Articoli di riviste: "Semi-solid extrusion"

1

Uetani, Yasuhiro, Ryotaro Nagata, Hidetoshi Takagi, Kenji Matsuda e Susumu Ikeno. "Effect of Granule Size in Semi-Solid Slurry on Rheo-Extrusion of A7075 Aluminum Alloy". Materials Science Forum 561-565 (ottobre 2007): 291–94. http://dx.doi.org/10.4028/www.scientific.net/msf.561-565.291.

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Abstract (sommario):

Rheo-extrusions of A7075 aluminum alloy were carried out utilizing semi-solid slurries with different solid granule sizes, which were made by a simple method combined a thin upright tube with a water-cooled tube. Every structure of slurries was granular and average solid granule sizes could be controlled by 0.05 to 0.11mm. These slurries were extruded to round bars at extrusion ratio of 36 and press ram speed of 10mm/s mainly, just after cooling to 833K ( fs > 0.9 ). All of the slurries could easily be extruded to bars with smooth surfaces at much low extrusion forces than those of hot-extrusions. Tensile strength of rheo-extruded bars after solution treatment increased with decreasing of the solid granule size. Peak hardness level at T6 condition equivalent to that of hot-extrusion could be obtained at the finest solid granule size.

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Hu, Lian Xi, Yuan Yuan e Shou Jing Luo. "Fabrication, Microstructure and Mechanical Properties of a SiCw/ZK51A Mg Composite by Semi-Solid Extrusion Directly Following Liquid Infiltration". Solid State Phenomena 116-117 (ottobre 2006): 354–57. http://dx.doi.org/10.4028/www.scientific.net/ssp.116-117.354.

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A 20vol.%SiCw/ZK51A Mg-based composite was fabricated by the process of semi-solid extrusion directly following liquid infiltration. The microstructure and mechanical properties of the composite were investigated in comparison with its squeeze cast and hot extruded counterpart. The results showed that, by semi-solid extrusion, the SiC whiskers were well aligned and microstructure defects associated with the casting technology were eliminated. In addition, as compared with the conventional hot extrusion, the damage to the SiC whiskers during semi-solid extrusion was reduced significantly. Consequently, the composite fabricated by the semi-solid extrusion presented the best whisker reinforcing effect, with its elastic modulus, 0.2% offset yield strength, and ultimate tensile strength achieving 82.5GPa, 383.6MPa, and 431.8MPa respectively.

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3

Neag, Adriana, Véronique Favier, Régis Bigot e Dan Frunză. "Study on Thixo-Extrusion of Semi-Solid Aluminium". Solid State Phenomena 141-143 (luglio 2008): 659–64. http://dx.doi.org/10.4028/www.scientific.net/ssp.141-143.659.

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Thixo-extrusion processing could become an important technique to extend the range and complexity of extruded profiles. This work presents the results of thixo-extrusion process applied on aluminium alloy and they were carried out with both computer numerical simulation and experimental methods. The thixo-extrusion set-up was made. Backward extrusion tests were particularly studied and simulated using Forge 2005 software. The constitutive equation used for these simulations is based on a micro-macro model for the semi-solid evolution. The constitutive equation parameters were identified due to comparisons of the simulated load-displacement responses with experimental ones for backward extrusion tests on 7075 semi-solid aluminium alloy, for different temperatures.

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4

Kam, Heng Keong, Chan Chin Wang, Ying Pio Lim e Wen Chiet Cheong. "Study of Forging Process of Yttrium-Modified A356 Aluminum Alloy and Numerical Simulation by Thermo-Viscoplastic Finite Element Method". Key Engineering Materials 701 (luglio 2016): 177–81. http://dx.doi.org/10.4028/www.scientific.net/kem.701.177.

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In this study, A356 aluminum alloy was heated up to semi-solid state and used as a billet for forward and backward extrusion. The workpiece will undergo solidification at the contact between billet and the tools when the material flowing through the die cavity during the semi-solid extrusion. The plasticity of A356 with 0.3wt% Y at semi-solid state was investigated by performing compression test. A numerical simulation code based on thermo-viscoplastic finite element method was developed to simulate the material flow and study the yttrium-modified A356 aluminum alloy under forward and backward extrusion. A minimum average punch strain rate is proposed for semi-solid extrusion.

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Mori, Nanako, Yasuhiro Uetani, Masayoshi Dohi, Kenji Matsuda e Susumu Ikeno. "Rheo-Extrusion of Hypereutectic Al-14.8Si-4.5Cu-1.1Mg Alloy". Advanced Materials Research 409 (novembre 2011): 57–62. http://dx.doi.org/10.4028/www.scientific.net/amr.409.57.

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Rheo-extrusion of hypereutectic Al-14.8%Si-4.5%Cu-1.1%Mg (in mass%) alloy which is considerably difficult to hot-extrude was tried using semi-solid slurry with fine solid granules and almost finely dispersed primary Si particles, made by a newly developed rotor process. Trials of rheo-extrusion at the constant extrusion ratio of 36 using this semi-solid slurry were carried out at the different conditions of the extrusion temperature and the ram speeds ranging from 520 to 560oC and from 5 to 20mm/s, respectively. Under the all rheo-extrusion conditions, this semi-solid slurry could easily be rheo-extruded to the round bars of 6mm diameter with sound surface at much lower extrusion force than that of hot-extrusion at very low extrusion ratio. In addition, the characteristic age-hardening behavior which is thought to be essential for the rheo-extrusion process has been found out, namely the peak hardness values of aged bars rheo-extruded at 520 and 540oC were considerably higher, 30HV at maximum, than that of a gravity casting.

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Yan, Hong, Ming Fu Fu, Xu Chun Tao e Hong We Hu. "Study on Thixo-Extrusion of Semi-Solid Wrought Magnesium Alloy". Key Engineering Materials 367 (febbraio 2008): 103–6. http://dx.doi.org/10.4028/www.scientific.net/kem.367.103.

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The traditional extrusion and thixo-extrusion processes of wrought magnesium alloy were studied with both computer numerical simulation and experimental methods. The thixo-extrusion set-up was made. The constitutive model of semi-solid AZ61 alloy was established in our prior literature. The comparison of two forming processes had been done. Results indicated that smaller load and uniform strain & stress were acquired in thixo-extrusion process. Simulation results were in good agreement with experimental ones.

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7

Xu, Yong Tao, Tian Yang Guan, Zhi Feng Zhang, Yue Long Bai e Wei Min Mao. "Semi-Solid Rheological Squeeze Casting Process of ZL114A Aluminum Alloy Thin-Wall Complex Casting". Materials Science Forum 993 (maggio 2020): 248–53. http://dx.doi.org/10.4028/www.scientific.net/msf.993.248.

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High-strength aluminum alloy with large-scale and thin-walled complex castings have broad application prospects in aerospace, weapons, electronics, defense and military industries. However, due to the uneven thickness of the plate, the casting defects are inevitable by the ordinary casting method, and it is impossible to accurately control the shape and performance of the casting in the casting process. Previous studies have found that the semi-solid rheological extrusion casting technology with short process and near-end type can help solve this technical problem. Therefore, this paper studies the semi-solid rheological extrusion casting process of thin-walled complex casting of ZL114A aluminum alloy. The combination of numerical simulation and experimental research is used to simulate and optimize the filling and solidification process of thin-walled specimens. Based on this, a semi-solid rheological extrusion casting test was conducted. The result showed that, (1) The optimized model can well reflect the filling and solidification process under different rheological extrusion casting parameters, and obtain defect-free castings through process optimization. (2) The thin-walled parts of the thin plate casting produced by semi-solid rheology extrusion have excellent mechanical property and ductility.

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8

Liu, Xiaobo, Miao Yang, Dekun Zhou e Yuguang Zhao. "Microstructure and Wear Resistance of Mg2Si–Al Composites Fabricated Using Semi-Solid Extrusion". Metals 10, n. 5 (2 maggio 2020): 596. http://dx.doi.org/10.3390/met10050596.

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In situ Mg2Si–Al composites were prepared by using gravity casting and semi-solid extrusion. After P modification, the primary Mg2Si transformed to polygonal blocks. Extraction tests showed that the Mg2Si crystals had octahedral and tetrakaidekahedral morphologies. The semi-solid microstructure of the double-spheroidized α-Al matrix and reinforced-phase Mg2Si was successfully obtained by using semi-solid extrusion. Extraction tests showed that the Mg2Si crystals had a spherical morphology. Dry sliding wear behaviors of in situ Mg2Si–Al composites fabricated by using gravity casting and semi-solid extrusion with isothermal heat treatment holding times of 50, 60, and 160 min against 45 steel, under conditions of different sliding speeds and loads, were investigated. The worn surfaces were analyzed using SEM and EDS techniques. The results showed that Mg2Si–Al composites fabricated by using semi-solid extrusion were superior in terms of wear resistance to Mg2Si–Al composites fabricated by using gravity casting, because the former had uniformly distributed spherical reinforced phase particles of Mg2Si with weaker stress concentration around the particles, delaying the generation and expansion of cracks. The Mg2Si particles were not easily detached from the matrix, and once they fell off, the Mg2Si particles only served as spherical abrasive grains, with relatively small cutting and wear properties for the composite material. It was found that the Mg2Si/Al composite fabricated by using semi-solid extrusion with an isothermal heat treatment holding time of 60 min had the best wear resistance. The failure mechanisms of Mg2Si/Al composites were found to be mainly adhesive wear and abrasive wear.

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9

Simlandi, Sudip, Nilkanta Barman e Himadri Chattaopadhyay. "Modelling of Extrusion Process for Aluminium A356 Alloy". Solid State Phenomena 217-218 (settembre 2014): 188–94. http://dx.doi.org/10.4028/www.scientific.net/ssp.217-218.188.

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In the present work, a model is developed to study extrusion process of A356 alloy in semi-solid state. The distinct rheology of the semisolid alloy reduces energy necessity during extrusion process. Accordingly, a proper rheological model of the alloy is considered in the model towards a detailed study of the process. A combination of analytical and numerical solutions is considered for solving the governing equations. The work finally predicts distribution of velocity and shear stress of the alloy under shear in the considered domain. It also predicts the energy requirement during the extrusion process. It is demonstrated that for semisolid extrusion, reasonably less energy is required as compared to a conventional extrusion process Keywords: Extrusion, semi-solid alloy, apparent viscosity, extrusion power

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10

Wang, Kai Kun, Fu Yu Wang e Yuan Ning Wang. "Investigation on Slurry Filling Sequence during Semi-Solid Forming of Complex Aluminum Part". Materials Science Forum 704-705 (dicembre 2011): 290–95. http://dx.doi.org/10.4028/www.scientific.net/msf.704-705.290.

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Semi-solid forming technology is a short metal processing method between the liquid casting and solid forming. Many forming factors have been found concerning the quality of the forming part. In this study, the influences of slurry filling sequence were investigated in semi-solid forming one complex aluminum part. Two different slurry filling methods were designed. Method one is thixo-upsetting + compound extrusion, method two is thixo-upsetting + extrusion. The experimental results showed that the optimised method of thixo-upsetting + extrusion could be the best strategy in improving the part quality during thixo-forming of aluminum alloy A356.

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11

Koeune, Roxane, e Jean Philippe Ponthot. "A Thermomechanical Model Dedicated to Thixoforming. Application to Semi-Solid Forming". Solid State Phenomena 192-193 (ottobre 2012): 269–75. http://dx.doi.org/10.4028/www.scientific.net/ssp.192-193.269.

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This paper deals with the simulation of two extrusion tests by thixoforming: a non stationary extrusion test and a double-cup extrusion test. The simulations are based on a thermo-mechanical one-phase constitutive law that has been presented in details in previous papers. A campaign of experimental extrusion testing has been conducted on a steel alloy and the comparison between the numerical and experimental results will validate the model under study. A new feature that has been added to the model is also discussed: the introduction of the phase change thermal effects such as the fusion latent heat and the contraction of the material.

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12

Knauf, Frederik, René Baadjou e Gerhard Hirt. "Process Window Determination for Thixoextrusion Processes Using a Steel Alloy". Solid State Phenomena 141-143 (luglio 2008): 61–66. http://dx.doi.org/10.4028/www.scientific.net/ssp.141-143.61.

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A direct semi-solid bar extrusion process is characterised by inserting a feed stock in a container and extruding through a forming die with a punch. Compared to conventional bar extrusion the use of semi-solid material complicates the process due to the requirement of solidification of the material. To achieve the solidification of the semi-solid bar, different basic tool concepts are presented. With a combination of these concepts experiments were carried out using the steel alloy X210CrW12 to detect the influence of the most influencing parameters press velocity, extrusion channel diameter, length and geometry. Numerical simulations enable a better understanding of the process mechanics like temperature development in the billet and forming die as well as the material flow in the deformation zone.

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13

Sugiyama, Sumio, Jun Yanagimoto, Jer-Liang Kuo e Su-Hai Hsiang. "2333 Semi solid Extrusion of AZ61 Magnesium Alloy". Proceedings of the JSME annual meeting 2005.1 (2005): 727–28. http://dx.doi.org/10.1299/jsmemecjo.2005.1.0_727.

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14

Mitsoulis, E., Th Zisis e S. G. Hatzikiriakos. "Modeling of Paste Extrusion in Semi-Solid State". International Journal of Material Forming 1, S1 (aprile 2008): 771–74. http://dx.doi.org/10.1007/s12289-008-0289-4.

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15

Li, Zhong, Xiao Gang Hu, Hong Xing Lu e Qiang Zhu. "Microstructure Design of Semi-Solid Slurry for Metal Direct Writing". Solid State Phenomena 348 (28 agosto 2023): 33–38. http://dx.doi.org/10.4028/p-qdk1x5.

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Metal direct writing in semi-solid slurry is an innovative technology to realize low-cost printing of load-bearing parts in contrast to laser-based additive manufacturing. However, it is challenging to achieve near net-forming of 3D parts in the current stage because of the out of controlled microstructure and hence the unstable macro extrusion of the used semi-solid slurry. Here, mixed powder remelting (MPR) is introduced to actively design the characteristics of solid phases, i.e., solid fraction, shape factor, and size distribution. Specifically, high-melting-point pure Al powder served as the dispersed solid phases in the liquid phase that transformed from Al-Si alloy powder after remelting, leading to hypoeutectic Al-Si semi-solid slurry. The effectiveness of this approach was experimentally examined and kinetically modelled, to prepare semi-solid slurry with pre-set microstructure. The improved extrusion stability of semi-solid slurry can be anticipated, and it is universal for manufacturing of metal matrix composites slurry.

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Koren, Z., H. Rosenson, G. I. Rosen e G. Segal. "Development of Semi-Solid Processes for Hot Extrusion of Magnesium Alloys". Materials Science Forum 488-489 (luglio 2005): 605–10. http://dx.doi.org/10.4028/www.scientific.net/msf.488-489.605.

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Technological barriers that relate to limited capability of magnesium extrusion technology still exist, especially for the higher alloyed grades. Part of this is associated with the unfavorable crystallographic structure of the magnesium, which is Hexagonal Close Packed (HCP). This work suggests an innovative and novel technology for reducing the production cycle from cast to finished product. A unique Semi-Solid casting system was designed and constructed in order to enable casting of large scale commercial billets having thixotropic properties. These have been further hot extruded via conventional direct extrusion press. It is shown that all essential parameters have improved significantly. These include extrusion temperature reduction (up to 1500C), press pressure reduction, increase of extrusion rate (up to four times), and, enhancement of surface quality. In addition good mechanical properties and corrosion resistance were achieved.

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Huang, Z. H., Rong Shi Chen e En Hou Han. "Preparation of Semi-Solid Billet of ZW61 Alloy by Equal Channel Angular Extrusion". Materials Science Forum 610-613 (gennaio 2009): 806–9. http://dx.doi.org/10.4028/www.scientific.net/msf.610-613.806.

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Strain induced and melt activated (SIMA) is used for the preparation of semi-solid billet through equal channel angular extrusion (ECAE) as strain induced step in SIMA and completing melt activated step by semi-solid isothermal treatment, by which semi-solid billet with fine spherical grains can be prepared. As comparison, extruded ZW61 alloy is also remelted to the semi-solid state. Furthermore, both of the semi-solid isothermal treatment microstructures in as-cast and extruded ZW61 alloy are discussed. ECAE process is found more potential for semi-solid thixoforming for as-cast ZW61 alloy.

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18

Zhang, Guang An, Cui Yan Ma e Qi Zhou. "Semi-Solid Billets of AZ91D Magnesium Alloy Prepared by Forward Extrusion/Equal-Channel Angular Pressing". Advanced Materials Research 299-300 (luglio 2011): 380–84. http://dx.doi.org/10.4028/www.scientific.net/amr.299-300.380.

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Stress-induced melt activation (SIMA) has a certain advantage during the preparation of semi-solid billet of Mg alloy. However, Equal-Channel Angular Pressing (ECAP) only can produce small billet by several channels to achieve large equivalent strain. To conquer this problem, the forward extrusion/(ECAP) method, a new process for preparing semi-solid Mg alloy was proposed. And the feasibility of forward extrusion/ECAP was analyzed. This new method simplified the processing procedure for providing commercial semisolid billets of Mg alloy. The experimental dies and experimental procedure were designed. The effect of extrusion ratio and equivalent strain on the microstructure of semisolid Mg alloy was investigated. It was found that when the extrusion ratio was larger than 10, the semisolid microstructure is refined, with increasing extrusion ratio, the microstructure is refined further.

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Zhou, T. G., Z. Y. Jiang, J. L. Wen, H. Li e A. K. Tieu. "Semi-solid continuous casting–extrusion of AA6201 feed rods". Materials Science and Engineering: A 485, n. 1-2 (giugno 2008): 108–14. http://dx.doi.org/10.1016/j.msea.2007.07.092.

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Zhang, Xiao Hua, Yan Ying Zhang, D. Z. Wu e Shou Jing Luo. "Numerical Simulation of Semi-Solid Billet Preparation by Equal Channel Angular Extrusion". Solid State Phenomena 141-143 (luglio 2008): 683–88. http://dx.doi.org/10.4028/www.scientific.net/ssp.141-143.683.

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Equal channel angular extrusion (ECAE) is a technology of refining crystal grain. In this paper, ECAE was introduced into the preparation of semi-solid billet and the extrusion process was simulated using finite element method. The variation of stress (mean stress, max principle stress, effective stress), the distribution of strain, the lattice change were obtained. The results show that not only does the shear stress exist, but also the normal stress in the extrusion process; the stresses in die inner corner of channel and outer corner of channel are not the same. In the inner corner, besides the simple shear, there are compression, and in the outer corner, tension. The strain is non-homogeneous and appears a graded distribution.

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Suárez-González, Javier, Eduardo Díaz-Torres, Cecilia N. Monzón-Rodríguez, Ana Santoveña-Estévez e José B. Fariña. "Revolutionizing Three-Dimensional Printing: Enhancing Quality Assurance and Point-of-Care Integration through Instrumentation". Pharmaceutics 16, n. 3 (16 marzo 2024): 408. http://dx.doi.org/10.3390/pharmaceutics16030408.

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Three-dimensional printing in the field of additive manufacturing shows potential for customized medicines and solving gaps in paediatric formulations. Despite successful clinical trials, 3D printing use in pharmaceutical point-of-care is limited by regulatory loopholes and a lack of Pharmacopoeia guidelines to ensure quality. Semi-solid extrusion is a 3D printing technology that stands out for its versatility, but understanding the fluid dynamics of the semi-solid mass is critical. The aim of this research is to look into the advantages of instrumenting a 3D printer with a semi-solid extrusion motor-driven printhead, which is able to record the printing pressure over time, for in situ characterization of the semi-solid mass and quality evaluation of dosage forms. Four formulations using hydrochlorothiazide as the active pharmaceutical ingredient and several excipients were used. Their flow properties were studied at different printing speeds and temperatures using traditional techniques (rheometer and Texture Analyzer) and the proposed semi-solid extrusion motor-driven printhead incorporated into a printing platform. In addition, the influence of printing speed in the printing process was also evaluated by the study of printing pressure and printlet quality. The results demonstrated the similarities between the use of a Texture Analyzer and the semi-solid extrusion motor-driven. However, the latter enables temperature selection and printing speed in accordance with the printing process which are critical printing parameters. In addition, due to the incorporation of a sensor, it was possible to conclude, for the first time, that there is a link between changes in essential printing parameters like printing speed or formulations and variations in printing pressure and printlet quality attributes such as the energy require to obtain a single dosage unit, weight or diameter. This breakthrough holds a lot of potential for assuring the quality of 3D printing dosage forms and paving the way for their future incorporation into point-of-care settings.

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Nagata, Ryotaro, Yasuhiro Uetani, Hidetoshi Takagi, Kenji Matsuda e Susumu Ikeno. "Rheo-Extrusion of A7075 Aluminium Alloy Utilizing Semi-Solid Slurry Manufactured by Simple Method". Materials Science Forum 519-521 (luglio 2006): 1847–52. http://dx.doi.org/10.4028/www.scientific.net/msf.519-521.1847.

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Abstract (sommario):

In order to extrude A7075 aluminum alloy soundly from melt without using feed stock billet, rheo-extrusion was tried by utilizing semi-solid slurry with fine solid granules made by employing cooling tube. When the melt moving down inside thin tube was adequately cooled in different ways and introduced into an extrusion container kept at semi-solid temperature of 873K, structure of solidified slurries were granular and mean grain sizes of about 60 to 120μm could be obtained. Subsequently, these slurries were extruded to round bars at various extrusion ratios (28 to 64) and press ram speed of 10mm/s, just after cooling to 833K. The newly developed slurries could easily be extruded to bars with smooth surfaces at lower forces. Although every tensile strength of extruded bars were lower than that of hot-extruded one, there was a tendency that finer the solid granules in slurry, higher the tensile strength of extruded bar.

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Fu, Jin Long, Yu Wei Wang, Kai Kun Wang e Xiao Wei Li. "Microstructure Evolution and Coarsening Mechanism of 7075 Semi-Solid Aluminum Alloy Pre-Deformed by ECAP Method". Solid State Phenomena 256 (settembre 2016): 294–300. http://dx.doi.org/10.4028/www.scientific.net/ssp.256.294.

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To investigate the influence of refined grains on the microstructure of 7075 aluminum alloy in semi-solid state, a new strain induced melting activation (SIMA) method was put forward containing two main stages: pre-deformation with equal channel angular pressing (ECAP) method and isothermally holding in the semi-solid temperature range. The breaking up and growth mechanisms of the grains and kinetics of equiaxed grains coarsening during the semi-solid holding were investigated. The results showed that the average grain size after ECAP extrusion decreased significantly, e.g., microstructure with average globular diameter less than 5μm was achieved after four-pass ECAP extrusion. Obvious grain coarsening had been found during isothermal holding in the semi-solid state and the roundness of the grains increased with the increasing holding time. The proper microstructure of 66.8μm in diameter and 1.22 in shape factor was obtained under proper soaking condition (at 590°C for 15 min). Two coarsening mechanisms, namely, coalescence in lower liquid fraction and Ostwald ripening in higher liquid fraction contributed to the grain growth process.

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Tian, Wen Tong, H. Yang e X. Cao. "Microstructural Evolution of 7A04 Alloy Prepared by FE-ECAE in Semi-Solid State". Key Engineering Materials 426-427 (gennaio 2010): 274–78. http://dx.doi.org/10.4028/www.scientific.net/kem.426-427.274.

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In the paper, forward extrusion-equal channel angular extrusion (FE-ECAE), which is new strain-induced melt activation (SIMA) method, is introduced in making semi-solid billet of 7A04 alloy. The principle of the method is that by using FE-ECAE as strain induced step and semi-solid isothermal treatment as melt activation step. The results show that semi-solid billet with highly spheroidal and homogeneous refined grains can be prepared by FE-ECAE method. The equivalent strain in FE-ECAE before reheating has a great influence on its microstructural evolution. Grain size decreases and its shape also approaches to sphericity with increasing equivalent strain. The main mechanism of the initial semi-solid grains coarsening was coalescence. With the prolongation of isothermal holding time, the grains grew up and spheroidized, in which the mean diameter of grain and liquid volume fraction increased. In the meantime, the higher the reheating temperature, the faster the grain grew and spheroidized. Subsequently, the main mechanism of grains coarsening was Ostwald ripening. The suitable reheating temperature of 7A04 alloy was 610°C.

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Uetani, Yasuhiro, Ryotaro Nagata, Hidetoshi Takagi, Kenji Matsuda e Susumu Ikeno. "Simple Manufacturing Method for A7075 Aluminum Alloy Slurry with Fine Granules and Application to Rheo-Extrusion". Solid State Phenomena 116-117 (ottobre 2006): 746–49. http://dx.doi.org/10.4028/www.scientific.net/ssp.116-117.746.

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Abstract (sommario):

Semi-solid slurry of A7075 aluminum alloy with fine solid granules was tried simply to make by passing the melt through upright tube followed by inclined water-cooled tube. Structures of solidified slurries were granular and mean grain sizes of about 0.06 to 0.11mm could be obtained. When the slurries introduced into an extrusion container kept at semi-solid temperature 873K were extruded to round bars at various extrusion ratios and press ram speed of 10mm/s, just after cooling to 833K, they could easily be extruded to bars with smooth surfaces at lower forces. Although every tensile strength of extruded bars were lower than that of hot-extruded one, there was a tendency that finer the solid granules in slurry, higher the tensile strength of extruded bar.

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Ch, Shashikanth, G. Venkateswarlu e Davidson M J. "Optimization of Process Parameters on the Mechanical Properties of Semi-Solid Extruded AA2017 Alloy Rods". International Journal of Materials Forming and Machining Processes 6, n. 2 (luglio 2019): 1–14. http://dx.doi.org/10.4018/ijmfmp.2019070101.

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The extrusion of copper-based aluminium alloys is difficult in the cold state. Extruding these alloys between the solidus and liquidus temperatures offer preferred properties on these alloys. In the present work, AA2017, a copper-based aluminium alloy has been extruded in the semi-solid state. The mechanical and metallurgical properties of the alloy vary at different temperatures between the solidus and liquidus temperatures. The aim of the present work is to optimize the process parameters, namely, temperature of billet, strain rate, approach angle and percentage reduction in area on the semi-solid extrusion of AA2017 alloy. Experiments were designed according to Taguchi experimental design and L9 orthogonal array was used to conduct the experiments. Analysis of variance (ANOVA) method was used to find the significance of every process parameter on the thixo-extrusion process responses. The results indicate that percentage reduction area is the most important factor influencing the mechanical properties of thixo-extrusion specimen followed by temperature and strain rate.

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Shang, Shu Zhen, Gui Min Lu, Xiao Ling Tang, Zu Xin Zhao e Wei Cao. "Numerical Simulation of 6061 Aluminum Alloys during the Semi-Solid Backward Extrusion". Applied Mechanics and Materials 52-54 (marzo 2011): 1532–37. http://dx.doi.org/10.4028/www.scientific.net/amm.52-54.1532.

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Effects of deformation temperature and strain rate on deformation behavior of semi-solid 6061 alloy were investigated on Gleeble3800 thermal-mechanical simulator. On basis of the experimental data of semi-solid 6061, a model was established to describe the relationship between the processing parameters and flow stress, which showed that the experimental results and calculation ones fitted well. It would be beneficial to realize the distribution of stress and strain during the semi-solid forming on the basis of numerical simulation technology. This research paper presented the numerical simulation results of the 6061 alloy during the backward extrusion thixoforming process.

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Kim, Dae-Hwan, Hyun-Ju Jung, Sung-Yong Shim, Su-Gun Lim e Sang-Yong Lee. "Thixo Extrusion and Reheating Characteristics of Semi Solid A356 Alloy". Journal of the Korea Foundry Society 34, n. 4 (31 agosto 2014): 123–29. http://dx.doi.org/10.7777/jkfs.2014.34.4.123.

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Feng, Jingkai, Dingfei Zhang, Hongjun Hu, Yang Zhao, Xia Chen, Bin Jiang e Fusheng Pan. "Improved microstructures of AZ31 magnesium alloy by semi-solid extrusion". Materials Science and Engineering: A 800 (gennaio 2021): 140204. http://dx.doi.org/10.1016/j.msea.2020.140204.

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30

Muenstermann, Simon, Rainer Telle, Frederik Knauf e Gerhard Hirt. "Semi-Solid Extrusion of Complex-Shaped Steel Rods Using Ceramic Dies". Solid State Phenomena 141-143 (luglio 2008): 243–48. http://dx.doi.org/10.4028/www.scientific.net/ssp.141-143.243.

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Abstract (sommario):

Isothermal semi-solid extrusion experiments using steel grade X210CrW12 as work material were performed on an industrial forging machine. An improved and up-scaled tool design was applied, based on the concept of self-heating ceramic dies tested in previous laboratory-scale studies and allowing for die preheating temperatures of up to 1400°C. Steel rods of complex cross sectional geometry were formed at low extrusion forces. Shape accuracy of as-formed rods is accurate and metallurgical examination yields no evidence of liquid phase separation. With a view on the intended industrial implementation construction of ceramic tools has to be improved in order to avoid rupture of ceramic parts due to thermo-mechanically induced stresses and to benefit from the advantages inherent to ceramics in metal forming.

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31

Rong, Wenjuan, Zhongde Shan, Baoyu Wang, Yongwei Wang e Jialin Wang. "Microstructure Evolution of 2A12 Aluminum Alloy under Isothermal Heat Treatment Direct Writing Process". Materials 15, n. 18 (9 settembre 2022): 6279. http://dx.doi.org/10.3390/ma15186279.

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Abstract (sommario):

A metal-melting direct writing process, using semi-solid isothermal heat treatment to form high-quality semi-solid components, realized the integrated innovation of semi-solid formation and additive manufacturing. An experimental study was carried out on semi-solid isothermal heat treatment for metal-melting direct-writing technology, using 2A12 aluminum alloy as raw material. The semi-solid isothermal heat treatment was carried out over different temperature ranges, and four-stages evolution mechanism of the semi-solid microstructure in the semi-solid melting direct writing process was investigated. The effects of holding temperature and time on the microstructure of the semi-solid isothermal heat treatment of the alloy were put forward. According to the analysis of the results of the semi-solid-melting direct-writing test, the corresponding relationship between semi-solid microstructure and extrusion formability was found. The results show that when the holding temperature is 640–650 °C and the holding time is 20–25 min, the liquid phase rate can reach about 40%, and the direct-writing forming technology can be carried out stably.

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32

Kareh, Kristina Maria, Peter D. Lee e Christopher M. Gourlay. "Globule-Globule Interactions during Deformation in Semi-Solid Al-Cu Using Time-Resolved X-Ray Tomography". Solid State Phenomena 192-193 (ottobre 2012): 179–84. http://dx.doi.org/10.4028/www.scientific.net/ssp.192-193.179.

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Abstract (sommario):

Optimising semi-solid processing and accurately modelling semi-solid deformation requires a fundamental understanding of the globule-scale mechanisms that cause the macroscopic rheological response. In this work, apparatus and analysis techniques are being developed for the time-resolved, three-dimensional imaging of semi-solid alloy deformation. This paper overviews synchrotron X-ray tomography results on globular Al-15wt%Cu deformed at 0.7 solid fraction using extrusion. The globule-globule interactions in response to load were quantified in terms of the response of individual globules with respect to globule translation, rotation, and deformation. The potential of time-resolved X-ray tomography in the study of semi-solid alloy deformation is then discussed.

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33

Wang, Yingwu, Xiaoqing Zuo, Songjiang Ran, Yushun Ye e Jihua Tian. "Effects of semi-solid extrusion and heat treatment on the microstructure, mechanics, and wear resistance of SiC/High aluminum zinc-base alloy composites". Modern Physics Letters B 34, n. 25 (31 maggio 2020): 2050261. http://dx.doi.org/10.1142/s0217984920502619.

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Abstract (sommario):

The effects of semi-solid extrusion temperature change, extrusion pressure, SiC content and T5 heat treatment on the microstructure, mechanical properties, and wear resistance of SiC particle strengthened high aluminum zinc-base alloy [Formula: see text] composites were studied. The results show that semi-solid extrusion broke the dendrites of [Formula: see text] composites, refined their grain structure, and improved particle aggregation. The density, hardness, yield strength, tensile strength and elongation of [Formula: see text] composites first increased and then decreased when the extrusion temperature and SiC content increased, and also increased when the extrusion pressure rose. The optimal extrusion temperature, pressure and SiC content are 475[Formula: see text], 15 MPa and 10 wt.%, respectively. T5 heat treatment further refined the crystalline grains and promoted [Formula: see text] and [Formula: see text] to precipitate as strengthening phases, which improve the mechanical properties and wear resistance of [Formula: see text] composites. Consequently, the hardness, yield strength, tensile strength and elongation of the heat-treated composites improved by 18.99%, 9.66%, 4.93% and 9.76%, respectively. The wear loss of the heat-treated composites reduced by 31.65% under a load of 1600 N and a rotational speed of 200 r/min compared with the as-cast composites.

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Su, L. Z., L. H. Qi, J. M. Zhou e H. J. Li. "Influence of extrusion temperature on deformation behavior of Csf/AZ91D composite during semi-solid extrusion". Journal of Alloys and Compounds 509, n. 3 (gennaio 2011): 775–81. http://dx.doi.org/10.1016/j.jallcom.2010.09.086.

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35

Jiang, Ju Fu, e Shou Jing Luo. "Microstructure Evolution of AZ91D Magnesium Alloy Semi-solid Billets Prepared by a New SIMA Method". Solid State Phenomena 116-117 (ottobre 2006): 132–35. http://dx.doi.org/10.4028/www.scientific.net/ssp.116-117.132.

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Abstract (sommario):

By using equal channel angular extrusion (ECAE) as strain induced step in strain induced melt activated (SIMA) and completing melt activated step by using semi-solid isothermal treatment, a new SIMA method is introduced firstly. The results show that semi-solid billet with highly spheroidal and homogeneous grains with the average grain size of 20μm can be prepared by new SIMA method. High mechanical properties, such as ultimate tensile strength of 321.8MPa and elongation of 15.2% are obtained in magazine plate components thixoforged using semi-solid billet prepared by new SIMA.

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36

Jiang, Ju Fu, e Shou Jing Luo. "Mechanical Behavior of Processed AZ91D by Equal Channel Angular Extrusion during Semi-Solid Isothermal Compression". Solid State Phenomena 116-117 (ottobre 2006): 530–33. http://dx.doi.org/10.4028/www.scientific.net/ssp.116-117.530.

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Abstract (sommario):

Mechanical behavior of processed AZ91D magnesium alloy by equal channel angular extrusion during semi-solid isothermal compression was investigated using semi-solid isothermal compression test. The results show that there are four stages, drastic increase of true stress, drastic falling of true stress, steady stage and increase of true stress. With the increase of holding time or deformation temperature, required true stress for obtaining same true strain falls evidently and peak stress and steady stress also fall in true stress-strain curve. With increasing strain rate, steady stress also increase. Peak stress will increase or decrease with the sudden increase or fall of strain rate. During semi-solid isothermal compression, plastic deformation of semi-solid billet mainly depends on plastic deformation of solid phases and their rotation and sliding. Coarse grains occur in upper position adjacent to compression die’s surface and fine grains occur in the central and free surface positions of billets.

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37

Cezard, Pierre, Régis Bigot, Véronique Favier e Marc Robelet. "Thixoforming of Steel – Influence of Thermal Parameters". Solid State Phenomena 116-117 (ottobre 2006): 721–24. http://dx.doi.org/10.4028/www.scientific.net/ssp.116-117.721.

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Abstract (sommario):

This paper presents experimental results on steel thixoforming. The influence of thermal effects on the semi-solid response is analysed through the influence of thermal exchanges with tools and environment. Several rheological experiments such as compression, extrusion or radial filling test were developed to understand the semi-solid steel behaviour and determine the parameters that have a major influence on thixoforming. Actually, in our experiments, the temperature of the slug and consequently the solid fraction were found first order parameters while; the morphology of the solid phase plays a minor role.

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38

Wang, Kai Kun, Peng Zhang, Yan Mei Du, Zeng Pan e Hong Gao Li. "Basic Study on Thixo-Co-Extrusion of Multi-Layer Tube with Al/Mg Alloys". Solid State Phenomena 141-143 (luglio 2008): 73–78. http://dx.doi.org/10.4028/www.scientific.net/ssp.141-143.73.

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Abstract (sommario):

Thixo-forming is in the forefront of metal processing technology in the 21st century. The research on thixo-co-extrusion of multi-layer tube as extension and development of the semi-solid forming technology is a completely new processing method for the composite material forming and is of great significance, in which different semi-solid billets (slurries) are extruded at the same time to form multi-layer tubes. In this study, different sizes of column-shaped and ring-shaped billets of Al/Mg alloys were firstly prepared by using specially designed molds. Then they were reheated by electric-resistance furnace，microstructures from different heating laws were investigated. Lastly, FEM simulation on thixo-co-extrusion of double-layer tube with A356/AZ91 was conducted.

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RATTANOCHAIKUL, T., S. JANUDOM, N. MEMONGKOL e J. WANNASIN. "Development of aluminum rheo-extrusion process using semi-solid slurry at low solid fraction". Transactions of Nonferrous Metals Society of China 20, n. 9 (settembre 2010): 1763–68. http://dx.doi.org/10.1016/s1003-6326(09)60371-x.

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40

Kim, Dae Hwan, Heek Yung Kim e Su Gun Lim. "Aging Behavior of Semi-Solid Mg-10Al-0.3Mn Alloy by the Hot Extrusion". Advanced Materials Research 658 (gennaio 2013): 102–7. http://dx.doi.org/10.4028/www.scientific.net/amr.658.102.

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Abstract (sommario):

In present study, the aging behavior of the hot extruded semi-solid Mg-10Al-0.3Mn alloy was investigated. In order to obtain the extruded bar, we carried out the hot extrusion at 380°C with an extrusion ratio of 25 and ram speed of 2.4mms-1. Vickers hardness test, electrical conductivity measurements, scanning and transmission electron microscopy and tensile testing were performed to identify the aging behaviors and mechanical properties during the aging treatment. Observations of the aging behavior and results of the tensile tests after the T6 heat treatment at each aging temperature show that the optimum aging conditions was indicated by a hardness increment of 72% and a tensile strength of 340MPa in the extruded bar.

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41

Jabbari, Amin, e Karen Abrinia. "A metal additive manufacturing method: semi-solid metal extrusion and deposition". International Journal of Advanced Manufacturing Technology 94, n. 9-12 (25 settembre 2017): 3819–28. http://dx.doi.org/10.1007/s00170-017-1058-7.

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42

Basner, T., A. Sachdev e R. Pehlke. "Thin-wall back extrusion of partially remelted semi-solid Sn-Pb". Metallurgical and Materials Transactions A 31, n. 1 (gennaio 2000): 57–62. http://dx.doi.org/10.1007/s11661-000-0052-z.

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43

Knauf, F., R. Baadjou e G. Hirt. "Analysis of semi-solid extrusion products made of steel alloy X210CRW12". International Journal of Material Forming 2, S1 (agosto 2009): 733–36. http://dx.doi.org/10.1007/s12289-009-0426-8.

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44

Wang, Fan, Ling Li, Xiaolong Zhu, Feng Chen e Xiaoxiao Han. "Development of pH-Responsive Polypills via Semi-Solid Extrusion 3D Printing". Bioengineering 10, n. 4 (24 marzo 2023): 402. http://dx.doi.org/10.3390/bioengineering10040402.

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Abstract (sommario):

The low bioavailability of orally administered drugs as a result of the instability in the gastrointestinal tract environment creates significant challenges to developing site-targeted drug delivery systems. This study proposes a novel hydrogel drug carrier using pH-responsive materials assisted with semi-solid extrusion 3D printing technology, enabling site-targeted drug release and customisation of temporal release profiles. The effects of material parameters on the pH-responsive behaviours of printed tablets were analysed thoroughly by investigating the swelling properties under both artificial gastric and intestinal fluids. It has been shown that high swelling rates at either acidic or alkaline conditions can be achieved by adjusting the mass ratio between sodium alginate and carboxymethyl chitosan, enabling site-targeted release. The drug release experiments reveal that gastric drug release can be achieved with a mass ratio of 1:3, whilst a ratio of 3:1 allows for intestinal release. Furthermore, controlled release is realised by tuning the infill density of the printing process. The method proposed in this study can not only significantly improve the bioavailability of oral drugs, but also offer the potential that each component of a compound drug tablet can be released in a controlled manner at a target location.

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45

Weiss, David, e Michael Black. "Using Semi-Solid Extrusion for the Production of Aluminum-Nanocomposite Master Alloys". Solid State Phenomena 217-218 (settembre 2014): 426–30. http://dx.doi.org/10.4028/www.scientific.net/ssp.217-218.426.

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Abstract (sommario):

The production of nanoreinforced aluminum alloys in volume and quality suitable for subsequent shape casting has been problematic. Large specific surface area and high interfacial energy of the particles combined with high surface tension of the aluminum melt makes it difficult to add appreciable numbers of particles to the melt, even when later de-agglomerated by techniques such as ultrasonic cavitation. Previous work by the authors used semi-solid squeeze casting to produce master alloys for dilution into the casting alloy. While the technique was shown to be effective, the master alloy proved difficult to remelt and was expensive to produce. The objective of this new work was to use an extrusion process that could be more readily scaled to produce nanoreinforced aluminum master alloys. This paper describes the process developed for incorporation of nanoparticles using semi-solid extrusion and the results of alloys produced using that process.

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46

Auriemma, Giulia, Carmela Tommasino, Giovanni Falcone, Tiziana Esposito, Carla Sardo e Rita Patrizia Aquino. "Additive Manufacturing Strategies for Personalized Drug Delivery Systems and Medical Devices: Fused Filament Fabrication and Semi Solid Extrusion". Molecules 27, n. 9 (27 aprile 2022): 2784. http://dx.doi.org/10.3390/molecules27092784.

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Abstract (sommario):

Novel additive manufacturing (AM) techniques and particularly 3D printing (3DP) have achieved a decade of success in pharmaceutical and biomedical fields. Highly innovative personalized therapeutical solutions may be designed and manufactured through a layer-by-layer approach starting from a digital model realized according to the needs of a specific patient or a patient group. The combination of patient-tailored drug dose, dosage, or diagnostic form (shape and size) and drug release adjustment has the potential to ensure the optimal patient therapy. Among the different 3D printing techniques, extrusion-based technologies, such as fused filament fabrication (FFF) and semi solid extrusion (SSE), are the most investigated for their high versatility, precision, feasibility, and cheapness. This review provides an overview on different 3DP techniques to produce personalized drug delivery systems and medical devices, highlighting, for each method, the critical printing process parameters, the main starting materials, as well as advantages and limitations. Furthermore, the recent developments of fused filament fabrication and semi solid extrusion 3DP are discussed. In this regard, the current state of the art, based on a detailed literature survey of the different 3D products printed via extrusion-based techniques, envisioning future directions in the clinical applications and diffusion of such systems, is summarized.

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47

Dindigala, Anil Kumar, e Mounika Rajya Lakshmi Kodam. "Application of Lipids in Hot Melt Extrusion Technology". Journal of Drug Delivery and Therapeutics 13, n. 5 (15 maggio 2023): 82–86. http://dx.doi.org/10.22270/jddt.v13i5.5816.

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Abstract (sommario):

Lipids are commonly used excipients in drug delivery for improving solubility of low soluble drugs, enhancing bioavailability through avoiding first pass metabolism through nanoparticulate approach, modifying the drug release, binders, permeation enhancers, transfection agents etc. Lipids alone or in combination of polymers are increasingly being used in hot melt extrusion (HME) technology for preparation of controlled release formulations, solid dispersions, self-emulsifying drug delivery systems, semi-solid formulations, solid lipid nanoparticles and others. Properties like low melting temperature, viscosity, ability to extrude at low temperature and ability to load high doses of drug favor use of lipids in HME technology. This review emphasizes the use of lipids for variety of applications in HME technology. Keywords: Lipids, Hot melt extrusion, solubility, bioavailability, parameters.

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48

Neag, Adriana, Véronique Favier, Liviu Nistor e Régis Bigot. "Numerical Simulation and Experimental Investigation on Thixo-Backward Extrusion of 7075 Aluminium Alloy". Advanced Engineering Forum 8-9 (giugno 2013): 269–76. http://dx.doi.org/10.4028/www.scientific.net/aef.8-9.269.

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Abstract (sommario):

The thixoextrusion process could become an important technique to extend the complexity of extruded profiles. However, the complex thixotropic flow behavior of semi-solid, during thixoextrusion is still partly characterized. The study described in this paper investigates thixoextrusion for 7075 aluminium alloy at different temperature conditions. A complete die filling and a good surface state of parts was obtained at high solid fraction (fS = 0.70), in heated dies, for an extrusion ram speed of 416 mm/s. The thixoextrusion process is simulated using the finite element code Forge2009©. The constitutive equation used for these simulations is based on a micro-macro model for the semi-solid evolution. The tendency of the experimental curves evolution, preserving the same parameters of the micro-macro constitutive model, for each values of solid fraction, was reproduced, except the last step of the ram displacement.

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49

Ghadiani, S., Hossein Aashuri, Ali Khosravani e A. Foroughi. "Viscosity Estimation of Semi-Solid Alloys by Drop Weight Backward Extrusion Test under High Speed Deformation". Solid State Phenomena 141-143 (luglio 2008): 379–84. http://dx.doi.org/10.4028/www.scientific.net/ssp.141-143.379.

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Abstract (sommario):

A simple method for estimating the apparent viscosity of semi-solid alloys was investigated. A drop weight of 50Kg and backward extrusion equipments were used to test the deformation. Backward extrusion was employed in a closed die system due to the very little separation of liquid from solid phases compared with other methods at very high deformation rate. The half of the calculated impact velocity, 700mm/s was considered as an average velocity for deformation during the test, since the slop of the velocity changes against time is constant in the middle stage of the deformation. The initial height of the sample and the thickness of the residual compressed solid at the bottom of the cup were used to calculate the amount of apparent viscosity of A356 aluminum alloy in this work.

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Aina, Morenikeji, Fabien Baillon, Romain Sescousse, Noelia M. Sanchez-Ballester, Sylvie Begu, Ian Soulairol e Martial Sauceau. "Development of Personalised Immediate-Release Gel-Based Formulations Using Semi-Solid Extrusion". Gels 10, n. 10 (17 ottobre 2024): 665. http://dx.doi.org/10.3390/gels10100665.

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Abstract (sommario):

Precision in dosing is crucial for optimizing therapeutic outcomes and preventing overdosing, especially in preterm infants. Traditional manual adjustments to adapt the dose often lead to inaccuracies, contamination risks, and reduced precision. To overcome these challenges, semi-solid extrusion 3D printing was used to create personalised gel-based caffeine dosage forms. The hydrogels, made from agar and hydroxypropyl methylcellulose, demonstrated excellent rheological properties, ensuring uniform extrusion and accurate shape retention during and after printing. This gel formulation allowed for precise adjustments of caffeine volume and content tailored to a neonate weighing 1.36 kg, achieving a recovery of 103.46%, well within acceptable limits. Additionally, three production batches confirmed the process’s reproducibility with minimal variability. Forced degradation studies showed that both pure caffeine and caffeine in the gel matrix exhibited similar stability profiles, confirming the drug’s chemical integrity. The printed gel dosage forms also displayed immediate-release characteristics, with over 80% of caffeine released within 45 min, highlighting their suitability for rapid therapeutic action. These findings emphasise the potential of SSE 3DP and gel-based formulations to produce personalised drug delivery systems with high precision, reproducibility, and reliability.

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