Layer | Fill | Outline |
---|
Map layers
Theme | Visible | Selectable | Appearance | Zoom Range (now: 0) |
---|
Fill | Stroke |
---|---|
Collaborating Authors
Results
ABSTRACT Pickling in dilute hydrochloric acid (HCl) and sulfuric acid (H2SO4) is the most common method for removing oxides formed on the surface of copper-based materials during mill processing and fabrication operations. Other methods of chemical cleaning can be used, depending on the desired finish.1 In general, the copper dissolution mechanism involves the formation and dissolution of cuprous chloride (CuCl) and cuprite (Cu2O) films.2-8 Tarnishing of copper alloys after pickling or degreasing operations is accelerated when the metal is inadequately dried or the final rinse solution is contaminated with the cleaning solution. Significant resistance to tarnishing after cleaning also can be obtained by incorporating inhibitors. Benzotriazole (BTA) is an effective corrosion inhibitor for copper in aqueous chloride solutions.9-11 Basically two mechanisms have been proposed in the literature: the adsorption of single BTA molecules on the copper surface and the formation of a polymeric coating involving the complex ions Cu(I) and (Cu+BTA)n.12-14 Nevertheless, despite the widespread use of BTA, no consensus has been reached on its mechanism. There is also a lack of agreement regarding the orientation of BTA on the copper surface. Some authors propose a flat orientation on the surface and bonding through the lone-pair nitrogen orbitals, with lone nitrogen atoms bonded to two copper atoms.9,15-16 The loss of the imino hydrogen converts each BTA molecule into a BTA ion, with a conjugated structure delocalized over the three nitrogen atoms.17-18 It also has been claimed that BTA does not lie flat on the surface, but that the nitrogen lone-pair orbitals bond to the copper surface atoms.19 An angle orientation not far from the horizontal and not vertically on the copper surface also has been proposed.20 On the
- Materials > Chemicals > Specialty Chemicals (0.71)
- Water & Waste Management > Water Management > Water & Sanitation Products (0.61)
- Materials > Chemicals > Commodity Chemicals (0.48)
- Well Completion > Well Integrity > Subsurface corrosion (tubing, casing, completion equipment, conductor) (1.00)
- Production and Well Operations > Production Chemistry, Metallurgy and Biology > Corrosion inhibition and management (including H2S and CO2) (1.00)
- Facilities Design, Construction and Operation > Pipelines, Flowlines and Risers > Materials and corrosion (1.00)
ABSTRACT Copper and copper alloys are widely used in many environments and applications, such as: --industrial equipment (heat exchangers and condensers, bearings and bushings, transportation, etc.) and applications based on the beneficial combination of electrical and/or thermal conductivity, corrosion resistance, strength, and wear resistance --building construction (plumbing goods, wires, heating, air conditioning systems, and roofing) --electricity and electronics (power cables, contacts, resistors and electronic circuitry [printed circuit boards, where the selective removal of the native copper oxide formed on copper upon exposure to air is unresolved], and semiconductor packages) --coinage and ornamental parts, as a result of their excellent corrosion resistance, remarkable castability (e.g., for church bells and statuary), and a variety of colors --medical applications --agriculture --water treatment, etc.1 Pickling in dilute sulfuric acid (H2SO4) and hydrochloric acid (HCl) is the most common method for removing oxides formed on the surface of copperbased materials during mill processing and fabrication operations. Other methods of chemical cleaning can be used, depending on the desired finish.1 Organic acids, such as citric acid (C6H8O7), have the advantage of being less corrosive, are capable of forming metal complexes, and are safe, easy to handle, and pose no health or ecological hazards, as compared to mineral acids. This type of environment is desirable for removing copper oxide--the discoloring formed on the surface of copper-based materials (tarnish stains) during exposure to the atmosphere--
- Europe > Spain (0.29)
- Europe > Switzerland (0.28)
- Well Completion > Well Integrity > Subsurface corrosion (tubing, casing, completion equipment, conductor) (0.96)
- Facilities Design, Construction and Operation > Pipelines, Flowlines and Risers > Materials and corrosion (0.96)
- Reservoir Description and Dynamics (0.86)
- Production and Well Operations > Production Chemistry, Metallurgy and Biology > Corrosion inhibition and management (including H2S and CO2) (0.86)
ABSTRACT In a previous paper, the authors presented the results of a study on the pitting corrosion of AISI 316L stainless steel (SS; UNS S31603)(1) in a 5% sodium chloride (NaCl) solution using the electrochemical impedance spectroscopy (EIS) method,1 concluding that stability conditions were not fulfilled for electrode processes, which indicates the existence of surface relaxation phenomena such as passivation, film growth, electro dissolution processes, etc. Kramers-Kronig (K-K) relations were violated because of the lack of stability for the AISI 316L SS/NaCl system. K-K transforms can be used to indicate whether data are erroneous or if the equivalent electrical circuit (EEC) is inadequate. The analyses performed on the EEC, with negative resistors and capacitors, were consistent with the instability of the SS/chloride system. It is of practical interest to extend the analyses to materials with high corrosion resistance, such as 254SMO SS (UNS S31254), and with low corrosion resistance, such as AISI 304 SS (UNS S30400), in an environment containing chloride ions. The EEC is representative of the physical processes taking place in the system under investigation. However, transfer functions are handled when the formalism of a linear system analysis is used. The transfer function of a linear, time-invariant, differential equation system is defined as the ratio between the Laplace transforms at the system output (response function) and input (driving function): Z(s ) = V(s ) / I(s ) (1) where V(s) and I(s) are the Laplace transforms of voltage and current, respectively,2 under the assumption that all initial conditions are zero; or: Z( j ) = Z ( ) + jZ ( ) (2) where Z() and Z() are the frequency-dependent real and imaginary parts of impedance, respectively, j2 = (1), and = 2f is the angular frequency.
- Materials > Metals & Mining > Steel (0.61)
- Transportation > Passenger (0.49)
- Transportation > Ground > Road (0.49)
- (2 more...)
ABSTRACT Pitting potential (Epit), measured using the electrochemical potentiokinetic method, is frequently used as an accelerated laboratory test to determine relative susceptibility to localized corrosion for iron- and nickel-based alloys in a chloride environment. The more noble the Epit obtained at a fixed potential scan rate (), the less susceptible the alloy is to the initiation of localized corrosion. Epit depends on a combination of environmental conditions, alloy composition, , etc.1 The frequently used ASTM G61(1) standard recommends 0.16 mV/s as the value for measuring Epit. However, there is disagreement among authors as to the interpretation of the electrochemical results. Too fast a may give noble Epit values because of the long induction time for pit initiation. On the other hand, too slow a rate also may give noble Epit values as a result of the development and amelioration of the passive film.2 The applicability of the potential scan rate parameter is an important factor in materials selection. Some researchers have observed that Epit depends on . Three main experimental relationships have been shown: Epit log();3-5 Epit ()1/2;6-13 and Epit ()1/3.14-17 Proposed models for stochastic pitting can be divided into two categories:18 birth stochastic models, which only consider pit generation events, and birth and death stochastic models, which consider pit repassivation (death) in addition to the activation process (birth). Both models include parallel or series combinations of the elemental Poisson process. Williams, et al., proposed a stochastic model involving pit generation, repassivation, and a critical age beyond which pits achieve a state of stable propagation.19-20 The goal of this study was to analyze the theory describing the statistics of a deterministic evolution of the current in excess of a critical value to obtain a relationship between pitting corrosion and the potential scan rate for AISI 304L(2) (UNS S30403)(3) and AISI 316L (UNS S31603) stainless steel (SS) specimens in an electrolyte containing sodium chloride (NaCl).