Rheological Properties of Mixtures of 316L Stainless Stell Powders With Polyproplylen Based Binders

Authors: Çetin KARATAŞ, Süleyman SARITAŞ

Abstract: The flowabilities of feedstocks for powder injection molding (PIM), of 316L stainless steel powders (mean diameters 5.84, 30.42, 40.35, 67.42 \mum) with thermoplastic binders (60% paraffin, 35% polypropylene, 5% stearic acid) were investigated. For this purpose, a capillary rheometer was designed and constructed. The rheometer was heated in 30 minutes to 300 °C with an accuracy of \pm 1 °C. Its load range was 63-55.000 grams. The best flow measurements were made at 175 °C for all feedstocks. The pressure used was 0.65 MPa which is the lowest acceptable pressure in PIM. The results showed that, therheological properties of the feedstocks improved as the powder size decreased and powder shape became spherical. The percentage of solid loading, allowing flowing of the feedstock through the rheometer, varied between 42 % to 74 % depending on powder size.

Keywords: Powder Injection Molding (PIM), Feedstock, Binder, Rheology

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