간행물
한국분말야금학회지 KCI 등재 Journal of Korean Powder Metallurgy Institute
- 발행기관 한국분말재료학회(구 한국분말야금학회)
- 자료유형 학술지
- 간기 격월간
- ISSN 1225-7591 (Print)2287-8173 (Online)
- 수록기간 1994 ~ 2024
- 주제분류 공학 > 금속공학 공학 분류의 다른 간행물
- 십진분류KDC 559DDC 629
권호리스트/논문검색
Vol. 29 No. 1 (2022년 2월) 9건
1.
2022.02
구독 인증기관 무료, 개인회원 유료
This study investigates the effect of process stopping and restarting on the microstructure and local nanoindentation properties of 316L stainless steel manufactured via selective laser melting (SLM). We find that stopping the SLM process midway, exposing the substrate to air having an oxygen concentration of 22% or more for 12 h, and subsequently restarting the process, makes little difference to the density of the restarted area (~ 99.8%) as compared to the previously melted area of the substrate below. While the microstructure and pore distribution near the stop/restart area changes, this modified process does not induce the development of unusual features, such as an inhomogeneous microstructure or irregular pore distribution in the substrate. An analysis of the stiffness and hardness values of the nano-indented steel also reveals very little change at the joint of the stop/restart area. Further, we discuss the possible and effective follow-up actions of stopping and subsequently restarting the SLM process.
4,000원
2.
2022.02
구독 인증기관 무료, 개인회원 유료
In this study, we have prepared a Ti-6Al-4V/V/17-4 PH composite structure via a direct energy deposition process, and analyzed the interfaces using scanning electron microscopy (SEM) and transmission electron microscopy (TEM). The joint interfaces comprise two zones, one being a mixed zone in which V and 17-4PH are partially mixed and another being a fusion zone in the 17-4PH region which consists of Fe+FeV. It is observed that the power of the laser used in the deposition process affects the thickness of the mixed zone. When a 210 W laser is used, the thickness of the mixed zone is wider than that obtained using a 150 W laser, and the interface resembles a serrated shape. Moreover, irrespective of the laser power used, the expected phase is found to be absent in the V/17-4 PH stainless steel joint; however, many VN precipitates are observed.
4,000원
3.
2022.02
구독 인증기관 무료, 개인회원 유료
In the powder bed fusion (PBF) process, a 3D shape is formed by the continuous stacking of very fine powder layers using computer-aided design (CAD) modeling data, following which laser irradiation can be used to fuse the layers forming the desired product. In this method, the main process parameters for manufacturing the desired 3D products are laser power, laser speed, powder form, powder size, laminated thickness, and laser diameter. Stainless steel (STS) 316L exhibits excellent strength at high temperatures, and is also corrosion resistant. Due to this, it is widely used in various additive manufacturing processes, and in the production of corrosion-resistant components with complicated shapes. In this study, rectangular specimens have been manufactured using STS 316L powder via the PBF process. Further, the effect of heat treatment at 800 °C on the microstructure and hardness has been investigated.
4,000원
4.
2022.02
구독 인증기관 무료, 개인회원 유료
Conventionally, metal materials are produced by subtractive manufacturing followed by melting. However, there has been an increasing interest in additive manufacturing, especially metal 3D printing technology, which is relatively inexpensive because of the absence of complicated processing steps. In this study, we focus on the effect of varying powder size on the synthesis quality, and suggest optimum process conditions for the preparation of AlCrFeNi high-entropy alloy powder. The SEM image of the as-fabricated specimens show countless, fine, as-synthesized powders. Furthermore, we have examined the phase and microstructure before and after 3D printing, and found that there are no noticeable changes in the phase or microstructure. However, it was determined that the larger the powder size, the better the Vickers hardness of the material. This study sheds light on the optimization of process conditions in the metal 3D printing field.
4,000원
5.
2022.02
구독 인증기관 무료, 개인회원 유료
Aluminum-based powders have attracted attention as key materials for 3D printing owing to their low density, high specific strength, high corrosion resistance, and formability. This study describes the effects of TiC addition on the microstructure of the A6013 alloy. The alloy powder was successfully prepared by gas atomization and further densified using an extrusion process. We have carried out energy dispersive X-ray spectrometry (EDS) and electron backscatter diffraction (EBSD) using scanning electron microscopy (SEM) in order to investigate the effect of TiC addition on the microstructure and texture evolution of the A6013 alloy. The atomized A6013-xTiC alloy powder is fine and spherical, with an initial powder size distribution of approximately 73 μm which decreases to 12.5, 13.9, 10.8, and 10.0 μm with increments in the amount of TiC.
4,000원
6.
2022.02
구독 인증기관 무료, 개인회원 유료
Recently, high-entropy carbides have attracted considerable attention owing to their excellent physical and chemical properties such as high hardness, fracture toughness, and conductivity. However, as an emerging class of novel materials, the synthesis methods, performance, and applications of high-entropy carbides have ample scope for further development. In this study, equiatomic (Hf-Ti-Ta-Zr-Nb)C high-entropy carbide powders have been prepared by an ultrahigh- energy ball-milling (UHEBM) process with different milling times (1, 5, 15, 30, and 60 min). Further, their refinement behavior and high-entropy synthesis potential have been investigated. With an increase in the milling time, the particle size rapidly reduces (under sub-micrometer size) and homogeneous mixing of the prepared powder is observed. The distortions in the crystal lattice, which occur as a result of the refinement process and the multicomponent effect, are found to improve the sintering, thereby notably enhancing the formation of a single-phase solid solution (high-entropy). Herein, we present a procedure for the bulk synthesis of highly pure, dense, and uniform FCC single-phase (Fm3m crystal structure) (Hf-Ti-Ta-Zr-Nb)C high-entropy carbide using a milling time of 60 min and a sintering temperature of 1,600oC.
4,000원
7.
2022.02
구독 인증기관 무료, 개인회원 유료
In this study, we report the microstructure and characteristics of Ag-SnO2-Bi2O3 contact materials using a controlled milling process with a subsequent compaction process. Using magnetic pulsed compaction (MPC), the milled Ag-SnO2-Bi2O3 powders have been consolidated into bulk samples. The effects of the compaction conditions on the microstructure and characteristics have been investigated in detail. The nanoscale SnO2 phase and microscale Bi2O3 phase are well-distributed homogeneously in the Ag matrix after the consolidation process. The successful consolidation of Ag-SnO2-Bi2O3 contact materials was achieved by an MPC process with subsequent atmospheric sintering, after which the hardness and electrical conductivity of the Ag-SnO2-Bi2O3 contact materials were found to be 62–75 HV and 52–63% IACS, respectively, which is related to the interfacial stability between the Ag matrix, the SnO2 phase, and the Bi2O3 phase.
4,000원
8.
2022.02
구독 인증기관 무료, 개인회원 유료
Tungsten carbide is widely used in carbide tools. However, its production process generates a significant number of end-of-life products and by-products. Therefore, it is necessary to develop efficient recycling methods and investigate the remanufacturing of tungsten carbide using recycled materials. Herein, we have recovered 99.9% of the tungsten in cemented carbide hard scrap as tungsten oxide via an alkali leaching process. Subsequently, using the recovered tungsten oxide as a starting material, tungsten carbide has been produced by employing a self-propagating high-temperature synthesis (SHS) method. SHS is advantageous as it reduces the reaction time and is energy-efficient. Tungsten carbide with a carbon content of 6.18 wt % and a particle size of 116 nm has been successfully synthesized by optimizing the SHS process parameters, pulverization, and mixing. In this study, a series of processes for the highefficiency recycling and quality improvement of tungsten-based materials have been developed.
4,000원
9.
2022.02
구독 인증기관 무료, 개인회원 유료
Atomic layer deposition (ALD) is a promising technology for the uniform deposition of thin films. ALD is based on a self-limiting mechanism, which can effectively deposit thin films on the surfaces of powders of various sizes. Numerous studies are underway to improve the performance of thermoelectric materials by forming core-shell structures in which various materials are deposited on the powder surface using ALD. Thermoelectric materials are especially relevant as clean energy storage materials due to their ability to interconvert between thermal and electrical energy by the Seebeck and Peltier effects. Herein, we introduce a surface and interface modification strategy based on ALD to control the performance of thermoelectric materials. We also discuss the properties of the interface between various deposition materials and thermoelectric materials.
4,000원
