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Continuous-Wave Laser-Induced Transfer of Metal Nanoparticles to Arbitrary Polymer Substrates
摘要： Laser-induced forward transfer (LIFT) and selective laser sintering (SLS) are two distinct laser processes that can be applied to metal nanoparticle (NP) ink for the fabrication of a conductive layer on various substrates. A pulsed laser and a continuous-wave (CW) laser are utilized respectively in the conventional LIFT and SLS processes; however, in this study, CW laser-induced transfer of the metal NP is proposed to achieve simultaneous sintering and transfer of the metal NP to a wide range of polymer substrates. At the optimum laser parameters, it was shown that a high-quality uniform metal conductor was created on the acceptor substrate while the metal NP was sharply detached from the donor substrate, and we anticipate that such an asymmetric transfer phenomenon is related to the di?erence in the adhesion strengths. The resultant metal electrode exhibits a low resistivity that is comparable to its bulk counterpart, together with strong adhesion to the target polymer substrate. The versatility of the proposed process in terms of the target substrate and applicable metal NPs brightens its prospects as a facile manufacturing scheme for ?exible electronics.
关键词： selective laser sintering,flexible electronics,metal nanoparticle ink,laser-induced forward transfer
更新于2025-09-23 15:21:01
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Selective Laser Sintering 3D Printing a?? An Overview of the Technology and Pharmaceutical Applications
摘要： Food and Drug Administration (FDA) has approved a drug product (Spritam?) and many medical devices manufactured by 3-dimensional printing (3DP) processes for human use. There is immense potential to print personalized medicines using 3DP. Many 3DP methods have been reported in the literature for pharmaceutical applications. However, selective laser sintering (SLS) printing has remained least explored for pharmaceutical applications. There are many advantages and challenges in adopting a SLS method for fabrication of personalized medicines. Solvent free nature, availability of FDA approved thermoplastic polymer/excipients (currently used in hot melt-extrusion process), minimal/no post-processing step, etc. are some of the advantages of the SLS printing process. Major challenges of the technology are requirement of at least one thermoplastic component in the formulation and thermal stability of drug and excipients. This review provides an overview of the SLS printing method, excipient requirements, process monitoring, quality defects, regulatory aspects and potential pharmaceutical applications.
关键词： in-process monitoring,selective laser sintering,personalized medication,3D printing,quality defects,pharmaceuticals
更新于2025-09-23 15:21:01
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Detection of powder bed defects in selective laser sintering using convolutional neural network
摘要： The presence of defects in a powder bed fusion (PBF) process can lead to the formation of flaws in consolidated parts. Powder bed defects (PBDs) have different sizes and shapes and occur in different locations in the built area. Those variations pose great challenges to their detection. In this study, a deep convolution neural network was applied to detect three typical types of PBDs in a selective laser sintering (SLS) process, namely warpage, part shifting, and short feed, which were intentionally generated by varying the process conditions. Images of the powder bed were captured using a digital camera, which were split into three single-channel images corresponding to the color channels in the color image. A deep residual neural network was then used to extract multiscale features, and a region proposal network was adopted to detect the object-level defect bounding box. In the final stage, a fully convolutional neural network was proposed to generate instance-level defect regions in the bounding box. Our results demonstrated that this method had higher accuracy and efficiency and was able to cope with geometrical distortion and image blurring, in comparison to the defect detection methods reported previously. Also, the detection system was cost-effective and could be easily installed outside the chamber of a PBF system. This study lays the groundwork for the development of a variety of automated technologies for additive manufacturing, such as real-time powder layer quality inspection and 3D quality certificate generation for finish parts.
关键词： Defect,Neural network,Selective laser sintering,Powder bed fusion,Detection
更新于2025-09-23 15:21:01
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Effects of raw material ratio and post-treatment on properties of soda lime glass-ceramics fabricated by selective laser sintering
摘要： A reliable method for fabricating soda lime glass-ceramics by selective laser sintering was demonstrated. The effect of the ratio of glass powder to epoxy resin and sintering process on the properties and microstructure of glass-ceramics was investigated. Research shows that: with the improvement of glass powder proportion, sintering shrinkage rate declined and mechanical strength could be improved gradually. When the mass ratio of glass powder and epoxy resin powder was 18:1 and heat-holding at 740℃ for 3 h, the shrinkage rate of the sample was 21.11% and the bending strength reached 95.45 MPa. Therefore, this research laid a foundation for 3D printing to fabricate high performance and complex structure glass-ceramics.
关键词： Selective Laser Sintering,3D printing,Glass-ceramics,Sintering
更新于2025-09-23 15:19:57
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Temperature field distribution in polymer particles during surface-selective laser sintering
摘要： The dynamics of polymer particle heating by laser irradiation during surface-selective laser sintering (SSLS) has been studied both experimentally and theoretically. Water aerosol wetting of the polymer particle surface was applied to increase the absorbance of thulium fiber laser radiation at 1.96 μm. Theoretical modeling of the laser-induced thermal processes was performed in thermolabile polylactic-co-glycolic acid powder coated with a thin water layer. Temperature gradients on the surface and inside the sintered particle volume were evaluated and analyzed. It was shown that for certain optimized SSLS parameters an effective sintering process can be achieved by delicate melting of the particle surface only, without noticeable changes in the chemical and phase compositions of the internal domains.
关键词： surface-selective laser sintering,thermal imaging,polymer particles,wetting,analysis of thermal processes
更新于2025-09-23 15:19:57
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Indirect selective laser sintering printed microporous biphasic calcium phosphate scaffold promotes endogenous bone regeneration via activation of ERK1/2 signaling
摘要： Fabrication technique determines the physicochemical and biological properties of scaffold, including porosity, mechanical strength, osteoconductivity, and bone regenerative potential. Biphasic calcium phosphate (BCP)-based scaffolds are superior in bone tissue engineering due to their suitable physicochemical and biological properties. We developed an indirect selective laser sintering (SLS) printing strategy to fabricate 3D microporous BCP scaffolds for bone tissue engineering purposes. The green part of BCP scaffold was fabricated by SLS at relevantly low temperature in the presence of epoxy resin (EP) and the remaining EP was decomposed, and eliminated by a subsequent sintering process to obtain the microporous BCP scaffolds. Physicochemical properties, cell adhesion, biocompatibility, in vitro osteogenic potential and rabbit critical size cranial bone defect healing potential of the scaffolds were extensively evaluated. This indirect SLS printing eliminated the drawbacks of conventional direct SLS printing at high working temperatures, i.e., wavy deformation of the scaffold, hydroxyapatite decomposition, and conversion of β-TCP to α-TCP. Among the scaffolds printed with various binder ratios (by weight) of BCP and EP, the scaffold with 50/50 binder ratio (S4) showed the highest mechanical strength and porosity with the smallest pore size. Scaffold S4 showed the highest effect on osteogenic differentiation of precursor cells in vitro, and this effect was ERK1/2 signaling dependent. Scaffold S4 robustly promoted precursor cells homing, endogenous bone regeneration, and vascularization in rabbit critical-size cranial defect. In conclusion, BCP scaffold fabricated by indirect SLS printing maintains the physicochemical properties of BCP and possess the capacity to recruit host precursor cells to the defect site and promote the endogenous bone regeneration possibly via activation of ERK1/2 signaling.
关键词： endogenous bone regeneration,ERK1/2 signaling,biphasic calcium phosphate,selective laser sintering,bone tissue engineering
更新于2025-09-23 15:19:57
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The effect of short glass fibers on the process behavior of polyamide 12 during selective laser beam melting
摘要： In additive manufacturing, polymer composites are used for setting tailored properties. Short glass fibers can be used as fillers for polyamide 12 for enhancing stiffness or tensile strength as well as for reducing shrinkage. In this paper, the effects of short glass fibers on polyamide 12 concerning powder properties, process behavior and part properties in laser beam melting of polymers (SLS) are investigated. It could be shown that by increasing the short glass fiber content powder properties as well as part properties are immensely affected. By adding glass fibers, powder properties, like flowability and diffuse reflection decrease. The isothermal crystallization changes resulting in a narrower processing window. Concerning mechanical properties, short glass fibers allow for a higher stiffness until a critical limit of filler concentration within this study is reached, after which the tensile strength decreases. The elongation of break decreases by rising the filler content.
关键词： Additive manufacturing,Short glass fibers,PA 12,Selective laser sintering,Filled systems
更新于2025-09-19 17:13:59
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Preparation of Highly Porous Carbonous Electrodes by Selective Laser Sintering
摘要： Selective laser sintering (SLS) 3D printing was utilized to fabricate highly porous carbonous electrodes. The electrodes were prepared by using a mixture of fine graphite powder and either polyamide-12, polystyrene, or polyurethane polymer powder as SLS printing material. During the printing process the graphite powder was dispersed uniformly on the supporting polymer matrix. Graphite’s concentration in the mixture was varied between 5 and 40 wt % to find the correlation between the carbon content and conductivity. The graphite concentration, polymer matrix, and printing conditions all had an impact on the final conductivity. Due to the SLS printing technique, all the 3D printed electrodes were highly porous. By using polyurethane as the supporting matrix it was possible to produce flexible electrodes in which the conductivity is sensitive to pressure and mechanical stress. Physical properties such as graphite distribution, attachment, and the overall porosity of the printed electrodes were studied using scanning electron microscopy (SEM), helium ion microscopy (HIM), and X-ray tomography. The results show that the combination of chemical design of the printing material and the utilization of SLS 3D printing enables fabrication of highly customizable electrodes with desired chemical, physical, mechanical, and flow-through properties.
关键词： conductivity,graphite,3D printing,selective laser sintering,porous electrodes
更新于2025-09-19 17:13:59
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Artificial bone scaffolds of coral imitation prepared by selective laser sintering
摘要： Coralline hydroxyapatite (CHA) has been used in clinical for over 20 years. However, coral is an endanger species and has been banned from mining. In addition, coral artificial bone has slow biodegradation of the defects, hindering the growth of new bone. In order to explore the natural coral artificial bone substitute materials, this work proposed using Selective Laser Sintering (SLS) to fabricate natural calcium carbonate/biopolymer composite imitation coral porous structures, and then the surface of the 3D printing product was transformed into a hydroxyapatite thin layer by hydrothermal conversion reaction. The mechanical properties and porosity were optimized by adjusting the SLS processing parameters including laser power, scanning speed and layer thickness. In the composites with the PLLA of 15 wt%, the SLS processing parameters with the laser power of 15 W, laser scanning speed of 1500 mm/s and single layer thickness of 0.08 mm result in the better mechanical properties. After hydrothermal conversion, the products were confirmed to be a mixture of hydroxyapatite (HA) and calcium carbonate by X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR) and energy dispersive X-ray spectroscopy (EDX). The TGA results revealed that increasing the reaction temperature or prolonging the reaction time can increase the degree of hydrothermal reaction and thus promote the transformation of calcium carbonate into hydroxyapatite. The results of cytotoxicity assay and Life/Dead staining showed that the scaffold is not toxic to L929 cells. This work has the materials system innovation and focuses on the study of the effects of the SLS and hydrothermal processes on the mechanical performance and the degree of hydroxylation. Then, the preparation process of imitation coral artificial bone preparation was optimized. it is concluded that the imitation coral artificial bone is a nontoxic biomaterial; however, further study on its osteogenic capacity should be warranted in the future.
关键词： Additive manufacturing,Coral imitation,Artificial bones,Selective laser sintering
更新于2025-09-19 17:13:59
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A three dimensional meshfree-simulation of the selective laser sintering process with constant thermal coefficients applied to nylon 12 powders
摘要： 3D printing is an intersting process in the context of creating original objects.Selective laser sintering printers use a laser to fuse polyamide particles together with specific resin and heat. The difference in temperature between the different areas in the process causes the appearance of deformations, the objective of this work is the modeling of the thermal SLS phenomenona, by following the evolution of the temperature as a function of time.This model is based on the resolution of the heat conduction equation coupling with convection and radiation conditions with a distribution heat source and constant thermal coefficients by the meshless method based on radial basis function , the result of this study,will be presented and compared with other works.
关键词： heat transfer,Meshfree method,radical basis function (RBF),thermal modeling,selective laser sintering(SLS)
更新于2025-09-19 17:13:59