scholarly journals Study of Titanium–Silver Monolayer and Multilayer Films for Protective Applications in Biomedical Devices

Molecules ◽  
2021 ◽  
Vol 26 (16) ◽  
pp. 4813
Author(s):  
Sebastián Mina-Aponzá ◽  
Sandra Patricia Castro-Narváez ◽  
Luz Dary Caicedo-Bejarano ◽  
Franklin Bermeo-Acosta
Keyword(s):  
High Efficiency ◽  
Corrosion Current ◽  
Morphological Properties ◽  
Biomedical Devices ◽  
Sessile Droplet ◽  
Biomedical Material ◽  
Tafel Polarization ◽  
Great Relevance ◽  
Current Densities ◽  
Useful Life

The search for coatings that extend the useful life of biomedical devices has been of great interest, and titanium has been of great relevance due to its innocuousness and low reactivity. This study contributes to the investigation of Ti/Ag films in different configurations (monolayer and multilayer) deposited by magnetron sputtering. The sessile droplet technique was applied to study wettability; greater film penetrability was obtained when Ag is the external layer, conferring high efficiency in cell adhesion. The morphological properties were characterized by SEM, which showed porous nuclei on the surface in the Ag coating and crystals embedded in the Ti film. The structural properties were studied by XRD, revealing the presence of TiO2 in the anatase crystalline phase in a proportion of 49.9% and the formation of a silver cubic network centered on the faces. Tafel polarization curves demonstrated improvements in the corrosion current densities of Ag/Ti/Ag/Ti/Ag/Ti/Ag/Ti and Ti/Ag compared to the Ag coating, with values of 0.1749, 0.4802, and 2.044 nA.m−2, respectively. Antimicrobial activity was evaluated against the bacteria Pseudomonas aeruginosa and Bacillus subtilis and the yeasts Candida krusei and Candida albicans, revealing that the Ti/Ag and Ag/Ti/Ag/Ti/Ag/Ti/Ag/Ti coatings exhibit promise in biomedical material applications.

scholarly journals Insights from corrosion current measurements on corrosion mechanisms in reinforced concrete and on the evaluation of other corrosion data

2019 ◽  
Vol 289 ◽  
pp. 03008 ◽  
Author(s):  
Ulrich Schneck
Keyword(s):  
Reinforced Concrete ◽  
Linear Polarization ◽  
Polarization Resistance ◽  
Corrosion Behaviour ◽  
Corrosion Current ◽  
Material Loss ◽  
Polarization Measurements ◽  
Tafel Polarization ◽  
Macro Cell ◽  
Current Densities

During the past years Tafel polarization measurements have been implemented into the scope of measurements of CITec corrosion diagnosis projects. This has created a vast database of different and corresponding corrosion parameters, such as chloride and water content in the rebar vicinity, open circuit potential, electrolyte resistance, polarization resistance (from galvanostatic pulse and linear polarization) and corrosion current from Tafel polarization measurements. Although general limitations in using these methods on macro cell systems such as reinforced concrete are known, the comparative assessment of these data has led to a better understanding of the corrosion behaviour and of specific circumstances of the structures which deviated partly from usual expectations. For instance, a low polarization resistance at high chloride content will not result necessarily in a high corrosion current, if the reinforcement in the wider vicinity of the test location is similar active, and cathodic rebar areas are either very distant or retarded by very wet concrete. So the extended range of corrosion testing gives a more precise evaluation of the corrosion situation and permits a tailored repair and maintenance concept to be found. It has also been found that the Stern-Geary equation which is often used to calculate corrosion current densities and material loss of the reinforcement from linear polarization (LPR) measurements, doesn’t seem very feasible if used on reinforced concrete structures, as there appears to be a dominant influence of macro cell corrosion over the corrosion model of a homogenous mixed electrode (for which the Stern-Geary equation applies), and the true corrosion current densities may be either larger or (very often) much smaller than those calculated from Stern-Geary. This is not a new observation, and the findings will be discussed for several project cases.

scholarly journals An electrochemical method to investigate the effects of compound composition on gold dissolution in thiosulfate solution

2020 ◽  
Vol 9 (1) ◽  
pp. 496-502 ◽  
Author(s):  
Zhaohui Zhang ◽  
Bailong Liu ◽  
Mei Wu ◽  
Longxin Sun
Keyword(s):  
Dissolution Rate ◽  
Current Density ◽  
Polarization Resistance ◽  
Electrochemical Method ◽  
Corrosion Current Density ◽  
Corrosion Potential ◽  
Corrosion Current ◽  
Gold Dissolution ◽  
Tafel Polarization ◽  
Edta Solution

AbstractThe electrochemical behavior of gold dissolution in the Cu2+–NH3–S2O32−–EDTA solution has been investigated in detail by deriving and analyzing the Tafel polarization curve, as this method is currently widely implemented for the electrode corrosion analysis. The dissolution rate of gold in Cu2+–NH3–S2O32−–EDTA solution was determined based on the Tafel polarization curves, and the effects of various compound compositions in a Cu2+–NH3–S2O32−–EDTA mixture on the corrosion potential and corrosion current density were analyzed. The results showed that the corrosion potential and polarization resistance decreased, whereas the corrosion current density increased for certain concentrations of S2O32−–NH3–Cu2+ and EDTA, indicating that the dissolution rate of gold had changed. The reason for promoting the dissolution of gold is also discussed.

scholarly journals Microstructure of Al-5Cu-1Li-0.6Mg-0.5Ag-0.5Mn Alloys

Metals ◽  
2020 ◽  
Vol 11 (1) ◽  
pp. 37
Author(s):  
Wenzheng Chen ◽  
Wenlong Zhang ◽  
Dongyan Ding ◽  
Daihong Xiao
Keyword(s):  
Mechanical Properties ◽  
Corrosion Current Density ◽  
Corrosion Potential ◽  
Aging Treatment ◽  
Corrosion Current ◽  
Homogenization Temperature ◽  
Tafel Polarization ◽  
Al2cu Phase ◽  
Different Temperatures ◽  
Microstructural Optimization

Microstructural optimization of Al-Li alloys plays a key role in the adjustment of mechanical properties as well as corrosion behavior. In this work, Al-5Cu-1Li-0.6Mg-0.5Ag-0.5Mn alloy was homogenized at different temperatures and holding times, followed by aging treatment. The microstructure and composition of the homogenized alloys and aged alloys were investigated. There were Al7Cu4Li phase, Al3Li phase, and Al2CuLi phases in the homogenized alloys. The Al7Cu4Li phase was dissolved with an increase in homogenization temperature and holding time. Al2Cu phase and Al2CuLi phase coarsened during the homogenization process. The alloy homogenized at 515 °C for 20 h was subjected to a two-stage aging treatment. Peak-age alloy, which had gone through age treatment at 120 °C for 4 h and 180 °C for 6 h, was mainly composed of α-Al, Al20Cu2Mn3, Al2CuLi, Al2Cu, and Al3Li phases. Tafel polarization of the peak-age alloys revealed the corrosion potential and corrosion current density to be −779 mV and 2.979 μA/cm2, respectively. The over-age alloy had a more positive corrosion potential of −658 mV but presented a higher corrosion current of 6.929 μA/cm2.

BIO-CORROSION RESISTANCE AND BIOCOMPATIBILITY OF A ZrTi-BASED BMGMC AS POTENTIAL HARD TISSUE IMPLANTS

2013 ◽  
Vol 27 (19) ◽  
pp. 1341029
Author(s):  
XIAOBO HUANG ◽  
JIAOJUAN ZOU ◽  
CHAN WANG ◽  
RUIQIANG HANG ◽  
JUNWEI QIAO ◽  
...  
Keyword(s):  
Cell Culture ◽  
Corrosion Resistance ◽  
Reference Material ◽  
Corrosion Current ◽  
Electrochemical Measurements ◽  
Ti Alloy ◽  
Cellular Viability ◽  
Hard Tissue ◽  
Cellular Behaviors ◽  
Current Densities

In this study, we compared the bio-corrosion resistance and biocompatibility of a ZrTi -based BMGMC ( Zr 58.5 Ti 14.3 Ni 4.9 Cu 6.1 Nb 5.2 Be 11.0). The Ti - 6Al - 4V alloy was used as a reference material. By utilizing the electrochemical measurements and M3T3 cell culture, the corrosion resistance and biocompatibility of this BMGMC were evaluated. The BMGMC displayed high positive corrosion potentials and low corrosion current densities, which indicated that this material exhibited a highly improved corrosion resistance than the Ti alloy. The cells could adhere on the surface of this BMGMC and exhibited improved cellular behaviors, such as cellular viability and cytoskeketal structure. In summary, the ZrTi -based BMGMC showed great potential for applications in the hard tissue implants.

Hydrogen failure sensitivity of A516-Gr70 and API 5L-X70 steels in sour environments

2015 ◽  
Vol 62 (5) ◽  
pp. 294-300 ◽  
Author(s):  
H Taheri ◽  
A Dolati ◽  
Behrooz Beidokhti
Keyword(s):  
Oil And Gas ◽  
Corrosion Current ◽  
Technical Committee ◽  
Committee Report ◽  
Three Solutions ◽  
Content Type ◽  
Hydrogen Induced Cracking ◽  
Two Temperatures ◽  
Current Densities ◽  
Api 5L X70 Steel

Purpose – This paper aims to clarify the corrosion behavior of two famous structural steels in sour environment. These steels have a vast application in oil and gas industries. The study aims to find the effect of different concentrations of sour solution on the origin of crack in these steels. Design/methodology/approach – After preparation of specimens, different sour solutions were made using the synthetic brine (according to National Association of Corrosion Engineers [NACE], Technical Committee Report 1D182) and various amounts of Na2S.9H2O and CH3COOH. The polarization test was done by Potansiostat apparatus model Zahner-IM6 at two temperatures, 25°C and 50°C. The corrosion current densities were obtained from the polarization curves. Finally, the corrosion products and hydrogen-induced cracking (HIC) were investigated by Tescan Vega II XMU scanning electron microscope (SEM) linked to a Rontec energy-dispersive X-ray spectroscopy (EDS) system. Findings – API 5L-X70 steel showed smaller corrosion current values than A516-Gr70 steel. The HIC cracks propagated parallel to the surface of A516-Gr70 steel in three solutions and confirmed the inappropriateness of this steel for sour environment applications. Originality/value – This paper studies the effect of sour environment on the behavior of two famous industrial steels at two temperatures by new method.

scholarly journals Troilite (FeS) Oxidation in the Presence of a Newly Synthesized TRIS-based Base

2019 ◽  
Vol 70 (7) ◽  
pp. 2639-2642
Author(s):  
Madalina Ionela Duinea ◽  
Geta Carac ◽  
Irina Daniela Dabuleanu ◽  
Mihaela Alexandra Petcu ◽  
Laura Gabriela Sarbu ◽  
...  
Keyword(s):  
Cyclic Voltammetry ◽  
Schiff Base ◽  
Optical Microscopy ◽  
Quantum Chemical Calculations ◽  
Potentiodynamic Polarization ◽  
Quantum Chemical ◽  
Corrosion Current ◽  
Inhibitory Effect ◽  
Oxidative Dissolution ◽  
Current Densities

The effect of a newly synthesized TRIS-based Schiff base (XC) on the oxidative dissolution of FeS in air-equilibrated solutions with pH 2.26 and temperature of 27�C was investigated by Potentiodynamic polarization, Cyclic Voltammetry, Optical Microscopy and quantum chemical calculations. The XC concentration varied between 0 and 0.52 mM. It was observed that XC decreases the corrosion current densities of the oxidative dissolution of FeS. Our results indicate that the inhibitory effect of XC is due to its adsorption on the FeS surface.

Testing of solid oxide cells at high current densities

2021 ◽  
Vol 0 (0) ◽  
Author(s):  
André Weber
Keyword(s):  
Single Cell ◽  
High Performance ◽  
High Efficiency ◽  
Electrochemical Impedance ◽  
Single Cells ◽  
Operating Conditions ◽  
Solid Oxide ◽  
Current Densities ◽  
Cell Testing ◽  
The Impact

Abstract Solid Oxide Cells (SOCs) have gained an increasing interest as electrochemical energy converters due to their high efficiency, fuel flexibility and ability of reversible fuel cell/electrolysis operation. During the development process as well as in quality assurance tests, the performance of single cells and cell stacks is commonly evaluated by means of current/voltage- (CV-) characteristics. Despite of the fact that the measurement of a CV-characteristic seems to be simple compared to more complex, dynamic methods as electrochemical impedance spectroscopy or current interrupt techniques, the resulting performance strongly depends on the test setup and the chosen operating conditions. In this paper, the impact of different single cell testing environments and operating conditions on the CV-characteristic of high performance cells is discussed. The influence of cell size, contacting and current collection, contact pressure, fuel flow rate and composition on the achievable cell performance is presented and limitations arising from the test bed and testing conditions will be pointed out. As today’s high performance cells are capable of delivering current densities of several ampere per cm2 a special emphasis will be laid on single cell testing in this current range.

scholarly journals A microstructural and corrosion resistance study of (Zr, Si, Ti)N-Ni coatings produced through co-sputtering

DYNA ◽  
2018 ◽  
Vol 85 (207) ◽  
pp. 192-197 ◽  
Author(s):  
Estrella Natali Borja-Goyeneche ◽  
Jhon Jairo Olaya-Florez
Keyword(s):  
Corrosion Resistance ◽  
Nickel Content ◽  
Corrosion Current ◽  
Nacl Solution ◽  
X Ray Diffraction ◽  
X Ray ◽  
X Ray Scattering ◽  
Current Densities ◽  
Fcc Phase

This work researches the influence of the nickel content on the structural and anticorrosive properties of ZrSiTiN films deposited by means of reactive co-sputtering on alloys of Ti6Al4V. The morphology and structure were analyzed by means of scanning electron microscopy (SEM) and X-ray diffraction (XRD), and the chemical composition was identified via X-ray scattering spectroscopy (EDS). The corrosion resistance was studied using potentiodynamic polarization (PP) tests employing a 3.5% by weight NaCl solution. In the films, an increase of Ni up to 6.97 at% was observed, while in XRD the FCC phase of (Zr, Ti) N was identified, with a mixed orientation in planes (111) and (200), which tended to diminish with the increase of Ni. Finally, with the addition of Ni, the corrosion current densities were reduced from 5.56 𝑥 10−8 to 2.64 𝑥 10−9 𝐴/𝑐m2. The improvement in the corrosion resistance is due to the effect of the Ni on the microstructure of the system (Zr, Ti) N, which can improve the quality of the passive film and prevent crystalline defects and corrosion zones.

scholarly journals Early-Stage Growth Mechanism and Synthesis Conditions-Dependent Morphology of Nanocrystalline Bi Films Electrodeposited from Perchlorate Electrolyte

Nanomaterials ◽  
2020 ◽  
Vol 10 (6) ◽  
pp. 1245 ◽  
Author(s):  
Daria Tishkevich ◽  
Sergey Grabchikov ◽  
Tatiana Zubar ◽  
Denis Vasin ◽  
Sergei Trukhanov ◽  
...  
Keyword(s):  
Growth Mechanism ◽  
Early Stage ◽  
Abnormal Behavior ◽  
Morphological Properties ◽  
Synthesis Conditions ◽  
Force Microscopy ◽  
Atomic Force ◽  
Galvanostatic Regime ◽  
Current Densities ◽  
Deposition Duration

Bi nanocrystalline films were formed from perchlorate electrolyte (PE) on Cu substrate via electrochemical deposition with different duration and current densities. The microstructural, morphological properties, and elemental composition were studied using scanning electron microscopy (SEM), atomic force microscopy (AFM), and energy-dispersive X-ray microanalysis (EDX). The optimal range of current densities for Bi electrodeposition in PE using polarization measurements was demonstrated. For the first time, it was shown and explained why, with a deposition duration of 1 s, co-deposition of Pb and Bi occurs. The correlation between synthesis conditions and chemical composition and microstructure for Bi films was discussed. The analysis of the microstructure evolution revealed the changing mechanism of the films’ growth from pillar-like (for Pb-rich phase) to layered granular form (for Bi) with deposition duration rising. This abnormal behavior is explained by the appearance of a strong Bi growth texture and coalescence effects. The investigations of porosity showed that Bi films have a closely-packed microstructure. The main stages and the growth mechanism of Bi films in the galvanostatic regime in PE with a deposition duration of 1–30 s are proposed.

scholarly journals Discrete Cosine Transformation and Temporal Adjacent Convolutional Neural Network-Based Remaining Useful Life Estimation of Bearings

2020 ◽  
Vol 2020 ◽  
pp. 1-14
Author(s):  
Yu Pang ◽  
Limin Jia ◽  
Zhan Liu
Keyword(s):  
Neural Network ◽  
Convolutional Neural Network ◽  
High Efficiency ◽  
Remaining Useful Life ◽  
Discrete Cosine Transformation ◽  
Time Frequency ◽  
Cosine Transformation ◽  
Useful Life ◽  
Spectrum Coding ◽  
Low Dimensional

In recent years, several time-frequency representation (TFR) and convolutional neural network- (CNN-) based approaches have been proposed to provide reliable remaining useful life (RUL) estimation for bearings. However, existing methods cannot tackle the spatiotemporal continuity between adjacent TFRs since temporal proposals are considered individually and their temporal dependencies are neglected. In allusion to this problem, a novel prognostic approach based on discrete cosine transformation (DCT) and temporal adjacent convolutional neural network (TACNN) is proposed. Wavelet transform (WT) is applied to effectively map the raw signals to the time frequency domain. Considering the high load and complexity of model computation, bilinear interpolation and DCT algorithm are introduced to convert TFRs into low-dimensional DCT spectrum coding matrix with strong sparsity. Furthermore, the TACNN model is proposed which is capable of learning discriminative features for temporal adjacent DCT spectrum coding matrix. Effectiveness of the proposed method is verified on the PRONOSTIA dataset, and experiment results show that the proposed model is able to realize automatic high-precision estimation of bearings RUL with high efficiency.

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