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Progress in Net-shaped PM (Powder Metallurgical) Parts

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A special issue of Materials (ISSN 1996-1944). This special issue belongs to the section "Manufacturing Processes and Systems".

Deadline for manuscript submissions: closed (31 July 2013) | Viewed by 46970

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Special Issue Editor

Prof. Dr. Jai-Sung Lee

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Guest Editor

Department of Materials Science and Chemical Engineering, Hanyang University ERICA, Ansan 15588, Republic of Korea
Interests: powder metallurgy; metal nanopowder fabrication; full density sintering; net-shaping process; powder injection molding; micro PM component; microstructure and interface control

Special Issue Information

Dear Colleagues,

Powder metallurgy (P/M) offers opportunity in making net shaped parts with competitive cost and strength for parts produced by stamping, machining, casting or forging. The versatility of this material shaping technology and its unique capabilities in fabricating extremely high performance and complex shaped components has developed over the past few decades. In particular, net-shaping process such as micro-powder injection molding is being explored as the optimal PM net-shaping technology for fabricating complex type PM micro-components. However, such net-shaping technology requires more critical processes to achieve shrinkage uniformity and sound microstructure with deceasing size of a part. To overcome these issues, great efforts have been paid to design optimal feedstock using fine powders including nanoscale powders. However, there are some restrictions to the usage of of fine powders because of the difficulties in entire PM processes from mixing, shaping to full-density sintering.

In this special issue, novel trends related to processing as net-shaping and consolidation, and powder material design suitable for the production of advanced net-shaped PM parts as well as related properties are highlighted and discussed.

Prof. Dr. Jai-Sung Lee
Guest Editor

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Keywords

near net- or net-shape technology and its applications
powder material design and fabrication
densification and consolidation mechanisms
microstructure and related material properties

Published Papers (5 papers)

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Research

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895 KiB

Open AccessArticle

Development of Metal Plate with Internal Structure Utilizing the Metal Injection Molding (MIM) Process

by Kwangho Shin, Youngmoo Heo, Hyungpil Park, Sungho Chang and Byungohk Rhee

Materials 2013, 6(12), 5878-5892; https://doi.org/10.3390/ma6125878 - 12 Dec 2013

Cited by 6 | Viewed by 7008

Abstract

In this study, we focus on making a double-sided metal plate with an internal structure, such as honeycomb. The stainless steel powder was used in the metal injection molding (MIM) process. The preliminary studies were carried out for the measurement of the viscosity of the stainless steel feedstock and for the prediction of the filling behavior through Computer Aided Engineering (CAE) simulation. PE (high density polyethylene (HDPE) and low density polyethylene (LDPE)) and polypropylene (PP) resins were used to make the sacrificed insert with a honeycomb structure using a plastic injection molding process. Additionally, these sacrificed insert parts were inserted in the metal injection mold, and the metal injection molding process was carried out to build a green part with rectangular shape. Subsequently, debinding and sintering processes were adopted to remove the sacrificed polymer insert. The insert had a suitable rigidity that was able to endure the filling pressure. The core shift analysis was conducted to predict the deformation of the insert part. The 17-4PH feedstock with a low melting temperature was applied. The glass transition temperature of the sacrificed polymer insert would be of a high grade, and this insert should be maintained during the MIM process. Through these processes, a square metal plate with a honeycomb structure was made. Full article

(This article belongs to the Special Issue Progress in Net-shaped PM (Powder Metallurgical) Parts)

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1017 KiB

Open AccessArticle

Localized Overheating Phenomena and Optimization of Spark-Plasma Sintering Tooling Design

by Diletta Giuntini, Eugene A. Olevsky, Cristina Garcia-Cardona, Andrey L. Maximenko, Maria S. Yurlova, Christopher D. Haines, Darold G. Martin and Deepak Kapoor

Materials 2013, 6(7), 2612-2632; https://doi.org/10.3390/ma6072612 - 25 Jun 2013

Cited by 59 | Viewed by 8195

Abstract

The present paper shows the application of a three-dimensional coupled electrical, thermal, mechanical finite element macro-scale modeling framework of Spark Plasma Sintering (SPS) to an actual problem of SPS tooling overheating, encountered during SPS experimentation. The overheating phenomenon is analyzed by varying the geometry of the tooling that exhibits the problem, namely by modeling various tooling configurations involving sequences of disk-shape spacers with step-wise increasing radii. The analysis is conducted by means of finite element simulations, intended to obtain temperature spatial distributions in the graphite press-forms, including punches, dies, and spacers; to identify the temperature peaks and their respective timing, and to propose a more suitable SPS tooling configuration with the avoidance of the overheating as a final aim. Electric currents-based Joule heating, heat transfer, mechanical conditions, and densification are imbedded in the model, utilizing the finite-element software COMSOL™, which possesses a distinguishing ability of coupling multiple physics. Thereby the implementation of a finite element method applicable to a broad range of SPS procedures is carried out, together with the more specific optimization of the SPS tooling design when dealing with excessive heating phenomena. Full article

(This article belongs to the Special Issue Progress in Net-shaped PM (Powder Metallurgical) Parts)

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Review

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2913 KiB

Open AccessReview

Outside Mainstream Electronic Databases: Review of Studies Conducted in the USSR and Post-Soviet Countries on Electric Current-Assisted Consolidation of Powder Materials

by Eugene A. Olevsky, Elena V. Aleksandrova, Alexandra M. Ilyina, Dina V. Dudina, Alexander N. Novoselov, Kirill Y. Pelve and Eugene G. Grigoryev

Materials 2013, 6(10), 4375-4440; https://doi.org/10.3390/ma6104375 - 30 Sep 2013

Cited by 34 | Viewed by 9806

Abstract

This paper reviews research articles published in the former USSR and post-soviet countries on the consolidation of powder materials using electric current that passes through the powder sample and/or a conductive die-punch set-up. Having been published in Russian, many of the reviewed papers are not included in the mainstream electronic databases of the scientific articles and thus are not known to the scientific community. The present review is aimed at filling this information gap. In the paper, the electric current-assisted sintering techniques based on high- and low-voltage approaches are presented. The main results of the theoretical modeling of the processes of electromagnetic field-assisted consolidation of powder materials are discussed. Sintering experiments and related equipment are described and the major experimental results are analyzed. Sintering conditions required to achieve the desired properties of the sintered materials are provided for selected material systems. Tooling materials used in the electric current-assisted consolidation set-ups are also described. Full article

(This article belongs to the Special Issue Progress in Net-shaped PM (Powder Metallurgical) Parts)

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1719 KiB

Open AccessReview

Consolidation of Hierarchy-Structured Nanopowder Agglomerates and Its Application to Net-Shaping Nanopowder Materials

by Jai-Sung Lee, Joon-Phil Choi and Geon-Yong Lee

Materials 2013, 6(9), 4046-4063; https://doi.org/10.3390/ma6094046 - 16 Sep 2013

Cited by 27 | Viewed by 7715

Abstract

This paper provides an overview on our recent investigations on the consolidation of hierarchy-structured nanopowder agglomerates and related applications to net-shaping nanopowder materials. Understanding the nanopowder agglomerate sintering (NAS) process is essential to processing of net-shaped nanopowder materials and components with small and complex shape. The key concept of the NAS process is to enhance material transport through controlling the powder interface volume of nanopowder agglomerates. Based upon this concept, we have suggested a new idea of full density processing for fabricating micro-powder injection molded part using metal nanopowder agglomerates produced by hydrogen reduction of metal oxide powders. Studies on the full density sintering of die compacted- and powder injection molded iron base nano-agglomerate powders are introduced and discussed in terms of densification process and microstructure. Full article

(This article belongs to the Special Issue Progress in Net-shaped PM (Powder Metallurgical) Parts)

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872 KiB

Open AccessReview

Progress in Titanium Metal Powder Injection Molding

by Randall M. German

Materials 2013, 6(8), 3641-3662; https://doi.org/10.3390/ma6083641 - 20 Aug 2013

Cited by 146 | Viewed by 13361

Abstract

Metal powder injection molding is a shaping technology that has achieved solid scientific underpinnings. It is from this science base that recent progress has occurred in titanium powder injection molding. Much of the progress awaited development of the required particles with specific characteristics of particle size, particle shape, and purity. The production of titanium components by injection molding is stabilized by a good understanding of how each process variable impacts density and impurity level. As summarized here, recent research has isolated the four critical success factors in titanium metal powder injection molding (Ti-MIM) that must be simultaneously satisfied—density, purity, alloying, and microstructure. The critical role of density and impurities, and the inability to remove impurities with sintering, compels attention to starting Ti-MIM with high quality alloy powders. This article addresses the four critical success factors to rationalize Ti-MIM processing conditions to the requirements for demanding applications in aerospace and medical fields. Based on extensive research, a baseline process is identified and reported here with attention to linking mechanical properties to the four critical success factors. Full article

(This article belongs to the Special Issue Progress in Net-shaped PM (Powder Metallurgical) Parts)

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