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3 pages, 169 KiB

Open AccessEditorial

Additive Manufacturing (AM) for Advanced Materials and Structures: Green and Intelligent Development Trend

by Menglin Liu, Hao Yi and Huajun Cao

Crystals 2023, 13(1), 92; https://doi.org/10.3390/cryst13010092 - 4 Jan 2023

Cited by 3 | Viewed by 1875

Abstract

Additive manufacturing (AM) is an emerging and rapidly evolving technology that has revolutionized the way products are developed, fabricated and commercialized [...] Full article

(This article belongs to the Special Issue Additive Manufacturing (AM) for Advanced Materials and Structures: Green and Intelligent Development Trend)

Research

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19 pages, 5000 KiB

Open AccessArticle

Specific Sensitivity Analysis and Imitative Full Stress Method for Optimal BCCZ Lattice Structure by Additive Manufacturing

by Haonan Li, Weidong Yang, Qianchao Ma, Zhihan Qian and Li Yang

Crystals 2022, 12(12), 1844; https://doi.org/10.3390/cryst12121844 - 16 Dec 2022

Cited by 3 | Viewed by 2117

Abstract

Additive manufacturing (AM) can quickly and easily obtain lattice structures with light weight and excellent mechanical properties. Body-centered cubic (BCC) lattice structure is a basic type of lattice structure. BCC with Z strut (BCCZ) lattice structure is a derivative structure of BCC lattice [...] Read more.

Additive manufacturing (AM) can quickly and easily obtain lattice structures with light weight and excellent mechanical properties. Body-centered cubic (BCC) lattice structure is a basic type of lattice structure. BCC with Z strut (BCCZ) lattice structure is a derivative structure of BCC lattice structure, and it has good adaptability to AM. Generally, the thickness of each pillar in the BCCZ lattice structure is uniform, which results in the uneven stress distribution of each pillar. This makes the potential of light weight and high strength of the BCCZ lattice structure not fully played, and the utilization rate of materials can be further improved. This paper designs an optimization method. Through the structural analysis of a BCCZ lattice structure, an optimization method of a BCCZ lattice structure based on parametric modeling parameters is presented. The section radius of all pillars in the BCCZ lattice is taken as a design variable, and the specific sensitivity analysis method and simulated full stress optimization idea are successively used to determine the optimal section radius of each pillar. Finally, the corresponding model is designed and samples are manufactured by LPBF technology for simulation and experimental verification. The results of simulation and experiment show that the strength limit of the optimized parts increased by 18.77% and 18.43%, respectively, compared with that before optimization. Full article

(This article belongs to the Special Issue Additive Manufacturing (AM) for Advanced Materials and Structures: Green and Intelligent Development Trend)

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7 pages, 3125 KiB

Open AccessCommunication

Effects of SiC Content on Wear Resistance of Al-Zn-Mg-Cu Matrix Composites Fabricated via Laser Powder Bed Fusion

by Zhigang Shen, Ning Li, Ting Wang and Zhisheng Wu

Crystals 2022, 12(12), 1801; https://doi.org/10.3390/cryst12121801 - 10 Dec 2022

Cited by 5 | Viewed by 1334

Abstract

In this paper, in situ SiC-reinforced Al-Zn-Mg-Cu composites were fabricated by laser powder bed fusion (LPBF). The effects of SiC content on the microstructure, phase composition, microhardness, and wear resistance of as-printed composites were preliminarily investigated. Results show that the microstructure was regulated, [...] Read more.

In this paper, in situ SiC-reinforced Al-Zn-Mg-Cu composites were fabricated by laser powder bed fusion (LPBF). The effects of SiC content on the microstructure, phase composition, microhardness, and wear resistance of as-printed composites were preliminarily investigated. Results show that the microstructure was regulated, the matrix grains were refined, and the tendency to orientation grain growth was suppressed. SiC particles reacted in situ with the Al matrix to produce Si, Al₄C₃, and Al₄SiC₄ phases. The microhardness and wear resistance of as-printed composites increased with SiC content due to the fine grain strengthening of the matrix and the second phase strengthening of precipitates and reinforcements. Full article

(This article belongs to the Special Issue Additive Manufacturing (AM) for Advanced Materials and Structures: Green and Intelligent Development Trend)

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22 pages, 6896 KiB

Open AccessArticle

Effect of Slag Adjustment on Inclusions and Mechanical Properties of Si-Killed 55SiCr Spring Steel

by Yang Li, Changyong Chen, Hao Hu, Hao Yang, Meng Sun and Zhouhua Jiang

Crystals 2022, 12(12), 1721; https://doi.org/10.3390/cryst12121721 - 27 Nov 2022

Cited by 4 | Viewed by 1712

Abstract

The effects of the Al₂O₃ content and basicity of CaO–SiO₂–Al₂O₃–10 wt.% MgO refining slag on inclusions removal in 55SiCr spring steel were investigated. The viscosity of slag was studied using a viscometer, while the [...] Read more.

The effects of the Al₂O₃ content and basicity of CaO–SiO₂–Al₂O₃–10 wt.% MgO refining slag on inclusions removal in 55SiCr spring steel were investigated. The viscosity of slag was studied using a viscometer, while the microstructure investigation involved using a water-quenching furnace and a Fourier-transform infrared spectrometer. The influence mechanism of the slag adjustment on inclusions was explored through thermodynamic calculations and kinetic analysis. The results indicated that the viscosity of the molten slag increased gradually with the content of Al₂O₃ increasing due to it increasing the degree of polymerization of the slag network structure, especially the [AlO₄]⁵⁻ and [Si-O-Si] structures. In contrast, the viscosity of molten slag experienced the opposite pattern, with the basicity of molten slag increasing. This was due to the fact that Ca²⁺ can significantly reduce the degree of polymerization of a slag network structure, especially the percentages of the [SiO₄]⁴⁻, [AlO₄]⁵⁻ and [Si-O-Si] network structures. Finally, the changes in physical properties and structure of slag significantly affected the removal effect of the inclusions in molten steel. As a result, the number, size distribution, composition distribution and morphology of the inclusions displayed significant changes when the content of Al₂O₃ increased from 3 wt.% to 12 wt.% and the basicity of the slag gradually increased from 0.5 to 1.2. Full article

(This article belongs to the Special Issue Additive Manufacturing (AM) for Advanced Materials and Structures: Green and Intelligent Development Trend)

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17 pages, 4881 KiB

Open AccessArticle

Experimental Analysis of Polycaprolactone High-Resolution Fused Deposition Manufacturing-Based Electric Field-Driven Jet Deposition

by Yanpu Chao, Hao Yi, Fulai Cao, Shuai Lu and Lianhui Ma

Crystals 2022, 12(11), 1660; https://doi.org/10.3390/cryst12111660 - 18 Nov 2022

Cited by 3 | Viewed by 1720

Abstract

Polycaprolactone (PCL) scaffolds have been widely used in biological manufacturing engineering. With the expansion of the PCL application field, the manufacture of high-resolution complex microstructure PCL scaffolds is becoming a technical challenge. In this paper, a novel PCL high-resolution fused deposition 3D printing [...] Read more.

Polycaprolactone (PCL) scaffolds have been widely used in biological manufacturing engineering. With the expansion of the PCL application field, the manufacture of high-resolution complex microstructure PCL scaffolds is becoming a technical challenge. In this paper, a novel PCL high-resolution fused deposition 3D printing based on electric field-driven (EFD) jet deposition is proposed to manufacture PCL porous scaffold structures. The process principle of continuous cone-jet printing mode was analyzed, and an experimental system was constructed based on an electric field driven jet to carry out PCL printing experiments. The experimental studies of PCL-fused deposition under different gas pressures, electric field voltages, motion velocities and deposition heights were carried out. Analysis of the experimental results shows that there is an effective range of deposition height (H) to realize stable jet printing when the applied voltage is constant. Under the stretching of electric field force and viscous drag force (F_D) with increasing movement velocities (V_s) at the same voltage and deposition height, the width of deposition lines was also gradually decreased. The width of the deposition line and the velocity of the deposition platform is approximately a quadratic curve. The bending phenomenon of deposition lines also gradually decreases with the increase of the movement velocities. According to the experiment results, a single layer linear grid structure was printed under the appropriate process parameters, with compact structure, uniform size and good straightness. The experimental results verify that the PCL porous scaffold structure can be accurately printed and manufactured. Full article

(This article belongs to the Special Issue Additive Manufacturing (AM) for Advanced Materials and Structures: Green and Intelligent Development Trend)

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9 pages, 2612 KiB

Open AccessArticle

Comparison of Dopant Incorporation and Near-Infrared Photoresponse for Se-Doped Silicon Fabricated by fs Laser and ps Laser Irradiation

by Lingyan Du, Shiping Liu, Jie Yin, Shangzhen Pang and Hao Yi

Crystals 2022, 12(11), 1589; https://doi.org/10.3390/cryst12111589 - 8 Nov 2022

Cited by 2 | Viewed by 1476

Abstract

Se-doped silicon films were fabricated by femtosecond (fs) laser and picosecond (ps) laser irradiating Si–Se bilayer film-coated silicon. The surface morphology, impurity distribution, crystal phase, and near-infrared photocurrent response of fs-laser-processed and ps-laser-processed Si are compared. With the same number of laser pulse [...] Read more.

Se-doped silicon films were fabricated by femtosecond (fs) laser and picosecond (ps) laser irradiating Si–Se bilayer film-coated silicon. The surface morphology, impurity distribution, crystal phase, and near-infrared photocurrent response of fs-laser-processed and ps-laser-processed Si are compared. With the same number of laser pulse irradiation, fs laser induces quasi-ordered micron-size columnar structures with some deeper gullies, and ps laser induces irregular nanoscale spherical particles with some cavities. Compared with the fs-laser-produced Se-doped layer, ps laser irradiation produces a Se-doped layer with better crystallinity and higher doping concentration, resulting in a higher photocurrent response for picosecond laser-processed Si in the near-infrared band. The changes brought about by ps laser processing facilitate the application of ultrafast laser-processed chalcogen-doped silicon for silicon-based integrated circuits. Full article

(This article belongs to the Special Issue Additive Manufacturing (AM) for Advanced Materials and Structures: Green and Intelligent Development Trend)

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16 pages, 4367 KiB

Open AccessArticle

Tribological Performance of Microcrystalline Diamond (MCD) and Nanocrystalline Diamond (NCD) Coating in Dry and Seawater Environment

by Hui Zhang, Hui Song, Ming Pang, Guoyong Yang, Fengqin Ji, Nan Jiang and Kazuhito Nishimura

Crystals 2022, 12(10), 1345; https://doi.org/10.3390/cryst12101345 - 23 Sep 2022

Cited by 5 | Viewed by 2153

Abstract

In the present study, the tribological properties of diverse crystalline diamond coating with micro (MCD) and nanometer (NCD) sizes, fabricated by the microwave plasma chemical vapor deposition (MPCVD) method, are systematically investigated in dry and seawater environments, respectively. Owing to the SiO₂ [...] Read more.

In the present study, the tribological properties of diverse crystalline diamond coating with micro (MCD) and nanometer (NCD) sizes, fabricated by the microwave plasma chemical vapor deposition (MPCVD) method, are systematically investigated in dry and seawater environments, respectively. Owing to the SiO₂ lubricating film with extraordinary hydrophilicity performance by a tribochemical reaction, the average friction coefficient (COF) and wear rate of NCD coating under seawater decreased by 37.8% and 26.5%, respectively, comparing with in dry conditions. Furthermore, graphite would be generated with the increment of surface roughness. Graphite transformed from the diamond under high contact pressure. Thus, with the synergism between SiO₂ lubricating film with extraordinary hydrophilicity performance and graphite, the corresponding COF and wear rate of MCD would be further decreased by up to 64.1% and 39.5%. Meanwhile, various characterizations on morphology, spectra, and tribological performance of the deposited diamond coating were conducted to explore the in-depth mechanism of the enhanced tribological performance of our NCD and MCD coatings in the extreme under seawater working conditions. We envision this work would provide significant insights into the wear behavior of diamond coatings in seawater and broaden their applications in protective coatings for marine science. Full article

(This article belongs to the Special Issue Additive Manufacturing (AM) for Advanced Materials and Structures: Green and Intelligent Development Trend)

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8 pages, 2860 KiB

Open AccessCommunication

Nanomechanical Characterization of High-Velocity Oxygen-Fuel NiCoCrAlYCe Coating

by Feifei Zhou, Donghui Guo, Baosheng Xu, Yiguang Wang and You Wang

Crystals 2022, 12(9), 1246; https://doi.org/10.3390/cryst12091246 - 2 Sep 2022

Cited by 3 | Viewed by 1456

Abstract

MCrAlY (M = Ni or/and Co) coatings have played an indispensable role in the high-temperature protection system for key components of aero-engines due to their excellent high-temperature oxidation and hot corrosion resistance. Nanoindentation is a useful and highly efficient method for characterizing the [...] Read more.

MCrAlY (M = Ni or/and Co) coatings have played an indispensable role in the high-temperature protection system for key components of aero-engines due to their excellent high-temperature oxidation and hot corrosion resistance. Nanoindentation is a useful and highly efficient method for characterizing the nanomechanical properties of materials. The rich information reflecting materials can be gained by load-displacement curves. In addition to common parameters such as elastic modulus and nanohardness, the indentation work and creep property at room temperature can also be extracted. Herein, nanomechanical properties of NiCoCrAlYCe coatings using high-velocity oxygen-fuel (HVOF) spraying were investigated systematically by nanoindentation. The microstructure of as-sprayed NiCoCrAlYCe coatings present mono-modal distribution. Results of nanoindentation reveal that the elastic modulus and nanohardness of NiCoCrAlYCe coatings are 121.08 ± 10.04 GPa and 6.09 ± 0.86 Gpa, respectively. Furthermore, the indentation work of coatings was also characterized. The elastic indentation work is 10.322 ± 0.721 nJ, and the plastic indentation work is 22.665 ± 1.702 nJ. The ratio of the plastic work to the total work of deformation during indentation is 0.687 ± 0.024, which can predict excellent wear resistance for NiCoCrAlYCe coatings. Meanwhile, the strain rate sensitivity determined by nanoindentation is 0.007 ± 0.001 at room temperature. These results can provide prediction of erosion resistance for MCrAlY coatings. Full article

(This article belongs to the Special Issue Additive Manufacturing (AM) for Advanced Materials and Structures: Green and Intelligent Development Trend)

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13 pages, 24566 KiB

Open AccessArticle

The Effect of Scanning Strategies on FeCrAl Nuclear Thin-Wall Cladding Manufacturing Accuracy by Laser Powder Bed Fusion

by Fusheng Cao, Haitian Zhang, Hang Zhou, Yu Han, Sai Li, Yang Ran, Jiawei Zhang, Kai Miao, Zhongliang Lu and Dichen Li

Crystals 2022, 12(9), 1197; https://doi.org/10.3390/cryst12091197 - 25 Aug 2022

Cited by 3 | Viewed by 1726

Abstract

FeCrAl alloy has been proposed as an alternative material for accident-tolerant fuel (ATF) cladding for nuclear reactors. Thin-wall cladding can be rapidly fabricated by laser powder bed fusion (LPBF). In this paper, a finite element model is established to simulate the transient temperature [...] Read more.

FeCrAl alloy has been proposed as an alternative material for accident-tolerant fuel (ATF) cladding for nuclear reactors. Thin-wall cladding can be rapidly fabricated by laser powder bed fusion (LPBF). In this paper, a finite element model is established to simulate the transient temperature fields of the cladding under two different laser scanning strategies (linear scanning and ring scanning). In linear scanning simulations, bidirectional scanning, compared with unidirectional scanning, had a smaller temperature gradient along the radial direction. In the ring scanning simulation, the maximum temperature gradually increased and then became stable with the increase of layers. Then, FeCrAl thin-wall cladding with a wall thickness of 0.14 mm was fabricated by LPBF. FeCrAl cladding using the ring scanning strategy had a smaller roughness value (Ra = 4.061 μm). Ring scanning had better accuracy than bidirectional scanning for FeCrAl thin-wall cladding with a wall thickness below 0.4 mm. Therefore, compared with the bidirectional scanning, the ring scanning is more suitable for the high-accuracy manufacturing of FeCrAl thin-wall cladding. Full article

(This article belongs to the Special Issue Additive Manufacturing (AM) for Advanced Materials and Structures: Green and Intelligent Development Trend)

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16 pages, 5888 KiB

Open AccessArticle

Experimental Investigation and Prediction of Mechanical Properties in a Fused Deposition Modeling Process

by Amanuel Diriba Tura, Hirpa G. Lemu and Hana Beyene Mamo

Crystals 2022, 12(6), 844; https://doi.org/10.3390/cryst12060844 - 15 Jun 2022

Cited by 11 | Viewed by 2525

Abstract

Additive manufacturing, also known as three-dimensional printing, is a computer-controlled advanced manufacturing process that produces three-dimensional items by depositing materials directly from a computer-aided design model, usually in layers. Due to its capacity to manufacture complicated objects utilizing a wide range of materials [...] Read more.

Additive manufacturing, also known as three-dimensional printing, is a computer-controlled advanced manufacturing process that produces three-dimensional items by depositing materials directly from a computer-aided design model, usually in layers. Due to its capacity to manufacture complicated objects utilizing a wide range of materials with outstanding mechanical qualities, fused deposition modeling is one of the most commonly used additive manufacturing technologies. For printing high-quality components with appropriate mechanical qualities, such as tensile strength and flexural strength, the selection of adequate processing parameters is critical. Experimentally, the influence of process parameters such as the raster angle, printing orientation, air gap, raster width, and layer height on the tensile strength of fused deposition modeling printed items was examined in this work. Through analysis of variance, the impact of each parameter was measured and rated. The system’s response was predicted using an adaptive neuro-fuzzy technique and an artificial neural network. In Minitab software, the Box-Behnken response surface experimental design was used to generate 46 experimental trials, which were then printed using acrylonitrile butadiene styrene polymer materials on a three-dimensional forge dreamer II fused deposition modelling printing machine. The results revealed that the raster angle, air gap, and raster width had significant impacts on the tensile strength. The adaptive neuro-fuzzy approach and artificial neural network predicted tensile strength accurately with an average percentage error of 0.0163 percent and 1.6437 percent, respectively. According to the findings, the model and experimental data are in good agreement. Full article

(This article belongs to the Special Issue Additive Manufacturing (AM) for Advanced Materials and Structures: Green and Intelligent Development Trend)

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13 pages, 4753 KiB

Open AccessArticle

Improvement of the Geometric Accuracy for Microstructures by Projection Stereolithography Additive Manufacturing

by Cheng Wen, Zhengda Chen, Zhuoxi Chen, Bin Zhang, Zhicheng Cheng, Hao Yi, Guiyun Jiang and Jigang Huang

Crystals 2022, 12(6), 819; https://doi.org/10.3390/cryst12060819 - 9 Jun 2022

Cited by 3 | Viewed by 2283

Abstract

Projection stereolithography creates 3D structures by projecting patterns onto the surface of a photosensitive material layer by layer. Benefiting from high efficiency and resolution, projection stereolithography 3D printing has been widely used to fabricate microstructures. To improve the geometric accuracy of projection stereolithography [...] Read more.

Projection stereolithography creates 3D structures by projecting patterns onto the surface of a photosensitive material layer by layer. Benefiting from high efficiency and resolution, projection stereolithography 3D printing has been widely used to fabricate microstructures. To improve the geometric accuracy of projection stereolithography 3D printing for microstructures, a compensation method based on structure optimization is proposed according to mathematical analysis and simulation tests. The performance of the proposed compensation method is verified both by the simulation and the 3D printing experiments. The results indicate that the proposed compensation method is able to significantly improve the shape accuracy and reduce the error of the feature size. The proposed compensation method is also proved to improve the dimension accuracy by 21.7%, 16.5% and 19.6% for the circular, square and triangular bosses respectively. While the improvements on the dimension accuracy by 16%, 17.6% and 13.8% for the circular, square and triangular holes are achieved with the proposed compensation method. This work is expected to provide a method to improve the geometric accuracy for 3D printing microstructures by projection stereolithography. Full article

(This article belongs to the Special Issue Additive Manufacturing (AM) for Advanced Materials and Structures: Green and Intelligent Development Trend)

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13 pages, 5549 KiB

Open AccessArticle

Fabrication and Formability of Continuous Carbon Fiber Reinforced Resin Matrix Composites Using Additive Manufacturing

by Lining Yang, Donghao Zheng, Guojie Jin and Guang Yang

Crystals 2022, 12(5), 649; https://doi.org/10.3390/cryst12050649 - 2 May 2022

Cited by 5 | Viewed by 3128

Abstract

In the current process for additive manufacturing of continuous carbon fiber reinforced resin matrix composites, the fiber and resin matrix are fed into the molten chamber, and then impregnated and compounded in the original position, and finally extruded and deposited on the substrate. [...] Read more.

In the current process for additive manufacturing of continuous carbon fiber reinforced resin matrix composites, the fiber and resin matrix are fed into the molten chamber, and then impregnated and compounded in the original position, and finally extruded and deposited on the substrate. It is difficult to control the ratio of fiber and resin, and to achieve good interface fusion, which results in an unsatisfactory enhancement effect. Therefore, an additive manufacturing process based on continuous carbon fiber reinforced polylactic acid composite prepreg filament was explored in this study. The effects of various process parameters on the formability of composites were studied through systematic process experiments. The results showed that the process parameters of additive manufacturing have a systematic influence on the forming quality, accuracy and efficiency, and on the mechanical properties of CFRP. Through the experimental optimization of various process parameters, a continuous and stable forming process was achieved when the nozzle aperture was 0.8 mm, the nozzle printing temperature was 240 °C, the substrate temperature was 60 °C, the wire feeding speed was 5 mm/s, the nozzle moving speed was 5 mm/s, the path bonding rate was 40%, and the printing layer thickness was 0.7 mm. Based on the optimized process parameters, direct additive manufacturing of a lightweight and high-strength composite cellular load-bearing structure could be realized. Its volume fraction of carbon fiber was approximately 7.7%, and the tensile strength was up to 224.3 MPa. Full article

(This article belongs to the Special Issue Additive Manufacturing (AM) for Advanced Materials and Structures: Green and Intelligent Development Trend)

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21 pages, 10233 KiB

Open AccessArticle

Research on the Preparation Process and Performance of a Wear-Resistant and Corrosion-Resistant Coating

by Xianbao Wang and Mingdi Wang

Crystals 2022, 12(5), 591; https://doi.org/10.3390/cryst12050591 - 22 Apr 2022

Cited by 3 | Viewed by 2021

Abstract

In order to study the wear resistance and corrosion resistance of a composite material with a Fe316L substrate and Co-Cr-WC coating, Co-Cr alloy coatings with different mass fractions of WC (hard tungsten carbide) were prepared on a Fe316L substrate by laser cladding technology. [...] Read more.

In order to study the wear resistance and corrosion resistance of a composite material with a Fe316L substrate and Co-Cr-WC coating, Co-Cr alloy coatings with different mass fractions of WC (hard tungsten carbide) were prepared on a Fe316L substrate by laser cladding technology. The phase composition, microstructure and element distribution were analyzed by X-ray diffraction (XRD), scanning electron microscopy (SEM) and energy dispersive spectroscopy (EDS). The hardness of the samples was tested by a Vickers microhardness tester, the friction coefficient and wear amount of the samples were tested by a friction and wear tester, and the corrosion resistance of the samples was tested by an electrochemical corrosion workstation. The results showed that the macroscopic appearance of the coating surface was good without obvious cracks, and the microstructures were mostly equiaxed crystals, cellular crystals and dendrites. With the addition of WC, the structures near the particles became more refined and extended from the surface of the WC particles. When the WC content was 40%, defects such as fine cracks appeared in the coating. The average microhardness of the 30%WC-Co-Cr coating was 732.6 HV, which was 2.29 times that of the Fe316L matrix; the friction coefficient was 0.16, and the wear amount was 14.64 × 10⁻⁶ mm³ N⁻¹ m⁻¹, which were 42.1% and 44.47% of the matrix, respectively; the self-corrosion voltage of the cladding layer was 120 mV, and the self-corrosion current was 7.263 × 10⁻⁴ A/cm², which were 30.3% and 7.62% of the substrate, respectively. The experimental results showed that the laser cladding Co-Cr-WC composite cladding layer could significantly improve the wear resistance and corrosion resistance of the Fe316L matrix under the optimal laser process parameters. Full article

(This article belongs to the Special Issue Additive Manufacturing (AM) for Advanced Materials and Structures: Green and Intelligent Development Trend)

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15 pages, 5300 KiB

Open AccessArticle

Comparison and Determination of Optimal Machine Learning Model for Predicting Generation of Coal Fly Ash

by Chongchong Qi, Mengting Wu, Xiang Lu, Qinli Zhang and Qiusong Chen

Crystals 2022, 12(4), 556; https://doi.org/10.3390/cryst12040556 - 15 Apr 2022

Cited by 6 | Viewed by 2353

Abstract

The rapid development of industry keeps increasing the demand for energy. Coal, as the main energy source, has a huge level of consumption, resulting in the continuous generation of its combustion byproduct coal fly ash (CFA). The accumulated CFA will occupy a large [...] Read more.

The rapid development of industry keeps increasing the demand for energy. Coal, as the main energy source, has a huge level of consumption, resulting in the continuous generation of its combustion byproduct coal fly ash (CFA). The accumulated CFA will occupy a large amount of land, but also cause serious environmental pollution and personal injury, which makes the resource utilization of CFA gradually to be attached importance. However, given the variability of the amount of CFA generation, predicting it in advance is the basis to ensure effective disposal and rational utilization. In this study, CFA generation was taken as the target variable, three machine learning (ML) algorithms were used to construct the model, and four evaluation indices were used to evaluate its performance. The results showed that the DNN model with the R = 0.89, R² = 0.77 on the testing set performed better than the traditional multiple linear regression equation and other ML algorithms, and the feasibility of DNN as the optimal model framework was demonstrated. Applying this model framework to the engineering field enables managers to identify the next step of the disposal method in advance, so as to rationally allocate ways of recycling and utilization to maximize the use and sales benefits of CFA while minimizing its disposal costs. In addition, sensitivity analysis further explains ML’s internal decisions and verifies that coal consumption is more important than installed capacity, which provides a certain reference for ensuring the rational utilization of CFA. Full article

(This article belongs to the Special Issue Additive Manufacturing (AM) for Advanced Materials and Structures: Green and Intelligent Development Trend)

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10 pages, 3436 KiB

Open AccessArticle

Compression Behavior of SLM-Prepared 316L Shwartz Diamond Structures under Dynamic Loading

by Qingyan Ma, Zhonghua Li and Jiaxin Li

Crystals 2022, 12(4), 447; https://doi.org/10.3390/cryst12040447 - 23 Mar 2022

Cited by 3 | Viewed by 1949

Abstract

In this paper, the compression behavior of a triply minimal periodic surface (Shwartz Diamond) fabricated by selective laser melting (SLM) under different loading rates was studied. A quasi-static strain rate of 2.22 × 10⁻³/s was tested using a universal testing machine, [...] Read more.

In this paper, the compression behavior of a triply minimal periodic surface (Shwartz Diamond) fabricated by selective laser melting (SLM) under different loading rates was studied. A quasi-static strain rate of 2.22 × 10⁻³/s was tested using a universal testing machine, and a strain rate of 650/s was tested by Hopkinson pressure bar (SHPB). The results showed that the yield stress of all structures increased under dynamic load, and the DIF of sheet structure was higher than that of the skeleton structure, among which the DIF of GSHD was the largest and most sensitive to strain rate. However, the normalized SEA of USHD was the highest. Full article

(This article belongs to the Special Issue Additive Manufacturing (AM) for Advanced Materials and Structures: Green and Intelligent Development Trend)

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11 pages, 74504 KiB

Open AccessArticle

Effect of Nano-Si₃N₄ Reinforcement on the Microstructure and Mechanical Properties of Laser-Powder-Bed-Fusioned AlSi10Mg Composites

by Zhongliang Lu, Yu Han, Yunpeng Gao, Fusheng Cao, Haitian Zhang, Kai Miao, Xin Deng and Dichen Li

Crystals 2022, 12(3), 366; https://doi.org/10.3390/cryst12030366 - 9 Mar 2022

Cited by 5 | Viewed by 2271

Abstract

Laser powder bed fusion (LPBF) technology is of great significance to the rapid manufacturing of high-performance metal parts. To improve the mechanical behavior of an LPBFed AlSi10Mg alloy, the influence of nano-Si₃N₄ reinforcement on densification behavior, microstructure, and tensile property [...] Read more.

Laser powder bed fusion (LPBF) technology is of great significance to the rapid manufacturing of high-performance metal parts. To improve the mechanical behavior of an LPBFed AlSi10Mg alloy, the influence of nano-Si₃N₄ reinforcement on densification behavior, microstructure, and tensile property of AlSi10Mg was studied. The experimental results show that 97% relative density of the 3 vol.% nano-Si₃N₄/AlSi10Mg composite was achieved via optimization of the LPBF process. With the increase in the nano-Si₃N₄ content, the tensile strength and the yield strength of the composite steadily increase as per the Orowan strengthening mechanism while the elongation decreases. In addition, nano-Si₃N₄ reinforcement reduces the width of the coarse cell structure region and the thermal influence region of the AlSi10Mg matrix. After annealing, the tensile strength of the nano-Si₃N₄/AlSi10Mg composite decreases and the elongation increases significantly. Full article

(This article belongs to the Special Issue Additive Manufacturing (AM) for Advanced Materials and Structures: Green and Intelligent Development Trend)

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16 pages, 5541 KiB

Open AccessArticle

Experimental Analysis of Wax Micro-Droplet 3D Printing Based on a High-Voltage Electric Field-Driven Jet Deposition Technology

by Yanpu Chao, Hao Yi, Fulai Cao, Yaohui Li, Hui Cen and Shuai Lu

Crystals 2022, 12(2), 277; https://doi.org/10.3390/cryst12020277 - 17 Feb 2022

Cited by 3 | Viewed by 2673

Abstract

High-voltage electric field-driven jet deposition technology is a novel high resolution micro scale 3D printing method. In this paper, a novel micro 3D printing method is proposed to fabricate wax micro-structures. The mechanism of the Taylor cone generation and droplet eject deposition was [...] Read more.

High-voltage electric field-driven jet deposition technology is a novel high resolution micro scale 3D printing method. In this paper, a novel micro 3D printing method is proposed to fabricate wax micro-structures. The mechanism of the Taylor cone generation and droplet eject deposition was analyzed, and a high-voltage electric field-driven jet printing experimental system was developed based on the principle of forming. The effects of process parameters, such as pulse voltages, gas pressures, pulse width, pulse frequency, and movement velocity, on wax printing were investigated. The experimental results show that the increasing of pulse width and duration of pulse high voltage increased at the same pulse frequency, resulting in the micro-droplet diameter being increased. The deposited droplet underwent a process of spreading, shrinking, and solidifying. The local remelting and bonding were acquired between the contact surfaces of the adjacent deposited droplets. According to the experiment results, a horizontal line and a vertical micro-column were fabricated by adjusting the process parameters; their size deviation was controlled within 2%. This research shows that it is feasible to fabricate the micro-scale wax structure using high-voltage electric field-driven jet deposition technology. Full article

(This article belongs to the Special Issue Additive Manufacturing (AM) for Advanced Materials and Structures: Green and Intelligent Development Trend)

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12 pages, 10954 KiB

Open AccessArticle

Numerical Analysis and Experimental Verification of Resistance Additive Manufacturing

by Suli Li, Kaiyue Ma, Chao Xu, Laixia Yang and Bingheng Lu

Crystals 2022, 12(2), 193; https://doi.org/10.3390/cryst12020193 - 28 Jan 2022

Cited by 6 | Viewed by 2512

Abstract

In recent years, scholars have proposed a metal wire forming method based on the Joule heat principle in order to improve the accuracy of additive manufacturing and reduce energy consumption and cost, but it is still in the theoretical stage. In this paper, [...] Read more.

In recent years, scholars have proposed a metal wire forming method based on the Joule heat principle in order to improve the accuracy of additive manufacturing and reduce energy consumption and cost, but it is still in the theoretical stage. In this paper, a mathematical model of resistance additive manufacturing was established using finite element software, and the temperature variation of the melting process under different currents was analyzed. A suitable current range was preliminarily selected, and an experimental system was built. Through experimental study of the current and wire feeding speed, the influences of different process parameters on the forming appearance of the coating were analyzed. The results showed that the forming appearance was the best for Ti-6Al-4V titanium alloy wire with a diameter of 0.8 mm, when the current was 160 A, the voltage was 10 V, the wire feeding speed was 2.4 m/min, the workbench moving speed was 5 mm/s, and the gas flow rate was 0.7 m³/h. Finally, the process parameters were used for continuous single-channel multilayer printing, verified the feasibility of the process at the experimental level and provided reference data for the subsequent development of this technology. Full article

(This article belongs to the Special Issue Additive Manufacturing (AM) for Advanced Materials and Structures: Green and Intelligent Development Trend)

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12 pages, 6392 KiB

Open AccessArticle

The Fracture Behavior of 316L Stainless Steel with Defects Fabricated by SLM Additive Manufacturing

by Hui Li and Jianhao Zhang

Crystals 2021, 11(12), 1542; https://doi.org/10.3390/cryst11121542 - 9 Dec 2021

Cited by 3 | Viewed by 3222

Abstract

In this paper, the fracture behaviors of 316L stainless steel with defects fabricated by the Selective Laser Melting (SLM) additive manufacturing are studied by a peridynamic method. Firstly, the incremental formulations in the peridynamic framework are presented for the elastic-plastic problems. Then, the [...] Read more.

In this paper, the fracture behaviors of 316L stainless steel with defects fabricated by the Selective Laser Melting (SLM) additive manufacturing are studied by a peridynamic method. Firstly, the incremental formulations in the peridynamic framework are presented for the elastic-plastic problems. Then, the pairwise force of a bond for orthotropic material model is proposed according to both the local and the global coordinate systems. A simple three-step approach is developed to describe the void defects that generated in the processing of the SLM additive manufacturing in the numerical model. Next, some representative numerical examples are carried out, whose results explain the validation and accuracy of the present method, and demonstrate that the orthotropic features, micro-cracks and voids of the materials have a significant influence on the ultimate bearing capacity, crack propagation and branching of the corresponding structures. It is also revealed that the crack initiations are induced actively by the defects and the crack branching is contributed to the complex multiple-crack propagation. Finally, the achievements of this paper lay a foundation for the engineering applications of the SLM additive manufacturing materials. Full article

(This article belongs to the Special Issue Additive Manufacturing (AM) for Advanced Materials and Structures: Green and Intelligent Development Trend)

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11 pages, 9054 KiB

Open AccessArticle

Study on the Properties of Coated Cutters on Functionally Graded WC-Co/Ni-Zr Substrates with FCC Phase Enriched Surfaces

by Shidi Li, Xiangyuan Xue, Jiaxing Chen, Tengxuan Lu, Zhe Zhao, Xin Deng, Zhongliang Lu, Zhongping Wang, Zhangxu Li and Zhi Qu

Crystals 2021, 11(12), 1538; https://doi.org/10.3390/cryst11121538 - 9 Dec 2021

Cited by 2 | Viewed by 2486

Abstract

Currently, the research on mechanical behavior and cutting performance of functionally graded carbides is quite limited, which limits the rapid development of high-performance cemented carbide cutting tools. Based on WC-Co-Zr and WC-Ni-Zr, this study synthesized two kinds of cemented carbide cutters, i.e., the [...] Read more.

Currently, the research on mechanical behavior and cutting performance of functionally graded carbides is quite limited, which limits the rapid development of high-performance cemented carbide cutting tools. Based on WC-Co-Zr and WC-Ni-Zr, this study synthesized two kinds of cemented carbide cutters, i.e., the cemented carbide cutters with homogeneous microstructure and functionally graded carbide (FGC) cutters with FCC phase ZrN-enriched surfaces. Furthermore, TiAlN coating has been investigated on these carbide cutters. Mechanical behavior, friction, wear performance, and cutting behavior have been investigated for these coated carbides and their corresponding substrates. It was found that, as compared with coated cutters on WC-Co/Ni-Zr carbide substrates with homogeneous microstructures, the coated cutters on WC-Co/Ni-Zr FGC substrates with FCC phase-enriched surfaces show higher wear resistance and cutting life, and the wear mechanism during cutting is mainly adhesion wear. Full article

(This article belongs to the Special Issue Additive Manufacturing (AM) for Advanced Materials and Structures: Green and Intelligent Development Trend)

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Review

Jump to: Editorial, Research

18 pages, 8185 KiB

Open AccessReview

A Review on Ultrafast-Laser Power Bed Fusion Technology

by Yuxiang Wu, Yongxiong Chen, Lingchao Kong, Zhiyuan Jing and Xiubing Liang

Crystals 2022, 12(10), 1480; https://doi.org/10.3390/cryst12101480 - 18 Oct 2022

Cited by 7 | Viewed by 2890

Abstract

Additive manufacturing of metals by employing continuous wave and short pulse lasers completely changes the way of modern industrial production. But the ultrafast laser has the superiority to short pulse laser and continuous wave laser in additive manufacturing. It has higher peak power, [...] Read more.

Additive manufacturing of metals by employing continuous wave and short pulse lasers completely changes the way of modern industrial production. But the ultrafast laser has the superiority to short pulse laser and continuous wave laser in additive manufacturing. It has higher peak power, small thermal effect, high machining accuracy and low damage threshold. It can effectively perform additive manufacturing for special materials and improve the mechanical properties of parts. This article reviews the mechanism of the interaction between ultrafast laser and metal materials to rule the manufacturing processes. The current application of ultrafast laser on forming and manufacturing special materials, including refractory metals, transparent materials, composite materials and high thermal conductivity materials are also discussed. Among the review, the shortcomings and challenges of the current experimental methods are discussed as well. Finally, suggestions are provided for the industrial application of ultrashort pulse laser in the field of additive manufacturing in the future. Full article

(This article belongs to the Special Issue Additive Manufacturing (AM) for Advanced Materials and Structures: Green and Intelligent Development Trend)

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