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

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

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

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

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

To 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.

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

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.

Electrochemical corrosion study of chitosan-hydroxyapatite coated dental implant

Neutron reflection (NR) and surface tension (ST) are used to show that there are serious limitations in applying the Gibbs equation accurately to ST data of cationic surfactants to obtain the limiting surface excess, Γ(CMC), at the critical micelle concentration (CMC). Nonionic impurities in C12TABr and C16TABr have been eliminated by extensive purification to give ST - ln(concentration) (σ - ln c) curves that are convex with respect to the ln c axis around the CMC, which is characteristic of a finite micellization width. Because NR shows that the surface excess often continues to increase at and above the CMC, this finite width makes it impossible to apply the Gibbs equation to obtain Γ(CMC) without knowledge of the effect of aggregation on the activity. NR data made it possible to apply the integrated Gibbs equation to the ST below the onset of the convex region of the σ - ln c curve and show that for C12TABr the micellization width causes the ST to underestimate Γ(CMC) by 12%. Hexadecyltrimethylammonium (C16TA) sulfate is used to show that divalent ion impurities are not a significant problem. For cationic surfactants, further errors are associated with ST methods that rely on complete wetting. Measurements using ring, plate, and bubble shape analyses indicate that with ring and plate incomplete wetting occurs at or above the CMC and may extend to lower concentrations and also causes the ST-Gibbs analysis to underestimate the surface excess. In combination with ion association and preaggregation in cationic gemini surfactants, this can cause errors as large as 100% in Γ(CMC). Comparison of ellipsometry and NR for C16TAX in 0.1 M KX (X = F or Cl) shows that ellipsometry cannot, as yet, be quantitatively modeled accurately enough for surface excess determination independent of NR calibration.

The nanosecond pulsed fibre laser (NsPFL) treatment is extensively employed to distinguish hospital surgical instruments (micro-surgical forceps, surgical blades, orthopaedic drills, and high-precision laparoscopic tools), which are generally composed of stainless steel. Nevertheless, if the laser parameters are not properly optimised, this process may unintentionally provoke corrosion. Maintaining the structural integrity of these materials is essential for ensuring patient safety and minimising long-term costs. This work aims to optimise the laser scanning parameters for marking 316L stainless steel (316L SS), seeking to improve its corrosion resistance. The corrosion behaviour was assessed by using open circuit potential (OCP), potentiodynamic polarisation curves (PPc), and electrochemical impedance spectroscopy (EIS) techniques, conducted in 0.9% wt NaCl solution at a controlled temperature of 25 ± 1 °C. A comprehensive study employing optical profilometry has significantly enhanced our understanding of the corrosion micromechanisms of 316L SS, comparing specimens both with and without NsPFL treatment. Considering applications involving environments rich in chloride ions, the results indicated that the NsPFL-316L SS samples demonstrated markedly enhanced performance compared to the untreated base material after 48 h of immersion in 0.9% wt NaCl solution. This improvement is particularly noteworthy given the widespread utilisation of 316L SS in the manufacturing of surgical instruments, where corrosion resistance is of paramount importance.

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.

A surface tension study (drop volume method) was performed at 30°C on micellization and adsorbed film formation of a mixed system of a cationic Gemini-type surfactant with a cationic surfactant in comparison with another mixed system of the same Gemini-type surfactant with a nonionic surfactant. The systems studied were Bis-ammonium Gemini derived from tartaric acid dibromide salt [BAGTB, 1,4-Bis(trimethylammonio)-2,3-dodecyloxy butane dibromide] with hexadecyltrimethylammonium bromide (HTAB): BAGTB / HTAB mixed system and with n-decanoyl-N-methylglucamide (MEGA-10): BAGTB / MEGA-10 mixed system. The data of surface tension (γ ) vs logarithmic molality plots as a function of mole fraction of surfactant 2 (2 corresponds to HTAB or MEGA-10), X 2, enabled us to determine the critical micellization concentration (CMC), the surface tension at CMC (γCMC), surface excess concentration (Γt ), the mean molecular surface area (A m), the partial molecular area (PMA), and the measures of efficiency of adsorption (pC20 = -log C20) and CMC / C20 which is available for evaluating the facilitating balance between adsorption and micellization. In addition, a newly defined measure of synergism in surface activity, i.e., the minimum surface Gibbs energy (G (S)min) was employed. Based on these data, the examination of synergism in micelle formation and in surface tension reduction elucidated that the Gemini-type surfactant does not exhibit any positive synergism for either BAGTB / HTAB or BAGTB / MEGA-10 mixed systems. Most of these parameters are found to depend conspicuously on the mixing ratio for both mixtures; indicating that the state of adsorbed film is divided into three ranges of X 2; the lower, the middle and the higher. The compositions of micelles formed at CMC (Y 2) and of adsorbed film (Z 2) equilibinated with bulk solution at a fixed surface tension were estimated.

This work mainly focuses on the preparation of novel nano triphasic bioceramic composite (nanoHAP/nanoβ-TCP/ nanoTiO2) (NTPC) coating on 316L Stainless Steel (316L SS) by an electrophoretic deposition process (EPD) followed by sintering in a vacuum atmosphere for 1 h at 800 °C. This type of composite coatings is prepared for the first time owing to the amelioration of the implant by improving the surface properties such as corrosion resistance, osseointegration, and biocompatibility. The NTPC coating on 316L SS were studied by X-ray diffraction, FT-IR spectroscopy, FESEM with EDS, AFM, adhesion strength, and cell culture studies. The electrochemical performance of the NTPC coated 316L SS samples were carried out by open circuit potential (OCP)-time measurements, electrochemical impedance spectroscopic (EIS) and cyclic potentiodynamic polarization (CPP) studies in Hank’s solution. In vitro studies for these coated samples indicate their non-toxic nature in the presence of MC3T3-E1 osteoblast cell along with high proliferation. The results showed that the NTPC coatings exhibit superior biocompatibility and enhanced corrosion resistance over 316L SS.

Досліджено вплив рН і йонної сили розчину на міцелоутворення і адсорбцію бінарних сумішей гексадецилпіридиній броміду (ГДПБ) і тритону Х-100 (ТХ-100.).З використанням моделі фазового поділу (підхід Рубіна-Розена) розраховані склад змішаних міцел і адсорбційних шарів, параметри взаємодії в міцелах β m і адсорбційних шарах β σ , а також надлишкові вільні енергії міцелоутворення та адсорбції. Розрахунки складу змішаних адсорбційних шарів показали, що адсорбційний шар на межі розділу розчин – повітря у всьому інтервалі досліджених об'ємних співвідношень збагачений молекулами нейонної поверхнево-активної речовини (ПАР), що має вищу поверхневу активність. Встановлено, що збільшення йонної сили розчину призводить до зниження сили взаємодій ПАР в змішаному адсорбційному шарі. Це підтверджує електростатичну природу взаємодій у сумішах катіонних і нейонних ПАР. Ключові слова : поверхнево-активні речовини, адсорбція, бінарні суміші, міцелоутворення, адсорбційний шар

Poor wear- and corrosion-resistance of 316L SS implants are critical problems in orthopedic implants. This study aims to improve the wear- and corrosion-resistance of 316L SS through surface coating. In this study, a bilayer composite coating consisting of polyether ether ketone (PEEK) as the first layer, and titania (TiO2)- and Cu-doped mesoporous bioactive glass nanoparticles (Cu-MBGNs) were deposited as the second layer on a 316L SS via electrophoretic deposition (EPD). Scanning electron microscopy (SEM) images of the bilayer composite coating showed the distribution of TiO2 and Cu-MBGNs within the PEEK matrix. Energy dispersive spectroscopy (EDS) analysis confirmed the presence of TiO2 and Cu-MBGNs in the bilayer composite coating. Fourier transform infrared spectroscopy (FTIR) identified the functional groups attributed to the PEEK, TiO2 and Cu-MBGNs. X-ray diffraction (XRD) analysis confirmed the presence of TiO2 (anatase) and Cu-MBGNs in the bilayer composite coating. The coating exhibited a strong antibacterial effect against Staphylococcus aureus (S. aureus) and Escherichia coli (E. coli). Incorporating TiO2/Cu-MBGNs into the bilayer composite coating significantly modified the surface of 316L SS by improving the wear- and corrosion-resistance. Pin on disc test revealed that the specific wear rate of ∼(0.4570 ± 0.009) × 10-6 mm3 Nm-1 of the PEEK coating decreased to (0.0482 ± 0.007) × 10-6 mm3 Nm-1 on incorporating TiO2/Cu-MBGNs in PEEK coating under a normal load of 10 N in Dulbecco's Modified Eagle Medium (DMEM). Furthermore, electrochemical impedance spectroscopy (EIS) results revealed that the impedance value of the bilayer composite coating remained ∼4.56 × 105 Ω cm2 compared to 8.81 × 103 Ω cm2 of 316L SS after 24 h immersion in phosphate-buffered saline (PBS). Thus, this study demonstrated that the wear- and corrosion-resistance of 316L SS can be improved by incorporating TiO2/Cu-MBGNs in PEEK-based composite coatings for orthopedic applications.