Film formation and characterization of anodic oxides on titanium for biomedical applications

Abstract

For a better understanding of the oxide growth and final film properties upon anodization of titanium in sulfuric and phosphoric acid containing electrolytes, the electrochemical behavior as studied by a.c. impedance was correlated to microstructural analysis (TEM, Raman). Chemical depth profiling of the films was performed with glow discharge optical emission spectroscopy (GDOES), XPS and RBS. The fitted capacitances and resistances from a.c. impedance measurements were greatly influenced by the ongoing crystallization as well as by film porosity as a function of increasing anodization potential. GDOES revealed a small sulfur contamination (with its maximum before the oxide-metal interface) upon anodization in 1 M H 2 SO 4 and a significant phosphorus content throughout the oxides for films grown in 1 M H 3 PO 4 , showing an accumulation at the surface. Small impurities of carbon in all films as well as an accumulation of hydrogen at/after the interface oxide-metal were also observed. Quantification of the hydrogen content by elastic recoil detection analysis (ERDA) indicated a peak concentration of 20-30 at%.

Anodic titanium oxide as immobilized photocatalyst in UV or visible light devices

“…Anodic Spark Deposition (ASD) processes in H 3 PO 4 and H 2 SO 4 mixtures cause the formation of partially crystalline oxides with enhanced surface area due to the formation of deep craters. Moreover, the oxide chemistry is partially modified because of the absorption of sulfur of phosphor ions from the electrolyte [17][18][19]. Deeper morphological modifications can be achieved in fluoride-containing electrolytes, where nanotubular amorphous oxides are obtained: these oxides can acquire photoactivity through annealing treatments, which modify the amorphous structure by inducing the formation of anatase crystals [20][21][22][23][24][25].…”

Surface morphology, phase structure and property evolution of anodized titanium during water vapor exposure

“…The breakdown voltage of titanium depends on the type and concentration of electrolyte [22][23][24]. For the anodization of titanium in 1 M phosphoric acid solution, the breakdown voltage is about 150 V [24]. The present applied voltage of 170 V exceeded the breakdown limit so that sparking occurred during the anodizing process.…”

“…1a and b presents the typical surface appearance of titanium anodized at a voltage exceeding the breakdown voltage. The breakdown voltage of titanium depends on the type and concentration of electrolyte [22][23][24]. For the anodization of titanium in 1 M phosphoric acid solution, the breakdown voltage is about 150 V [24].…”

Steam-induced changes in surface characteristics and corrosion resistance of spark-anodized titanium

“…1a and b present the typical surface morphology of spark-anodized titanium. When the applied anodization voltage exceeds the breakdown limit (about 150 V for titanium in 1 M phosphoric acid solution [11]), sparking will occur during the anodization process. The sparks initiated at weak points of the oxide film and then spread over the whole sample surface quickly with audible cracking, copious gas evolution and local oxide overgrowth.…”