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Evaluation of Repetitively Used Feedstock for Powder Injection Molding

Jang Jin Man

Archives of Metallurgy and Materials

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2022

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Vol. 67, iss. 4

1511--1515

EN

This study investigates the effects of repetitive injection molding on the properties of feedstock using the AISI 4140 feedstock. The properties of feedstock are evaluated from the mixing homogeneity of powder and binder, rheological properties, and dimensional accuracy of parts sintered. The feedstock after the 1st injection molding shows a better homogeneity than as-received feedstock due to re-mixing effects between the screw and barrel during the injection molding process. As the number of recycling numbers increases, the homogeneity, viscosities ad shrinkage ratio of recycled feedstocks show slight differences with those of the as-received feedstock until the 6th molding injection. However, some rheological parameters like the moldability index sharply increased up to the 4th injection but shows a tendency to decrease thereafter.

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Formowanie wtryskowe proszku

Matula Grzegorz

LAB Laboratoria, Aparatura, Badania

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2020

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R. 25, nr 2

33--37

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Master Curve Model for Characterization of Decomposition and Densification Behavior of PbAlNbO3-PbZrTiO3 Ceramics

Han Jun Sae, Park Jae Man, Park Seong Jin

Archives of Metallurgy and Materials

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2020

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Vol. 65, iss. 3

1099--1103

EN

In this study, decomposition and densification behavior of PbAlNbO3-PbZrTiO3 (PAN-PZT) ceramics were characterized for powder injection molding process. Thermal gravity analysis and in-situ dilatometer experiment were carried out to construct master curve. Based on master curve model approach, one-combined master debinding curve (MDC) and master sintering curve (MSC) were constructed for piezoelectric PAN-PZT ceramics. Derived curves matched well with the experimental data. Process optimization and material development will be conducted based on characterization of master curve parameters.

4

Development of Hydrophobic Surgical Forceps using Powder Injection Molding and Surface Treatment

Park D. Y., Park B. R., Gal C. W., Lin D., Han J. S., Jeong M.-S., Bollina R., Hwang W., Park S. J.

Archives of Metallurgy and Materials

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2018

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Vol. 63, iss. 1

473--480

EN

Hydrophobic surgical forceps of end-effectors for laparoscopic operations or minimally invasive surgery were developed through powder injection molding (PIM) and surface treatment. Processing conditions for mixing, debinding, and sintering were investigated to produce defect-free components. An optimum solid loading was determined by torque rheometry experiments. The optimized processing conditions for debinding and sintering were designed through the measurement of weight loss and shrinkage behavior by thermogravimetric analysis and dilatometry experiments. After producing the surgical forceps based on the optimized processing conditions via PIM, surface treatment was carried out to generate the hydrophobic structure on the surface.

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An Analysis of Rheological Properties of Inconel 625 Superalloy Feedstocks Formulated with Backbone Binder Polypropylene System for Powder Injection Molding

Gökmen U., Türker M.

Archives of Metallurgy and Materials

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2017

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Vol. 62, iss. 4

1937--1944

EN

Binder formula is one of the most significant factors which has a considerable influence on powder injection molding (PIM) processes. In the study, rheological behaviors and properties of different binder systems containing PIM feedstocks, Inconel 625 powder commonly used in space industry, were investigated. The feedstocks were prepared 59%-69% (volume) powder loading ratios with three diversified binder systems by use of Polypropylene as backbone binder. The average particle size of the Inconel 625 powder used was 12.86 microns. Components used in the binder were mixed for 30 minutes as dry in three dimensional mixing to prepare binder systems. Rheological features of the feedstock were characterized by using a capillary rheometer. Viscosities of the feedstocks were calculated within the range of 37.996-1900 Pa.s based on the shear rate, shear stress, binder formula and temperature. “n” parameters for PIM feedstocks were determined to be less than 1. Influences of temperature on the viscosities of the feedstocks were also studied and “Ea” under various shear stresses were determined within the range of 24.41-70.89 kJ/mol.

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Porous material produced by ceramic injection molding

Matula G., Krzysteczko J.

Journal of Achievements in Materials and Manufacturing Engineering

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2015

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Vol. 71, nr 1

14--21

EN

Purpose: The aim of this research is presented the process of alumina injection molding with a multicomponent binder system based on polymer (polypropylene – PP/polyethylene- HDPE), paraffin wax (PW) and stearic acid (SA). Debinding and sintering process was also studied. Design/methodology/approach: The volume fractions of powder in the feedstocks were 50%vol and the volume of polypropylene and polyethylene were changed from 0-22%vol. The concentrations of SA were kept at 6%vol. The feedstock was heated to melt the binder and injected into a mold. Debinding process was carried out after injection step. The organic part was removed through combination of solvent and thermal debinding. Samples were sintered at 1200-1600°C in one cycle with debinding process. Findings: Thermogravimetric analysis (TGA) was performed to determine decomposition temperatures of polypropylene, polyethylene, paraffin wax and stearic acid. Morphology of alumina powder by scanning electron microscopy (SEM) was disclosed. The microstructure and properties was tested to see how the selected sintering parameter ,as a temperature, affects the structure. Originality/value: The paper presents ceramic injection molding process of alumina parts and sintering to produce porous material which is possible to use as a preform for infiltration by aluminium alloys.

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Oxide Formation In Metal Injection Molding Of 316L Stainless Steel

Jang J. M., Lee W., Ko S.-H., Han C., Choi H.

Archives of Metallurgy and Materials

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2015

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Vol. 60, iss. 2B

1281--1285

EN

The effects of sintering condition and powder size on the microstructure of MIMed parts were investigated using water-atomized 316L stainless steel powder. The 316L stainless steel feedstock was injected into micro mold with micro features of various shapes and dimensions. The green parts were debound and pre-sintered at 800°C in hydrogen atmosphere and then sintered at 1300°C and 1350°C in argon atmosphere of 5torr and 760torr, respectively. The oxide particles were formed and distributed homogeneously inside the sample except for the outermost region regardless of sintering condition and powder size. The width of layer without oxide particles are increased with decrease of sintering atmosphere pressure and powder size. The fine oxides act as the obstacle on grain growth and the high sintering temperature causes severe grain growth in micro features due to larger amount of heat gain than that in macro ones.