NOVEL POWDER INJECTION MOULDING FEEDSTOCK SYSTEM AND TECHNOLOGY BASED ON DUAL MAIN BINDER CONCEPT, METHODS AND USES

摘要

The present invention belongs to the field of technology known as powder injection moulding. It includes producing a part by powder injection moulding at low to high injection pressure and it discloses a novel binder system for optimized feedstock design. The primary subject matter of the invention resides in introducing a secondary main binder into the feedstock binder composition, meeting, simultaneously, the five (5) following criteria: partially soluble in the primary binder, soluble in water, thermally evaporable, possessing a dispersant functionality and increasing the viscosity at near zero feedstock shear rate. In addition to this binder, the feedstock may contain a small fraction of another dispersant and a back-bone polymer when needed, depending on the type of powder material used for the feedstock. Based on the main modes of binder removal (thermal or water extraction) this novel binder system is denominated as Te-Wex™ system. Using this binder concept feedstocks with a wide variety of powders, including alumina, zirconia, silicon nitride, stainless steel and low-alloyed steel could be prepared and subsequently injected using the MPIM (Medium pressure Powder Injection Moulding) technique into one- or multiple cavity tools to make parts of variable thickness. These parts could be debinded either by partial water extraction and/or thermal evaporation and sintered to final density of over 99 vol % of the respective theoretical values.