MATERIALS FOR MICROMINIATURE POWDER INJECTION MOLDED MEDICAL AND DENTAL DEVICES

摘要

One of the key successes of PIM has come from its penetration into the medical and dental fields. This started with dental orthodontic brackets, moved to surgical and dental tools and, in recent years, has included implants out of both metals and ceramics. Today there is serious discussion of replacement components, such as heart valves, using PIM. This maturation has come slowly since considerable concern arises over the difference between PIM and standard materials. For example, surface depletion of high-vapor-pressure species, such as chromium during the sintering of stainless steel, creates significant concerns over a loss of corrosion resistance and biocompatibility in a sintered device. Thus, through meeting bulk chemistry specifications, special care is required to ensure that the performance is equivalent to previously qualified materials. For μPIM components, the ratio of surface area to bulk makes it imperative to secure the highest possible passivity, so conservative materials selection is the routine approach. In the companion paper by Cheng and Hwang the surface-area effect is turned into an advantage as a means to convert a traditional PIM 316L stainless steel into a high-strength option useful in notebook computers.