Interpretation of Bronze Disease and Related Copper Corrosion Mechanisms in Terms of Log-Activity Diagrams

1992 ◽  
Vol 267 ◽  
Author(s):  
Michael B. McNeil ◽  
D. W. Mohr
Keyword(s):  
Chloride Ions ◽  
Copper Corrosion ◽  
Activity Diagram ◽  
Standard Temperature ◽  
Copper Species ◽  
Pourbaix Diagrams ◽  
Activity Diagrams ◽  
Temperature And Pressure ◽  
Thermodynamic Variables ◽  
Corrosion Mechanisms

ABSTRACTThermochemical data are used to construct a modified log-activity diagram for the system Cu-H-O-Cl-(C02) at standard temperature and pressure(STP). In these diagrams, coordinate axes represent activities of aqueous copper species and chloride ions other thermodynamic variables are collapsed onto the diagram. Modified log-activity diagrams are used as a supplement to study Pourbaix diagrams for the equilibria relevant to bronze disease and copper pitting and to show the relation between them.

Some aspects of copper corrosion in presence of benzotriazole and chloride ions

2009 ◽  
Vol 51 (1) ◽  
pp. 28-34 ◽  
Author(s):  
S.M. Milić ◽  
M.M. Antonijević
Keyword(s):  
Chloride Ions ◽  
Copper Corrosion

A New Type of Muffler Based on Microperforated Tubes

2011 ◽  
Vol 133 (3) ◽  
Author(s):  
S. Allam ◽  
M. Åbom
Keyword(s):  
Acoustic Impedance ◽  
Noise Control ◽  
Wave Impedance ◽  
Sound Waves ◽  
Submillimeter Range ◽  
Perforated Plates ◽  
Characteristic Wave ◽  
Standard Temperature ◽  
New Type ◽  
Temperature And Pressure

Microperforated plate (MPP) absorbers are perforated plates with holes typically in the submillimeter range and perforation ratios around 1%. The values are typical for applications in air at standard temperature and pressure (STP). The underlying acoustic principle is simple: It is to create a surface with a built in damping, which effectively absorbs sound waves. To achieve this, the specific acoustic impedance of a MPP absorber is normally tuned to be of the order of the characteristic wave impedance in the medium (∼400 Pa s/m in air at STP). The traditional application for MPP absorbers has been building acoustics often combined with a so called panel absorber to create an absorption peak at a selected frequency. However, MPP absorbers made of metal could also be used for noise control close to or at the source for noise control in ducts. In this paper, the possibility to build dissipative silencers, e.g., for use in automotive exhaust or ventilation systems, is investigated.

scholarly journals Investigating the Effect of Solid Boundaries on the Gas Molecular Mean-Free-Path

2009 ◽  
Author(s):  
Erik J. Arlemark ◽  
Jason M. Reese
Keyword(s):  
Molecular Dynamics ◽  
Boundary Conditions ◽  
Free Path ◽  
Mean Free Path ◽  
Gas Flows ◽  
Standard Temperature ◽  
Binary Collisions ◽  
The Mean ◽  
Temperature And Pressure ◽  
Definition Of

A key parameter for micro-gas-flows, the mean free path, is investigated in this paper. The mean free path is used in various models for predicting micro gas flows, both in the governing equations and their boundary conditions. The conventional definition of the mean free path is based on the assumption that only binary collisions occur and is commonly described using the macroscopic quantities density, viscosity and temperature. In this paper we compare the prediction by this definition of the mean free paths for helium, neon and argon gases under standard temperature and pressure conditions, with the mean free paths achieved by measurements of individual molecules using the numerical simulation technique of molecular dynamics. Our simulation using molecular dynamics consists of a cube with six periodic boundary conditions, allowing us to simulate an unconfined gas “package”. Although, the size of this package is important, since its impact on computational cost is considerable, it is also important to have enough simulated molecules to average data from. We find that the molecular dynamics method using 20520 simulated molecules yields results that are within 1% accuracy from the conventional definition of the mean free paths for neon and argon and within 2.5% for helium. We can also conclude that the normal approximation of only considering binary collisions is seemingly adequate for these gases under standard temperature and pressure conditions. We introduce a single planar wall and two parallel planar walls to the simulated gas of neon and record the mean free paths at various distances to the walls. It is found that the mean free paths affected by molecular collisions with the walls corresponds well with theoretical models up to Knudsen numbers of 0.2.

scholarly journals Effects of Variations in Salt-Spray Conditions on the Corrosion Mechanisms of an AE44 Magnesium Alloy

2010 ◽  
Vol 2010 ◽  
pp. 1-10 ◽  
Author(s):  
Holly J. Martin ◽  
M. F. Horstemeyer ◽  
Paul T. Wang
Keyword(s):  
Galvanic Corrosion ◽  
Salt Spray ◽  
Chloride Ions ◽  
General Corrosion ◽  
Multiple Exposure ◽  
Test Conditions ◽  
Lightweight Alloys ◽  
Pit Nucleation ◽  
Corrosion Mechanisms ◽  
By Products

The understanding of how corrosion affects magnesium alloys is of utmost importance as the automotive and aerospace industries have become interested in the use of these lightweight alloys. However, the standardized salt-spray test does not produce adequate corrosion results when compared with field data, due to the lack of multiple exposure environments. This research explored four test combinations through three sets of cycles to determine how the corrosion mechanisms of pitting, intergranular corrosion, and general corrosion were affected by the environment. Of the four test combinations, Humidity-Drying was the least corrosive, while the most corrosive test condition was Salt Spray-Humidity-Drying. The differences in corrosivity of the test conditions are due to the various reactions needed to cause corrosion, including the presence of chloride ions to cause pit nucleation, the presence of humidity to cause galvanic corrosion, and the drying phase which trapped chloride ions beneath the corrosion by-products.

Copper Corrosion Mechanisms of Polysulfides

1997 ◽  
Vol 492 ◽  
Author(s):  
Anne M. Chaka ◽  
John Harris ◽  
X. P. Li
Keyword(s):  
Density Functional ◽  
Copper Surface ◽  
Minor Role ◽  
Copper Corrosion ◽  
Dramatic Decrease ◽  
Functional Theory ◽  
Hartree Fock ◽  
Thiyl Radicals ◽  
Corrosion Mechanisms ◽  
A Minor

ABSTRACTCorrosive behavior of commercial organopolysulfides of the type R-(S)n-R is known to increase dramatically towards copper-based alloys when n ≥ 4, whereas di- and trisulfides are essentially inert. Three possible reasons for this behavior are examined using local and nonlocal density-functional theory as well as post-Hartree-Fock theory at the MP2 level. The hypotheses are: the shorter chains are protected from the surface by steric hindrance of the terminal organic groups, longer polysulfides can chelate copper atoms and remove them from the surface, and S-S bonds become weaker and more reactive as the polysulfide chains become longer. We find the predominant reason for the increase in corrosive behavior to be a dramatic decrease in S-S bond dissociation energy when n ≥ 4 due to stabilization of the unpaired electron via delocalization in RSS• thiyl radicals. The thiyl radicals are thus the species which is capable of attacking and corroding the copper surface. Chelation is eliminated as a possible mechanism, and steric protection and oil solubility afforded by the organic terminal groups are found to play a minor role.

scholarly journals 2021 F.N. Speller Award Lecture: CORROSION MECHANISMS OF STEEL AND COPPER IN ENGINEERING APPLICATIONS

CORROSION ◽  
10.5006/3916 ◽  
2021 ◽  
Author(s):  
Jose M Bastidas
Keyword(s):  
Corrosion Inhibitors ◽  
Cementitious Materials ◽  
Copper Corrosion ◽  
Engineering Applications ◽  
Main Research ◽  
Structural Applications ◽  
Protection Mechanisms ◽  
Copper Tubing ◽  
Corrosion Mechanisms ◽  
Air Conditioning Systems

The main research lines of the scientific career of the author are herein, exemplified including corrosion and protection mechanisms of steel in different environments, and copper corrosion in climate systems. Stainless steel (SS) due to its high corrosion resistance is a material widely used for many engineering applications. Impedance measurements were performed on polarized at the pitting region AISI 304 SS in environment containing chloride at 25 and 60 ºC. The transfer function was analyzed indicating instability system, corroborating results obtained using the Kramers-Kronig transforms. Steel reinforcement has been studied for structural applications in civil engineering and architecture using cementitious materials, alkaline activated fly ash (AAFA), alternative to the ordinary Portland cement (OPC). The main compounds used as corrosion inhibitors in concrete were included. Carbon steel embedded in OPC mortar was tested in the presence of phosphates as corrosion inhibitors. An organic lacquer was applied to tinplate with titanium-passivation treatment and, in general, acceptable and comparable behavior was obtained to conventional chromium-passivated lacquered tinplate. Copper is also a material used in many engineering applications. Ant-nest corrosion of copper tubing in air-conditioning systems has been reported. The copper corrosion rate occasioned by carboxylic acids, formic, acetic, propionic and butyric, was included.

scholarly journals Complexity Assessment based on UML-Activity Diagram

2019 ◽  
Vol 8 (2) ◽  
pp. 2391-2397
Keyword(s):  
Product Quality ◽  
Activity Diagram ◽  
Activity Diagrams ◽  
Class Function ◽  
Process View ◽  
Assessment Approach ◽  
Uml Activity Diagram ◽  
Complexity Assessment ◽  
Factor C ◽  
The Given

Assessing complexity can significantly contribute to the attainment of the various quality attributes associated with a system. The avoidable complexity can be identified and reduced on the basis of the assessment. It holds the key to success of the system being developed. Various evaluation methods exist which have specific objectives and basis and all contribute to enhance product quality. In this paper a Complexity Assessment approach based on Activity Diagrams (CAAD) is proposed to evaluate the process view of the architecture of a system. The proposed approach estimates the complexity of the system/class/function from the UML representation of the process view of the architecture in the form of activity diagrams. This complexity measure may be used to assess and estimate the time and effort required to develop the system. This approach can estimate the coding complexity in terms of size without actually developing the code for the system/class/function. The paper is on calculating a complexity factor C from the given activity diagram and further develop a relationship between C and LOC metrics.

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