Journal of Powder Materials

A New PIM Joining Process: Hideshi Miura; J Korean Powder Metall Inst. 2002;9(4):203-210.; DOI: https://doi.org/10.4150/KPMI.2002.9.4.203

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Abstract PDF: A new PIM in-process joining technique has been developed for more complicated and functional PIM components by application of the exuded wax from the green compacts during solvent debinding step. At first, various stainless steels and iron compacts with rectangular shape were combined, and the joining behaviors and properties were investigated by shear and tensile test, and microscopic observation. Subsequently, perfect joined three pieces of thin and hollow compacts were obtained for the combination of same and different stainless steels, and it was difficult to join the iron and stainless steel compacts in hydrogen atmosphere because of the different starting temperature of shrinkage. However, pretty good joined iron and stainless steel compacts were obtained by consideration of particle size and vacuum atmosphere. Finally, for the combination of ferro-silicon and austenitic stainless steel compacts, high functionality (magnetic (1.60Tes1a) & non-magnetic) and perfect joint were obtained.

Effect of Relative Density on the Tensile Properties of Powder Injection Molded PH 17-4 Stainless Steel: J Korean Powder Metall Inst. 2002;9(4):211-217.; DOI: https://doi.org/10.4150/KPMI.2002.9.4.211

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Abstract PDF: It is well known that the powder injection molding(PIM) process can overcome the shape limitations of traditional powder compaction, the costs of machining, the productivity limits of isostatic pressing and slip casting, and the defect and tolerance limitations of conventional casting. Increasing demands from industry for not only the dimensional accuracy nut mechanical strength in PIMed parts have had much effort focused on the investigation of mechanical properties of mechanical strength in PIMed parts have had much effort focused on the investigation of mechanical properties of sintered parts formed with high-strength metallic powders. The 17_4 PH 10mum were injection-molded into flat tensile specimens. Sintering of the compacts was carried out at the various temperatures ranging from 900 to 1350°C. Sintering behavior of the compacts and tensile properties of sintered specimens were investigated.

Effect of Debinding and Sintering Conditions on the Tensile Properties of Water-atomized STS 316 L Parts by Powder Injection Molding: J Korean Powder Metall Inst. 2002;9(4):218-226.; DOI: https://doi.org/10.4150/KPMI.2002.9.4.218

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Abstract PDF: The purpose of the present study is to investigate the influence of thermal debinding and sintering conditions on the sintering behavior and mechanical properties of PIMed 316L stainless steel. The water atomized powders were mixed with multi-component wax-base binder system, injection molded into flat tensile specimens. Binder was removed by solvent immersion method followed by thermal debinding, which was carried out in air and hydrogen atmospheres. Sintering was done in hydrogen for 1 hour at temperatures ranging from 1000℃ to 1350℃ The weight loss, residual carbon and oxygen contents were monitored at each stage of debinding and sintering processes. Tensile properties of the sintered specimen varied depending on the densification and the characteristics of the grain boundaries, which includes the pore morphology and residual oxides at the boundaries. The sinter density, tensile strength (UTS), and elongation to fracture of the optimized specimen were 95%, 540 MPa, and 53%, respectively.

Mechanical and Antibacterial Properties of Copper-added Austenitic Stainless Steel (304L) by MIM: Kazuaki Nishiyabu, Yoshikaze Masai, Masashi Ishida, Shigeo Tanaka; J Korean Powder Metall Inst. 2002;9(4):227-234.; DOI: https://doi.org/10.4150/KPMI.2002.9.4.227

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For the austenitic stainless steel (304L) manufactured by metal injection molding(MIM), the effects of copper content and sintering temperature on the mechanical properties, antibacterial activities, corrosion resistance, and electric resistances were investigated. The specimens were prepared by injection molding of the premixed powders of water-atomized 304 L and Cu with poly-acetyl binders. The green compacts were prepared with various copper contents from 0 to 10 wt.% Cu, which were debound thermally at 873 K for 7.2 ks in N_2gas atmosphere and subsequently sintered at various temperatures from 1323 K to 1623 K for 7.2 ks in Ar gas atmosphere. The relative density and tensile strength of the sintered compacts showed the minimum values at 5 and 8 wt.% Cu, respectively. Both the relative density and the tensile strength of the specimen with 10 wt.% Cu sintered at 1373 K showed the highest values, higher than those of copper-free specimen. Antibacterial activities investigated by the plastic film contact printing method for bacilli and the quantitative analysis of copper ion dissolved in water increased as the increase of the copper content to stainless steels. It was also verified by the measurement of pitting potential that the copper addition in 304 L could improve the corrosion resistance. Furthermore the electric conductivity increased with the increase of copper content.

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A Fe-rich Co-free high entropy alloy with excellent mechanical and anti-bacterial properties in cold-rolled state
Nuo Lei, Xuefeng Li, Wenzhuo Li, Guangzeng Zhang, Ran Wei, Tan Wang, Shaojie Wu, Tao Zhang, Shaokang Guan, Bin Kong, Fushan Li, Chen Chen
Materials Letters.2022; 328: 133139. CrossRef
Cu-bearing 316L stainless steel coatings produced by laser melting deposition: Microstructure and corrosion behavior in simulated body fluids
Ying Liu, Junjie Yang, Huan Yang, Kunmao Li, Yating Qiu, Wencai Zhang, Shengfeng Zhou
Surface and Coatings Technology.2021; 428: 127868. CrossRef
Fabrication of Advanced Springs by Micro-Sacrificial Plastic Mold Inserted Metal Powder Injection Molding
Kazuaki NISHIYABU, Kenichi KAKISHITA, Yasuhiro KANOKO, Shigeo TANAKA
Transactions of Japan Society of Spring Engineers.2006; 2006(51): 55. CrossRef

Effect of Residual Impurities on Solid State Sintering of the Powder Injection Molded W-15 wt%Cu Nanocomposite Powder: J Korean Powder Metall Inst. 2002;9(4):235-244.; DOI: https://doi.org/10.4150/KPMI.2002.9.4.235

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Abstract PDF: The effects of residual impurities on solid state sintering of the powder injection molded (PIMed) W-15wt%Cu nanocomposite powder were investigated. The W-Cu nanocomposite powder was produced by the mech-ano-chemical process consisting of high energy ball-milling and hydrogen reduction of W blue powder-cuO mixture. Solid state sintering of the powder compacts was conducted at 1050°C for 2~10 h in hydrogen atmosphere. The den-sification of PIM specimen was slightly larger than that of PM(conventional PM specimen), being due to fast coalescence of aggregate in the PIM. The only difference between PIM and PM specimens was the amount of residual impurities. The carbon as a strong reduction agent effectively reduced residual W oxide in the PIM specimen. The H_2O formed by H_2 reduction of oxide disintegrated W-Cu aggregates during removal process, on the contrary to this, micropore volume rapidly decreased due to coalescence of the disintegrated W-Cu aggregates during evolution of CO.It can be concluded that the higher densification was due to the earlier occurred Cu phase spreading that was induced by effective removal of residual oxides by carbon.

Modeling of Numerical Simulation in Powder Injection Molding Filling Process: J Korean Powder Metall Inst. 2002;9(4):245-250.; DOI: https://doi.org/10.4150/KPMI.2002.9.4.245

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Abstract PDF: In this paper we presented numerical method for the simulation of powder injection molding filling process, which is one of the key processes in powder injection molding. Rheological properties of powder binder mixture such as slip phenomena and yield stress were introduced into the numerical analysis model of powder injection molding filling simulation. Numerical model can be classified into two types. One is 2.5D model which can be introduced to a arbitrary thin geometry and the other is full 3D model which can be applied to a general 3D shape. For 2.5D model we showed the validity of our CAE system with several verification examples. Finally we suggested flow analysis model for 3D powder injection molding filling simulation.

Effect of Surface Roughness of Rheometer on the Slip Phenomenon in the Viscosity Measurement of PIM Feedstock: J Korean Powder Metall Inst. 2002;9(4):251-260.; DOI: https://doi.org/10.4150/KPMI.2002.9.4.251

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Abstract PDF: In the viscosity measurement of PIM feedstock, slip correction methods require a number of experiments and produce a high level of error. In this study, a rotational rheometer with a parallel-discs configuration having different surface roughness was tried to minimize the effect of the slip phenomenon. Disc surface was prepared in 3 different roughness conditions - a smooth and 2 roughened surfaces. Results with the roughened surfaces were compared with the results obtained with a slip correction method. Relationship between powder characteristics such as size and shape and a surface roughness of the disc was examined for feedstock of 4 different powders with a same binder. As results, the effect of the slip phenomenon could be sufficiently minimized on the roughened surface in most cases. However, the effect of the slip phenomenon could not be sufficiently minimized for feedstock of a round-particular-shape powder and in the case of very narrow gap size.

Applications of Numerical Analysis Technology in Powder Injection Molding Process: V. Sunder, M. Randall; J Korean Powder Metall Inst. 2002;9(4):261-266.; DOI: https://doi.org/10.4150/KPMI.2002.9.4.261

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Abstract PDF: CAE technology is an integrated tool including all aspects such as powder, binder system, mixing, injection molding, debinding and sintering. Therefore, CAE technology is considered as one of core technologies for PIM industry in the future. Recently many researchers are developing not only CAE software itself but also application procedures of CAE software. In this study, the applications for CAE technology in PIM industry are presented including feedstock mixing effect, several cases of troubleshooting and optimization procedure.

Micro Metal Powder Injection Molding in the W-Cu System: J Korean Powder Metall Inst. 2002;9(4):267-272.; DOI: https://doi.org/10.4150/KPMI.2002.9.4.267

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Abstract PDF: The production of micro components is one of the leading technologies in the fields of information and communiation, medical and biotechnology, and micro sensor and micro actuator system. Microfabrication (micromachining) techniques such as X-ray lithography, electroforming, micromolding and excimer laser ablation are used for the production of micro components out of silicon, polymer and a limited number of pure metals or binary alloys. However, since the first development of microfabrication technologies there have been demands for the cost-effective replication in large scale series as well as the extended range of available material. One such promising process is micro powder injection molding (PIM), which inherits the advantages of the conventional PIM technology, such as low production cost, shape complexity, applicability to many materials, applicability to many materials, and good tolerance. This paper reports on a fundamental investigation of the application of W-Cu powder to micro metal injection molding (MIM), especially in view of achieving a good filling and a safe removal of a micro mold conducted in the experiment. It is absolutely legitimate and meaningful, at the present state of the technique, to continue developing the micro MIM towards production processes for micro components.

Synthesis and Sintering Behaviors of Nanostructured WC-Co Hardmetal Powders doped Grain Growth Inhibitors of VC/TaC: J Korean Powder Metall Inst. 2002;9(4):273-279.; DOI: https://doi.org/10.4150/KPMI.2002.9.4.273

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In this study, the WC-10 wt.%Co nanopowders doped by grain growth inhibiter were produced by three different methods based on the spray conversion process. Agglomerated powders with homeogenous distribution of alloying elements and with internal particles of about 100-200 nm in diameter were synthesized. The microstructural changes and sintering behavior of hardmetal compacts were compared with doping method and sintering conditions. The microstructure of hardmetals was very sensitive to doping methods of inhibitor. Nanostructured WC-Co hardmetal powder compacts containing TaC/VC doped by chemical method instead of ball-milling shown superior sintering densification, and the microstructure maintained ultrafine scale with rounded WC particles.

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Effect of Si on the Mechanical Properties of WC-Ni Hard Metal
Ki Hwan Jang, Seung Pil Seo, Chan Yeong Kim, Ki Yeol Kim, Gil Geun Lee
Advanced Materials Research.2010; 123-125: 1211. CrossRef

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