Effect of Binder Constituents and Solids Loading on the Rheological Behavior of Irregular Iron-Based Feedstocks

Abstract

This work presents an experimental approach employed to evaluate the influence of binder constituents and solids loading on the rheological behavior and molding properties of irregular shape iron-based feedstocks used in low-pressure powder injection molding. Thirty-six (36) different feedstocks formulated from one new in-development iron-based powder and different wax-based binder systems (paraffin wax with surfactant and thickening agents) were obtained for solids loading varying from 50 to 68 vol. %. The viscosity profiles were experimentally measured at different temperatures using a rotational rheometer in order to quantify the threshold proportions of each ingredient in the binder systems, identify the best feedstock candidates, and calculate their moldability indices, which were finally validated using real-scale injections. Results confirmed that the best feedstock formulation was the one containing paraffin wax with 1 vol. % stearic acid used as a surfactant, 2 vol. % ethylene-vinyl acetate used as a thickening agent, and 2 vol. % carnauba wax used as a shrinking agent. An irregular shape iron-based feedstock with maximum solids loading of 58 vol. % was successfully injected.

Optimization of the printability envelope of low-viscosity powder-binder feedstocks used in material extrusion 3D printing

“…The slope of this graph is E/R , from which the values of E ≈ 30 kJ/mol can be calculated using the gas constant ( R ). This 3D printing feedstock exhibits activation energy for flow similar to those calculated from similar wax-based feedstocks formulated from titanium-, iron-, aluminum-silicon carbide- or stainless steel-based powders used in the LPIM process (Ghanmi and Demers, 2021; Tafti et al , 2021; Khakbiz et al , 2005; Ghanbari et al , 2015; Ben Trad et al , 2019).…”

Effect of powder particle shape and size distributions on the properties of low-viscosity iron-based feedstocks used in low-pressure powder injection moulding

“…Four feedstocks were formulated from the four iron powder lots using similar binder proportions but different solid loadings, each representing the maximum reachable value for each powder lot. Based on recent works on similar water atomised iron-based powders [34], the binder proportion was set at 1 vol.-% of SA, 2 vol.-% of CW, 2 vol.-% of EVA and the balance of PW, to create adequate surfactant, demoulding and thickening effects. Dry powders were mixed in a laboratory mixer with the molten binders for 4 h at 80 °C under a vacuum to remove micro-bubbles from the feedstock.…”

“…Based on recent works on similar water atomised iron-based powders [34], the binder proportion was set at 1 vol.-% of SA, 2 vol.-% of CW, 2 vol.-% of EVA and the balance of PW, to create adequate surfactant, demoulding and thickening effects. Dry powders were mixed in a laboratory mixer with the molten binders for 4 h at 80 °C under a vacuum to remove microbubbles from the feedstock.…”

Influence of binder content on physical and mechanical properties of composite materials such as metal powder-waxy substance

“…Це перешкоджає створенню наукових основ виготовлення розхідних матеріалів заданого складу. Виходом з існуючої ситуації є дослідження властивостей композитів, де як зв'язуючий використовується окремий компонент композитного зв'язуючого, з подальшим дослідженням різноманітних комбінацій складових [3,8].…”