiaxed grains with an average grain size of 21.72μm,uniformly distributed nano-sized Mg_(24)(Gd,Y)_(5)secondary phase,and numerous dislocations.Consequently,the as-built GW63K alloy displays enhanced tensile strengths and ductility compared to the as-cast alloy,with yield strength(YS),ultimate tensile strength(UTS)and elongation(EL)values of 218±4 MPa,284±5 MPa and 11.9±1.6%respectively.Additionally,due to the absence of coarse micron-sized secondary phase,a specific direct aging(T5)heat treatment regime at 200℃for 128 h is optimized for the as-built GW63K alloy to introduce dense and dispersedβ’aging precipitates.This T5 treatment surpasses the conventional solution plus aging(T6)heat treatment in enhancing mechanical properties.The LPBF-T5 GW63K alloy exhibits YS,UTS and EL values of 293±6 MPa,359±4 MPa and 2.9±0.7%,respectively.Notably,the YS of the LPBF-T5 alloy represents the highest value for the GW63K alloy,even surpassing that of the extrusion-T5 alloy.This study indicates that the GW63K alloy is a highly promising material for manufacturing near-net-shape high-strength Mg alloy components with intricate geometries using LPBF.展开更多
Three-dimensional(3D)extrusion-based bioprinting is widely used in tissue engineering and regenerative medicine to create cell-incorporated constructs or scaffolds based on the extrusion technique.One critical issue i...Three-dimensional(3D)extrusion-based bioprinting is widely used in tissue engineering and regenerative medicine to create cell-incorporated constructs or scaffolds based on the extrusion technique.One critical issue in 3D extrusion-based bioprinting is printability or the capability to form and maintain reproducible 3D scaffolds from bioink(a mixture of biomaterials and cells).Research shows that printability can be affected by many factors or parameters,including those associated with the bioink,printing process,and scaffold design,but these are far from certain.This review highlights recent developments in the printability assessment of extrusion-based bioprinting with a focus on the definition of printability,printability measurements and characterization,and printability-affecting factors.Key issues and challenges related to printability are also identified and discussed,along with approaches or strategies for improving printability in extrusion-based bioprinting.展开更多
Additive manufacturing provides achievability for the fabrication of bimetallic and multi-material structures;however,the material compatibility and bondability directly affect the parts’formability and final quality...Additive manufacturing provides achievability for the fabrication of bimetallic and multi-material structures;however,the material compatibility and bondability directly affect the parts’formability and final quality.It is essential to understand the underlying printability of different material combinations based on an adapted process.Here,the printability disparities of two common and attractive material combinations(nickel-and iron-based alloys)are evaluated at the macro and micro levels via laser directed energy deposition(DED).The deposition processes were captured using in situ high-speed imaging,and the dissimilarities in melt pool features and track morphology were quantitatively investigated within specific process windows.Moreover,the microstructure diversity of the tracks and blocks processed with varied material pairs was comparatively elaborated and,complemented with the informative multi-physics modeling,the presented non-uniformity in mechanical properties(microhardness)among the heterogeneous material pairs was rationalized.The differences in melt flow induced by the unlike thermophysical properties of the material pairs and the resulting element intermixing and localized re-alloying during solidification dominate the presented dissimilarity in printability among the material combinations.This work provides an in-depth understanding of the phenomenological differences in the deposition of dissimilar materials and aims to guide more reliable DED forming of bimetallic parts.展开更多
Recently, 3D bioprinting is developed as an emerging approach, increasingly applied to materials for healthcare;while, the precise placement of cells and materials, and the shape fidelity of forming constructs is of g...Recently, 3D bioprinting is developed as an emerging approach, increasingly applied to materials for healthcare;while, the precise placement of cells and materials, and the shape fidelity of forming constructs is of great importance for successful application of 3D bioprinting. Research efforts have been made to develop new bioinks as "raw materials" with better biocompatibility and biofunctionality, but the printability of bioinks is largely ignored and still needs to be carefully examined to enable robotic bioprinting. This article aims to introduce a recent published review (Appl. Phys. Rev. 2018, 5, 041304) on the evaluation of bioink printability by Huang's research group from University of Florida. Huang et al. comprehensively reviewed the bioink printability based on the physical point of view during inkjet printing, laser printing, and microextrusion, and a series of self-consistent time scales and dimensi on less quantities were utilized to physically understand and evaluate bioink printability. This article would be helpful to know the trends on physical understanding of bioink printability.展开更多
Direct ink writing(DIW)holds enormous potential in fabricating multiscale and multi-functional architectures by virtue of its wide range of printable materials,simple operation,and ease of rapid prototyping.Although i...Direct ink writing(DIW)holds enormous potential in fabricating multiscale and multi-functional architectures by virtue of its wide range of printable materials,simple operation,and ease of rapid prototyping.Although it is well known that ink rheology and processing parameters have a direct impact on the resolution and shape of the printed objects,the underlying mechanisms of these key factors on the printability and quality of DIW technique remain poorly understood.To tackle this issue,we systematically analyzed the printability and quality through extrusion mechanism modeling and experimental validating.Hybrid non-Newtonian fluid inks were first prepared,and their rheological properties were measured.Then,finite element analysis of the whole DIW process was conducted to reveal the flow dynamics of these inks.The obtained optimal process parameters(ink rheology,applied pressure,printing speed,etc)were also validated by experiments where high-resolution(<100μm)patterns were fabricated rapidly(>70 mm s^(-1)).Finally,as a process research demonstration,we printed a series of microstructures and circuit systems with hybrid inks and silver inks,showing the suitability of the printable process parameters.This study provides a strong quantitative illustration of the use of DIW for the high-speed preparation of high-resolution,high-precision samples.展开更多
Rheological properties of microemulsions(MEs) and their printability in three dimensional printing(3DP) systems were investigated.A series of MEs with different contents of oil phase were prepared using sonication met...Rheological properties of microemulsions(MEs) and their printability in three dimensional printing(3DP) systems were investigated.A series of MEs with different contents of oil phase were prepared using sonication method with ibuprofen as model drug and soybean lecithin as emulfier.Stationary and transient rheological properties of MEs were investigated by ARES-SRF using concentric cylinders measuring systems.3DP systems with piezoelectric drop-on-demand print heads were employed to test the printability of the MEs.Results demonstrate that the apparent viscosity and dynamic linear viscoelastic regions of the MEs are the most important parameters for continuous and stable printing of MEs by 3DP.The incorporation of drug in the MEs has little influence on the MEs' stationary rheological behaviors and dynamic viscoelasticity,but the concentration of oil phase has a strong influence on them.The rheological property of binder liquids has a close relationship with their printability in 3DP system.展开更多
High levels of Al and Ti in superalloy compositions normally lead to cracking formation during the laser powder bed fusion process,while these elements are key constituents of strengthening phases.In the current study...High levels of Al and Ti in superalloy compositions normally lead to cracking formation during the laser powder bed fusion process,while these elements are key constituents of strengthening phases.In the current study,a novel Co-based superalloy with the basic chemical composition of Co-Al-W-Ta-Ti resolved this contradiction,indicating that the part was formed without cracking and simultaneously contained a large amount of strengthening precipitates in the microstructure fabricated via laser powder bed fusion.The printability,microstructures,and mechanical properties of the sample were analysed before and after heat treatment,providing a potential superalloy that can replace Ni-based superalloys fabricated by additive manufacturing in aerospace and other industries with higher temperature and more efficiency.展开更多
In order to improve environmental pollution of printing industry,it has developed new environmental ink which is called UV Soy Ink.The purpose of this research is to investigate screen printability of UV Soy Ink.To pr...In order to improve environmental pollution of printing industry,it has developed new environmental ink which is called UV Soy Ink.The purpose of this research is to investigate screen printability of UV Soy Ink.To print UV Soy Ink on four different plastics for hardness tested,strips tested,abrasion resistance tested,and solvent resistance tested.The test results will be compared with UV Ink According to experimental results and finding out:(1)For hardness tested,the printability of UV Ink and UV Soy Ink are not different.(2)For strips tested,abrasion resistance tested,and solvent resistance tested,the printability of UV Ink is a little better than UV Soy Ink.But to respond to the environmental issue and the sustainable development of printing industry,it's still worthwhile to promote UV Soy Ink and use it.展开更多
Embedded printing is a highly promising approach for creating complex structures within a yield-stress support bath.However,the accurate prediction and control of printability remain fundamental challenges due to the ...Embedded printing is a highly promising approach for creating complex structures within a yield-stress support bath.However,the accurate prediction and control of printability remain fundamental challenges due to the complex interactions between inks and support baths.Here,we present an artificial intelligence(AI)-driven framework that interprets and predicts embedded printability using rheological data.Using a standardized workflow,we extracted 21 rheological descriptors and established 12 indicators to evaluate structural continuity and geometric fidelity.Interpretable machine learning models revealed that direction-dependent defects are governed by the synergistic interplay among ink yield stress,support bath zero shear viscosity,flow behavior index,and time constant.To enable the prediction of printability in a generalizable manner,we further developed a cascaded neural network,which achieved mean relative prediction errors below 15%across all indicators.Experimental validation using three-dimensional(3 D)-printed constructs and micro-computed tomography(μCT)reconstructions confirmed a strong correlation between predicted and actual fidelity.This work establishes a physics-informed,data-driven paradigm for decoding and optimizing embedded printing,offering broad applicability and providing a robust tool for the rapid pairing of suitable printable ink-support bath combinations.展开更多
The rapid advancement of flexible electronics creates an urgent demand for high-performance printed electronic materials.MXene-based inks have been widely studied and used for screen-printing electronics,while they us...The rapid advancement of flexible electronics creates an urgent demand for high-performance printed electronic materials.MXene-based inks have been widely studied and used for screen-printing electronics,while they usually suffer from poor screen-printability and inadequate mechanical properties of the printed coatings.Therefore,we incorporate 2,2,6,6-tetramethylpiperidinooxy oxidized cellulose nanofibers into MXene ink to regulate its rheology and enhance printability on both porous A4 paper and compact polyethylene terephthalate substrates.The introduction of cellulose enables precise control over the rheology and microstructure of the resultant MXene coatings.Critically,the strong interfacial hydrogen bonding and physical entanglement between cellulose and MXene contribute to the substantial enhancements of the mechanical properties and structural stability of the resultant composite coatings,where a remarkable 9.04-fold increase of hardness and a 1.74-fold increase of Young’s modulus are achieved.The interfacial binding strength between the coating and substrate is also well enhanced with the anchoring of cellulose.This work thereby presents a promising strategy for the design and fabrication of flexible screen-printed electronics.展开更多
Accurately reconstructing the intricate structure of natural organisms is the long-standing goal of 3-dimensional(3D)bioprinting.Projection-based 3D printing boasts the highest resolution-to-manufacturing time ratio a...Accurately reconstructing the intricate structure of natural organisms is the long-standing goal of 3-dimensional(3D)bioprinting.Projection-based 3D printing boasts the highest resolution-to-manufacturing time ratio among all 3D-printing technologies,rendering it a highly promising technique in this field.However,achieving standardized,high-fidelity,and high-resolution printing of composite structures using bioinks with diverse mechanical properties remains a marked challenge.The root of this challenge lies in the long-standing neglect of multi-material printability research.Multi-material printing is far from a simple physical assembly of different materials;rather,effective control of material interfaces is a crucial factor that governs print quality.The current research gap in this area substantively hinders the widespread application and rapid development of multi-material projection-based 3D bioprinting.To bridge this critical gap,we developed a multi-material projection-based 3D bioprinter capable of simultaneous printing with 6 materials.Building upon this,we established a fundamental framework for multi-material printability research,encompassing its core logic and essential process specifications.Furthermore,we clarified several critical issues,including the cross-linking behavior of multicomponent bioinks,mechanical mismatch and interface strength in soft-hard composite structures,the penetration behavior of viscous bioinks within hydrogel polymer networks,liquid entrapment and adsorption phenomena in porous heterogeneous structures,and error source analysis along with resolution evaluation in multi-material printing.This study offers a solid theoretical foundation and guidance for the quantitative assessment of multi-material projection-based 3D bioprinting,holding promise to advance the field toward higher precision and the reconstruction of more intricate biological structures.展开更多
Using an in situ lunar regolith as a construction material in combination with 3D printing not only reduces the weight of materials carried from the Earth but also improves the automation of lunar infrastructure const...Using an in situ lunar regolith as a construction material in combination with 3D printing not only reduces the weight of materials carried from the Earth but also improves the automation of lunar infrastructure construction.This study aims to improve the printability of a geopolymer based on a BH-1 lunar regolith simulant,including the extrudability,open time,and buildability,by controlling the temperature and adding admixtures.Rheological parameters were used to represent printability with different water-to-binder ratios,printing temperatures,and contents of additives.The mechanical properties of the hardening geopolymer with different filling paths and loading directions were tested.The results show that heating the printed filaments with a water-to-binder ratio of 0.32 at 80°C can adjust the printability without adding any additive,which can reduce the construction cost of lunar infrastructure.The printability of the BH-1 geopolymer can also be improved by adding 0.3%Attagel-50 and 0.5%polypropylene fiber by mass at a temperature of 20℃to cope with the changeable environmental conditions on the Moon.After curing under a simulated lunar environment,the 72-h flexural and compressive strengths of the geopolymer specimens reach 4.1 and 48.1 MPa,respectively,which are promising considering that the acceleration of gravity on the Moon is 1/6 of that on the Earth.展开更多
Correlation of related factors(texture,gel strength,rheological properties)were analyzed for better characterize 3D material printability.Moreover,printability calculation formula also was established to represent mat...Correlation of related factors(texture,gel strength,rheological properties)were analyzed for better characterize 3D material printability.Moreover,printability calculation formula also was established to represent material plasticity.Pennahia argentata surimi shown best plasticity with 78%moisture content and 20%rice starch respectively.Additionally,starch and carrageenan increased gel strength,yield stress of surimi and starch respectively,which brought better mechanical strength and supporting ability.They also affected viscosity of surimi(increasing)and starch(decreasing),which brought better fluidity and adhesion respectively,resulting in good printability,especially starch(8%)-surimi,carrageenan(0.5%)-starch.Based on their interaction relationships,3D printability equation of printing inkswas established their relevance and corresponding unified values.To judge the printability of same materials under different conditions were consistent with real print results.These could provide methods for judging material printability by specific values and promote the application and spread of 3D materials.展开更多
The extrusion-based bioprinting(EBBP)applications in the medical field tremendously increase due to its ver-satility in fabricating intricate geometry components with reasonable accuracy and precision.The bioink and i...The extrusion-based bioprinting(EBBP)applications in the medical field tremendously increase due to its ver-satility in fabricating intricate geometry components with reasonable accuracy and precision.The bioink and its properties for an EBBP process are crucial in manufacturing parts with significant biocompatibility and functionality.The EBBP demands optimized parameters for obtaining good printability and cell viability.A better understanding of the various process parameters is essential for the researcher to optimize the mechanical and biological properties of the printed constructs.The biological,mechanical,and rheological parameters all together need to be evaluated to enhance the printability of tissue.This article concisely delineates the effect of the rheological and physiochemical parameters on the biological and mechanical properties of the printed tissues.The printing parameters and nozzle geometry,which considerably influence the printability,and shape fidelity of the bioprinted scaffolds are exemplified in detail.Additionally,the challenges and future aspects of enhancing printability are discussed succinctly.展开更多
A novel laser-based additive manufacturing approach of metal additive manufacturing using powder sheets(MAPS)has been introduced recently.The method utilizes polymer-bound powder sheets for metal AM as a feedstock,ins...A novel laser-based additive manufacturing approach of metal additive manufacturing using powder sheets(MAPS)has been introduced recently.The method utilizes polymer-bound powder sheets for metal AM as a feedstock,instead of loose powders.Conventional laser beam powder bed fusion(LPBF)additive manufacturing(AM)is among the most widespread 3D printing technologies.However,LPBF faces challenges related to safety and the impracticality of changing materials due to its reliance on loose powders.Thus,MAPS demonstrates the capability to overcome the limitations of LPBF by offering enhanced safety and the ability to print multi-material structures without the risk of material cross-contamination.As a part of developing processes,we investigate the effects of polymeric binder content on the printability and microstructural characteristics of MAPS-printed stainless steel 316 L.The results indicate that the average layer thickness of solidified material improves as the scanning speed decreases from 1000 mm/s to 50 mm/s across three different polymeric binder contents:10 wt%,20 wt%,and 30 wt%PCL.Additionally,a higher polymeric binder content(i.e.20 wt%and 30 wt%)in the powder sheets reduces the likelihood of crack formation.Electron backscatter diffraction(EBSD)analysis reveals that an increase in scanning speed promotes the formation of more equiaxed grains,while an increase in polymer content results in a reduction in grain size.These findings provide valuable insights into optimizing MAPS configurations for enhanced productivity and functionality in metal component manufacturing.展开更多
Modulating the interface between the electron transport layer(ETL)and perovskite to minimize interfacial recombination is pivotal for developing efficient and stable perovskite solar cells.Here,we introduce an ultra-t...Modulating the interface between the electron transport layer(ETL)and perovskite to minimize interfacial recombination is pivotal for developing efficient and stable perovskite solar cells.Here,we introduce an ultra-thin ZrO_(2)insulating interface layer onto the inner surface of the mesoporous TiO_(2)ETL via the chemical bath deposition in the zirconium n-butoxide solution,which alters the interface characteristics between TiO_(2)and perovskite for the printable hole-conductor-free mesoscopic perovskite solar cells(p-MPSCs).The insulating ZrO_(2)interface layer reduces interface defects and suppresses interfacial non-radiative recombination.Furthermore,the ZrO_(2)interface layer improves the wettability of the mesoporous TiO_(2)ETL,which favors the crystallization of perovskite within the mesoporous scaffold.Meanwhile,the device performance presents thickness dependence on the interface layer.While increased thickness improves the open-circuit voltage,excessive thickness negatively impacts both the short-circuit current density and fill factor.Consequently,an improved power conversion efficiency of 19.9% was achieved for p-MPSCs with the ZrO_(2)interface layer at its optimized thickness.展开更多
Lightweight aluminum(Al)alloys have been widely used in frontier fields like aerospace and automotive industries,which attracts great interest in additive manufacturing(AM)to process high-value Al parts.As a mainstrea...Lightweight aluminum(Al)alloys have been widely used in frontier fields like aerospace and automotive industries,which attracts great interest in additive manufacturing(AM)to process high-value Al parts.As a mainstream AM technique,laser-directed energy deposition(LDED)shows good scalability to meet the requirements for large-format component manufacturing and repair.However,LDED Al alloys are highly challenging due to their inherent poor printability(e.g.low laser absorption,high oxidation sensitivity and cracking tendency).To further promote the development of LDED high-performance Al alloys,this review offers a deep understanding of the challenges and strategies to improve printability in LDED Al alloys.The porosity,cracking,distortion,inclusions,element evaporation and resultant inferior mechanical properties(worse than laser powder bed fusion)are the key challenges in LDED Al alloys.Processing parameter optimizations,in-situ alloy design,reinforcing particle addition and field assistance are the efficient approaches to improving the printability and performance of LDED Al alloys.The underlying correlations between processes,alloy innovation,characteristic microstructures,and achievable performances in LDED Al alloys are discussed.The benchmark mechanical properties and primary strengthening mechanism of LDED Al alloys are summarized.This review aims to provide a critical and in-depth evaluation of current progress in LDED Al alloys.Future opportunities and perspectives in LDED high-performance Al alloys are also outlined.展开更多
Metal additive manufacturing(AM)has been extensively studied in recent decades.Despite the significant progress achieved in manufacturing complex shapes and structures,challenges such as severe cracking when using exi...Metal additive manufacturing(AM)has been extensively studied in recent decades.Despite the significant progress achieved in manufacturing complex shapes and structures,challenges such as severe cracking when using existing alloys for laser powder bed fusion(L-PBF)AM have persisted.These challenges arise because commercial alloys are primarily designed for conventional casting or forging processes,overlooking the fast cooling rates,steep temperature gradients and multiple thermal cycles of L-PBF.To address this,there is an urgent need to develop novel alloys specifically tailored for L-PBF technologies.This review provides a comprehensive summary of the strategies employed in alloy design for L-PBF.It aims to guide future research on designing novel alloys dedicated to L-PBF instead of adapting existing alloys.The review begins by discussing the features of the L-PBF processes,focusing on rapid solidification and intrinsic heat treatment.Next,the printability of the four main existing alloys(Fe-,Ni-,Al-and Ti-based alloys)is critically assessed,with a comparison of their conventional weldability.It was found that the weldability criteria are not always applicable in estimating printability.Furthermore,the review presents recent advances in alloy development and associated strategies,categorizing them into crack mitigation-oriented,microstructure manipulation-oriented and machine learning-assisted approaches.Lastly,an outlook and suggestions are given to highlight the issues that need to be addressed in future work.展开更多
In order to mimic the natural heterogeneity of native tissue and provide a better microenvironment for cell culturing,multi-material bioprinting has become a common solution to construct tissue models in vitro.With th...In order to mimic the natural heterogeneity of native tissue and provide a better microenvironment for cell culturing,multi-material bioprinting has become a common solution to construct tissue models in vitro.With the embedded printing method,complex 3D structure can be printed using soft biomaterials with reasonable shape fidelity.However,the current sequential multi-material embedded printing method faces a major challenge,which is the inevitable trade-off between the printed structural integrity and printing precision.Here,we propose a simultaneous multi-material embedded printing method.With this method,we can easily print firmly attached and high-precision multilayer structures.With multiple individually controlled nozzles,different biomaterials can be precisely deposited into a single crevasse,minimizing uncontrolled squeezing and guarantees no contamination of embedding medium within the structure.We analyse the dynamics of the extruded bioink in the embedding medium both analytically and experimentally,and quantitatively evaluate the effects of printing parameters including printing speed and rheology of embedding medium,on the 3D morphology of the printed filament.We demonstrate the printing of double-layer thin-walled structures,each layer less than 200μm,as well as intestine and liver models with 5%gelatin methacryloyl that are crosslinked and extracted from the embedding medium without significant impairment or delamination.The peeling test further proves that the proposed method offers better structural integrity than conventional sequential printing methods.The proposed simultaneous multi-material embedded printing method can serve as a powerful tool to support the complex heterogeneous structure fabrication and open unique prospects for personalized medicine.展开更多
The droplet formation dynamics of a Newtonian liquid in a drop-on-demand (DOD) inkjet process is numerically investigated by using a volume-of-fluid (VOF) method. We focus on the nozzle geometry, wettability of the in...The droplet formation dynamics of a Newtonian liquid in a drop-on-demand (DOD) inkjet process is numerically investigated by using a volume-of-fluid (VOF) method. We focus on the nozzle geometry, wettability of the interior surface, and the fluid properties to achieve the stable droplet formation with higher velocity. It is found that a nozzle with contracting angle of 45° generates the most stable and fastest single droplet, which is beneficial for the enhanced printing quality and high-throughput printing rate. For this nozzle with the optimal geometry, we systematically change the wettability of the interior surface, i.e., different contact angles. As the contact angle increases, pinch-off time increases and the droplet speed reduces. Finally, fluids with different properties are investigated to identify the printability range.展开更多
基金supported by the National Key Research and Development Program of China (No.2021YFB3701000)the National Natural Science Foundation of China (Nos. U21A2047, 52201129, 51821001,U2037601)+1 种基金the support by the China Postdoctoral Science Foundation (No. 2023M742219)the Postdoctoral Fellowship Program (Grade B) of CPSF(No. GZB20240419)
文摘As a universal casting Mg-RE alloy,Mg-6Gd-3Y-Zr(GW63K,wt.%)alloy exhibits superior strength-ductility synergy and holds significant potential for engineering applications.In this study,the GW63K alloy is produced using the laser powder bed fusion(LPBF)additive manufacturing(AM)process for the first time.The printability,microstructure characteristics,and post-heat treatment conditions of the GW63K alloy are systematically investigated.The as-built GW63K samples demonstrate high relative densities exceeding 99.6%and exhibit no macroscopic and microscopic cracking across a wide range of process parameters,indicating excellent printability.An exceptional heterogeneous microstructure is observed in the as-built GW63K alloy,comprising coarse columnar grains,fine equiaxed grains with an average grain size of 21.72μm,uniformly distributed nano-sized Mg_(24)(Gd,Y)_(5)secondary phase,and numerous dislocations.Consequently,the as-built GW63K alloy displays enhanced tensile strengths and ductility compared to the as-cast alloy,with yield strength(YS),ultimate tensile strength(UTS)and elongation(EL)values of 218±4 MPa,284±5 MPa and 11.9±1.6%respectively.Additionally,due to the absence of coarse micron-sized secondary phase,a specific direct aging(T5)heat treatment regime at 200℃for 128 h is optimized for the as-built GW63K alloy to introduce dense and dispersedβ’aging precipitates.This T5 treatment surpasses the conventional solution plus aging(T6)heat treatment in enhancing mechanical properties.The LPBF-T5 GW63K alloy exhibits YS,UTS and EL values of 293±6 MPa,359±4 MPa and 2.9±0.7%,respectively.Notably,the YS of the LPBF-T5 alloy represents the highest value for the GW63K alloy,even surpassing that of the extrusion-T5 alloy.This study indicates that the GW63K alloy is a highly promising material for manufacturing near-net-shape high-strength Mg alloy components with intricate geometries using LPBF.
基金The authors acknowledge financial support from the Natural Sciences and Engineering Research Council of Canada(NSERC,Grant No.:RGPIN-2014-05648).
文摘Three-dimensional(3D)extrusion-based bioprinting is widely used in tissue engineering and regenerative medicine to create cell-incorporated constructs or scaffolds based on the extrusion technique.One critical issue in 3D extrusion-based bioprinting is printability or the capability to form and maintain reproducible 3D scaffolds from bioink(a mixture of biomaterials and cells).Research shows that printability can be affected by many factors or parameters,including those associated with the bioink,printing process,and scaffold design,but these are far from certain.This review highlights recent developments in the printability assessment of extrusion-based bioprinting with a focus on the definition of printability,printability measurements and characterization,and printability-affecting factors.Key issues and challenges related to printability are also identified and discussed,along with approaches or strategies for improving printability in extrusion-based bioprinting.
基金supported by the National Natural Science Foundation of China(51975112,52375412)Fundamental Research Funds for Central Universities(N2203011)。
文摘Additive manufacturing provides achievability for the fabrication of bimetallic and multi-material structures;however,the material compatibility and bondability directly affect the parts’formability and final quality.It is essential to understand the underlying printability of different material combinations based on an adapted process.Here,the printability disparities of two common and attractive material combinations(nickel-and iron-based alloys)are evaluated at the macro and micro levels via laser directed energy deposition(DED).The deposition processes were captured using in situ high-speed imaging,and the dissimilarities in melt pool features and track morphology were quantitatively investigated within specific process windows.Moreover,the microstructure diversity of the tracks and blocks processed with varied material pairs was comparatively elaborated and,complemented with the informative multi-physics modeling,the presented non-uniformity in mechanical properties(microhardness)among the heterogeneous material pairs was rationalized.The differences in melt flow induced by the unlike thermophysical properties of the material pairs and the resulting element intermixing and localized re-alloying during solidification dominate the presented dissimilarity in printability among the material combinations.This work provides an in-depth understanding of the phenomenological differences in the deposition of dissimilar materials and aims to guide more reliable DED forming of bimetallic parts.
文摘Recently, 3D bioprinting is developed as an emerging approach, increasingly applied to materials for healthcare;while, the precise placement of cells and materials, and the shape fidelity of forming constructs is of great importance for successful application of 3D bioprinting. Research efforts have been made to develop new bioinks as "raw materials" with better biocompatibility and biofunctionality, but the printability of bioinks is largely ignored and still needs to be carefully examined to enable robotic bioprinting. This article aims to introduce a recent published review (Appl. Phys. Rev. 2018, 5, 041304) on the evaluation of bioink printability by Huang's research group from University of Florida. Huang et al. comprehensively reviewed the bioink printability based on the physical point of view during inkjet printing, laser printing, and microextrusion, and a series of self-consistent time scales and dimensi on less quantities were utilized to physically understand and evaluate bioink printability. This article would be helpful to know the trends on physical understanding of bioink printability.
基金supported by National Natural Science Foundation of China(Nos.52188102,U2013213,51820105008)the Technology Innovation Project of Hubei Province of China under Grant No.2019AEA171+1 种基金The project of introducing innovative leading talents in Songshan Lake High-tech Zone,Dongguan City,Guangdong Province(No.2019342101RSFJ-G)the support from Flexible Electronics Research Center of HUST for providing experiment facility。
文摘Direct ink writing(DIW)holds enormous potential in fabricating multiscale and multi-functional architectures by virtue of its wide range of printable materials,simple operation,and ease of rapid prototyping.Although it is well known that ink rheology and processing parameters have a direct impact on the resolution and shape of the printed objects,the underlying mechanisms of these key factors on the printability and quality of DIW technique remain poorly understood.To tackle this issue,we systematically analyzed the printability and quality through extrusion mechanism modeling and experimental validating.Hybrid non-Newtonian fluid inks were first prepared,and their rheological properties were measured.Then,finite element analysis of the whole DIW process was conducted to reveal the flow dynamics of these inks.The obtained optimal process parameters(ink rheology,applied pressure,printing speed,etc)were also validated by experiments where high-resolution(<100μm)patterns were fabricated rapidly(>70 mm s^(-1)).Finally,as a process research demonstration,we printed a series of microstructures and circuit systems with hybrid inks and silver inks,showing the suitability of the printable process parameters.This study provides a strong quantitative illustration of the use of DIW for the high-speed preparation of high-resolution,high-precision samples.
基金Project(B07024) supported by Biomedical Textile Materials "111 Project" from Ministry of Education of ChinaProject(50773009) supported by the National Natural Science Foundation of ChinaProject(Grant IRT0526) supported by Program for Changjiang Scholars and Innovative Research Team in University
文摘Rheological properties of microemulsions(MEs) and their printability in three dimensional printing(3DP) systems were investigated.A series of MEs with different contents of oil phase were prepared using sonication method with ibuprofen as model drug and soybean lecithin as emulfier.Stationary and transient rheological properties of MEs were investigated by ARES-SRF using concentric cylinders measuring systems.3DP systems with piezoelectric drop-on-demand print heads were employed to test the printability of the MEs.Results demonstrate that the apparent viscosity and dynamic linear viscoelastic regions of the MEs are the most important parameters for continuous and stable printing of MEs by 3DP.The incorporation of drug in the MEs has little influence on the MEs' stationary rheological behaviors and dynamic viscoelasticity,but the concentration of oil phase has a strong influence on them.The rheological property of binder liquids has a close relationship with their printability in 3DP system.
基金supported by the Shenzhen-Hong Kong Sci-ence and Technology Innovation Cooperation Zone Shenzhen Park Project(Grant No.HZQB-KCZYB-2020030)the RGC Theme-based Research Scheme(Grant No.AoE/M-402/20)+1 种基金National Nat-ural Science Foundation of China(Grant No.52250710160)Shenzhen Science and Technology Innovation Committee(Grant Nos.KQTD20170328154443162,JCYJ20210324104610029,and JCYJ20220818100613028).
文摘High levels of Al and Ti in superalloy compositions normally lead to cracking formation during the laser powder bed fusion process,while these elements are key constituents of strengthening phases.In the current study,a novel Co-based superalloy with the basic chemical composition of Co-Al-W-Ta-Ti resolved this contradiction,indicating that the part was formed without cracking and simultaneously contained a large amount of strengthening precipitates in the microstructure fabricated via laser powder bed fusion.The printability,microstructures,and mechanical properties of the sample were analysed before and after heat treatment,providing a potential superalloy that can replace Ni-based superalloys fabricated by additive manufacturing in aerospace and other industries with higher temperature and more efficiency.
文摘In order to improve environmental pollution of printing industry,it has developed new environmental ink which is called UV Soy Ink.The purpose of this research is to investigate screen printability of UV Soy Ink.To print UV Soy Ink on four different plastics for hardness tested,strips tested,abrasion resistance tested,and solvent resistance tested.The test results will be compared with UV Ink According to experimental results and finding out:(1)For hardness tested,the printability of UV Ink and UV Soy Ink are not different.(2)For strips tested,abrasion resistance tested,and solvent resistance tested,the printability of UV Ink is a little better than UV Soy Ink.But to respond to the environmental issue and the sustainable development of printing industry,it's still worthwhile to promote UV Soy Ink and use it.
基金supported by the National Natural Science Foundation of China(Nos.52305314 and U21A20394)the Beijing Natural Science Foundation(Nos.7252285 and L246001)the National Key Research and Development Program of China(No.2023YFB4605800)。
文摘Embedded printing is a highly promising approach for creating complex structures within a yield-stress support bath.However,the accurate prediction and control of printability remain fundamental challenges due to the complex interactions between inks and support baths.Here,we present an artificial intelligence(AI)-driven framework that interprets and predicts embedded printability using rheological data.Using a standardized workflow,we extracted 21 rheological descriptors and established 12 indicators to evaluate structural continuity and geometric fidelity.Interpretable machine learning models revealed that direction-dependent defects are governed by the synergistic interplay among ink yield stress,support bath zero shear viscosity,flow behavior index,and time constant.To enable the prediction of printability in a generalizable manner,we further developed a cascaded neural network,which achieved mean relative prediction errors below 15%across all indicators.Experimental validation using three-dimensional(3 D)-printed constructs and micro-computed tomography(μCT)reconstructions confirmed a strong correlation between predicted and actual fidelity.This work establishes a physics-informed,data-driven paradigm for decoding and optimizing embedded printing,offering broad applicability and providing a robust tool for the rapid pairing of suitable printable ink-support bath combinations.
基金supported by the Tianfu Yongxing Laboratory Organized Research Project Funding(Grant No.2023KJGG12)the State Key Laboratory of Polymer Materials Engineering(Grant No.sklpme2022-3-20)+1 种基金the Joint Project for Talent Innovation Sharing Alliance of Quanzhou(Grant No.2022C001L)the Opening Project of Guangxi Key Laboratory of Calcium Carbonate Resources Comprehensive Utilization(Grant No.HZXYKFKT202306).
文摘The rapid advancement of flexible electronics creates an urgent demand for high-performance printed electronic materials.MXene-based inks have been widely studied and used for screen-printing electronics,while they usually suffer from poor screen-printability and inadequate mechanical properties of the printed coatings.Therefore,we incorporate 2,2,6,6-tetramethylpiperidinooxy oxidized cellulose nanofibers into MXene ink to regulate its rheology and enhance printability on both porous A4 paper and compact polyethylene terephthalate substrates.The introduction of cellulose enables precise control over the rheology and microstructure of the resultant MXene coatings.Critically,the strong interfacial hydrogen bonding and physical entanglement between cellulose and MXene contribute to the substantial enhancements of the mechanical properties and structural stability of the resultant composite coatings,where a remarkable 9.04-fold increase of hardness and a 1.74-fold increase of Young’s modulus are achieved.The interfacial binding strength between the coating and substrate is also well enhanced with the anchoring of cellulose.This work thereby presents a promising strategy for the design and fabrication of flexible screen-printed electronics.
基金supported by the National Natural Science Foundation of China(grant numbers:52235007,T2121004,52325504,and 2021YFC2501800)the Key R&D Program of Zhejiang(2024SSYS0027).
文摘Accurately reconstructing the intricate structure of natural organisms is the long-standing goal of 3-dimensional(3D)bioprinting.Projection-based 3D printing boasts the highest resolution-to-manufacturing time ratio among all 3D-printing technologies,rendering it a highly promising technique in this field.However,achieving standardized,high-fidelity,and high-resolution printing of composite structures using bioinks with diverse mechanical properties remains a marked challenge.The root of this challenge lies in the long-standing neglect of multi-material printability research.Multi-material printing is far from a simple physical assembly of different materials;rather,effective control of material interfaces is a crucial factor that governs print quality.The current research gap in this area substantively hinders the widespread application and rapid development of multi-material projection-based 3D bioprinting.To bridge this critical gap,we developed a multi-material projection-based 3D bioprinter capable of simultaneous printing with 6 materials.Building upon this,we established a fundamental framework for multi-material printability research,encompassing its core logic and essential process specifications.Furthermore,we clarified several critical issues,including the cross-linking behavior of multicomponent bioinks,mechanical mismatch and interface strength in soft-hard composite structures,the penetration behavior of viscous bioinks within hydrogel polymer networks,liquid entrapment and adsorption phenomena in porous heterogeneous structures,and error source analysis along with resolution evaluation in multi-material printing.This study offers a solid theoretical foundation and guidance for the quantitative assessment of multi-material projection-based 3D bioprinting,holding promise to advance the field toward higher precision and the reconstruction of more intricate biological structures.
基金supported by the National Natural Science Foundation of China(Grant Nos.42241128,51978029)Key Laboratory of Road and Traffic Engineering of the Ministry of Education,Tongji University(No.K202206)+1 种基金China Postdoctoral Science Foundation(No.2023M730174)Young Elite Scientist Sponsorship Program by Beijing Association for Science and Technology(No.BYESS2023418).
文摘Using an in situ lunar regolith as a construction material in combination with 3D printing not only reduces the weight of materials carried from the Earth but also improves the automation of lunar infrastructure construction.This study aims to improve the printability of a geopolymer based on a BH-1 lunar regolith simulant,including the extrudability,open time,and buildability,by controlling the temperature and adding admixtures.Rheological parameters were used to represent printability with different water-to-binder ratios,printing temperatures,and contents of additives.The mechanical properties of the hardening geopolymer with different filling paths and loading directions were tested.The results show that heating the printed filaments with a water-to-binder ratio of 0.32 at 80°C can adjust the printability without adding any additive,which can reduce the construction cost of lunar infrastructure.The printability of the BH-1 geopolymer can also be improved by adding 0.3%Attagel-50 and 0.5%polypropylene fiber by mass at a temperature of 20℃to cope with the changeable environmental conditions on the Moon.After curing under a simulated lunar environment,the 72-h flexural and compressive strengths of the geopolymer specimens reach 4.1 and 48.1 MPa,respectively,which are promising considering that the acceleration of gravity on the Moon is 1/6 of that on the Earth.
基金support of National Science Funding of China(31871868)National Science of Hainan province(321CXTD1012)+1 种基金Scientific Research Foundation of Hainan Tropical Ocean University(RHDRC202117)Japan Society for the Promotion of Science(19H05611).
文摘Correlation of related factors(texture,gel strength,rheological properties)were analyzed for better characterize 3D material printability.Moreover,printability calculation formula also was established to represent material plasticity.Pennahia argentata surimi shown best plasticity with 78%moisture content and 20%rice starch respectively.Additionally,starch and carrageenan increased gel strength,yield stress of surimi and starch respectively,which brought better mechanical strength and supporting ability.They also affected viscosity of surimi(increasing)and starch(decreasing),which brought better fluidity and adhesion respectively,resulting in good printability,especially starch(8%)-surimi,carrageenan(0.5%)-starch.Based on their interaction relationships,3D printability equation of printing inkswas established their relevance and corresponding unified values.To judge the printability of same materials under different conditions were consistent with real print results.These could provide methods for judging material printability by specific values and promote the application and spread of 3D materials.
文摘The extrusion-based bioprinting(EBBP)applications in the medical field tremendously increase due to its ver-satility in fabricating intricate geometry components with reasonable accuracy and precision.The bioink and its properties for an EBBP process are crucial in manufacturing parts with significant biocompatibility and functionality.The EBBP demands optimized parameters for obtaining good printability and cell viability.A better understanding of the various process parameters is essential for the researcher to optimize the mechanical and biological properties of the printed constructs.The biological,mechanical,and rheological parameters all together need to be evaluated to enhance the printability of tissue.This article concisely delineates the effect of the rheological and physiochemical parameters on the biological and mechanical properties of the printed tissues.The printing parameters and nozzle geometry,which considerably influence the printability,and shape fidelity of the bioprinted scaffolds are exemplified in detail.Additionally,the challenges and future aspects of enhancing printability are discussed succinctly.
基金supported by PoSAddive–Powder Sheet Additive Manufacturing(co-funded by EIT Raw Materials,Grant No.22021)the AML in Trinity College Dublin.EIT Raw Materials is supported by EIT,a body of the European Union.
文摘A novel laser-based additive manufacturing approach of metal additive manufacturing using powder sheets(MAPS)has been introduced recently.The method utilizes polymer-bound powder sheets for metal AM as a feedstock,instead of loose powders.Conventional laser beam powder bed fusion(LPBF)additive manufacturing(AM)is among the most widespread 3D printing technologies.However,LPBF faces challenges related to safety and the impracticality of changing materials due to its reliance on loose powders.Thus,MAPS demonstrates the capability to overcome the limitations of LPBF by offering enhanced safety and the ability to print multi-material structures without the risk of material cross-contamination.As a part of developing processes,we investigate the effects of polymeric binder content on the printability and microstructural characteristics of MAPS-printed stainless steel 316 L.The results indicate that the average layer thickness of solidified material improves as the scanning speed decreases from 1000 mm/s to 50 mm/s across three different polymeric binder contents:10 wt%,20 wt%,and 30 wt%PCL.Additionally,a higher polymeric binder content(i.e.20 wt%and 30 wt%)in the powder sheets reduces the likelihood of crack formation.Electron backscatter diffraction(EBSD)analysis reveals that an increase in scanning speed promotes the formation of more equiaxed grains,while an increase in polymer content results in a reduction in grain size.These findings provide valuable insights into optimizing MAPS configurations for enhanced productivity and functionality in metal component manufacturing.
基金financial support from the National Natural Science Foundation of China(22439001,52172198,51902117)supported by the Innovation Fund of Wuhan National Laboratory for Optoelectronicsthe Analytical and Testing Center of Huazhong University of Science and Technology(HUST)for performing various characterizations。
文摘Modulating the interface between the electron transport layer(ETL)and perovskite to minimize interfacial recombination is pivotal for developing efficient and stable perovskite solar cells.Here,we introduce an ultra-thin ZrO_(2)insulating interface layer onto the inner surface of the mesoporous TiO_(2)ETL via the chemical bath deposition in the zirconium n-butoxide solution,which alters the interface characteristics between TiO_(2)and perovskite for the printable hole-conductor-free mesoscopic perovskite solar cells(p-MPSCs).The insulating ZrO_(2)interface layer reduces interface defects and suppresses interfacial non-radiative recombination.Furthermore,the ZrO_(2)interface layer improves the wettability of the mesoporous TiO_(2)ETL,which favors the crystallization of perovskite within the mesoporous scaffold.Meanwhile,the device performance presents thickness dependence on the interface layer.While increased thickness improves the open-circuit voltage,excessive thickness negatively impacts both the short-circuit current density and fill factor.Consequently,an improved power conversion efficiency of 19.9% was achieved for p-MPSCs with the ZrO_(2)interface layer at its optimized thickness.
基金supported by the 2022 MTC Young Individual Research Grants(Grant No.M22K3c0097)the Singapore Research,Innovation and Enterprise(RIE)2025 PlanSingapore Aerospace Programme Cycle 16(Grant No.M2215a0073)。
文摘Lightweight aluminum(Al)alloys have been widely used in frontier fields like aerospace and automotive industries,which attracts great interest in additive manufacturing(AM)to process high-value Al parts.As a mainstream AM technique,laser-directed energy deposition(LDED)shows good scalability to meet the requirements for large-format component manufacturing and repair.However,LDED Al alloys are highly challenging due to their inherent poor printability(e.g.low laser absorption,high oxidation sensitivity and cracking tendency).To further promote the development of LDED high-performance Al alloys,this review offers a deep understanding of the challenges and strategies to improve printability in LDED Al alloys.The porosity,cracking,distortion,inclusions,element evaporation and resultant inferior mechanical properties(worse than laser powder bed fusion)are the key challenges in LDED Al alloys.Processing parameter optimizations,in-situ alloy design,reinforcing particle addition and field assistance are the efficient approaches to improving the printability and performance of LDED Al alloys.The underlying correlations between processes,alloy innovation,characteristic microstructures,and achievable performances in LDED Al alloys are discussed.The benchmark mechanical properties and primary strengthening mechanism of LDED Al alloys are summarized.This review aims to provide a critical and in-depth evaluation of current progress in LDED Al alloys.Future opportunities and perspectives in LDED high-performance Al alloys are also outlined.
基金financially supported by the National Key Research and Development Program of China(2022YFB4600302)National Natural Science Foundation of China(52090041)+1 种基金National Natural Science Foundation of China(52104368)National Major Science and Technology Projects of China(J2019-VII-0010-0150)。
文摘Metal additive manufacturing(AM)has been extensively studied in recent decades.Despite the significant progress achieved in manufacturing complex shapes and structures,challenges such as severe cracking when using existing alloys for laser powder bed fusion(L-PBF)AM have persisted.These challenges arise because commercial alloys are primarily designed for conventional casting or forging processes,overlooking the fast cooling rates,steep temperature gradients and multiple thermal cycles of L-PBF.To address this,there is an urgent need to develop novel alloys specifically tailored for L-PBF technologies.This review provides a comprehensive summary of the strategies employed in alloy design for L-PBF.It aims to guide future research on designing novel alloys dedicated to L-PBF instead of adapting existing alloys.The review begins by discussing the features of the L-PBF processes,focusing on rapid solidification and intrinsic heat treatment.Next,the printability of the four main existing alloys(Fe-,Ni-,Al-and Ti-based alloys)is critically assessed,with a comparison of their conventional weldability.It was found that the weldability criteria are not always applicable in estimating printability.Furthermore,the review presents recent advances in alloy development and associated strategies,categorizing them into crack mitigation-oriented,microstructure manipulation-oriented and machine learning-assisted approaches.Lastly,an outlook and suggestions are given to highlight the issues that need to be addressed in future work.
基金the support by National Key Research and Development Program of China(2018YFA0703000)National Natural Science Foundation of China(Grant No.52105310)+1 种基金Natural Science Foundation of Zhejiang Province(Grant No.LDQ23E050001)the Starry Night Science Fund of Zhejiang University Shanghai Institute for Advanced Study(Grant No.SN-ZJU-SIAS-004)。
文摘In order to mimic the natural heterogeneity of native tissue and provide a better microenvironment for cell culturing,multi-material bioprinting has become a common solution to construct tissue models in vitro.With the embedded printing method,complex 3D structure can be printed using soft biomaterials with reasonable shape fidelity.However,the current sequential multi-material embedded printing method faces a major challenge,which is the inevitable trade-off between the printed structural integrity and printing precision.Here,we propose a simultaneous multi-material embedded printing method.With this method,we can easily print firmly attached and high-precision multilayer structures.With multiple individually controlled nozzles,different biomaterials can be precisely deposited into a single crevasse,minimizing uncontrolled squeezing and guarantees no contamination of embedding medium within the structure.We analyse the dynamics of the extruded bioink in the embedding medium both analytically and experimentally,and quantitatively evaluate the effects of printing parameters including printing speed and rheology of embedding medium,on the 3D morphology of the printed filament.We demonstrate the printing of double-layer thin-walled structures,each layer less than 200μm,as well as intestine and liver models with 5%gelatin methacryloyl that are crosslinked and extracted from the embedding medium without significant impairment or delamination.The peeling test further proves that the proposed method offers better structural integrity than conventional sequential printing methods.The proposed simultaneous multi-material embedded printing method can serve as a powerful tool to support the complex heterogeneous structure fabrication and open unique prospects for personalized medicine.
基金Project supported by the National Natural Science Foundation of China(No.11802004)
文摘The droplet formation dynamics of a Newtonian liquid in a drop-on-demand (DOD) inkjet process is numerically investigated by using a volume-of-fluid (VOF) method. We focus on the nozzle geometry, wettability of the interior surface, and the fluid properties to achieve the stable droplet formation with higher velocity. It is found that a nozzle with contracting angle of 45° generates the most stable and fastest single droplet, which is beneficial for the enhanced printing quality and high-throughput printing rate. For this nozzle with the optimal geometry, we systematically change the wettability of the interior surface, i.e., different contact angles. As the contact angle increases, pinch-off time increases and the droplet speed reduces. Finally, fluids with different properties are investigated to identify the printability range.
