BI-MATERIAL COMPONENTS USING POWDER INJECTION MOLDING: DENSIFICATION, SHAPE COMPLEXITY, AND PERFORMANCE ATTRIBUTES

摘要

Tailored materials, possible via selective placement of different compositions within a component, are useful in several transportation systems ranging from rocket nozzles to automotive engine fuel injectors. Research at Penn State has focused on use of powder injection molding to combine shape complexity with functional design. Controlled sintering of two different compositions within the component is the major difficulty with these structures. Differential shrinkage strains during heating often result in delamination, warpage, or cracking. Via experimentation and modeling, options have been isolated to allow co-sintering; these are through adjustments in solids loading, particle size, minor alloying, and heating cycle to minimize damage during heating. Consequently, co-injection molding of bi-material structures has been realized in several material and property combinations, such as glass sealing alloys linked to heat dissipation alloys, and other combinations based on magnetic response, corrosion resistance, hardness, and low cost. This paper introduces the problems, opportunities, and sintering protocol, and shows products fabricated using this new technology.