During the last decennia it is demonstrated that the injection molding used in polymers could be the solution to decrease the price of parts / devices of metallic alloys for large-scale series production. The metal powder injection molding (MIM) technique has five main steps: selection of powder and binder, production of feedstock, injection molding, debinding and sintering. The material selected was the 316L steel due to its wide use as biomaterial associated to low cost of powders and its high injectability. The feedstock was suitable optimized and produced by torque rheometry technique. The ideal feedstock has 60:40% vol. of powders:binder and has low torque value (suitable to injection step). It is important to decrease the friction coefficient (between the molding parts and mold surfaces) and to improve significantly the wear strength of mold surfaces. The (micro) mold was designed and developed for producing dental implants in large series that means coated with a high hardness and near frictionless thin film of dichalcogenides sulphides (W-S-C). The injection step was carried out at 10MPa and the binder was efficiently removed from green implants. After sintering step (at 12500C), dental implants have a good finishing and the shrinkage of dental implants was evaluated. The osseointegrability was promoted by coating the sintered implants with a thin film of non-modified and Si modified hydroxyapatite (HA). The coated dental implants were mechanically evaluated during implantation using a bovine rib. The new strategic production leads cheaper implants, called "implants for crisis", where surface modification assures a similar or superior bioactivity than commercial implants.
Ferreira TJ, Vieira MT, Costa J, Silva M and Gago PT
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