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    Manufacturing of multi-functional micro parts by two-component metal injection moulding

    , Article International Journal of Advanced Manufacturing Technology ; Volume 33, Issue 1-2 , 2007 , Pages 176-186 ; 02683768 (ISSN) Imgrund, P ; Rota, A ; Petzoldt, F ; Simchi, A ; Sharif University of Technology
    2007
    Abstract
    Several metals and alloys can be used to enhance the mechanical and physical properties of micro parts and components for micromechanical, micro-chemical or sensor applications. Such parts can be produced in series by the powder metallurgical process of micro metal injection moulding (μ-MIM). This paper describes a novel manufacturing route for metallic multi-material micro components, two-component micro metal injection moulding (2C-μ-MIM). Similar to "two-colour" injection moulding of plastics, the process allows the integration of multiple functions in a micro part by simultaneously injecting and joining two materials in one mould. Net-shape parts with solid material interfaces are... 

    An approach for assessment of sintering behavior of co-injection moulded PIM feedstocks by dilatometric analysis

    , Article European Powder Metallurgy Congress and Exhibition, Euro PM 2005, Prague, 2 October 2005 through 5 October 2005 ; Volume 2 , 2005 , Pages 365-370 ; 9781899072187 (ISBN) Simchi, A ; Petzoldt, F ; Hartwig, T ; European Powder Metallurgy Association ; Sharif University of Technology
    European Powder Metallurgy Association (EPMA)  2005
    Abstract
    In the present work, co-sintering of various powder injection molding (PIM) feedstocks including iron, low-alloy steels, high-alloy steels, and hardmetals was investigated. Dilatometric analysis was used to evaluate the sintering behaviour of co-injection moulded feedstocks after debinding. An approach based on the data of dimensional change versus time and temperature was proposed to determine the compatibility of two materials system for the two component powder injection molding (2C-PIM) process. The similarity of sintering behaviour of the twobody parts produced by 2C-PIM was quantified trough definition of a parameter termed as Apparent Co-Sintering Index (ACSI). The results determined... 

    Microinjection moulding of 316L/17-4PH and 316L/Fe powders for fabrication of magnetic-nonmagnetic bimetals

    , Article Journal of Materials Processing Technology ; Volume 200, Issue 1-3 , 2008 , Pages 259-264 ; 09240136 (ISSN) Imgrund, Ph ; Rota, A ; Simchi, A ; Sharif University of Technology
    2008
    Abstract
    In the investigations presented here, the feasibility of producing magnetic-nonmagnetic bimetals made of 316L/17-4PH and 316L/Fe powders by micro-metal injection moulding process (μ-MIM) was studied. In order to achieve sound replication of small specimens with dimensions less than 1 mm, very fine powders with mean particle sizes in the range of 3-7 μm were used. A wax-polymer binder system specially designed for micro-moulding was used to make up the feedstock. The isothermal and non-isothermal sintering behaviour of the moulded components was evaluated under hydrogen atmosphere. The effect of powder-binder-ratio of the feedstock, master alloy addition, and sintering conditions on the... 

    Analysis of the rheological behavior and stability of 316L stainless steel-TiC powder injection molding feedstock

    , Article Materials Science and Engineering A ; Volume 407, Issue 1-2 , 2005 , Pages 105-113 ; 09215093 (ISSN) Khakbiz, M ; Simchi, A ; Bagheri, R ; Sharif University of Technology
    2005
    Abstract
    An experimental rheological study has been performed to evaluate the influence of TiC addition on the rheological behavior and stability of 316L stainless steel powder injection molding (PIM) feedstock. The effects of TiC concentration, solid loading, shear rate and temperature were investigated via capillary rheometer method. The stability of feedstocks was evaluated quantitatively using "instability index", which describes the threshold beyond which the variation of viscosity becomes unacceptable for PIM purposes. The results show that the rheological behavior of PIM feedstocks highly depends on the blend composition. The addition of TiC particles to the stainless steel powder increases... 

    Cosintering of powder injection molding parts made from ultrafine WC-Co and 316L stainless steel powders for fabrication of novel composite structures

    , Article Metallurgical and Materials Transactions A: Physical Metallurgy and Materials Science ; Volume 41, Issue 1, January 2010, Pages 233-241 Simchi, A. (Abdolreza) ; Petzoldt, F ; Sharif University of Technology
    Abstract
    Abstract Sintering response and phase formation during sintering of WC-Co/316L stainless steel composites produced by assembling of powder injection molding (PIM) parts were studied. It is shown that during cosintering a significant mismatch strain (> 4 pct) is developed in the temperature range of 1080° C to 1350° C. This mismatch strain induces biaxial stresses at the interface, leading to interface delamination. Experimental results revealed that sintering at a heating rate of 20 K/min could be used to decrease the  

    A theoretical analysis on resin injection/compression molding

    , Article Key Engineering Materials ; Volume 334-335 I , 2007 , Pages 209-212 ; 10139826 (ISSN) Shojaei, A ; Spah, A ; Sharif University of Technology
    Trans Tech Publications Ltd  2007
    Abstract
    In the present investigation, mold filling process of resin injection/compression molding (RI/CM) is compared with resin transfer molding (RTM) for simple mold geometry. To do this, analytical solutions are obtained for RI/CM in unidirectional flow. Based on the analytical solutions, flow front progression and pressure distribution are compared with RTM at different fiber content. The results indicate that the RI/CM reduces the mold filling time significantly, particularly for composite parts with higher fiber content  

    Plastic injection molding dies using hybrid additively manufactured 420/CX stainless steels: electrochemical considerations

    , Article npj Materials Degradation ; Volume 6, Issue 1 , 2022 ; 23972106 (ISSN) Shahriari, A ; Samei, J ; Sanjari, M ; Jahanbakht, M ; Amirkhiz, B. S ; Mohammadi, M ; Sharif University of Technology
    Nature Publishing Group  2022
    Abstract
    This research focused on the corrosion resistance and microstructure of hybrid additively manufactured (HAM) samples of AISI 420/CX (420/CX SS) stainless steels. Potentiodynamic polarization, electrochemical impedance spectroscopy (EIS), and Mott–Schottky analyses as well as the electrochemical noise (EN) technique were used to evaluate the electrochemical behavior of the as-built and heat-treated HAM parts in NaCl solution. The results showed a more protective passive layer formed on the CX SS side. The distribution of Cr-rich M23C6 carbides in matrix of 420 SS side resulted in a lower corrosion resistance compared to the CX SS side. The noise data analysis confirmed an increase in the... 

    Fabrication and Study of Mechanical Behavior of in Situ Microfibrillar- Reinforced Composites of Polypropylene/Recycled Poly (Ethylene Terephthalate)Toughened with Rubber Particles

    , M.Sc. Thesis Sharif University of Technology Motahari, Tayebeh (Author) ; Bagheri, Reza (Supervisor) ; Alizadeh, Reza (Supervisor)
    Abstract
    The use of polymers is increasing day by day due to low density, reasonable price and ability to produce different products. On the other hand, the accumulation of polymer wastes in nature is one of the environmental concerns in today's world, which is mainly due to the widespread use of polymers in the packaging industry and disposable applications. In order to solve this problem, recycling is recommended as the most appropriate and economical solution. Because in addition to consuming polymer waste, it also saves energy and reduces carbon footprint.Polyethylene terephthalate (PET) is one of the polymeric materials which; It has a special place in the packaging industry and is widely used... 

    Synthesis of One-Dimensional Nanoneedle-Like Arrays Hydroxyapatite for Bone Tissue Engineering Applications

    , M.Sc. Thesis Sharif University of Technology Hassanzadeh Chinijani, Turan (Author) ; Nemati, Ali (Supervisor) ; Khachatourian, Adrine Malek (Supervisor) ; Shokri, Babak (Co-Supervisor)
    Abstract
    Implant primary stability is a crucial component of implant survival. Primary mechanical stability is correlated with implant type, surgical technique, quantity and quality of bone at the recipient site. Since bone integration (BI) significance has been acknowledged, a variety of techniques have been developed to quicken BI and achieve faster fixation. Studies have shown that material type, and many surface properties, including as surface composition, roughness, topography, and energy, have a significant influence during the early stages of bone integration to the implant. In this work, we did synthesis one-dimensional nanoneedle-like arrays of hydroxyapatite using the injection method... 

    Sintering viscosity and sintering stress of nanostructured WC-Co parts prepared by powder injection moulding

    , Article Powder Metallurgy ; Volume 54, Issue 1 , Nov , 2011 , Pages 84-88 ; 00325899 (ISSN) Simchi, A ; Sharif University of Technology
    2011
    Abstract
    The uniaxial viscosity and sintering stress of WC-10Co-0·9VC (wt-%) were obtained by a loading dilatometer as functions of fractional density (0·64<ρ<0·93) and temperature (1084

    Sintering of nanostructured WC-10Co/316L stainless-steel composite parts made by assembling of the PIM parts

    , Article World Powder Metallurgy Congress and Exhibition, World PM 2010, Florence, 10 October 2010 through 14 October 2010 ; Volume 4 , 2010 ; 9781899072194 (ISBN) Simchi, A ; Petzoldt, F ; Hartwig, T ; Veltl, G ; Sharif University of Technology
    European Powder Metallurgy Association (EPMA)  2010
    Abstract
    This paper reports co-sintering response of nanostructured WC-Co/316L stainless steel composite produced by assembling of powder injection molding (PIM) parts. A significant mismatch sintering shrinkage (>4%) was observed in the temperature range of 1080-1350 °C. The reaction between WC and Fe at the contact area resulted in the diffusion of C and Co into the iron lattice and eventually formation of a low-temperature liquid phase that in fact affects the shape control of the PIM parts during sintering. In order to make the co-sintering feasible, a special sintering cycle was developed. The reaction between the cemented carbide and stainless steel was also retarded by developing a special... 

    Sintering of zirconia/430l stainless steel bilayers for co-powder injection moulding

    , Article European International Powder Metallurgy Congress and Exhibition, Euro PM 2008, Mannheim, 29 September 2008 through 1 October 2008 ; Volume 2 , January , 2008 , Pages 299-303 ; 9781899072033 (ISBN) Dourandish, M ; Simchi, A ; Hartwig, T ; Sharif University of Technology
    European Powder Metallurgy Association (EPMA)  2008
    Abstract
    To fabricate ceramic/metal complex-shaped part by co-powder injection moulding process (2KPIM), it is essential to tailor the sintering parameters in order to gain a low mismatch shrinkage, i.e. high sintering compatibility. In the present work, nanocrystalline 3Y-TZP and commercial 430L MIM grade stainless steel powders were co-sintered at various sintering cycles. Isothermal and non-isothermal sintering behavior of the individual and composite layers in argon and vacuum atmospheres were examined. High resolution scanning electron microscopy (HRSEM) coupled with energy dispersive X-ray (EDX) analysis was used to study the bonding interface between the ceramic and metal joints. It is shown... 

    Fabrication of porosity-graded biocompatible structures by 3D printing of Co-Cr-Mo alloy

    , Article European Powder Metallurgy Congress and Exhibition, Euro PM 2007, Toulouse, 15 October 2007 through 17 October 2007 ; Volume 3 , 2007 , Pages 255-260 ; 9781899072293 (ISBN) Dourandish, M ; Simchi, A ; Godlinski, D ; Sharif University of Technology
    European Powder Metallurgy Association (EPMA)  2007
    Abstract
    Manufacturing of complex-shaped bimetals utilizing two-color powder injection molding (2C-PIM) and three-dimensional printing (3DP) processes, which basically involve sintering of a powder/binder mixture, has been attracted a great interest. This article addresses sintering of biocompatible Co-Cr-Mo alloy for manufacturing stepwise porosity-graded composite structures. Such composite structures provide strength at the core and a porous layer for the tissue growth. To evaluate the process, two grades of gas atomized Co-Cr-Mo powder with an average particle size of 19 and 63 μm were used. Isothermal and nonisothermal sintering behavior of the loose powders under hydrogen and argon atmospheres... 

    A numerical study of filling process through multilayer preforms in resin injection/compression molding

    , Article Composites Science and Technology ; Volume 66, Issue 11-12 , 2006 , Pages 1546-1557 ; 02663538 (ISSN) Shojaei, A ; Sharif University of Technology
    2006
    Abstract
    In resin injection/compression molding (RI/CM), a preform often comprises layers of different fiber reinforcements. Each fiber reinforcement has unique through thickness and in-plane permeabilities as well as compressibility, creating a heterogeneous porous medium in the mold cavity. In the present article, numerical simulation is utilized to investigate the filling process of RI/CM in such a heterogeneous porous medium. The filling stage is simulated in a full three-dimensional space by using control volume/finite element method and based upon an appropriate filling algorithm. The flow in the open gap which may be present in the mold cavity is modeled by Darcy's law using an equivalent... 

    Advanced steel powder for direct metal laser sintering

    , Article European Powder Metallurgy Congress and Exhibition, Euro PM 2005, Prague, 2 October 2005 through 5 October 2005 ; Volume 3 , 2005 , Pages 35-40 ; 9781899072187 (ISBN) Petzoldt, F ; Pohl, H ; Simchi, A ; Alcantara, B ; Sharif University of Technology
    European Powder Metallurgy Association (EPMA)  2005
    Abstract
    Recent advances in material issues for Direct Metal Laser Sintering (DMLS) process are presented. The concept is to decrease the powder particle size with the aim of enhancing the sintering kinetics and improving the surface quality of the produced parts. The outcome is particularly suitable for overcoming existing limitations with the rapid tooling, e.g. manufacturing of mould inserts for injection moulding and die casting, by the DMLS process. The powder composition was adapted near to the conventional P/M steels in order to get identical properties with a favourable price. Such novel powder material provides an opportunity to considerably reduce the product development time for P/M... 

    Investigation of rheological behaviour of 316L stainless steel-3 wt-%TiC powder injection moulding feedstock

    , Article Powder Metallurgy ; Volume 48, Issue 2 , 2005 , Pages 144-150 ; 00325899 (ISSN) Khakbiz, M ; Simchi, A ; Bagheri, R ; Sharif University of Technology
    2005
    Abstract
    The rheological behaviour of powder injection moulding feedstock comprising of 316L stainless steel and 3 wt-%TiC powders was studied using a capillary rheometer. The flowability and the sensitivity of viscosity to shear rate and temperature of the feedstock were investigated and compared with those of the binder system and the 316L SS PIM feedstock. The general rheological indexes were examined through relevant equations and the influence of TiC addition on the mouldability of the 316L SS feedstock was determined. It was found that all the feedstocks are basically pseudoplastic but the values of flow behaviour index n are influenced by the TiC addition, the solid volume fraction and the... 

    Mold filling simulation in the injection molding process with openFOAM software for non-isothermal newtonian fluid

    , Article Proceedings of the 2nd IASTED Asian Conference on Modelling, Identification, and Control, AsiaMIC 2012 ; 2012 , Pages 291-296 ; 9780889869110 (ISBN) Fazelpour, F ; Vafaeipour, M ; Etemadi, H ; Dabbaghian, A ; Bardestani, R ; Dehghan, M ; Sharif University of Technology
    2012
    Abstract
    Injection molding is one of the most important manufacturing processes for mass production of complex plastic parts. In this study, mold filling is simulated by using the OpenFOAM software for Non- isothermal Newtonian fluid. The OpenFOAM is an open source software that is used in Computational Fluid Dynamics (CFD) tools. The studied mold shape has a rectangular structure with a gate for Newtonian fluid injection. The simulation carried out at non-isothermal conditions and two-dimensional flow is considered. The velocity, shear stress and temperature changes in different parts of the mold are critically studied. We show that vortex formation plays an important role on changes of shear stress... 

    Cosintering of powder injection molding parts made from ultrafine WC-Co and 316L stainless steel powders for fabrication of novel composite structures

    , Article Metallurgical and Materials Transactions A: Physical Metallurgy and Materials Science ; Volume 41, Issue 1 , 2010 , Pages 233-241 ; 10735623 (ISSN) Simchi, A ; Petzoldt, F ; Sharif University of Technology
    Abstract
    Sintering response and phase formation during sintering of WC-Co/316L stainless steel composites produced by assembling of powder injection molding (PIM) parts were studied. It is shown that during cosintering a significant mismatch strain (>4 pct) is developed in the temperature range of 1080 °C to 1350 °C. This mismatch strain induces biaxial stresses at the interface, leading to interface delamination. Experimental results revealed that sintering at a heating rate of 20 K/min could be used to decrease the mismatch strain to <2 pct. Meanwhile, WC is decomposed at the contact area and the diffusion of C and Co into the iron lattice results in the formation of a liquid and MC and M6C... 

    Study the sintering behavior of nanocrystalline 3Y-TZP/430L stainless-steel composite layers for co-powder injection molding

    , Article Journal of Materials Science ; Volume 44, Issue 5 , 2009 , Pages 1264-1274 ; 00222461 (ISSN) Dourandish, M ; Simchi, A ; Sharif University of Technology
    2009
    Abstract
    Recently, co-powder injection molding process (2C-PIM) has attained considerable interest to fabricate complex-shaped functional materials. The aim of this work is to study the sintering compatibility between nanocrystalline yttria-stabilized zirconia (3Y-TZP) and PIM grade 430L stainless steel (SS) powders, which is the utmost important step in the 2C-PIM process. To evaluate the mismatch strain development during the co-sintering, the isothermal and nonisothermal behaviors of the ceramic and metal powders were studied. Small bilayers of 3Y-TZP/430L were made by a powder metallurgy technique and the feasibility of simultaneous sintering and joining of the composite layer was examined.... 

    Thermoplastic starch/ethylene vinyl alcohol/forsterite nanocomposite as a candidate material for bone tissue engineering

    , Article Materials Science and Engineering C ; Volume 69 , 2016 , Pages 301-310 ; 09284931 (ISSN) Mahdieh, Z ; Bagheri, R ; Eslami, M ; Amiri, M ; Shokrgozar, M. A ; Mehrjoo, M ; Sharif University of Technology
    Elsevier Ltd 
    Abstract
    Recently, biodegradable polymers such as starch based blends have been well renowned in the biomedical field. Studies have considered them suitable for bone scaffolds, bone cements, tissue engineering scaffolds, drug delivery systems and hydrogels. The aim of this study was to synthesize nanocomposite biomaterial consisting a blend of thermoplastic starch and ethylene vinyl alcohol as the polymer matrix, and nano-structured forsterite as the ceramic reinforcing phase for bone tissue engineering applications. Furthermore, vitamin E was applied as a thermal stabilizer during melt compounding. Extrusion and injection molding were incorporated for melt blending and shaping of samples,...