Influence of binder composition on powder injection moulding process

Powder injection moulding (PIM) is a modern technological process combining powder metallurgy and plastic injection moulding. PIM is suitable for mass production of small metal or ceramic items, with complex geometry and tight tolerances. Polymer binders for PIM technology are still in the developing area due to the complexity of their requirements. One of the main challenges in PIM technology is optimization of PIM process and detection/elimination of powder binder separation resulting in inhomogeneous final products. The research team at Tomas Bata University in Zlín under prof. Hausnerová has been involved in investigating the interactions and chemical mechanisms occurring within a binder system. The aim of this thesis is devoted to polymer binder composition based on previous results, including binder components characterization and their influence on PIM process. Particular emphasis was also placed on an eco-friendly approach and maximisation of solid loading. Major component/s of binder systems provide low viscosity and easy removal in the first stage of debinding. Polyethylene glycol (PEG) is a suitable candidate due its non-toxicity, solubility in water and commercial availability. The first part was dedicated to the effect of PEG molecular weight on the overall PIM process. Results showed that PEG molecular weight affected processing parameters, but without any final impact on mechanical properties of sintered Inconel 718. Feedstock viscosity can be tailored via PEG molecular weight. The second part was devoted to backbone components, especially to carnauba wax (CW) and acrawax (AW) as possible substituents of polyolefin based binder systems. Previous research showed twice stronger binding for AW/PEG than for CW/PEG, suggesting strong interactions between polymers. Feedstocks based on CW and AW showed overall lower viscosity than polyolefin‐based ones and commercial feedstocks, and additionally a binder based on CW, could be used for reactive powders due to low processing temperatures. Concentration of stearic acid (SA) as a surface active agent was investigated in third part in order to increase powder loading and improve flow properties of feedstocks. Surfactant SA positively affected processing parameters and its appropriate concentration is strongly dependent on binder composition. Optimal concentration of SA can increase maximal powder loading. Binders are designed as multi-component polymer systems, in which each component performs a specific task. Better understanding of each component in this process can help eliminate some drawbacks, improve processing and produce less defective parts.

ISBN:	978-80-7454-840-6
EAN:	9788074548406
Počet stran	56 stran
Datum vydání	15. 07. 2019
Pořadí vydání	První
Jazyk	anglický
Vazba	e-kniha - pdf
Autor:	Eva Hnátková
Nakladatelství	Univerzita Tomáše Bati ve Zlíně
Tématická skupina	999 - nezařazeno