Porous Titanium Coatings Through Electrophoretic Deposition of TiH₂ Suspensions

Abstract

In the biomedical field, modification of titanium surfaces to improve the osteoinductive and antibacterial behavior is widely investigated. This functionalization can be further ameliorated by providing a porous coating with high loading capacity for bioactive materials and drug delivery carriers at the implant surface. In this work, a new powder metallurgical processing route used to deposit such porous pure titanium coatings on Ti based substrates is presented. The coatings were prepared by electrophoretic deposition (EPD) of TiH2 powder suspensions followed by dehydrogenation and sintering in vacuum. The use of hydrides allowed to lower the sintering temperature below that of the α–β transition of the Ti6Al4V substrate. Measurement of the tensile bond strength confirmed a strong adhesion of the porous coating. Deposition of powders with different grain sizes resulted in porous titanium coatings with varying thickness, pore morphology, and surface roughness. The possibility to extend this coating technique to complex shaped implants is highlighted.

Novel anti-infective implant substrates: Controlled release of antibiofilm compounds from mesoporous silica-containing macroporous titanium

“…Powder metallurgy based on partial sintering of metal powders is a common technique to produce porous metallic biomaterials. Limiting the sintering temperature and time, high pore interconnectivity can be established, while the pore size can be tuned by optimizing the starting powder particle size [45,46]. However, because oxidation hinders particle bonding, pure Ti powders require a high vacuum environment as well as high temperature (>1100 • C) for sintering in order to obtain a good mechanical integrity [45].…”

“…Hydrogen release during heat treatment (between 450 and 650 • C) reduces oxide impurities at the powder surface and allows lowering the sintering temperature significantly without compromising the mechanical strength [46,47]. Moreover, the hydrogen content after heat treatment remains well below the accepted level of hydrogen impurity for commercially pure Ti grades 1-4 according to ASTM F67 [46]. For the current application, we selected a Ti powder with a broad particle size distribution up to 45 m in combination with a small amount of finer sized TiH 2 .…”

Bioactive glass–ceramic coated titanium implants prepared by electrophoretic deposition

“…The reported values are an average of 12 measurements divided as 4 equidistant point analyses on 3 samples. The tensile adhesion bond strength of the coatings on the metallic substrate was evaluated with an adapted version of ASTM 1147 using an INSTRON 4467 with a load cell of 30 kN at a crosshead speed of 2.5 mm/min as described elsewhere [28]. A specimen assembly of a coated Ti-6Al-4V substrate (Ø = 15.5 mm) and an uncoated counterbody (titanium rod, Ø = 10 mm), glued together with FM 1000 Adhesive Film (Cytec), was subjected to a tensile load perpendicular to the coating surface.…”

Electrophoretic deposition of colloidal TiO2 nanorods towards nano-porous thin-films

“…As drawbacks, EPD requires the use of strong electric fields (E > 100V/mm) [12]. Colloidal synthesis of nanoparticles and the subsequent EPD process open to the possibility to immobilize any pre-synthesized nanomaterials, with specific chemical-physical properties, on any substrates, imparting to them the peculiar properties resulting from the nano-sized phase [13].…”