Formability and mechanical properties of porous titanium produced by a moldless process

Abstract

Tailor-made porous titanium implants show great promise in both orthopedic and dental applications. However, traditional powder metallurgical processes require a high-cost mold, making them economically unviable for producing unique devices. In this study, a mixture of titanium powder and an inlay wax binder was developed for moldless forming and sintering. The formability of the mixture, the dimensional changes after sintering, and the physical and mechanical properties of the sintered porous titanium were evaluated. A 90:10 wt % mixture of Ti powder and wax binder was created manually at 70°C. After debindering, the specimen was sintered in Ar at 1100°C without any mold for 1, 5, and 10 h. The shrinkage, porosity, absorption ratio, bending and compressive strength, and elastic modulus were measured. The bending strength (135-356 MPa), compression strength (178-1226 MPa), and elastic modulus (24-54 GPa) increased with sintering time; the shrinkage also increased, whereas the porosity (from 37.1 to 29.7%) and absorption ratio decreased. The high formability of the binder/metal powder mixture presents a clear advantage for fabricating tailor-made bone and hard tissue substitution units. Moreover, the sintered compacts showed high strength and an elastic modulus comparable to that of cortical bone.

Influence of microstructure topology on the mechanical properties of powder compacted materials

“…and grey circles represent literature data for nanoporous foams formed by dealloying [24] and macroscopic foams formed by direct foaming [41] respectively. Literature data for powder compacted titanium (Ti) [17,54], magnesium (Mg) [21,55], copper (Cu) and stainless steel (SS) with spherical, irregular and dendritic powder morphologies (45 m ≤ d ≤ 300 m) [31] are plotted as black data points. Solid lines represent static loading data from finite element simulations, while dashed lines represent analytical solutions.…”

Bone ingrowth of various porous titanium scaffolds produced by a moldless and space holder technique: anin vivostudy in rabbits

“…An inlay casting wax (custom ordered colorless type I; GC Corporation, Tokyo, Japan) was used as a binder to maintain the form until initial sinter ing. Thereafter, 90 wt% titanium powder and 10 wt% wax were mixed and shaped manually at 70 °C on a hot plate to obtain a green compact [11].…”

Powder metallurgy with space holder for porous titanium implants: A review

“…One of the main reasons for the preference of Ti use over other biometals is that it provides less stress shielding effect for the bone. Ti owns an elastic modulus (100)(101)(102)(103)(104)(105)(106)(107)(108)(109)(110) far lower than other implantable metals such as cobalt alloys (220)(221)(222)(223)(224)(225)(226)(227)(228)(229)(230)(231)(232)(233)(234) or stainless steel (SS) (200)(201)(202)(203)(204)(205)(206)(207)(208)(209)(210). However, the elastic modulus of human bone is even lower.…”