scholarly journals The Corrosiveness of Muskeg Waters: A Review

1965 ◽  
Vol 2 (4) ◽  
pp. 327-336
Author(s):  
L C MacFarlane
Keyword(s):  
Surface Coating ◽  
Anaerobic Bacteria ◽  
High Alumina ◽  
Ph Measurements ◽  
Metal Structures ◽  
Aggressive Environment ◽  
Long Period ◽  
Free Carbon Dioxide ◽  
Aggressive Attack ◽  
Dissolved Salts

Muskeg waters are generally acidic and potentially corrosive to concrete and metal structures. The amount of dissolved salts and free carbon dioxide in the water is an important factor in its aggressive attack on concrete. Although pH measurements are not the only criterion of aggressiveness, they are a reasonable indication in many instances of potential severity. A good defence against an aggressive environment is a high quality, very dense concrete. High alumina concrete and air-entraining agencies provide further protection in extremely aggressive environments. Surface treatments of concrete have not proved to be very successful over a long period of time.Corrosion of metals in a muskeg environment is an electrochemical action; the type and rate of corrosion are functions of the property of the metal as well as the soil and water conditions. Factors such as dissolved salts, pH, total acidity, resistivity, aeration, and presence of anaerobic bacteria influence corrosion. Optimum protection to metals in an aggressive environment is provided by a combination of a surface coating and cathodic protection.

scholarly journals Improving the Protectiveness of 3-Mercaptopropyl-Trimethoxysilane Coatings on Bronze by Addition of Oxidic Nano- and Microparticles

Coatings ◽  
2020 ◽  
Vol 10 (3) ◽  
pp. 225
Author(s):  
Cecilia Monticelli ◽  
Federica Zanotto ◽  
Vincenzo Grassi ◽  
Mahla Seyedi ◽  
Andrea Balbo
Keyword(s):  
Positive Influence ◽  
Curing Time ◽  
Chemical Analyses ◽  
Ph Measurements ◽  
Energy Dispersion Spectroscopy ◽  
Coating Application ◽  
Electrochemical Tests ◽  
Aggressive Environment ◽  
Nanoparticle Suspensions ◽  
Synthetic Acid

The protectiveness of coatings based on 3-mercaptopropyl-trimethoxysilane (PropS-SH) applied on bronze artworks was enhanced by investigating and tuning a variety of factors. In particular, the coating performances were optimized by proper additive choice among oxide nanoparticles (CeO2, La2O3, TiO2) and microparticles (fly ash (FA)), and by varying the aging time of the nanoparticle suspensions before coating application and the RT curing time of the coatings. Moreover, the possibility of conservation of the silane solution under refrigerated conditions was assessed. The aggressive environment was a tenfold concentrated synthetic acid rain (AR × 10). The techniques adopted comprised electrochemical tests (polarization curve recording and EIS tests) and SEM-Energy Dispersion Spectroscopy (EDS) observations. In the case of FA microparticles, never used before as additives in silane coatings, further tests were performed in FA suspensions in AR × 10 to clarify the contribution of these particles to PropS-SH coating protectiveness. The tests included pH measurements, elemental chemical analyses, and electrochemical tests on bare bronze. Improved performances of PropS-SH coatings were achieved by La2O3, CeO2, and FA addition, with La2O3 affording the best results during 20 days of immersion. The positive influence of FA was connected to its alkaline character and to the release of soluble silicates.

scholarly journals Reaction of Converter Slag with Supercritical Carbon Dioxide and Its Potential Applicability as Aggregate for Concrete

2021 ◽  
Vol 11 (4) ◽  
pp. 1918
Author(s):  
Hoon Moon ◽  
Kyeongtae Kim ◽  
Ji-Hyun Kim ◽  
Minhee Lee ◽  
Chul-Woo Chung
Keyword(s):  
Supercritical Co2 ◽  
Converter Slag ◽  
Concrete Aggregate ◽  
Co2 Uptake ◽  
Free Lime ◽  
Aggressive Environment ◽  
Long Period ◽  
Aging Period ◽  
Potential Applicability ◽  
Mortar Bar

The presence of free lime and periclase in converter slag prevents it from directly being utilized as a source of concrete aggregate due to the deleterious expansion caused by reaction of free lime and periclase. In general, a six-month aging period is suggested in order to avoid any potential problems, but it is a tedious process that requires a long period of time. In this work, supercritical CO2 (SCD) was used to reduce the aging period down to one day or so. Since SCD creates a more aggressive environment for reaction, it can directly attack the surface of free lime and periclase to induce expansive reaction before using converter slag as concrete aggregate. According to the experimental results, the surface of converter slag was successfully carbonated by SCD, showing 7.80% of CO2 uptake by weight of converter slag. It was found that the mortar bar made of reacted converter slag reduced the amount of expansion. The 28-day compressive strength of mortar with converter slag was slightly reduced after reaction with SCD, but it was still 32% higher than mortar made of conventional sand.

THE INFLUENCE OF SECTION FORM OF METAL STRUCTURE ELEMENTS ON CORROSION WEAR

2020 ◽  
pp. 15-18
Keyword(s):  
Technological Process ◽  
Metal Structure ◽  
Corrosion Wear ◽  
Cross Sectional ◽  
Corrosion Resistant ◽  
Metal Structures ◽  
Aggressive Environment ◽  
Profile Element ◽  
The Cross ◽  
Section Form

The article provides the corrosion examples in metal structures, as well as their types. In most cases, metal structures are used in buildings with an aggressive environment. Corrosion is influenced by factors such as humidity, dust, various gases, technological process and etc. And also corrosion is influenced by the cross-sectional shapes which made the structural rods. There are given recommendations for the corrosion-resistant profiles use in metal structures and measures for their protection against corrosion. Keywords: corrosion, gas, dustiness, aggressive environment, operation, humidity, condensate, profile element, wear, destruction, durability, speed, section.

scholarly journals Features of strengthening metal structures with composite materials under the influence of an aggressive environment

Vestnik MGSU ◽  
2020 ◽  
pp. 496-509
Author(s):  
Anna N. Leonova ◽  
Oleg D. Sofyanikov ◽  
Irina A. Skripkina
Keyword(s):  
Composite Materials ◽  
Carbon Fiber ◽  
Bearing Capacity ◽  
Galvanic Corrosion ◽  
Practical Experience ◽  
Building Structures ◽  
Metal Structures ◽  
Aggressive Environment ◽  
External Reinforcement ◽  
Fiber Materials

Introduction. This article is devoted to the issues of reinforcing metal building structures with external reinforcement systems with composite materials. The application of these strengthening methods in domestic literature and in practice has not been fully studied. As a result, it is relevant to study the characteristics of strengthening under the action of an external aggressive environment, namely when exposed to galvanic corrosion, elevated ambient temperatures and extreme temperatures from firing. The purpose of the study is to establish the effectiveness of reinforcing metal structures with composite materials under the influence of various force factors, including cyclic loads, and under the action of an external aggressive environment. Materials and methods. The methodological basis of scientific research was the analysis of publications of domestic and foreign scientists on the theoretical and practical experience of using composite materials to strengthen metal structures. During the study, when describing the dependences of physical quantities on external and internal force and non-force factors, scientific methods of induction, deduction, generalization and comparison were used. Results. Performed a comprehensive study of the effectiveness of the use of composite materials to enhance the metal structures in hostile environments. The dependence of the increase in strength of reinforced steel samples on the length of the adhesive joint of external reinforcement is analyzed, the possibility of applying reinforcement at fatigue stresses is investigated. Recommendations on the use of protective insulating systems and materials that prevent the reduction of the bearing capacity of structures from external non-force factors are given. Conclusions. The effectiveness of reinforcing metal structures using composite carbon fiber materials is revealed. The bearing capacity of reinforced structures may be increased by 59 %. When the glass transition temperature of carbon fiber materials is reached, the increase in the bearing capacity from external amplification systems decreases by 50 %, and when the temperature is increased to 60 °C, the external amplification systems are ineffective and do not increase the bearing capacity. To achieve the required fire resistance of the amplification systems, equal to at least one hour, it is necessary to use external fire insulation.

scholarly journals Filling and retouching of losses in a Portuguese Army model 1859 clothes backpack

2020 ◽  
Vol 18 (1) ◽  
pp. 258-265
Author(s):  
André Fernandes ◽  
Ana Bailão
Keyword(s):  
19Th Century ◽  
Surface Coating ◽  
Organic Coating ◽  
Late 19Th Century ◽  
Long Period ◽  
Good Outcome ◽  
Ultrasonic Humidifier ◽  
Treatment Procedures ◽  
Realistic Goal ◽  
Original Coating

Two identical backpacks were treated on two occasions to be exhibited alongside at the Lisbon Military Museum. Although both backpacks are the model 1859, the treatment procedures related to the painted canvas were approached differently. The distortions and losses of canvas on the first treated backpack were easily addressed with an ultrasonic humidifier and the insertion of new canvas. Regarding the surface coating, it was consolidated with BEVA® 371, and the inserted canvas was filled with a pigmented wax paste described in a book from the late 19th century. The second backpack was in far worse condition, which, when compared with archive record, seemed likely that it was exhibited for a long period in a damp environment. There were also traces of an organic coating distinct from the original coating. These conditions resulted in a stiffer backpack, with more losses of canvas and surface coating. As a result, the distortions could not be removed, new fabric could not be properly inserted, and the consolidation of the surface coating had to be addressed in a different way. For these motives, the goal of treatment of the second treated backpack was cut short for a more realistic goal, but resulted in a good outcome, nonetheles.

On nearly-commensurable periods in the restricted problem of three bodies, with calculations of the long-period variations in the interior 2:1 case

1966 ◽  
Vol 25 ◽  
pp. 197-222 ◽  
Author(s):  
P. J. Message
Keyword(s):  
Periodic Solution ◽  
Periodic Solutions ◽  
Large Amplitude ◽  
Restricted Problem ◽  
Small Amplitude ◽  
Minor Planets ◽  
Long Period ◽  
Numerical Integrations ◽  
Period Variations ◽  
The Mean

An analytical discussion of that case of motion in the restricted problem, in which the mean motions of the infinitesimal, and smaller-massed, bodies about the larger one are nearly in the ratio of two small integers displays the existence of a series of periodic solutions which, for commensurabilities of the typep+ 1:p, includes solutions of Poincaré'sdeuxième sortewhen the commensurability is very close, and of thepremière sortewhen it is less close. A linear treatment of the long-period variations of the elements, valid for motions in which the elements remain close to a particular periodic solution of this type, shows the continuity of near-commensurable motion with other motion, and some of the properties of long-period librations of small amplitude.To extend the investigation to other types of motion near commensurability, numerical integrations of the equations for the long-period variations of the elements were carried out for the 2:1 interior case (of which the planet 108 “Hecuba” is an example) to survey those motions in which the eccentricity takes values less than 0·1. An investigation of the effect of the large amplitude perturbations near commensurability on a distribution of minor planets, which is originally uniform over mean motion, shows a “draining off” effect from the vicinity of exact commensurability of a magnitude large enough to account for the observed gap in the distribution at the 2:1 commensurability.

Discussion following the presentation by F. Deubner

1977 ◽  
Vol 36 ◽  
pp. 69-74
Keyword(s):  
List Type ◽  
The Sun ◽  
Type Number ◽  
Harmonic Motion ◽  
Locally Excited ◽  
Long Period ◽  
Coherent Wave ◽  
Short Period ◽  
Global Modes

The discussion was separated into 3 different topics according to the separation made by the reviewer between the different periods of waves observed in the sun :1) global modes (long period oscillations) with predominantly radial harmonic motion.2) modes with large coherent - wave systems but not necessarily global excitation (300 s oscillation).3) locally excited - short period waves.

The growth of mica polytypes as studied by conventional and high-resolution TEM

1983 ◽  
Vol 41 ◽  
pp. 174-177
Author(s):  
A. Baronnet ◽  
M. Amouric
Keyword(s):  
Water Pressure ◽  
Point Of View ◽  
Temperature Fields ◽  
Natural Occurrence ◽  
Growth Mechanisms ◽  
Long Period ◽  
High Resolution Tem ◽  
Layer Stacking ◽  
Experimental Works ◽  
Potential Use

The origin of mica polytypes has long been a challenging problem for crystal- lographers, mineralogists and petrologists. From the petrological point of view, interest in this field arose from the potential use of layer stacking data to furnish further informations about equilibrium and/or kinetic conditions prevailing during the crystallization of the widespread mica-bearing rocks. From the compilation of previous experimental works dealing with the occurrence domains of the various mica "polymorphs" (1Mr, 1M, 2M1, 2M2 and 3T) within water-pressure vs temperature fields, it became clear that most of these modifications should be considered as metastable for a fixed mica species. Furthermore, the natural occurrence of long-period (or complex) polytypes could not be accounted for by phase considerations. This highlighted the need of a more detailed kinetic approach of the problem and, in particular, of the role growth mechanisms of basal faces could play in this crystallographic phenomenon.

TEM Analysis of Long-Period Polytypes in SiC—S

1976 ◽  
Vol 34 ◽  
pp. 630-631
Author(s):  
S. Shinozaki ◽  
J. W. Sprys
Keyword(s):  
Electron Diffraction ◽  
Isothermal Annealing ◽  
Tem Analysis ◽  
Long Period ◽  
Transmission Electron ◽  
Average Grain Size ◽  
High Resolution Tem ◽  
Structural Lattice ◽  
The Stability ◽  
Continuous Curves

In reaction sintered SiC (∽ 5um average grain size), about 15% of the grains were found to have long-period structures, which were identifiable by transmission electron microscopy (TEM). In order to investigate the stability of the long-period polytypes at high temperature, crystal structures as well as microstructural changes in the long-period polytypes were analyzed as a function of time in isothermal annealing.Each polytype was analyzed by two methods: (1) Electron diffraction, and (2) Electron micrograph analysis. Fig. 1 shows microdensitometer traces of ED patterns (continuous curves) and calculated intensities (vertical lines) along 10.l row for 6H and 84R (Ramsdell notation). Intensity distributions were calculated based on the Zhdanov notation of (33) for 6H and [ (33)3 (32)2 ]3 for 84R. Because of the dynamical effect in electron diffraction, the observed intensities do not exactly coincide with those intensities obtained by structure factor calculations. Fig. 2 shows the high resolution TEM micrographs, where the striped patterns correspond to direct resolution of the structural lattice periodicities of 6H and 84R structures and the spacings shown in the figures are as expected for those structures.

Directional observation on lipid of male nectary of Lindera megaphylla hemsl. by the rapid embedding method with polyethylene glycol (PEG)

1990 ◽  
Vol 48 (3) ◽  
pp. 718-719
Author(s):  
Dai Dalin ◽  
Guo Jianmin
Keyword(s):  
Electron Microscope ◽  
Polyethylene Glycol ◽  
Chemical Reaction ◽  
Traditional Method ◽  
Osmium Tetroxide ◽  
Unsaturated Lipid ◽  
Embedding Method ◽  
Long Period ◽  
New Methods

Lipid cytochemistry has not yet advanced far at the EM level. A major problem has been the loss of lipid during dehydration and embedding. Although the adoption of glutaraldehyde and osmium tetroxide accelerate the chemical reaction of lipid and osmium tetroxide can react on the double bouds of unsaturated lipid to from the osmium black, osmium tetroxide can be reduced in saturated lipid and subsequently some of unsaturated lipid are lost during dehydration. In order to reduce the loss of lipid by traditional method, some researchers adopted a few new methods, such as the change of embedding procedure and the adoption of new embedding media, to solve the problem. In a sense, these new methods are effective. They, however, usually require a long period of preparation. In this paper, we do research on the fiora nectary strucure of lauraceae by the rapid-embedding method wwith PEG under electron microscope and attempt to find a better method to solve the problem mentioned above.

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