Journal of Powder Materials

[Korean]
Investigation for Microstructure and Hardness of Welded Zone of Cu-Ni Alloy using W92-Ni-Fe Sintering Tool: Tae-Jin Yoon, Sang-Won Park, Myung-Chang Kang, Joong-Suk Noh, Sung-Wook Chung, Chung-Yun Kang; J Korean Powder Metall Inst. 2015;22(3):181-186. Published online June 1, 2015; DOI: https://doi.org/10.4150/KPMI.2015.22.3.181

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Abstract PDF: 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.

[Korean]
Micro-EDM Feasibility and Material Properties of Hybrid Ti₂AlC Ceramic Bulk Materials: Guk-Hyun Jeong, Kwang-Ho Kim, Myung-Chang Kang; J Korean Powder Metall Inst. 2014;21(4):301-306. Published online August 1, 2014; DOI: https://doi.org/10.4150/KPMI.2014.21.4.301

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Titanium alloys are extensively used in high-temperature applications due to their excellent high strength and corrosion resistance properties. However, titanium alloys are problematic because they tend to be extremely difficult-tocut material. In this paper, the powder synthesis, spark plasma sintering (SPS), bulk material characteristics and machinability test of hybrid Ti₂AlC ceramic bulk materials were systematically examined. The bulk samples mainly consisted of Ti₂AlC materials with density close to theoretical value were synthesized by a SPS method. Random orientation and good crystallization of the Ti₂AlC was observed at 1100°C for 10 min under SPS sintering conditions. Scanning electron microscopy results indicated a homogeneous distribution and nano-laminated structure of Ti₂AlC MAX phase. The hardness and electrical conductivity of Ti₂AlC were higher than that of Ti 6242 alloy at sintering temperature of 1000°C~1100°C. Consequently, the machinability of the hybrid Ti₂AlC bulk materials is better than that of the Ti 6242 alloy for micro-EDM process of micro-hole shape workpiece.

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Evaluation of Material Characteristics with Sintering Temperature in Ti2AlC MAX Phase Material using Spark Plasma Sintering Method
Chang-Hun Lee, Gyung Rae Baek, Hee Sang Jung, Young-Keun Jeong, Myung Chang Kang
Journal of Korean Powder Metallurgy Institute.2015; 22(3): 175. CrossRef

[Korean]
Comparison of Micro Trench Machining Characteristics with Nonferrous Metal and Polymer using Single Diamond Cutting Tool: Hwan-Jin Choi, Eun-Chae Jeon, Doo-Sun Choi, Tae-Jin Je, Myung-Chang Kang; J Korean Powder Metall Inst. 2013;20(5):355-358.; DOI: https://doi.org/10.4150/KPMI.2013.20.5.355

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Abstract PDF: Micro trench structures are applied in gratings, security films, wave guides, and micro fluidics. These micro trench structures have commonly been fabricated by micro electro mechanical system (MEMS) process. However, if the micro trench structures are machined using a diamond tool on large area plate, the resulting process is the most effective manufacturing method for products with high quality surfaces and outstanding optical characteristics. A nonferrous metal has been used as a workpiece; recently, and hybrid materials, including polymer materials, have been applied to mold for display fields. Thus, the machining characteristics of polymer materials should be analyzed. In this study, machining characteristics were compared between nonferrous metals and polymer materials using single crystal diamond (SCD) tools; the use of such materials is increasing in machining applications. The experiment was conducted using a square type diamond tool and a shaper machine tool with cutting depths of 2, 4, 6 and 10 µm and a cutting speed of 200 mm/s. The machined surfaces, chip, and cutting force were compared through the experiment.

[Korean]
Development of Vibration Assisted Hybrid Femtosecond Laser Ultra-precision Machining System and Cu-Zn alloy Application: Won-Suk Choi, Ji-Wook Yoon, Sung-Hak Cho, Myung-Chang Kang; J Korean Powder Metall Inst. 2013;20(4):308-312.; DOI: https://doi.org/10.4150/KPMI.2013.20.4.308

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Abstract PDF: In this paper, we describe experiment results using a vibration assisted hybrid femtosecond laser (lambda:795 nm) ultra-precision machining system. The hybrid system we have developed is possible that optical focal point of the femtosecond laser constantly and frequently within the range of PZT(piezoactuator) vibrator working distance. Using the hybrid system, We have experimented on brass and studied about differences of result of hole aspect ratio compare to general experiment setup of femtosecond laser system. Aspect ratio of a micro hole on brass is increased as 54% with 100 Hz vibration frequency and surface roughness of the side wall also improved compare to non-vibration.

[Korean]
Effects of Welding Conditions and Material Arrangement on Tensile Properties of Friction Stir Lap Welded of Dissimilar Al Alloy, A5J32/A5052: Tae-Jin Yoon, Myung-Chang Kang, Chung-Yun Kang; J Korean Powder Metall Inst. 2013;20(4):302-307.; DOI: https://doi.org/10.4150/KPMI.2013.20.4.302

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A5J32-T4 and A5052-H32 dissimilar aluminum alloy plates with thickness of 1.6 and 1.5 mm were welded by friction stir lap welding (FSLW). The FSLW were studied using different probe length tool and various welding conditions which is rotation speed of 1000, 1500 rpm and welding speed of 100 to 600 mm/min and material arrangement, respectively. The effects of plunge depth of tool and welding conditions on tensile properties and weld nugget formation. The results showed that three type nugget shapes such as hooking, void, sound have been observed with revolutionary pitch. This plunge depth and material arrangement were found to effect on the void and hooking formation, which in turn significantly influenced the mechanical properties. The maximum joint efficiency of the FSLWed plates was about 90% compared to base metal, A5052-H32 when the A5052-H32 was positioned upper plate and plunge depth was positioned at near interface between upper and lower plates.

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Effects of Rotation Speed on Microstructure and Mechanical Properties in Ti/Cu Dissimilar Friction Stir Welding
Yong-Jae Lee, Won-Ki Jung, Se-Eun Shin, Dong-Geun Lee
Korean Journal of Metals and Materials.2021; 59(12): 886. CrossRef
Investigation for Microstructure and Hardness of Welded Zone of Cu-Ni Alloy using W92-Ni-Fe Sintering Tool
Tae-Jin Yoon, Sang-Won Park, Myung-Chang Kang, Joong-Suk Noh, Sung-Wook Chung, Chung-Yun Kang
Journal of Korean Powder Metallurgy Institute.2015; 22(3): 181. CrossRef

[Korean]
Comparison of Machinability Between PCD Tool and SCD Tool for Large Area Mirror Surface Machining Using Multi-tool by Planer: Chang-Eui Kim, Hwan-Jin Choi, Eun-Chae Jeon, Tae-Jin Je, Myung-Chang Kang; J Korean Powder Metall Inst. 2013;20(4):297-301.; DOI: https://doi.org/10.4150/KPMI.2013.20.4.297

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Mirror surface machining for large area flattening in the display field has a problem such as a tool wear and a increase in machining time due to large area machining. It should be studied to decrease machining time and tool wear. In this paper, multi-tool machining method using a PCD tool and a SCD tool was applied in order to decrease machining time and tool wear. Machining characteristics (cutting force, machined surface and surface roughness) of PCD tool and SCD tool were evaluated in order to apply PCD tool to flattening machining. Based on basic experiments, the PCD/SCD multi-tool method and the SCD single-tool method were compared through surface roughness and machining time for appllying large area mold machining.

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Machining Characteristics of Micro Structure using Single-Crystal Diamond Tool on Cu-plated Mold
Chang-Eui Kim, Eun-chae Jeon, Tae-Jin Je, Myung Chang Kang
Journal of Korean Powder Metallurgy Institute.2015; 22(3): 169. CrossRef
Analysis Of Drilling Of A Metal Plate With Pilot Hole
K.S. Kim
Archives of Metallurgy and Materials.2015; 60(2): 1307. CrossRef

[Korean]
Machinability Evaluation of Hybrid Ti₂ Ceramic Composites with Conductivity in Micro Electrical Discharge Drilling Operation: Jae-Young Heo, Young-Keun Jeong, Myung-Chang Kang, Ahmed Busnaina; J Korean Powder Metall Inst. 2013;20(4):285-290.; DOI: https://doi.org/10.4150/KPMI.2013.20.4.285

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Ti_2AlN composites are a laminated compounds that posses unique combination of typical ceramic properties and typical metallic(Ti alloy) properties. In this paper, the powder synthesis, SPS sintering, composite characteristics and machinability evaluation were systematically conducted. The random orientation characteristics and good crystallization of the Ti_2AlN phase are observed. The electrical and thermal conductivity of Ti_2AlN is higher than that of Ti6242 alloy. A machining test was carried out to compare the effect of material properties on micro electrical discharge drilling for Ti_2AlN composite and Ti6242 alloy. Also, mixture table as a kind of tables of orthogonal arrays was used to know how parameter is main effective at experimental design. Consequently, hybrid Ti_2AlN ceramic composites showed good machining time and electrode wear shape under micro ED-drilling process. This conclusion proves the feasibility in the industrial applications.

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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
Analysis Of Drilling Of A Metal Plate With Pilot Hole
K.S. Kim
Archives of Metallurgy and Materials.2015; 60(2): 1307. CrossRef

[Korean]
Coatings Properties and Efficiency Performance of Cr-DLC Films Deposited by Hybrid Linear Ion Source for Hydraulic Gear Pump: Sun-Yong Cha, Wang-Ryeol Kim, Min-Suk Park, Se-Hun Kwon, Won-Sub Chung, Myung-Chang Kang; J Korean Powder Metall Inst. 2010;17(6):456-463.; DOI: https://doi.org/10.4150/KPMI.2010.17.6.456

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Abstract PDF: This paper describes the results of the application of Cr-Diamond-like carbon (DLC) films for efficiency improvement through surface modification of spur gear parts in the hydraulic gear pump. Cr-DLC films were successfully deposited on SCM 415 substrates by a hybrid coating process using linear ion source (LIS) and magnetron sputtering method. The characteristics of the films were systematically investigated using FE-SEM, nano-indentation, sliding tester and AFM instrument. The microstructure of Cr-DLC films turned into the dense and fine grains with relatively preferred orientation. The thickness formed in our Cr buffer layer and DLC coating layer were obtained the 487 nm and 1.14;µm. The average friction coefficient of Cr-DLC films considerably decreased to 0.15 for 0.50 of uncoated SCM415 material. The hardness and surface roughness of Cr-DLC films were measured 20 GPa and 10.76 nm, respectively. And then, efficiency tests were performed on the hydraulic gear pump to investigate the efficiency performance of the Cr-DLC coated spur gear. The experimental results show that the volumetric and mechanical efficiency of hydraulic gear pump using the Cr-DLC spur gear were improved up to 2~5% and better efficiency improvement could be attributed to its excellent microstructure, higher hardness, and lower friction coefficient. This conclusion proves the feasibility in the efficiency improvement of hydraulic gear pump for industrial applications.

[Korean]
The Effect of Electrical Characteristics and Electrode Shape on Alignment of Multi-walled Carbon Nanotubes: Se-Hun Kwon, Young-Keun Jeong, Chang-Sik Jung, Myung-Chang Kang, Hyung-Woo Lee; J Korean Powder Metall Inst. 2010;17(4):326-335.; DOI: https://doi.org/10.4150/KPMI.2010.17.4.326

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Abstract PDF: In this paper, the effect of electrical characteristics and electrode shape on the alignment and attachment of multi-walled carbon nanotubes (MWNTs) has been studied. The attraction and alignment of MWNTs between the gaps has been investigated by applying electric field which is called electrophoresis and dielectrophoresis. According to the frequency of electric field, positive or negative dielectrophoretic force can be determined. The concentration of MWNTs solution was 5;µg/ml, and a droplet of 1.0sim1.5;µl was dropped between two electrodes. Through the repeated experiments, the optimal electrical conditions for aligning and attaching MWNTs in the desired places were obtained. Since the frequency range of 100 kHz~10 MHz generated positive dielectrophoretic force, MWNTs were attracted and aligned between the gaps with this frequency range. For generating enough force to attract MWNTs, the appropriate voltage range was 0.3sim1.3;V_rms/µm. Furthermore, the effect of electrode shape on the alignment of MWNTs was investigated. A single MWNT attachment was accomplished on the round shaped with 70% yield.

[Korean]
Characteristics of Micro EDM using Wire Electrical Discharge Grinding for Al₂O₃/CNTs Hybrid Materials: Hyun-Seok Tak, Jong-Hun Kim, Han-Suk Lim, Choon-Tae Lee, Young-Keun Jeong, Myung-Chang Kang; J Korean Powder Metall Inst. 2010;17(4):319-325.; DOI: https://doi.org/10.4150/KPMI.2010.17.4.319

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Electrical discharge machining (EDM) is an attractive machining technique but it requires electrically conductive ceramic materials. In this study, Alumina matrix composites reinforced with CNTs were fabricated through CNT purification, mixing, compaction and spark plasma sintering (SPS) processes. Al_2O_3 nanocomposites with the different CNT concentrations were synthesized. The mechanical and electrical characteristics of Al_2O_3/CNTs composites were examined in order to apply the materials to the EDM process. In addition, micro-EDM using wire electrical discharge grinding (WEDG) was conducted under the various EDM parameters to investigate the machining characteristics of machined hole by Field Emission Scanning Electron Microscope (FE-SEM). The results show that Al_2O_3/CNTs 10%Vol. was more suitable than the other materials because high conductivity and large discharge energy caused violent sparks resulting in bad machining accuracy and surface quality.

Citations

Citations to this article as recorded by

Development of Vibration Assisted Hybrid Femtosecond Laser Ultra-precision Machining System and Cu-Zn alloy Application
Won-Suk Choi, Ji-Wook Yoon, Sung-Hak Cho, Myung-Chang Kang
Journal of Korean Powder Metallurgy Institute.2013; 20(4): 308. CrossRef
Machinability Evaluation of Hybrid Ti2Ceramic Composites with Conductivity in Micro Electrical Discharge Drilling Operation
Jae-Young Heo, Young-Keun Jeong, Myung-Chang Kang, Ahmed Busnaina
Journal of Korean Powder Metallurgy Institute.2013; 20(4): 285. CrossRef

[Korean]
Performance Evaluation on the Endmill of High Speed Machining for Selection of Tungsten Carbide (WC-Co) Material: Dong-Hee Kwon, Jeong-Suk Kim, Min-Wook Kim, Young-Keun Jeong, Myung-Chang Kang; J Korean Powder Metall Inst. 2008;15(5):359-364.; DOI: https://doi.org/10.4150/KPMI.2008.15.5.359

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To satisfy the demand of higher cutting performance, mechanical properties with tungsten carbide (WC-Co) tool materials were investigated. Hardness and transverse rupture strength with WC grain size, Co content and density were measured. Compared to H, K, and S manufacture maker as tungsten carbide (WC-Co) tool materials were used for high-speed machining of end-milling operation. The three tungsten carbide (WC-Co) tool materials were evaluated by cutting of STD 11 cold-worked die steel (HRC25) under high-speed cutting condition. Also, tool life was obtained from measuring flank wear by CCD wear measuring system. Tool dynamometer was used to measure cutting force. The cutting force and tool wear are discussed along with tool material characteristics. Consequently, the end-mill of K, H manufacture maker showed higher wear-resistance due to its higher hardness, while the S maker endmill tool showed better performance for high metal removal.

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Tool Wear Characteristics of Tungsten Carbide Implanted with Plasma Source Nitrogen Ions in High-speed Machining
Sung-Ho Park, Duck Hyun Wang
Journal of the Korean Society of Manufacturing Process Engineers.2022; 21(5): 34. CrossRef

[Korean]
Research and Development of Hybrid Materials: Young-Keun Jeong, Myung-Chang Kang, Kwang-Ho Kim; J Korean Powder Metall Inst. 2007;14(1):1-7.; DOI: https://doi.org/10.4150/KPMI.2007.14.1.001

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Effect of Casting Speed on Microstructure and Mechanical Properties of Al-Mg-Si/Al Hybrid Material by Duo-Casting
Sung Jin Park, Jun-Young Suh, Hee-Kwon Lee, Si Young Chang
Korean Journal of Materials Research.2020; 30(3): 111. CrossRef
Fabrication of Ultra Fine Grained Molybdenum and Mechanical Properties
Se-Hoon Kim, Young-Ik Seo, Dae-Gun Kim, Myung-Jin Suk, Young-Do Kim
Journal of Korean Powder Metallurgy Institute.2010; 17(3): 235. CrossRef

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