Abstract
In this study, environmentally convenient highly metal powder filled feedstocks intended for powder injection molding is presented. The composition of 60 vol % 316L stainless steel gas atomized powder feedstocks containing semicrystalline waxes: acrawax or carnauba wax and paraffin wax, combined with polyethylene glycol and modifier, was optimized to provide defect-free parts. Rheological as well as thermogravimetric analyses supported with scanning electron microscopy and metallography were employed to set up optimum conditions for molding, debinding and sintering. The performance of the novel feedstock was compared with currently available polyolefines-based materials, and results showed an efficiency enhancement due to the substantially lower (about 100 °C) mixing and molding temperatures as well as a reduction of debinding and sintering times at the simultaneous achievement of better mechanical properties in terms of elongation and tensile strength, in comparison to the mass production feedstock.
Highlights
Injection molding of metal and ceramic powder feedstocks (PIM—Powder Injection Molding) provides high performance products without residual waste
The compositions of feedstocks reflect our previous research devoted to the quantification of interactions among various polymers used as binder components [9,15]
The loading of 60 vol % of steel powder was chosen as a maximum due to a relative fragility, which samples exhibited after water debinding, when most of the polyethylene glycol (PEG) was removed from the green parts
Summary
Injection molding of metal and ceramic powder feedstocks (PIM—Powder Injection Molding) provides high performance products without residual waste. Inherent compromises between speed of the processes, sintered densities, amount of residual stresses and mechanical integrity [1,2,3], and demands on binder systems used, are limiting the efficiency of both processing routes. Another aspect is the requirement to make the production less energy consuming, and to employ environmentally benign materials. Primary (backbone) binders for highly filled metal and ceramic powder feedstocks are mostly based on polyolefins (low- and high-density polyethylenes and polypropylene) [4,5,6]. Water-soluble binders based on polyethylene glycol (PEG) steadily gain attention [7,8,9,10]
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