Powder and binder systems for use in metal and ceramic powder injection molding

摘要

A powder injection molding composition or feedstock is made of 70% or more by weight of a powdered metal or ceramic and 30% or less by weight of a binder system. The binder system contains a sufficient amount of polypropylene or polyethylene to hold the so-called brown preform of the molded metal or ceramic powder together for the sintering step of the injection molding process and a sufficient amount of partially hydrolyzed cold water soluble polyvinyl alcohol to facilitate molding of the composition into the so-called green preform of the article to be manufactured. The debinding step of the injection molding process for transforming the green preform into the brown preform consists simply of immersing the green preform ill water at ambient temperature to dissolve the polyvinyl alcohol, water and plasticizer. The binder system is nonhazardous, safe, harmless and fully degradable.