Investigating the Corrosion Behaviour of Corrosion Resistant Alloys in Solutions Containing Dilute Fluoride

CORROSION ◽  
10.5006/3736 ◽  
2021 ◽  
Author(s):  
Jeffrey Henderson ◽  
Sridhar Ramamurthy ◽  
Fraser Filice ◽  
Mark Biesinger ◽  
David Shoesmith ◽  
...  
Keyword(s):  
Corrosion Behaviour ◽  
Fluoride Ion ◽  
Potential Range ◽  
Acidic Media ◽  
Fluoride Ions ◽  
Film Stability ◽  
Corrosion Resistant ◽  
Film Instability ◽  
Static Polarization ◽  
Trace Concentrations

The ability of fluoride ions, in trace concentrations, to promote film instability and transpassive dissolution was shown for several corrosion resistant alloys. While the addition of fluoride ion was found to decrease the transpassive dissolution potential by approximately 0.1 V, the decrease was particularly pronounced in mildly acidic media (pH 5). Results suggest that the decreased potential range of stability for the heavily-relied-upon Cr(III)-rich oxide film is a concern in the presence of oxidizing impurities which may push the corrosion potentials toward the transpassive region. The decreased potential range of passive film stability was observed using both dynamic and static polarization experiments and supported by solution and surface analyses.

scholarly journals Comparative Study of Strength and Corrosion Resistant Properties of Plain and Blended Cement Concrete Types

2017 ◽  
Vol 2017 ◽  
pp. 1-14 ◽  
Author(s):  
Velu Saraswathy ◽  
Subbiah Karthick ◽  
Han Seung Lee ◽  
Seung-Jun Kwon ◽  
Hyun-Min Yang
Keyword(s):  
Water Absorption ◽  
Corrosion Behaviour ◽  
Blended Cement ◽  
Effective Porosity ◽  
Chloride Diffusion ◽  
Chloride Diffusion Coefficient ◽  
Chloride Permeability ◽  
Corrosion Resistant ◽  
Lower Corrosion Rate ◽  
Portland Slag Cement

The relative performances of mechanical, permeability, and corrosion resistance properties of different concrete types were compared. Concrete types were made from ordinary Portland cement (OPC), Portland pozzolana cement (PPC), and Portland slag cement (PSC). Compressive strength test, effective porosity test, coefficient of water absorption, short-term accelerated impressed voltage test, and rapid chloride permeability test (RCPT) were conducted on M30 and M40 grades of concrete designed with OPC, PPC, and PSC cements for 28- and 90-day cured concrete types. Long-term studies such as microcell and electrochemical evaluation were carried out to understand the corrosion behaviour of rebar embedded in different concrete types. Better corrosion resistant properties were observed for PSC concrete by showing a minimum current flow, lowest free chloride contents, and lesser porosity. Besides, PSC concrete has shown less coefficient of water absorption, chloride diffusion coefficient (CDC), and lower corrosion rate and thereby the time taken for initiation of crack extended.

Si-corrole-based fluoride fluorometric turn-on sensor

2020 ◽  
Vol 24 (05n07) ◽  
pp. 929-937
Author(s):  
Ewa Jaworska ◽  
Fabrizio Caroleo ◽  
Corrado Di Natale ◽  
Krzysztof Maksymiuk ◽  
Roberto Paolesse ◽  
...  
Keyword(s):  
Optical Sensors ◽  
Linear Dependence ◽  
Porous Membrane ◽  
Ion Concentration ◽  
Fluoride Ion ◽  
Fluoride Ions ◽  
Acidic Solutions ◽  
Turn On ◽  
New Type ◽  
Receptor Layer

We present here a new type of fluoride ion optode, constituted by a highly lipophilic PVDF porous membrane modified with a liquid receptor layer containing the emission-active Si corrole F[Formula: see text] selective ionophore. For the optimized composition of the receptor layer, in acidic solutions an increase of Si-corrole emission was observed by increasing fluoride ion concentration, a behavior different from most porphyrinoid-based optical sensors. An observed linear dependence of the Si corrole emission intensity (read at 635 nm) was within the range 10[Formula: see text] to 10[Formula: see text] M of fluoride ions.

scholarly journals Mechanical and Functional Properties of a Novel Apatite-Ionomer Cement for Prevention and Remineralization of Dental Caries

Materials ◽  
2019 ◽  
Vol 12 (23) ◽  
pp. 3998 ◽  
Author(s):  
Rie Imataki ◽  
Yukari Shinonaga ◽  
Takako Nishimura ◽  
Yoko Abe ◽  
Kenji Arita
Keyword(s):  
Fracture Toughness ◽  
Functional Properties ◽  
Glass Ionomer Cement ◽  
Pediatric Dentistry ◽  
Cement Matrix ◽  
Fluoride Ion ◽  
Ion Release ◽  
Fluoride Ions ◽  
Acid Buffer ◽  
Ionomer Cement

Especially in pediatric dentistry, prevention by the control of initial lesions prior to cavitation is very important, and application of a pit and fissure sealant is essential to achieve this. Numerous reports have suggested that resin-based sealants are inferior to sealants based on glass-ionomer cement (GIC), because of GIC’s many advantages, such as fluoride ion release properties and its good adhesion to tooth structures. However, the use of GIC is impeded due to its low flexural strength and fracture toughness. In this paper, we developed and characterized an apatite-ionomer cement (AIC) that incorporates hydroxyapatite (HAp) into the GIC; this development was aimed at not only reinforcing the flexural and compressive strength but also improving some functional properties for the creation of the material suitable for sealant. We examined the influence of differences in the compounding conditions of GIC powder, liquid, and HAp on flexural and compressive strengths, fracture toughness, fluoride ion release property, shear bond strength to bovine enamel, surface pH of setting cements, and acid buffer capability. These methods were aimed at elucidating the reaction mechanism of porous spherical-shaped HAp (HApS) in AIC. The following observations were deduced. (1) HAp can improve the mechanical strengths of AIC by strengthening the cement matrix. (2) The functional properties of AIC, such as acid buffer capability, improved by increasing the releasing amounts of various ions including fluoride ions. The novel AIC developed in this study is a clinically effective dental material for prevention and remineralization of tooth and initial carious lesion.

scholarly journals Ratiometric sensing of fluoride ions using Raman spectroscopy

2020 ◽  
Vol 56 (92) ◽  
pp. 14463-14466
Author(s):  
William J. Tipping ◽  
Liam T. Wilson ◽  
Sonja K. Blaseio ◽  
Nicholas C. O. Tomkinson ◽  
Karen Faulds ◽  
...  
Keyword(s):  
Raman Spectroscopy ◽  
Fluoride Ion ◽  
Ion Detection ◽  
Fluoride Ions ◽  
Ratiometric Sensing ◽  
Ratiometric Sensor

A simple ratiometric sensor based on Raman spectroscopy enables rapid fluoride ion detection in a paper-based assay using a portable spectrometer.

scholarly journals Fluoride ion adsorption from wastewater using magnesium(II), aluminum(III) and titanium(IV) modified natural zeolite: kinetics, thermodynamics, and mechanistic aspects of adsorption

2017 ◽  
Vol 8 (4) ◽  
pp. 479-489 ◽  
Author(s):  
Zhijun Ma ◽  
Qi Zhang ◽  
Xingyuan Weng ◽  
Changye Mang ◽  
Liwei Si ◽  
...  
Keyword(s):  
Natural Zeolite ◽  
Adsorption Process ◽  
Fluoride Ion ◽  
Ion Adsorption ◽  
Order Model ◽  
Fluoride Ions ◽  
Modified Zeolite ◽  
Fluoride Adsorption ◽  
Pseudo Second Order ◽  
Modified Zeolites

Abstract Natural zeolite was modified using metal ions, including magnesium(II), aluminum(III) and titanium(IV). The modified zeolite was then used as an adsorbent for the investigation of the adsorption kinetics, isotherms, and thermodynamic parameters of fluoride ions in wastewater at various pHs and temperatures. The kinetics and thermodynamics for the removal of the fluoride ions onto the modified zeolite have also been investigated. The fluoride ion adsorption capacity of the three types of modified zeolites exhibited an increase, then decrease, with rising pH. The fluoride adsorption capacity of the modified zeolites decreased with an increase in temperature. The pseudo-second-order model is more suitable for describing the adsorption kinetic data than the pseudo-first-order model for modified zeolite and the adsorption process of the fluoride ions reveals pseudo-second-order kinetic behavior, respectively. It was found that the adsorption equilibrium data fit the Freundlich isothermal equation better than that of the Langmuir isothermal and Dubinin–Radushkevich (D–R) isothermal equations. Thermodynamic analysis suggests that the negative values of ΔG0 and ΔH0 further indicate that the fluoride adsorption process is both spontaneous and exothermic. The results of competitive adsorption tests suggest that the modified metal zeolite materials adsorb fluoride ions with high selectivity.

scholarly journals Investigation of Corrosion Methods for Bipolar Plates for High Temperature Polymer Electrolyte Membrane Fuel Cell Application

Energies ◽  
2020 ◽  
Vol 13 (1) ◽  
pp. 235
Author(s):  
Nadine Pilinski ◽  
Claudia Käding ◽  
Anastasia Dushina ◽  
Thorsten Hickmann ◽  
Alexander Dyck ◽  
...  
Keyword(s):  
High Temperature ◽  
Fuel Cell ◽  
Polymer Electrolyte ◽  
Corrosion Behaviour ◽  
Polymer Electrolyte Membrane ◽  
Carbon Surface ◽  
Potential Range ◽  
Bipolar Plates ◽  
Electrolyte Membrane ◽  
Fuel Cell Application

In this work, different methods and electrochemical set-ups were investigated in order to study the corrosion behaviour of bipolar plates (BPP) for high temperature (HT) polymer electrolyte membrane fuel cell application. Using confocal and scanning electron microscopy, it was shown that chemical and electrochemical aging significantly increases surface roughness as well as morphology changes, confirming material degradation. Identical electrochemical corrosion behaviour was observed for both set-ups with typical quinone/hydroquinone peaks in the potential range ~0.6–0.7 V versus reversible hydrogen electrode (RHE). The appearance of the peaks and an increase of double layer capacitance can be related to the oxidation of carbon surface and, consequently, material corrosion. Simultaneously, an optimised corrosion set-up was introduced and verified regarding suitability. Both investigated set-ups and methods are useful to analyse the oxidation behaviour and corrosion resistance.

Purification of Water from Fluoride Ions by a Lanthanum-Containing Ceramic Material

2018 ◽  
Vol 22 (8) ◽  
pp. 28-31 ◽  
Author(s):  
V.Yu. Chukhlanov ◽  
O.G. Selivanov ◽  
E.S. Pikalov ◽  
C.M. Chesnokova ◽  
A.A. Podolets
Keyword(s):  
Ceramic Material ◽  
Mechanical Characteristics ◽  
Binding Capacity ◽  
Environmental Safety ◽  
Fluoride Ion ◽  
Ion Content ◽  
Fluoride Ions ◽  
Phosphate Ions ◽  
Environmentally Safe ◽  
Purification Of Water

Studies have been carried out to create a lanthanum-containing ceramic material that can be used to purify water from fluoride ions. A composition was developed for the preparation of a ceramic material, the physico-mechanical characteristics of its samples were determined, and their binding capacity to fluoride ions was investigated. There was researched environmental safety of a material. It is proved that when 6% by weight of lanthanum carbonate is added to the charge, an environmentally safe material for cleaning aqueous systems with a fluoride ion content of up to 10 mg/l can be obtained. It has been established that this material can be used with sufficient efficiency to purify water from phosphate ions.

Electrical Characterization of the Structure and Other Phenomena in Superionic PbSnF4

1995 ◽  
Vol 411 ◽  
Author(s):  
Galina Milova ◽  
Georges Denes ◽  
M. Cecilia Madamba ◽  
M. Perfiliev
Keyword(s):  
Ion Mobility ◽  
Complex Impedance ◽  
Electrical Characterization ◽  
Fold Increase ◽  
Fluoride Ion ◽  
Fluoride Ions ◽  
Covalently Bonded ◽  
Frenkel Defects ◽  
Fluorite Type

ABSTRACTThe structure of PbSnF4 is derived from that of fluorite-type β-PbF2 The replacement of half the lead by tin results in a thousand-fold increase of the fluoride ion mobility, even though tin-fluorine bonds are strongly covalent. This is due to an increase of fluoride ion disorder on some sites. The structure of α-PbSnF4 can be interpreted as resulting from the insertion of two layers of [SnF]+ cations between each pair of layers of PbF8 cubes. This has profound bearings on the texture and properties of this material, since the tin(II) stereoactive lone pairs create very effective cleavage planes. In addition, the fluorine covalently bonded to tin occupy all vacant sites used to create Frenkel defects. However, superionicity is observed by complex impedance measurements. Transport number measurements show that fluoride ions are the charge carriers.

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