Özet:

In this study, powder injection molding (PIM) feedstock was prepared using boron carbide (B4C) powder and various polymeric binders. The effects of B4C powder addition on the attributes of feedstock including critical solid loading, rheological behavior and binder decomposition behavior were studied using rotational rheometry at different temperatures. As a result of the examinations carried out in the powder loading range of 50-60% with an increase of 2.5% in volume, it was determined that the critical powder loading value was 55%, and the feedstock was obtained by mixing the B4C powder at this solid loading rate with polymeric binders. Rheological behaviour shows that feedstock exhibits a pseudoplastic flow behavior which is one of the main requirements for PIM. It was also observed that the feedstock at high powder loading showed high sensitivity to temperature. The binder system has been used to provide acceptable mixing homogeneity, excellent moldability, suitable fast solvent and thermal debinding rate. Solvent and thermal debinding techniques were used to remove binders from the samples obtained after the molding step. The debinded samples were sintered under high purity Ar atmosphere. Initial powder morphologies, fracture surfaces of molded, debinded and sintered samples were investigated using scanning electron microscope (SEM). Experimental results showed that feedstocks at 55% powder loading rates can be successfully molded and subjected to undamaged solvent debinding at temperatures of 50-70°C.

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