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1.
Bioactive sodium-substituted titania coating on 316L SS substrate was prepared. XRD patterns exhibited the formation of a mixture of two phases (Na2Ti3O7, Na2Ti6O13) with monoclinic structure. FTIR spectra showed that the set of overlapping peaks in the range of 800–400 cm−1 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.  相似文献   

2.
A simple surface pre-treatment method was attempted to establish a stable passive layer on the surface of surgical grade stainless steel (SS) of type 316L for biomedical applications. Surgical grade type 316L SS specimens were subjected to H3PO4 treatment for 1 h by completely immersing them in the acid solutions to develop a passive barrier film. The effect of various concentrations of phosphoric acid on the localized corrosion resistance behavior of type 316L SS was investigated through electrochemical techniques using cyclic polarization studies and electrochemical impedance spectroscopy (EIS). X-ray photoelectron spectroscopy (XPS) was used to evaluate the nature and composition of the passive films. The surface morphology and relative elemental composition of the untreated and acid treated surfaces subjected to anodic polarization was studied by scanning electron microscopy (SEM) and energy dispersive X-ray analysis (EDAX) techniques, respectively. Compared with untreated (pristine) 316L SS, the 40% acid treated surface formed a stable passive layer that had superior corrosion resistance.  相似文献   

3.
The localised corrosion resistance of 316L SS metallic implant due to H2SO4 treatment is being studied through electrochemical studies involving cyclic polarisation experiments and impedance studies. The efficiency of hydroxyapatite (HAP) coatings on H2SO4 treated 316L SS is also been investigated through electrochemical studies and the dissolution characteristics of the coatings. The study reveal that 15% H2SO4 treatment was found to be efficient in the corrosion resistance of 316L SS and dissolution of alloy is considerably reduced in the hydroxyapatite coatings on 15% H2SO4 treated 316L SS.  相似文献   

4.
The development of Hydroxyapatite (HAP)/Titania (TiO2) composite coatings on metallic implants have received a great deal of attention during the recent years owing to their superior advantages in biomedical applications. The present study has focused on the in situ formation of HAP/TiO2 composite powders through aqueous precipitation technique. Five different HAP/TiO2 composite powders of varied HAP to TiO2 ratios has been synthesized in the present study and the results were compared with the stoichiometric HAP, Rutile TiO2 and Anatase TiO2 which also have been synthesized by adapting a similar synthetic procedure. All the synthesized powders have been analyzed using X-ray diffraction (XRD) and X-ray fluorescence (XRF) techniques. Rietveld Refinement technique has been employed to generate quantitative information about the structural characteristics and phase content in all the powder samples. Further, the electrophoretic deposition (EPD) method has been employed to fabricate HAP/TiO2 composite coatings on 316 L SS and the resultant coatings were analyzed for its quantitative structural characteristics. The results from the present investigation has confirmed that concentration of TiO2 in the HAP/TiO2 composites and heat treatment temperatures have played a major role in the degradation of HAP to β-Tricalcium phosphate and also in the conversion of Anatase to Rutile TiO2 phase.  相似文献   

5.
《Ceramics International》2016,42(3):3855-3863
Three sets of FGMs of stainless steel 316L (SS) reinforced with micro-, nano- and mixed (1:1 mass ratio) hydroxyapatite (HA) were fabricated by powder metallurgy route. The concentration of the HA was varied from 0 to 20 wt% with the increment of 5 wt% in all sets to strengthen the discrete layers of FGMs. The sintered densities along the discrete layers of FGMs continually decreased as a function of HA content which enhanced the bioactivity of the FGMs towards the end with high content of HA. All FGMs experienced an excellent corrosion response in the 0.9% NaCl solution with high passivity. Heavy diffusion of chromium (Cr) form SS to HA made the matrix Cr deficient. The chromium depletion regions around the interface of SS and HA caused an active corrosion behavior of FGMs in 0.1 M HCl solution. FGMs with micro-sized HA demonstrated the better corrosion properties than that of other FGMs. After being immersed in the simulated body fluid (SBF) solution for 7 days, the apatite layer formed on the surface of FGMs with micro-sized HA had a mature spherical morphology and leaf like shape for the other two FGMs. The apatite morphology and gained weight results proved the highest bioactivity for micro-sized HA reinforced FGMs.  相似文献   

6.
《Ceramics International》2017,43(15):11569-11579
Niobium oxide is known for its biocompatibility; however it lacks on bioactivity. Sodium is one of the essential elements required for the formation and maintenance of bone. In this present study, we focus on improving the bioactivity of niobium oxide by incorporating sodium ions and obtaining nanoporous morphology by adding polyethylene glycol. Sodium niobate was prepared using sol-gel method and dip coated on 316L SS. The coated sample was sintered at the optimised heating rate of 0.5 °C min−1. The surface morphology, chemical composition, phase composition and porosity were analysed using scanning electron microscopy (SEM), energy dispersive X-ray analysis (EDX), X-ray diffraction analysis (XRD) and porosimetry. The BET analysis and AFM studies showed that the coating exhibited pores with the average diameter of 97 and 101 nm. The Vicker's microhardness test showed that sodium niobate coating exhibits three fold higher microhardness compared to 316L SS. In vitro studies show that the coating exhibited good bioactivity. Electrochemical studies confirmed that the coating offers better corrosion resistance to the substrate at pH 5.2 and pH 7.4. The hemolysis percentage of the coating was found to be 1.54% and anticoagulation studies showed that coagulation time of sodium niobate coating was similar to that of the plasma. Better adhesion, proliferation and differentiation of MG-63 cells with significant cell spreading were observed in the coating.  相似文献   

7.
Titanium and its alloys are widely used for medical implant applications, but their corrosion in the physiological environment leads to the discharge of metal ions, which can trigger severe health issues. In the present study, calcium silicate reinforced hydroxyapatite (HA-CS) coatings were deposited on the Ti6Al4V substrate by using atmospheric plasma spray (APS) process with an aim to improve the corrosion resistance and bioactivity. The coatings were prepared by varying the weight percentage (wt %) of calcium silicate (CS) reinforcement in hydroxyapatite (HA) as Ha/x CS (x = 0, 10, 20 wt %). The SEM analysis of the pure HA coating revealed the presence of surface microcracks, whereas HA-CS coatings displayed the crack-free surface morphology. The corrosion investigation revealed that with the progressive increment of CS content in HA coating, the corrosion resistance of HA-CS coatings improved. In addition, surface roughness, porosity, microhardness and crystallinity increased with the increase of CS content in HA. The findings of this study indicate that the development of plasma sprayed HA-CS coatings is a promising approach to improve the performance of Ti6Al4V alloy for medical implant applications.  相似文献   

8.
Antimicrobial hydroxyapatite (HAp) nanoparticles with different concentrations (0, 3, and 6 mol%) of zinc were prepared by the ultrasonication process. The prepared nanoparticles and chitosan (CTS) composite were coated on 316L stainless steel implant by spin coating technique. The powder samples were characterised by particle size analyser, X-ray fluorescence, and X-ray diffraction studies. The morphology of the coating was investigated by scanning electron microscopy. The diameter of the particle size decreased with increase in the concentration of zinc in HAp structure. The structure of the coated implant was found to be uniform without any cracks and pores. Antimicrobial activity of the composites against Bacillus subtilis, Staphylococcus aureus, Klebsiella pneumonia, Salmonella typhi and Pseudomonas aeruginosa was analysed. The results showed that the increase in the concentration of zinc enhances the antimicrobial properties of 316L stainless steel implant. The stability of the implant in physiological environment was characterised by electrochemical impedance spectroscopy and polarisation analysis. The higher concentration of the ZnHAp/CTS composite shows higher corrosion resistance than that of the HAp/CTS-coated implant. This study shows that the coating provides corrosion resistance to the stainless steel substrate in simulated body fluid (SBF). The in vitro bioactivity study of the coated samples immersed in SBF solution confirms the formation of bone-like apatite layer on the surface of the implant. Thus, highly biocompatible ZnHAp/CTS-coated materials could be very useful in the long-term stability of the biomedical applications.  相似文献   

9.
Bone, a natural composite, comprises non-stoichiometric calcium hydroxyapatite (HAp) precipitated in a controlled reaction environment of a highly aligned, anisotropic organic template (type I collagen) that leads to its exotic tensile and compressive strength. It differs from stoichiometric hydroxyapatite in composition, crystallinity, and other physical and mechanical properties. In the present study, functionalized biomolecular template-induced precipitation of HAp on an SS 316 L substrate following biomimetic route exhibits distinct alterations in crystal growth and geometry, which in turn indicates the potential of the process to develop a non-stoichiometric HAp coating on metal implants.  相似文献   

10.
Biocompatible nanocomposite coatings can be synthesized to offer improved surface properties for biomaterials and biomedical implants. Nanocomposite coatings containing polypyrrole (PPy) matrix reinforced with functionalized multi-wall carbon nanotubes (f-CNTs) were deposited on 316L SS substrates using electrochemical route. FT-IR, XRD, SEM, and TEM were employed to characterize the nanocomposite microstructure. High resolution imaging showed relatively uniform dispersion of the CNTs in the nanocomposite with a typical tubular structure. Micro-indentation tests revealed improvement in the hardness of the PPy/CNTs coatings. Measurement of the contact angle indicated enhanced surface wettability of the nanocomposite coatings. The corrosion behavior of 316L SS samples coated with PPy/CNTs was studied in SBF medium. The corrosion potential and the breakdown potential of coated 316L SS substrates shifted to more noble values as compared to uncoated 316L SS samples. The results suggest that incorporating CNTs as reinforcements in PPy coatings can provide enhanced properties in terms of surface hardness, biocompatibility, and corrosion resistance.  相似文献   

11.
Pure and CuO-dispersed hybrid silica nanocomposite coatings were generated using sols synthesized from acid catalyzed hydrolysis and condensation of n-propyl trimethoxysilane and tetraethoxysilane in combination with copper nitrate. Coatings were initially deposited on soda lime glass substrates by dip coating followed by heat treatment at 150, 250 and 350 °C for 2 h in air and characterized. Coatings were subsequently deposited by dip coating on stainless steel 304 substrates. An optimized heat treatment temperature of 250 °C was chosen based on the contact angles of coatings on soda lime glass substrates and results of thermogravimetric/differential thermal analysis on the dried gels obtained from the sol synthesized from the combination of n-propyl trimethoxysilane and tetraethoxysilane. Gels heat-treated at 250 °C were characterized by X-ray diffraction, X-ray photoelectron spectroscopy and transmission electron microscopy for crystallinity. Characterization of the coatings was carried out with respect to thickness, water contact angle and adhesion. Corrosion testing of coatings on SS 304 was studied by potentiodynamic polarization measurements and electrochemical impedance spectroscopy after 1 h and 24 h exposure to 3.5% NaCl. The corrosion resistances of CuO-dispersed hybrid silica coatings after 1 h and 24 h exposure to 3.5% NaCl solution were higher than that of pure hybrid silica coatings, both of which had thicknesses ranging from 140 nm–200 nm.  相似文献   

12.
This work presents a study on an alternative coating method based on electrochemical techniques which are designed to form a crystalline hydroxyapatite layer very similar to the process corresponding to the formation of natural bone. In this study, a sample electrochemical method of coating the solid surfaces of zinc, with a film of apatite, was developed. The hydroxyapatite deposit was investigated by means of scanning electron microscopy, X-ray diffraction, infrared spectroscopy, and chemical analysis. The data suggest that the method utilized in this work can be successfully applied to obtain deposition of uniform coatings of crystalline hydroxyapatite on zinc substrates. As a result, both the lattice parameters a and c of the apatite layer decreased with increasing Zn fraction.  相似文献   

13.
The current work focused on the development of hydroxyapatite (HAP) coating on laser textured metallic implants using electrophoretic deposition. HAP was synthesized by sol-gel technique and its phase purity and surface morphology were confirmed by FT-IR, XRD and SEM analysis. 316 L SS and Ti-6Al-4V metal implants were polished and the surface was modified using Nd-YAG laser operating at a pulse interval of 10 ns at various overlapping rate of 0%, 25% and 50%. The laser treated surface was characterized for its surface roughness using surface profilometry and surface morphology. The surface roughness of the metallic implants was increased by increase in the overlapping rate. The prepared HAP powder was electrophoretically deposited on bare and laser textured Ti-6Al-4V and 316 L stainless steel followed by vacuum sintering at 300 °C for 2 h. Scratch analysis results showed an improvement in adhesion strength for the HAP coatings on laser treated specimens than untreated metal. Corrosion efficiency of the coated samples was studied in SBF solution using EIS and potentiodynamic polarization studies. The result from the corrosion experiments proved increased corrosion resistance property of laser textured coated samples when compared to bare alloy due to higher adhesion of HAP coating on the metal surface.  相似文献   

14.

Introduction

Achievement of bioactive coatings on metallic implant surface with higher adhesive strength and corrosive resistance was one of the main challenges for the current biomaterial researchers. Hydroxyapatite was one of the promising bioactive ceramic which can be applied as a coating on the metallic substrate due to its similarity with the human bone.

Methods

The work describes the in-situ preparation of HAP/f-MWCNTs composite by sol-gel method. MWCNTs were functionalized by acid treatment. HAP composites have been prepared by varying the molar percentage of f-MWCNTs from 1% to 5%. The prepared composites with various concentrations of f-MWCNTs were characterized by FT-IR and XRD for its functional group analysis and phase purity. The morphology of the prepared powder was analyzed using SEM and TEM. In-vitro corrosive behavior on SBF was studied for the coating prepared HAP composite sol on 316L SS. The triple layer composite coating was obtained at the spin speed of 3000?rpm/min and subjected to sintering at 500?°C/2?h.

Results

X-ray diffraction results confirmed the formation of pure HAP up to the addition of 3% of f-MWCNTs without any secondary phases. The average crystallite size of the prepared particles was decreased from 40?±?2.1 to 17?±?2.5?nm with the addition f-MWCNTs. The morphological studies confirm the incorporation of f-MWCNTs in HAP matrix. The prepared HAP/f-MWCNTs composite efficiently inhibits the growth of the pathogens such as S. Aureus and E.coli. Improved hardness was observed with reinforcement of f-MWCNTs into the hydroxyapatite matrix. Electrochemical studies confirm the HAP/f-MWCNTs composites having increased corrosive resistance properties. The bonding strength of the composite coatings showed improved adhesion to the 316L surface.

Conclusion

In this work we have fabricated sol-gel derived anti-microbial composite coating on the 316L substrate by means of spin coating at optimized conditions with higher adhesive strength and improved corrosion resistance.  相似文献   

15.
Journal of Applied Electrochemistry - Nowadays, massive NiMo alloys are considered highly active catalysts for the hydrogen evolution reaction (HER) in industrial alkaline electrolysers. Thus, it...  相似文献   

16.
Plasma spray coating with ceramic carbide is a promising approach for improving the surface quality of the materials. In this work, the effectiveness of tungsten carbide (WC), chromium carbide (Cr3C2), and the composite coating of the two powders in the weight ratio of 50:50 were investigated. In the erosion test, aluminum oxide (Al2O3) particles were combined with a high-speed air-jet and impinged at 90° on the top surface of the material. Electrochemical polarization and electrochemical impedance spectroscopy studies were conducted with a 3.5 wt.% of sodium chloride (NaCl) solution as the electrolyte. Using a scanning electron microscope, the surface morphology of powders and coatings, as well as the mechanisms of erosion and corrosion, were studied. Energy-dispersive X-ray analysis and X-ray diffractometry were used to reveal the composition and elemental distribution of the feedstock powders and coatings. Because of the presence of hard phases, the composite coating shows the highest average microhardness of 1350.2 HV. The composite coating exhibits improved erosive wear resistance with an increase in erodent exposure time. The Cr3C2 coating has a reduced corrosion current density of 1.404 × 10−5 mA/cm2 and a higher charge transfer resistance of 2086.75 Ω cm2 due to passivation.  相似文献   

17.
Graphene oxide (GO) was firstly employed as nanoscale reinforcement fillers in hydroxyapatite (HA) coatings by a cathodic electrophoretic deposition process, and GO/HA coatings were fabricated on pure Ti substrate. The transmission electron microscopy observation and particle size analysis of the suspensions indicated that HA nanoparticles were uniformly decorated on GO sheets, forming a large GO/HA particle group. The addition of GO into HA coatings could reduce the surface cracks and increase the coating adhesion strength from 1.55 ± 0.39 MPa (pure HA) to 2.75 ± 0.38 MPa (2 wt.% GO/HA) and 3.3 ± 0.25 MPa (5 wt.% GO/HA), respectively. Potentiodynamic polarization and electrochemical impedance spectroscopy studies indicated that the GO/HA composite coatings exhibited higher corrosion resistance in comparison with pure HA coatings in simulated body fluid. In addition, superior (around 95% cell viability for 2 wt.% GO/HA) or comparable (80–90% cell viability for 5 wt.% GO/HA) in vitro biocompatibility were observed in comparison with HA coated and uncoated Ti substrate.  相似文献   

18.
In this paper, a study has been done on the solid-state coating of SS316 over medium-carbon steel EN8. The objective is to determine the characterization of friction-surfaced joints with process parameters such as axial load, traverse speed and rotational speed. Coating thickness and coating width depend on the traverse and rotational speeds, which decrease with the increase in axial load. A maximum bending strength of 134 MPa was obtained for the sample with highest axial load of 9 kN, rotational speed of 1600 rpm and traverse speed of 2.2 mm/s. The XRD peaks of SS316-coated EN08 sample show a considerable shift, indicating martensite (α ) formation. It has been observed that strong bonding could be obtained under specific conditions, as the substrate bonding materials are metallurgically inconsistent and have a tendency to form brittle compounds. External degradation occurred when the specimen was exposed to elevated temperatures. The results were analyzed statistically. To access its potential application corrosion studies were carried out, which shows SS316 overlaid EN8 exhibits better corrosion resistance than the substrate EN8 sample.  相似文献   

19.
The preparation of silica-doped high aspect-ratio TiO2 nanotubes and their apatite-forming ability were demonstrated in this study. The high aspect-ratio TiO2 nanotube layers were produced by electrochemical anodic oxidation of Ti in chloride-containing electrolytes. Nanotubes were doped with different concentrations of silica particles through anodization in NaCl electrolyte containing different concentrations of water glass (24 g/L or 48 g/L Na2SiO3). The biomimetic apatite deposition behavior was evaluated under simulated body fluid (SBF) with an ion concentration nearly equal to human blood plasma. The experimental results collectively demonstrate the successful silica doping of the resultant nanotube layers with significant abundant OH groups on their surfaces. The results of hydroxyapatite (HA) growth on nanotubes clearly show that the silica doping greatly enhances the fast nucleation and growth of HA, especially for the tubes in their “as-formed” amorphous state, which usually require a long time for apatite induction. The nanotubes doped with high silica content combined with an anatase or a mixture of anatase and rutile led to the formation of very thick and continuous apatite layers with a thickness of ∼7 μm in 21 days. In contrast, to the tubes doped with a low concentration of silica (grown in an electrolyte containing 24 g/L Na2SiO3), the HA deposited in the form of closely packed spheroid particles and never developed into continuous films. This effect could be attributed to the critical active-site density (silanol groups, >Si-OH), which provides the sterochemical match for apatite growth. Finally, the results of this study provide, for the first time, evidence for the dependence of HA morphology/microstructure on the crystallographic structure and the density of active sites (>Si-OH groups).  相似文献   

20.
In order to improve biological and mechanical properties of hydroxyapatite, the concept of hydroxyapatite-included nanocomposite coatings was introduced. By judiciously choosing constituent ceramics for composites preparation, the biological and mechanical performance of coatings can be tailored in order to meet various clinical requirements. The aim of this work was fabrication, development and characterization of novel hydroxyapatite-forsterite-bioactive glass nanocomposite coatings. The sol-gel technique was used to prepare hydroxyapatite-forsterite-bioactive glass nanocomposite in order to apply coating on 316L stainless steel (SS) by dip coating technique. The X-ray diffraction (XRD), scanning electron microscopy (SEM) and energy dispersive X-ray analysis (EDX) were used to investigate the phase structure, microstructure and morphology of the coating. In order to evaluate the forsterite incorporation influence upon bioactivity, the changes on the surfaces of the prepared composite coatings after the predicted days of contact with simulated body fluid (SBF) were investigated by SEM. Results showed that the suitable calcined temperature for nanocomposite coatings with different amounts of forsterite was 600 °C. At this temperature, the homogenous and crack-free coating could attach to the 316L SS substrate. The crystallite sizes of the prepared coatings were lower than 100 nm. The EDX analysis of hydroxyapatite-forsterite-bioglass, coated 316L SS surface, indicated consisting elements of prepared coatings and the substrate. During immersion in the SBF at pre-determined time intervals, apatite layer was formed and stimulation for apatite formation was increased with increase in forsterite amounts. It seems that hydroxyapatite-forsterite-bioactive glass nanocomposite coatings might be good candidates for biomedical applications.  相似文献   

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