SKD11 (ASTM D2) tool steel is a versatile high-carbon, high-chromium, air-hardening tool steel that is characterized by a relatively high attainable hardness and numerous, large, chromium rich alloy carbide in the microstructure. SKD11 tool steel provides an effective combination of wear resistance and toughness, tool performance, price, and a wide variety of product forms. Adding of CNTs increased the performance of mechanical properties more. 1, 3 vol% CNTs was dispersed in SKD11 matrix by mechanical alloying. SKD11 carbon nanocomposite powder was sintered by spark plasma sintering process. FE-SEM, HR-TEM and Raman analysis were carried out for the SKD11 carbon nanocomposites.

Citations

Citations to this article as recorded by  

• Study on Effects of Mold Temperature on the Injection Molded Article
  J.-H. Han, Y.-C. Kim
  Archives of Metallurgy and Materials.2017; 62(2): 1271.     CrossRef

Ti alloys are extensively used in high-technology application because of their strength, oxidation resistance at high temperature. However, Ti alloys tend to be classified very difficult to cut material. In this paper, The powder synthesis, spark plasma sintering (SPS), bulk material properties such as electrical conductivity and thermal conductivity are systematically examined on Ti₂AlN and Ti₂AlC materials having most light-weight and oxidation resistance among the MAX phases. The bulk samples mainly consisted of Ti₂AlN and Ti₂AlC materials with density close to theoretical value were synthesized by a SPS method. Machining characteristics such as machining time, surface quality are analyzed with measurement of voltage and current waveform according to machining condition of micro-electrical discharge machining with micro-channel shape.

Citations

Citations to this article as recorded by  

• Comparative Study on Ablation Characteristics of Ti-6Al-4V Alloy and Ti₂AlN Bulks Irradiated by Femto-second Laser
  Ki Ha Hwang, Hua Feng Wu, Won Suk Choi, Sung Hak Cho, Myungchang Kang
  Journal of the Korean Society of Manufacturing Process Engineers.2019; 18(7): 90.     CrossRef

The optical film for light luminance improvement of back light unit that is used in light emitting diode/liquid crystal display and retro-reflective film is used as luminous sign consist of square and triangular pyramid structure pattern based on V-shape micro prism pattern. In this study, we analyzed machining characteristics of Cu-plated flat mold by shaping with diamond tool. First, cutting conditions were optimized as V-groove machining for the experiment of micro prism structure mold machining with prism pattern shape, cutting force and roughness. Second, the micro prism structure such as square and triangular pyramid pattern were machined by cross machining method with optimizing cutting conditions. Variation of Burr and chip shape were discussed by material properties and machining method.

Citations

Citations to this article as recorded by  

• Investigation of ultra-precision planing process to fabricate high luminance retroreflector based on cutting force and tool vibration analysis
  Ji-Young Jeong, Jun Sae Han, Chung-Mo Kang, Eun-Ji Gwak, Doo-Sun Choi, Tae-Jin Je
  Scientific Reports.2022;[Epub]     CrossRef
• Precision Cutting of the Molds of an Optical Functional Texture Film with a Triangular Pyramid Texture
  Huang Li, Zhilong Xu, Jun Pi, Fei Zhou
  Micromachines.2020; 11(3): 248.     CrossRef

In this study, ternary compound Max Phase Ti₂AlC material was mixed by 3D ball milling as a function of ball milling time. More than 99.5 wt% pure Ti₂AlC was synthesized by using spark plasma sintering method at 1000, 1100, 1200, and 1300°C for 60 min. The material characteristics of synthesized samples were examined with relative density, hardness, and electrical conductivity as a function of sintering temperature. The phase composition of bulk was identified by X-ray diffraction. On the basis of FE-SEM result, a terraced structures which consists of several laminated layers were observed. And Ti₂AlC bulk material obtained a vickers hardness of 5.1 GPa at the sintering temperature of 1100°C.

Citations

Citations to this article as recorded by  

• Synthesis and reaction path of Ti‐Al‐C MAX phases by reaction with Ti‐Al intermetallic compounds and TiC
  Hojun Lee, Si Yeon Kim, Young‐In Lee, Jongmin Byun
  Journal of the American Ceramic Society.2023; 106(12): 7230.     CrossRef

In this study, the effect of the friction stir welding (FSW) was compared with that of the gas tungsten arc welding (GTAW) on the microstructure and microhardness of Cu-Ni alloy weldment. The weldment of 10 mm thickness was fabricated by FSW and GTAW, respectively. Both weldments were compared with each other by optical microstructure, microhardness test and grain size measurement. Results of this study suggest that the microhardness decreased from the base metal (BM) to the heat affected zone (HAZ) and increased at fusion zone (FZ) of GTAW and stir zone (SZ) of FSW. the minimum Hv value of both weldment was obtained at HAZ, respectively, which represents the softening zone, whereas Hv value of FSW weldment was little higher than that of GTAW weldment. These phenomena can be explained by the grain size difference between HAZs of each weldment. Grain size was increased at the HAZ during FSW and GTAW. Because FSW is a solid-state joining process obtaining the lower heat-input generated by rotating shoulder than heat generated in the arc of GTAW.

With the stabilization of Korea’s industrialization, it has become interested in the efficient use of rare metals, climate change and industrial environment and safety etc. It is thus making efforts to implement economic policies that address such issues. Therefore it is necessary to understand the demand, supply and use of metal materials. Since 2010, the Korean government has developed the integrated material flow methodology and has been trying to examine the demand, supply and use of metal materials. In 2013, the Korean government surveyed the material flow of chromium. Material flow analysis and environment emission of chromium were investigated 8 steps; (1) raw material, (2) first process, (3) Intermediate product, (4) End product, (5) Use/accumulation, (6) Collection, (7) Recycling, (8) Disposal. Chromium was used for stainless steel, alloy steel, coated sheets, refractory material and coating materials. Recycling was done mainly in use of stainless steel scrap. To ensure efficient use of chromium, process improvement is required to reduce the scrap in the intermediate product stage. In the process of producing of the products using chromium, it was confirmed that chromium was exposed to the environment. It requires more attention and protection against environment emission of chromium.

In this study, porous stainless steel (STS316L) sintered body was fabricated by powder metallurgy method and its properties such as porosity, compressive yield strength, hardness, and permeability were evaluated. 67.5Fe-17Cr- 13Ni-2.5Mo (wt%) powder was produced by a water atomization. The atomized powder was classified into size with under 45 μm and over 180 μm, and then they were compacted with various pressures and sintered at 1210°C for 1 h in a vacuum atmosphere. The porosities of sintered bodies could be obtained in range of 20~53% by controlling the compaction pressure. Compressive yield strength and hardness were achieved up to 268 MPa and 94 Shore D, respectively. Air permeability was obtained up to 79 l/min·cm₂. As a result, mechanical properties and air permeability of the optimized porous body having a porosity of 25~40% were very superior to that of Al alloy.

Citations

Citations to this article as recorded by  

• Printability and physical properties of iron slag powder composites using material extrusion-based 3D printing
  Hyungjin Kim, Sangkyu Lee
  Journal of Iron and Steel Research International.2021; 28(1): 111.     CrossRef
• Study on Effects of Mold Temperature on the Injection Molded Article
  J.-H. Han, Y.-C. Kim
  Archives of Metallurgy and Materials.2017; 62(2): 1271.     CrossRef

This study investigated the microstructure and wear resistance property of HPHT (high pressure high temperature) sintered PDC (polycrystalline diamond compact) in accordance with initial molding pressure. After quantifying an identical amount of diamond powder, the powder was inserted in top of WC-Co sintered material, and molded under four different pressure conditions (50, 100, 150, 200 kgf/cm²). The obtained diamond compact underwent sintering in high pressure, high temperature conditions. In the case of the 50 kgf/cm2 initial molding pressure condition, cracks were formed on the surface of PDC. On the other hand, PDCs obtained from 100~200 kgf/cm² initial molding pressure conditions showed a meticulous structure. As molding pressure increased, low Co composition within PDC was detected. A wear resistance test was performed on the PDC, and the 200 kgf/cm² condition PDC showed the highest wear resistance property.

Citations

Citations to this article as recorded by  

• Effect of Co Leaching on the Vertical Turning Lathe Wear Properties of Polycrystalline Diamond Compact Manufactured by High Temperature and High Pressure Sintering Process
  Min-Seok Baek, Ji-Won Kim, Bae-Gun Park, Hee-Sub Park, Kee-Ahn Lee
  Korean Journal of Metals and Materials.2020; 58(7): 480.     CrossRef
• Enhanced wear resistivity of a Zr-based bulk metallic glass processed by high-pressure torsion under reciprocating dry conditions
  Soo-Hyun Joo, Dong-Hai Pi, Jing Guo, Hidemi Kato, Sunghak Lee, Hyoung Seop Kim
  Metals and Materials International.2016; 22(3): 383.     CrossRef

Fe-TiC composite powders are fabricated by planetary ball mill processing. Two kinds of powder mixtures are prepared from the starting materials of (a) (Fe, TiC) powders and (b) (Fe, TiH₂, Carbon) powders. Milling speed (300, 500 and 700 rpm) and time (1, 2, and 3 h) are varied. For (Fe, TiH₂, Carbon) powders, an in situ reaction synthesis of TiC after the planetary ball mill processing is added to obtain a homogeneous distribution of ultrafine TiC particulates in Fe matrix. Powder characteristics such as particle size, size distribution, shape, and mixing homogeneity are investigated. In case of (Fe, TiC) powder many coarse TiC particulates with size of several μm are unevenly distributed in Fe-matrix. The composite powder prepared from (Fe, TiH₂, C) powder mixture showed a homogeneous dispersion of ulatrafine TiC particulates.

Citations

Citations to this article as recorded by  

• Abrasive Wear Performance of Spherical Hierarchical Structured TiC/High-Manganese Steel Composites
  Tao He, Shengnian Zhao, Dehong Lu, Yehua Jiang, Mojin Zhou
  Materials.2024; 18(1): 130.     CrossRef
• Effect of TiC particle size on high temperature oxidation behavior of TiC reinforced stainless steel
  Yeong-Hwan Lee, Sungmin Ko, Hyeonjae Park, Donghyun Lee, Sangmin Shin, Ilguk Jo, Sang-Bok Lee, Sang-Kwan Lee, Yangdo Kim, Seungchan Cho
  Applied Surface Science.2019; 480: 951.     CrossRef
• Effect of TiC addition on surface oxidation behavior of SKD11 tool steel composites
  Seungchan Cho, Ilguk Jo, Heebong Kim, Hyuk-Tae Kwon, Sang-Kwan Lee, Sang-Bok Lee
  Applied Surface Science.2017; 415: 155.     CrossRef
• Sintering of Fe-30 wt% TiC Composite Powders Fabricated from (Fe, TiH2, C) Powder Mixture
  Byunghoon Lee, Ji Soon Kim
  Journal of Korean Powder Metallurgy Institute.2015; 22(5): 356.     CrossRef
• Pressureless Sintering and Spark-Plasma Sintering of Fe-TiC Composite Powders
  B. H. Lee, S. W. Bae, S. W. Bae, H. X. Khoa, J. S. Kim
  journal of Korean Powder Metallurgy Institute.1970; 22(4): 283.     CrossRef

Vertically oriented nickel nanowire arrays with a different diameter and length are synthesized in porous anodic aluminium oxide templates by an electrodeposition method. The pore diameters of the templates are adjusted by controlling the anodization conditions and then they are utilized as templates to grow nickel nanowire arrays. The nickel nanowires have the average diameters of approximately 25 and 260 nm and the crystal structure, morphology and microstructure of the nanowires are systematically investigated using XRD, FE-SEM and TEM analysis. The nickel nanowire arrays show a magnetic anisotropy with the easy axis parallel to the nanowires and the coercivity and remanence enhance with decreasing a wire diameter and increasing a wire length.