Surface characterisation and electrochemical behaviour of porous titanium dioxide coated 316L stainless steel for orthopaedic applications

Srinivasan, Naveen; Rajendran, N.

doi:10.1016/j.apsusc.2008.10.058

Cited by 70 publications

(31 citation statements)

References 31 publications

(29 reference statements)

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“…In the region above 1600 cm -1 only absorbed water related vibrations were observed. Those were also observed between 2400 and 3800 cm -1 , in samples roasted below 600 °C (Nagarajan and Rajendran, 2009;Ryskin, 1974). The absorption band at 1080 cm -1 observed in all samples is attributed to Si-O bonds in SiO 4 tetrahedral groups (Farmer, 1974;Vicente-Rodriguez et al, 1996;Méndez-Vivar et al, 2001;Ratnasamy et al, 2004).…”

Section: Alkali Decomposition Reactionmentioning

confidence: 75%

Titania recovery from low-grade titanoferrous minerals

2011

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In this study a novel process for extraction of titanium valuables from its minerals is presented. The process entails roasting of titanium ore with alkaline metal salt, hydrolysing fused cake and dissolution in acid. Optimum conditions were found to be 1 hr fusion at 850 °C, using 2:1 mole ratio, NaOH:FeTiO 4 , irrespective of the particle size interval used in this work. It was found that under these conditions » 80% of titanium was recovered. Na 0.75 Fe 0.75 Ti 0.25 O 2 , NaFeTiO 4 and Na 2 Fe 2 Ti 3 O 10 were the dominant phases at this temperature. The presence of these phases is viewed as beneficial to the economics of the process, it consumes less NaOH. Fusions conducted at 550 °C or below produced chiefly binary phases, Na 2 TiO 3 and NaFeO 4 , reducing process economy. Optimum leaching conditions were S/L= 0.26, leaching at 75 ºC, for 15 min. 85% of NaOH were recovered, under these conditions. Leaching obeys shrinking core mechanism model. IntroductionTitania (TiO 2 ) is a white pigment used in paints, paper, plastics, cosmetics and coatings. Its wide application is due to its higher opacity and covering power. There are two commercial methods of TiO 2 production, the chloride and the sulphate process. In the chloride process titanium mineral is converted into TiCl 4 which is subsequently oxidized at high temperatures.In the sulphate process the ore is converted into sulphate solution and then thermally hydrolysed to hydrous titanium. The later is calcined to produce the pigment (Braun et al, 1992;Nielsen and Chang, 1996;Xue et al, 2009).According to Pong et al (1995) a commercially viable process has to be environmentally benign, to generate a minimum waste, be able to use all grades of ores and be economically favourable. The above processes are, either environmentally unfriendly, costly, generate high levels of waste or recycle, are unable to process low grade ores, as well as, ores such as anatase, sphene, and perovskite (Bulatovic, 1999;Cole, 2001;Nielsen and Chang, 1996;Van Dyk et al, 2004;Yuan et al, 2005).Generally low grade titanoferrous ores are submitted to slagging process. The slagging process however faces uncertain future due to its higher energy consumption and green house gases emission. Additionally slagging is unable to treat radioactive ores, since the radionuclides remain in the solid solution during slagging process. With increasingly restringent environmental policies on radionuclides content, further treatment has to be conducted to reduce it. This will result in additional production costs (Nielsen and Chang, 1996; Habashi, 1997;Doan, 2003; Jha et al, 2005;Lahiri et al, 2006;Lahiri and Jha, 2007

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Section: Alkali Decomposition Reactionmentioning

confidence: 75%

Titania recovery from low-grade titanoferrous minerals

2011

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“…Phase angle curves for the uncoated stents at the immersion times of 0.1 day, 1 day, and 21 days show a plateau from 10 21 to 10 2 Hz with values around 280 , which confirms the that the natural oxide layer over the surface is capacitive and protective. 40,41 The phase angle plots for the DC-TMS plasma coating depict two plateaus that remain relatively stable for the immersion period of up to 21 days, indicating that the coating barrier property did not deteriorate noticeably over time. The plateau at higher frequency region (10 3 210 4 Hz) is confirmation of the presence of plasma coating whereas the broader region near 10 21 210 0 Hz indicates the oxide layer.…”

Section: Resultsmentioning

confidence: 97%

Corrosion resistance improvement for 316L stainless steel coronary artery stents by trimethylsilane plasma nanocoatings

Jones

Chen

2014

J Biomed Mater Res

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To improve their corrosion resistance and thus long-term biocompatibility, 316L stainless steel coronary artery stents were coated with trimethylsilane (TMS) plasma coatings of 20–25 nm in thickness. Both direct current (DC) and radio-frequency (RF) glow discharges were utilized for TMS plasma coatings and additional NH3/O2 plasma treatment to tailor the surface properties. X-ray photoelectron spectroscopy (XPS) was used to characterize the coating surface chemistry. It was found that both DC and RF TMS plasma coatings had Si- and C-rich composition, and the O-and N-contents on the surfaces were substantially increased after NH3/O2 plasma treatment. Surface contact angle measurements showed that DC TMS plasma nanocoating with NH3/O2 plasma treatment generated very hydrophilic surface. The corrosion resistance of TMS plasma coated stents was evaluated through potentiodynamic polarization and electro-chemical impedance spectroscopy (EIS) techniques. The potentiodynamic polarization demonstrated that the TMS plasma coated stents imparted higher corrosion potential and pitting potential, as well as lower corrosion current densities as compared with uncoated controls. The surface morphology of stents before and after potentiodynamic polarization testing was analyzed with scanning electron microscopy, which indicated less corrosion on coated stents than uncoated controls. It was also noted that, from EIS data, the hydrophobic TMS plasma nanocoatings showed stable impedance modulus at 0.1 Hz after 21 day immersion in an electrolyte solution. These results suggest improved corrosion resistance of the 316L stainless steel stents by TMS plasma nanocoatings and great promise in reducing and blocking metallic ions releasing into the bloodstream.

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“…This behavior is due to the high stability of the coatings. 24 The electrochemical impedance spectra of uncoated and sodium titanate-coated 316L SS substrates during immediate immersion in SBF solution are shown in Fig. 11a.…”

Section: Bioelectrochemical Corrosion Studiesmentioning

confidence: 99%

Synthesis and characterization of nanoporous sodium-substituted hydrophilic titania ceramics coated on 316L SS for biomedical applications

2011

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Bioactive sodium-substituted titania coating on 316L SS substrate was prepared. XRD patterns exhibited the formation of a mixture of two phases (Na 2 Ti 3 O 7 , Na 2 Ti 6 O 13 ) with monoclinic structure. FTIR spectra showed that the set of overlapping peaks in the range of 800-400 cm À1 are related to Ti-O and Ti-O-Ti groups. SEM-EDAX, AFM, and TEM showed the surface morphology of the coated surface to be nanoporous and uniform. The influence of the bioactivity of the coating in a simulated body fluid (SBF) medium was examined. Excellent adhesion of the ceramic composites to the substrate was achieved. The hydrophilic nature of the sodium titanate coating induced the formation of hydroxyapatite layer on the metal surface. The corrosion protection performance of the coatings has been evaluated using potentiodynamic polarization and electrochemical impedance spectroscopy measurements, which proved increased corrosion resistance of nanosodium titanate-coated 316L SS. These results imply that the sodium titanate-coated 316L SS acts as a barrier layer to the metallic substrate.

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Surface characterisation and electrochemical behaviour of porous titanium dioxide coated 316L stainless steel for orthopaedic applications

Cited by 70 publications

References 31 publications

Titania recovery from low-grade titanoferrous minerals

Titania recovery from low-grade titanoferrous minerals

Corrosion resistance improvement for 316L stainless steel coronary artery stents by trimethylsilane plasma nanocoatings

Synthesis and characterization of nanoporous sodium-substituted hydrophilic titania ceramics coated on 316L SS for biomedical applications

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