Corrosion Resistance Of 316L SS Research Articles

Electrochemical corrosion study of chitosan-hydroxyapatite coated dental implant

Chitosan (Ch) is a naturally occurring biocompatible and bio-degradable material with high corrosion protective capacities for metals in various corrosive media. Hydroxyapatite (HA) is a significant biodegradable and bioactive material. In the present work, chitosan-hydroxyapatite (Ch-HA) composite coatings with various concentrations of chitosan were made on 316L stainless steel (316L SS) using sol–gel dip coating technique. The coatings were characterized by X-ray diffraction (XRD), FTIR, SEM, and electrochemical measurements. The surface morphology results (SEM) of coated implants exposed the fairly dense microstructures having uniformity without cracks and pores indicating that coating was successfully deposited. From electrochemical analyses, it was observed that the value of corrosion current density and the corrosion rate decreased from 6.03 to 0.15 and 5.56-0.13 respectively indicating that 1.5gCh-HA is the best coating concentration. The electrochemical results demonstrated an improvement in the corrosion resistance of 316L SS than the bare one. The decrease in slope and loop area of cyclic voltammograms reveals about improvement in corrosion resistance. This increment in corrosion resistance of the Ch-HA coated SS implant in the artificial saliva is as 1.5gCh-HA > 2gCh-HA >1gCh-HA >0.5gCh-HA. Furthermore, Ch-HA coatings revealed appropriate adhesion with 316L SS substrate for its use in dental implants.

Effect of multilayer CrN/CrAlN coating on the corrosion and contact resistance behavior of 316L SS bipolar plate for high temperature proton exchange membrane fuel cell

• The CrN/CrAlN coating greatly improved the contact angle and corrosion resistance of 316L SS. • The CrN/CrAlN coating reduced the ICR and increased the surface conductivity of 316LSS. • Single fuel cell test assembled with CrN/CrAlN coating enhanced the performance of HT-PEMFC. Stainless steels have received wide attention as a substitute material for bipolar plates in high temperature proton exchange membrane fuel cell (HT-PEMFC). In the present work, the CrN, CrAlN and multilayer CrN/CrAlN coatings were deposited on 316L SS to increase the corrosion resistance and decrease the interfacial contact resistance. The deposited coatings exhibited face centered cubic phase structure and it was verified from the X-ray diffraction pattern. X-ray photo electron spectroscopy results showed the formation of both CrN and CrAlN layers on 316L SS. CrN/CrAlN coating is more helpful in water management due to low surface roughness and high contact angle in the HT-PEMFC environment. The corrosion resistance behavior of all the samples were studied in 85% H 3 PO 4 solution at 140 °C purged with H 2 (HT-PEMFC anode) and O 2 (HT-PEMFC cathode) gases. The results showed that all the coatings considerably improved the performance of 316L SS and superior corrosion resistance was observed for CrN/CrAlN multilayer coating, whose protective efficiency was 98.12% and 96.14% in the two simulated HT-PEMFC environments. The results of electrochemical impedance spectroscopic studies demonstrated higher impedance for CrN/CrAlN coating. Surface morphological studies performed after corrosion studies revealed that protection ability of CrN/CrAlN coating still remained acceptable. A very low interfacial contact resistance value of 6 mΩ cm 2 at 140 N/cm 2 was observed for CrN/CrAlN coating. Moreover, after corrosion studies, the interfacial contact resistance value of CrN/CrAlN coated 316L was much lower than that of CrN and CrAlN coatings due to the increased oxidation resistance. The maximum power density of about 0.93 W/cm 2 at 2 A/cm 2 and output voltage of 0.96 V was observed for CrN/CrAlN coating.

Study on Mechanism of Structure Angle on Microstructure and Properties of SLM-Fabricated 316L Stainless Steel.

In this study, seven 316L stainless steel (316L SS) bulks with different angles (0°, 15°, 30°, 45°, 60°, 75°, and 90°) relative to a build substrate were built via selective laser melting (SLM). The influences of different angles on the metallography, microstructure evolution, tensile properties, and corrosion resistance of 316L SS were studied. The 0° sample showed the morphology of corrugated columnar grains, while the 90° sample exhibited equiaxed grains but with a strong <101> texture. The 60° sample had a good strength and plasticity: the tensile strength with 708 MPa, the yield strength with 588 MPa, and the elongation with 54.51%. The dislocation strengthening and grain refinement play a vital role in the mechanical properties for different anisotropy of the SLM-fabricated 316L SS. The 90° sample had greater toughness and corrosion resistance, owing to the higher volume fraction of low-angle grain boundaries and finer grains.

Corrosion behavior of 316L stainless steel manufactured by laser powder bed fusion (L-PBF) in an alkaline solution

This study investigates the microstructure and electrochemical behavior of 316 L processed through laser powder bed fusion (L-PBF) and the related commercial wrought counterpart in the concrete pore solution (0.9 M NaOH + 0.9 wt% NaCl). Analyses showed that the L-PBF method did not decline the corrosion resistance of 316L SS in the alkaline solution. Even in some cases, L-PBF processed alloy showed better electrochemical behavior compared the wrought alloy. Microscopy evaluation indicated that L-PBF processed specimen showed an ultrafine cellular/columnar structure with the more uniform morphology at the higher magnifications compared to the wrought sample, possibly because of the excessive cooling rate of the L-PBF process. Besides, electrochemical studies revealed that corrosion current density related to the L-PBF processed sample reported about one-third of wrought counterpart. Also, L-PBF processed alloy identified the lower defect density compared to the wrought one. The better corrosion performance of the L-PBF processed 316L SS could be related to the fabrication method of the additively manufactured samples, which hindered the presence of detrimental phases and more stability of the passive film.

Enhancement of corrosion resistance in MSF desalination plants during acid cleaning operation by cationic surfactant

The influence of cationic surfactant benzethonium chloride (BCCS) on the corrosion resistance of 316L SS in MSF desalination plants during the scales removing by sulfuric acid solution has been studied. The investigations involved electrochemical polarization, weight loss, surface tension, conductivity, surface characterizations and quantum chemical studies. Results confirmed that the cationic surfactant plays a great role in retarding the corrosion 316L SS in 1.0 M H2SO4. The highest efficiency 92.3% is obtained at 3.5 × 10−4 M of BCCS. The maximum inhibition efficiency is around the critical micelle concentration (CMC) of BCCS. Temkin isotherm describes by high precise the adsorption of BCCS on 316L SS. Polarization curves explained that BCCS is a mixed inhibitor. Theoretical quantum chemistry was utilized to support the effectiveness of BCCS compound.

Orthopaedic bioactive glass/chitosan composites coated 316L stainless steel by green electrophoretic co-deposition

Single-step electrophoretic co-deposition (EPD) technique was used to enhance the bioactivity of the 316L stainless steel (316L SS) surface by bioactive glass/chitosan composite coatings. Two modified glass compositions of Bioglass® by the addition of boron were utilized to prepare such composite layers, and the Bioglass® was synthesized for comparison. Different EPD coating factors were studied. Namely, voltage, time, glass powder, and chitosan concentrations, to obtain crack-free and good adhesive coatings. The achieved surfaces were characterized by SEM/EDX, TGA, XRD and FTIR and their wettability and roughness were investigated. The in vitro bioactivity of the coated metals was compared in simulated body fluid (SBF) and Dulbecco's modified eagle medium (DMEM) for up to 15days. The electrochemical corrosion behavior of the coated metals was evaluated using potentiodynamic polarisation and impedance techniques in the two biological solutions SBF and DMEM at 37°C. The results showed that the achieved coatings were uniform, homogenous and crack-free with desirable thickness. Moreover, the coating layers were exhibited by very high wettability, and their roughness values ranged from 170±18 to 234±17μm. The in vitro bioactivities proved that the coating layers represented a better ability to form hydroxyapatite crystals on their surfaces in SBF than in DMEM. The corrosion resistance of 316L SS was improved by the bioactive composite coatings.

Electrochemical Properties of Niobium Modified AISI316L Stainless Steel Bipolar Plates for Direct Formic Acid Fuel Cell

AbstractTo ameliorate the corrosion resistance and surface electrical conductivity of AISI316L stainless steel (316L SS) as bipolar plates for direct formic acid fuel cell (DFAFC), a niobium diffusion layer has been successfully prepared on 316L SS substrate via the plasma surface diffusion alloying (PSDA) technique. The niobium modified AISI316L stainless steel (Nb‐316L SS) has a compact and successive niobium diffusion layer with a lower interfacial contact resistance (ICR) compared with bare 316L SS. The electrochemical behaviors of Nb‐316L SS in simulated varied anode (0.05M H2SO4 + 2 ppm HF + xM formic acid (x = 2, 5, 10 and 15) solution at 50 °C) and cathode (0.05M H2SO4 + 2 ppm HF solution at 50 °C, bubbled with air) DFAFC environments are systematically studied. The results show that the corrosion resistance of 316L SS is distinctly bettered in both anode and cathode environments of DFAFC after the PSDA modification. After 4 h potentiostatic polarization tests, the ICR of bare and Nb‐316L SS have increased at the clamping force of 140 N cm−2, but the increasing amplitude of the ICR for Nb‐316L SS is much smaller than that of bare 316L SS.

Performance of niobium nitride-modified AISI316L stainless steel as bipolar plates for direct formic acid fuel cells

A niobium nitride diffusion layer (Nb–N layer) has been synthesized via the plasma surface diffusion alloying (PSDA) technique on the surface of AISI316L stainless steel (316L SS), which is used as bipolar plates of direct formic acid fuel cells (DFAFCs). The niobium nitride-modified AISI316L stainless steel (Nb–N 316L SS) has a compact and successive niobium nitride diffusion layer with a single cubic NbN phase. The corrosion resistance and surface conductivity of Nb–N 316L SS are systematically investigated in the simulated anodic environments of DFAFC (0.05 M H2SO4 + 2 ppm HF + x M formic acid (x = 2, 5, 10 and 15) at 50 °C). The potentiodynamic and potentiostatic polarization tests demonstrate that the corrosion resistance of 316L SS is distinctly ameliorated in the simulated DFAFC environments after the PSDA modification. The interfacial contact resistances (ICR) of Nb–N 316L SS are much smaller than those of bare 316L SS before and after potentiostatic polarization tests.

Biocompatibility of sol-gel hydroxyapatite-titania composite and bilayer coatings

Titania-Hydroxyapatite (TiO2/HAP) reinforced coatings are proposed to enhance the bioactivity and corrosion resistance of 316L stainless steel (316L SS). Herein, spin- and dip-coating sol-gel processes were investigated to construct two kinds of coatings: TiO2/HAP composite and TiO2/HAP bilayer. Physicochemical characterization highlighted the bioactivity response of the TiO2/HAP composite once incubated in physiological conditions for 7days whereas the TiO2/HAP bilayer showed instability and dissolution. Biological analysis revealed a failure in human stem cells adhesion on TiO2/HAP bilayer whereas on TiO2/HAP composite the presence of polygonal shaped cells, possessing good behaviour attested a good biocompatibility of the composite coating. Finally, TiO2/HAP composite with hardness up to 0.6GPa and elastic modulus up to 18GPa, showed an increased corrosion resistance of 316L SS. In conclusion, the user-friendly sol-gel processes led to bioactive TiO2/HAP composite buildup suitable for biomedical applications.

The effect of surface treatment AISI 316L welded joints on its corrosion behaviour in chloride solution

Investigation of different surface treatment effects on the corrosion resistance of AISI 316L stainless steel welded joints is presented in this paper. Research was conducted using gravimetric tests in 6 wt. % ferric chloride solution as well as polarization measurements in 1 mol dm-3 NaCl solution. Additionally, the mechanism of corrosion attack developed on the steel surface was analyzed by optical microscopy, scanning electron microscopy and energy dispersive X-ray analysis. Prior to the measurements, the surface of stainless steel welded joints samples was treated by ultrasonic cleaning in ethanol (sample A), ultrasonic cleaning and pickling (sample B), ultrasonic cleaning, pickling and passivation (sample C) and grinding, polishing, ultrasonic cleaning, pickling and passivation (sample D). The results have shown that the corrosion resistance of 316L SS welded joints has increased due to the surface treatment.

Corrosion Studies of Thermal Sprayed HA and HA+Al2O3-TiO2 Coatings on 316L Stainless Steel

This study was performed to evaluate corrosion behavior of thermal sprayed hydroxyapatite (HA) and hydroxyapatite+Alumina-titania (HA+Al2O3-TiO2) coatings on 316L stainless steel (316L SS) implant material. HA powder was mixed with Al2O3-TiO2 in 60:40 wt. % for depositing HA+Al2O3-TiO2 composite coatings. The coatings were characterized by X-ray diffraction (XRD) and scanning electron microscopy (SEM)/energy-dispersive X-ray spectroscopy (EDS) analyses. Tafel and Potentiodynamic techniques were used to access the in-vitro corrosion behavior of two coatings and un-coated 316L SS in Hank’s solution. The corrosion resistance of 316L SS showed a significant improvement after the deposition of coatings.

Fabrication of nanoporous Sr incorporated TiO2 coating on 316L SS: Evaluation of bioactivity and corrosion protection

In this paper, nanoporous TiO2 and Sr-incorporated TiO2 coated 316L SS were prepared by sol–gel methodology. The effect of Sr incorporation into TiO2 coating on bioactivity and corrosion resistance was investigated. Attenuated total reflectance–Fourier transform infrared (ATR–FTIR) spectroscopy, X-ray diffraction analysis (XRD), atomic force microscopy (AFM), scanning electron microscopy (SEM) and energy dispersive X-ray analysis (EDX) results obtained after in vitro bioactivity test confirm the excellent growth of crystalline hydroxyapatite (HAp) over nanoporous Sr-incorporated TiO2 coated 316L SS which may be attributed to the slow and steady release of Sr ions from the coatings. The electrochemical evaluation of the coatings confirms that Sr-incorporated TiO2 coating offer excellent protection to 316L SS by acting as a barrier layer. The results showed that the incorporation of Sr enhanced both bioactivity and corrosion resistance of 316L SS. Hence Sr-incorporated TiO2 coated 316L SS is a promising material for orthopaedic implant applications.

Pitting corrosion of 316L stainless steel under low stress below yield strength

Pitting corrosion of 316L stainless steel (316L SS) under various stress was studied by potentiodynamic polarization, electrochemical impedance spectroscopy (EIS) and Mott-Schottky (M-S) analysis in 3.5% NaCl solution. The results of polarization curves show that, with the increase of the stress, the pitting potentials and the passive current density markedly decrease fi rstly (180 MPa), and then increase greatly (200 MPa). The corresponding surface morphologies of the samples after the polarization test well correspond to the results. Mott-Schottky analysis proved the least Cl− adsorbed to the surface of passive fi lm with more positive fl at potential, indicating that a moderate stress could increase the pitting corrosion resistance of 316L SS in 3.5% NaCl solution.

The Influence of pH Values on Corrosion Properties of 316L Stainless Steel in Simulated Circulating Cooling Water

Effects of pH values on corrosion properties of 316L stainless steel were investigated to clarify the usability of 316L SS in circulating cooling water system. The polarization, EIS and Mott-Schottky measurements showed the superior corrosion resistance of 316L SS in the simulated cooling water solution with NaCl+Na2SO4. The Fe hydroxides and oxides products resulted in the passive film of 316L SS thicker during the cooling water convection, as the pH increased from 6.5 to 9.0.

Study of CNx films on 316L stainless steel for orthodontic application

In order to improve the friction property and corrosion resistance of 316L stainless steel (316LSS) in orthodontic application, carbon nitride (CNx) films were synthesized by using IBAD technique at a set of assisted N ion beam currents. X-ray photoelectron spectroscopy and Raman spectroscopy were used to characterize the bonding state and the microstructure of the CNx films. Results of tribological tests indicated that the 316LSS coated by CNx films exhibited lower friction coefficients than the uncoated one both in air and in artificial saliva. The electrochemical tests in artificial saliva confirmed that the corrosion resistance of 316LSS was evidently improved after coated with CNx films.

Comparative Study of Corrosion in Physiological Serum of Ceramic Coatings Applied on 316L Stainless Steel Substrate

In recent years the use of ceramic coatings to reduce metallic corrosion has been greatly improved. It has been proved by several studies that coating of TiO2, ZrO2, SiO2, and other oxides or mixed oxides provide efficient protection against the corrosion of stainless steel in different media. In this work, alumina and zirconia films were obtained by electrophoretic deposition to investigate their use as protective coatings of 316L-Stainless steel for prostheses and dental implants. These were characterized by scanning electron microscopy (SEM), grazing incidence X-ray diffraction (GID), and atomic force microscopy (AFM). The corrosion behaviour in Hank’s solution at room temperature was studied using a potentiodynamic polarization technique. The electrochemical measurements showed a high corrosion resistance of 316L-SS coated by both types of ceramic film. The best behaviour was presented by the alumina coating. The morphologies of the corroded films showed that the alumina and zirconia films presented low damage with little pitting corrosion compared with the uncoated 316L-SS.

05/02069 A non-interior point approach to optimum power flow solution

A niobium nitride diffusion layer (Nb–N layer) has been synthesized via the plasma surface diffusion alloying (PSDA) technique on the surface of AISI316L stainless steel (316L SS), which is used as bipolar plates of direct formic acid fuel cells (DFAFCs). The niobium nitride-modified AISI316L stainless steel (Nb–N 316L SS) has a compact and successive niobium nitride diffusion layer with a single cubic NbN phase. The corrosion resistance and surface conductivity of Nb–N 316L SS are systematically investigated in the simulated anodic environments of DFAFC (0.05 M H2SO4 + 2 ppm HF + x M formic acid (x = 2, 5, 10 and 15) at 50 °C). The potentiodynamic and potentiostatic polarization tests demonstrate that the corrosion resistance of 316L SS is distinctly ameliorated in the simulated DFAFC environments after the PSDA modification. The interfacial contact resistances (ICR) of Nb–N 316L SS are much smaller than those of bare 316L SS before and after potentiostatic polarization tests.

H2SO4 as a passivating medium on the localised corrosion resistance of surgical 316L SS metallic implant and its effect on hydroxyapatite coatings

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.