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Thursday, August 26, 2004 - 4:30 PM
SES 6B.4

Powder Injection Molding of Titanium Components

K. L. Simmons, E. A. Nyberg, K. S. Weil, Pacific Northwest National Laboratory, Richland, WA

Powder injection molding (PIM) is a well-established, cost-effective method of fabricating small-to-moderate size metal components. Derived from plastic injection molding and employing a mixture of metal powder and plastic binder, the process has been used with great success in manufacturing a wide variety of metal products, including those made from stainless steel, nickel-based superalloys, and copper alloys. Less progress has been achieved with titanium and other refractory metal alloys because of problems with alloy impurities that are directly attributable to the injection molding process. Specifically, carbon, oxygen, and nitrogen are left behind during binder removal and become incorporated into the chemistry and microstructure of the material during densification. Even at low concentration, these impurities can cause severe degradation in the mechanical properties of titanium and its alloys. We have developed a unique blend of PIM constituents where only a small volume fraction of binder (~5 – 10 vol%) is required for injection molding; the remainder of the mixture consists of the metal powder and binder solvent. Because of the nature of decomposition in the binder system and the relatively small amount used, the binder is eliminated almost completely from the pre-sintered component during the initial stage of a two-step heat treatment process. Results will be presented on the first phase of this research, in which the binder, injection molding, de-binding and sintering schedule were developed. Additional data on the mechanical and physical properties of the material produced will be discussed.