• Elastomers and Composites
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• v.58 no.1
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• pp.44-56
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• 2023

Additive manufacturing (AM) or three-dimensional (3D) printing of metals has been drawing significant attention due to its reliability, usefulness, and low cost with rapid prototyping. Among the various AM technologies, fused deposition modeling (FDM) or fused filament fabrication is receiving much interest because of its simple manufacturing processing, low material waste, and cost-effective equipment. FDM technology uses metal-filled polymer filaments for 3D printing, followed by debinding and sintering to fabricate complex metal parts. An efficient binder is essential for producing polymer filaments and the thermal post-processing of printed objects. This study involved an in-depth investigation of and a fabrication route for a novel multi-component binder system with steel alloy powder (45 vol.%) ranging from filament fabrication and 3D printing to debinding and sintering. The binder system consisted of polyvinyl pyrrolidone (PVP) as a binder and thermoplastic polyurethane (TPU) and polylactic acid (PLA) as a carrier. The PVP binder held the metal components tightly by maintaining their stoichiometry, and the TPU and PLA in the ratio of 9:1 provided flexibility, stiffness, and strength to the filament for 3D printing. The efficacy of the binder system was examined by fabricating 3D-printed cubic structures. The results revealed that the thermal debinding and sintering processes effectively removed the binder/carrier from the cubic structures, resulting in isotropic shrinkage of approximately 15.8% in all directions. The scanning electron microscopy (SEM) and energy dispersive X-ray spectroscopy (EDX) patterns displayed the microstructure behavior, phase transition, and elemental composition of the 3D cubic structure.

• Journal of Integrative Natural Science
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• v.17 no.3
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• pp.67-73
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• 2024

Hydrophilic contact lens was prepared by dispersing MXene material in a hydrogel mixture, and the purpose of this study was to evaluate its properties as an ophthalmic material. The MXene used in the experiment was manufactured through an etching process using titanium aluminum carbide 312 [Ti3AlC2] and hydrofluoric acid [HF]. For the preparation of hydrophilic contact lenses, 2-hydroxyethyl methacrylate [HEMA], a photoinitiator 2-hydroxy-2-methylpropiophenone [2H2M], and a cross-linker Ethylene glycol dimethacrylate [EGDMA] were used, and UV-rays was irradiated for 50 seconds for photopolymerization. Optical transmittance, refractive index, water content, contact angle, electromagnetic wave shielding ability, and photo-thermal conversion effect were measured to evaluate the physical properties of the manufactured contact lens. Compared to MXene materials, MXene mixed with Dimethyl sulfoxide [DMSO] had superior dispersion ability in organic solvents, and the transparency of the prepared hydrophilic contact lenses was high. MXene did not significantly affect the refractive index and water content, and improved the wettability of the contact lens. In addition, the MXene material used as an additive showed electromagnetic wave shielding ability and photo-thermal conversion effect based on its excellent electrical conductivity. It is judged that the mixture using MXene as an additive can be used as a functional contact lens material for electromagnetic wave shielding and ocular photo-thermal therapy.

• The Journal of Advanced Prosthodontics
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• v.10 no.4
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• pp.321-327
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• 2018

PURPOSE. The purpose of this study was to compare the cutting method and the lamination method to investigate whether the CAD data of the proposed inlay shape are machined correctly. MATERIALS AND METHODS. The Mesial-Occlusal shape of the inlay was modeled by changing the stereolithography (STL). Each group used SLS (metal powder) or SLA (photocurable resin) in the additive method, and wax or zirconia in the subtractive method (n=10 per group, total n=40). Three-dimensional (3D) analysis program (Geomagic Control X inspection software; 3D systems) was used for the alignment and analysis. The root mean square (RMS) in the 2D plane state was measured within $50{\mu}m$ radius of eight comparison measuring points (CMP). Differences were analyzed using one-way analysis of variance and post-hoc Tukey's test were used (${\alpha}=.05$). RESULTS. There was a significant difference in RMS only in SLA and SLS of 2D section (P<.05). In CMP mean, CMP 4 ($-5.3{\pm}46.7{\mu}m$) had a value closest to 0, while CMP 6 ($20.1{\pm}42.4{\mu}m$) and CMP 1 ($-89.2{\pm}61.4{\mu}m$) had the greatest positive value and the greatest negative value, respectively. CONCLUSION. Since the errors obtained from the study do not exceed the clinically acceptable values, the lamination method and the cutting method can be used clinically.

• Journal of the Korea institute for structural maintenance and inspection
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• v.24 no.5
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• pp.143-149
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• 2020

The purpose of this study is to manufacture a variable density - hybrid lattice structure control by filling the pore of the metal addictive manufactured lattice structure with lightweight reactive acrylic compounds(RAC). To apply the variable density - hybrid lattice structure to the construction industry, the enhancing adhesion - reactive acrylic compounds(EA-RAC) which increased the adhesion strength was manufactured by adding ordinary portland cement to the RAC. Finally, the EA-RAC was filled into the lattice structure to test the specific density, water absorption, and adhesion strength of the variable density - hybrid lattice structure. The results were obtained with density controllable, water absorption less than 1.0%, and 1-day bonding strength of 1.78 MPa to 1.98 MPa.

• Journal of Technologic Dentistry
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• v.40 no.4
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• pp.209-215
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• 2018

Purpose: The purpose of this study was to evaluate the clinical acceptability of the marginal and internal gap of Co-Cr metal copings fabricated with stereolithography (SLA). Methods: Titanium master dies were milled after scanning of the prepared tooth (n=30). For group I, Co-Cr metal copings were made from conventional lost-wax technique(LWT, n=10). For group II, the master dies were scanned and designed with CAD system. Then, metal copings were milled with Co-Cr(SUB, n=10). For group III(ADD, n=10), the scanning and design procedures were same as group II and burn-out resins were fabricated with SLA device. The marginal and internal discrepancies were measured under an optical microscope(100x) on ten reference points and were statistically analyzed with one-way ANOVA(${\alpha}=.05$). Results: The mean total discrepancies were $53.76{\pm}12.42{\mu}m$ in the LWT group and $69.82{\pm}15.48{\mu}m$ in the ADD group. The SUB group showed the largest total mean value $110.33{\pm}13.77{\mu}m$. There was statistically significant difference between the SUB and the other groups(P<0.05). Conclusion : Co-Cr metal copings fabricated with SLA technology showed clinically acceptable value on marginal and internal gap and there was no statistically significant difference between conventional lost-wax technique and SLA.

• Transactions of the Korean Society of Pressure Vessels and Piping
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• v.16 no.1
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• pp.117-124
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• 2020

3D printing is a technology that has significantly grown in recent years, particularly in the aerospace, defense, and medical sectors where it offers significant potential cost savings and reduction of the supply chain by allowing parts to be manufactured on-site rather than at a distance supplier. In nuclear industry, 3D printing technology should be applied according to the manufacturing trend change. For the application of 3D printing technology to the nuclear power plant, several problems, including the absence of code & standards of materials, processes and testing & inspection methods etc, should be solved. Preemptively, the improvement of reliability of 3D printing technology, including mechanical properties, structural performance, service performance and aging degradation of 3D printed parts should be supported. These results can be achieved by collaboration of many organizations such as institute, 3D printer manufacturer, metal powder supplier, nuclear part manufacturer, standard developing organization, and nuclear utility.

• Journal of Korea Foundry Society
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• v.39 no.6
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• pp.110-115
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• 2019

Recently, various studies have been conducted on additive manufacturing technology developed using metal materials. In this study, a numerical analysis was introduced to analyze the effects of the thermal deformation and residual stress which arise during the SLM (selective laser melting) manufacturing process. A phase-transformation mechanism is implemented with the use of the Ti-6Al-4V material, in which a solid-state phase transformation (SSPT) can be induced during a numerical analysis. In this case, the phase of the Ti-6Al-4V material changes from a powder to a solid state and then to the Martensite phase in sequence during heating and cooling steps. The numerical analysis during the SLM process was verified by comparing the results of tensile tests with those from the numerical analysis based on the SSPT material properties.

• Laser Solutions
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• v.18 no.3
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• pp.1-5
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• 2015

A 3D printer based on laser powder deposition (LPD), also known as DED (direct energy deposition), has been developed for fabricating metal parts. The printer uses a ytterbium fiber laser (1070nm, 1kW) and is equipped with an Ar purge chamber, a three-dimensional translation stage and a powder feeding system composed of a powder chamber and delivery nozzles. To demonstrate the performance of the printer, a tapered cylinder of 320mm in height has been fabricated successfully using Ti-6Al-4V powders. The process parameters including the laser output power, the scan speed, and the powder feeding rate have been optimized. A 3D printed test specimen shows mechanical properties (yield strength, ultimate tensile strength, and elongation) exceeding the criteria to employed in a variety of Ti alloy applications.

• Journal of Powder Materials
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• v.9 no.6
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• pp.441-448
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• 2002

Dispersions of non-soluble ceramic particles in a metallic matrix can enhance the strength and heat resistance of materials. With the advent of mechanical alloying it became possible to put the theoretical concept into practice by incorporating very fine particles in a flirty uniform distribution into often oxidation- and corrosion- resistant metal matrices. e.g. superalloys. The present paper will give an overview about the mechanical alloying technique as a dry, high energy ball milling process for producing composite metal powders with a fine controlled microstructure. The common way is milling of a mixture of metallic and nonmetallic powders (e.g. oxides. carbides, nitrides, borides) in a high energy ball mill. The heavy mechanical deformation during milling causes also fracture of the ceramic particles to be distributed homogeneously by further milling. The mechanisms of the process are described. To obtain a homogeneous distribution of nano-sized dispersoids in a more ductile matrix (e.g. aluminium-or copper based alloys) a reaction milling is suitable. Dispersoid can be formed in a solid state reaction by introducing materials that react with the matrix either during milling or during a subsequent heat treatment. The pre-conditions for obtaining high quality materials, which require a homogeneous distribution of small dis-persoids, are: milling behaviour of the ductile phase (Al, Cu) will be improved by the additives (e.g. graphite), homogeneous introduction of the additives into the granules is possible and the additive reacts with the matrix or an alloying element to form hard particles that are inert with respect to the matrix also at elevated temperatures. The mechanism of the in-situ formation of dispersoids is described using copper-based alloys as an example. A comparison between the in-situ formation of dispersoids (TiC) in the copper matrix and the milling of Cu-TiC mixtures is given with respect to the microstructure and properties, obtained.

• KIPS Transactions on Software and Data Engineering
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• v.12 no.5
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• pp.229-236
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• 2023

Since 3D printed medical implant parts usually have surface defects, it is necessary to inspect the surface after manufacturing. In order to automate the surface inspection, it is effective to 3D scan the implant and reconstruct it as a scan model such as a point cloud. When constructing a scan model, the characteristics of the shape and material of the implant must be considered because it has characteristics different from those of general 3D printed parts. In this paper, we present a method to reconstruct the 3D scan model of a 3D printed metal bone-plate that is one kind of medical implant parts. Multiple partial scan data are produced by multi-view 3D scan, and then, we reconstruct a scan model by alignment and merging of partial data. We also present the process of the scan model reconstruction through experiments.