Influence of cathodic polarization on the properties of epoxy powder coatings

2019 ◽  
Vol 24 (4) ◽  
pp. 7-14
Author(s):  
D.N. Zapevalov ◽  
A.Р. Sazonov ◽  
E.V. Sheverdenkin ◽  
A.V. Latyshev ◽  
N.I. Savostina ◽  
...  
Keyword(s):  
Mechanical Load ◽  
Large Diameter ◽  
Powder Coating ◽  
Operational Reliability ◽  
Powder Coatings ◽  
Active Centers ◽  
Cathode Polarization ◽  
Epoxy Coatings ◽  
Large Diameter Pipes ◽  
The Impact

The article discusses the effect of cathode polarization on the protective properties of powder epoxy coatings, assesses their operational reliability, statistics of failures and describes the problems found during their operation. In the process of applying commercially available pipes with epoxy powder coating on the existing gas pipeline, a not previously manifested defect was observed - the formation of dome-shaped swellings. This led to some restrictions on the use of epoxy powder coatings. With the advent of a new generation of epoxy materials, as well as in connection with the revision of the regulatory documentation GOST R 51164-98, the issue of removing these restrictions on their use for insulating large diameter pipes (up to 1,420 mm). Without additional protection has become topical. As a result, it became necessary to estimate the probability of the appearance of defects of this type when using modern powder coatings. We carried out laboratory studies of the effect of cathode polarization on the properties of modern two-layer epoxy coatings after exposure to them of shock loads of a certain size. The results indicate that the impact of such a mechanical load may cause the appearance of microdefects of the coating, which are not determined by the existing methods of control. Due to the penetration of electrolyte under the coating and the occurrence of certain physicochemical and electrochemical processes that are enhanced by imposing the potential of cathodic protection and increasing the operating temperature, these microdamages can serve as active centers for the formation of a cupola-shaped swelling.

Study of rheological behaviours of electrostatic thermoset powder coatings

e-Polymers ◽  
2009 ◽  
Vol 9 (1) ◽  
Author(s):  
Morteza Ehsani ◽  
Ali Akbar Yousefi ◽  
Saeed Samiei Yeganeh
Keyword(s):  
Mechanical Properties ◽  
Dynamic Viscosity ◽  
Physical And Mechanical Properties ◽  
Powder Coating ◽  
Curing Temperature ◽  
Design Parameters ◽  
Powder Coatings ◽  
Gel Time ◽  
Rheological Measurements ◽  
The Impact

AbstractThe use of dynamic viscosity/time (temperature) cure curves is seen as a powerful technique to quantify formulation and resin design parameters. The behaviour of different thermoset powder coating systems, epoxy/polyester (50/50, 40/60 and 30/70) as well as the impact of the filler, the curing temperature and the frequency upon gel-time have been examined based upon the rheological measurements and compared with PE/TGIC systems. Two disparate methodologies have been utilized to determine gel-time. The behaviour of dissimilar systems bearing different formulations has been compared by means of the non-isothermal DSC test. The effects of resin percentage and the formulation on physical and mechanical properties of coating have been studied.

MAGNETIC FIELD IMPACT UPON TRIBOTECHNICAL CHARACTERISTICS OF PERMANENT CONNECTIONS IN RELATION TO FRICTION SHOCK ABSORBERS

2020 ◽  
Vol 2020 (10) ◽  
pp. 4-11
Author(s):  
Victor Tikhomirov ◽  
Aleksandr Gorlenko ◽  
Stanislav Volohov ◽  
Mikhail Izmerov
Keyword(s):  
Magnetic Field ◽  
Friction Factor ◽  
Physical Contact ◽  
Active Centers ◽  
Press Fit ◽  
Electro Magnetic Field ◽  
Investigation Methods ◽  
Electro Magnetic ◽  
The Impact ◽  
The Magnetic Field

The work purpose is the investigation of magnetic field impact upon properties of friction steel surfaces at fit stripping with tightness through manifested effects and their wear visually observed. On the spots of a real contact the magnetic field increases active centers, their amount and saturation with the time of dislocation outlet, and has an influence upon tribo-mating. The external electro-magnetic field promotes the increase of the number of active centers at the expense of dislocations outlet on the contact surface, and the increase of a physical contact area results in friction tie strengthening and growth of a friction factor. By the example of friction pairs of a spentonly unit in the suspension of coach cars there is given a substantiation of actuality and possibility for the creation of technical devices with the controlled factor of friction and the stability of effects achieved is also confirmed experimentally. Investigation methods: the fulfillment of laboratory physical experiments on the laboratory plant developed and patented on bush-rod samples inserted with the fit and tightness. The results of investigations and novelty: the impact of the magnetic field upon the value of a stripping force of a press fit with the guaranteed tightness is defined. Conclusion: there is a possibility to control a friction factor through the magnetic field impact upon a friction contact.

scholarly journals Elastic Modulus and Elasticity Ratio of Malignant Breast Lesions with Shear Wave Ultrasound Elastography: Variations with Different Region of Interest and Lesion Size

Diagnostics ◽  
2021 ◽  
Vol 11 (6) ◽  
pp. 1015
Author(s):  
Antonio Bulum ◽  
Gordana Ivanac ◽  
Eugen Divjak ◽  
Iva Biondić Špoljar ◽  
Martina Džoić Dominković ◽  
...  
Keyword(s):  
Elastic Modulus ◽  
Shear Wave ◽  
Large Diameter ◽  
Small Diameter ◽  
Shear Wave Elastography ◽  
Lesion Size ◽  
Ultrasound Elastography ◽  
Breast Lesions ◽  
Malignant Breast ◽  
The Impact

Shear wave elastography (SWE) is a type of ultrasound elastography with which the elastic properties of breast tissues can be quantitatively assessed. The purpose of this study was to determine the impact of different regions of interest (ROI) and lesion size on the performance of SWE in differentiating malignant breast lesions. The study included 150 female patients with histopathologically confirmed malignant breast lesions. Minimal (Emin), mean (Emean), maximal (Emax) elastic modulus and elasticity ratio (e-ratio) values were measured using a circular ROI size of 2, 4 and 6 mm diameters and the lesions were divided into large (diameter ≥ 15 mm) and small (diameter < 15 mm). Highest Emin, Emean and e-ratio values and lowest variability were observed when using the 2 mm ROI. Emax values did not differ between different ROI sizes. Larger lesions had significantly higher Emean and Emax values, but there was no difference in e-ratio values between lesions of different sizes. In conclusion, when measuring the Emin, Emean and e-ratio of malignant breast lesions using SWE the smallest possible ROI size should be used regardless of lesion size. ROI size has no impact on Emax values while lesion size has no impact on e-ratio values.

THM analysIs of natural and engineered barriers for large excavations in deep nuclear waste repository

2021 ◽  
Author(s):  
Matias Alonso ◽  
Jean Vaunat ◽  
Minh-Ngoc Vu ◽  
Antonio Gens
Keyword(s):  
Nuclear Waste ◽  
Host Rock ◽  
Thermal Load ◽  
Water Pressure ◽  
Large Diameter ◽  
Coupled Processes ◽  
Nuclear Waste Repository ◽  
Damaged Zone ◽  
Waste Repository ◽  
The Impact

&lt;p&gt;Argillaceous rocks have great potential as possible geological host medium to store radioactive waste. &amp;#160;Andra is leading the design of a deep geological nuclear waste repository to be located in the Callovo-Oxfordian formation. In the framework of this project, excavations of large diameter galleries are contemplated to access and to store intermediate-level long-lived nuclear waste at repository main level. The closure of the repository will be realized by building sealing structures of expansive material.&lt;/p&gt;&lt;p&gt;The response of such structures is affected by several thermo-hydro-mechanical coupled processes taking place in the near and far field of the argillaceous formations. They include the formation of an excavation induced damaged zone around the galleries, the impact of the thermal load on host rock pressures and deformations, the long-term interaction with support concrete structural elements and the hydration and swelling of sealing materials. As a result, the study of their performance requires to perform simulation works of increasing complexity in terms of coupling equations, problem geometry and material behaviour. As well, challenging computational aspects, as the ones related to fractures creation and propagation, have to be considered for a representative analysis of the problem.&lt;/p&gt;&lt;p&gt;This work presents advanced large scale THM numerical models to provide keys about the response of the host rock around large diameter galleries during excavation and further thermal load as well as to analyse the performance of large diameter sealing structures. Particular features of the models include on one hand advanced constitutive laws to capture the development of the fractured zone around excavations, the behaviour of host rock/gallery support interfaces and the multi-scale response of bentonitic backfill. On the other hand, simulations consider geometries including constructive details of interest at decimetre scale within large discretization domain covering the whole formation stratigraphic column.&lt;/p&gt;&lt;p&gt;These challenging simulations provided qualitative and quantitative results on key aspects for natural and engineered barrier integrity, like extension of the damaged zone, impact of the thermal load and water pressure variations in the surrounding geological layers, duration of natural hydration phase, swelling pressure development and seals global stability.&lt;/p&gt;

Load-carrying ability of large-diameter pipes

1978 ◽  
Vol 10 (1) ◽  
pp. 29-34 ◽  
Author(s):  
V. V. Chelyshev ◽  
V. G. Burdukovskii ◽  
B. N. Gubashov ◽  
V. V. Kirichenko
Keyword(s):  
Large Diameter ◽  
Load Carrying ◽  
Large Diameter Pipes

Factory-applied anticorrosive insulation for large-diameter pipes

Metallurgist ◽  
1987 ◽  
Vol 31 (10) ◽  
pp. 320-321
Author(s):  
V. M. Ryabov ◽  
L. A. Usova
Keyword(s):  
Large Diameter ◽  
Large Diameter Pipes

scholarly journals EFFICIENCY OF MODIFYING ADDITIVES IN POWDER COATING MATERIALS

2021 ◽  
pp. 47-57
Author(s):  
V.І. Gots ◽  
◽  
О.V. Lastivka ◽  
О.О. Tomin ◽  
◽  
...  
Keyword(s):  
Surface Tension ◽  
Silicon Dioxide ◽  
Mechanical Characteristics ◽  
Powder Coating ◽  
Coating Film ◽  
Powder Coatings ◽  
High Effectiveness ◽  
Modifying Additives ◽  
Polymer Resin ◽  
Technical Specifications

Rapid rates of development in production of powder coatings are, in comparison to liquid paint-and-lacquer materials, evidence of their importance, high effectiveness and prospectivity. The increase in popularity of powder coatings can be explained by their environmental adequacy and attractiveness from the perspective of the environmental protection as well as high effectiveness related to the possibility of obtaining high quality protective and decorative coatings during the one-layer application. At the same time, it is obvious that during modern powder coating-and-lacquer materials have not exhausted all possibilities of improving pharmaceutical compositions and expanding the assortment as well as modernizing their production technology the relatively short period of their development. The composition of the thermosetting powder coating contains five key components: polymer resin, hardener, pigments, fillers and functional additives. In general, the polymer resin and hardener play a key role in ensuring necessary mechanical characteristics and lifespan of the powder coating. In this case, the role of functional (modifying) additives is extremely important to obtain characteristics that are often fundamentally required to meet predetermined technical specifications of the products and needs of end users. Additives play an important role in forming properties of powder coatings and coatings based on them as they have become their integral part for several main reasons: because of control of rheological properties, surface defects as well as light and temperature stabilization of coatings. The study deals influence of modifying additives on properties of the powder coating. The authors using rheological and degassing modifying additives with different nature of the main active substance. It was found that the additives based on the acrylate polymer adsorbed on the silicon dioxide in the form of Byk-3900P and on the polyoxyethylene derivative of the castor oil in the form of Luvotix R400 decreasing the surface tension in the coating film, which, in its turn, contributes to the increase in the wettability of base during the melting of the powder coating, decrease the ‘orange peel’ effect during the cross-linking, reduction in pinholes on the obtained surface and improvement of mechanical characteristics of the coating. At the same time, rheological additives based on the bentonite in the form of Luvogel 4B and on the hydrophilic silicon dioxide in the form of Cab-o-sil M5 cause the increase in the surface tension in the coating film, which, in its turn, leads to the worsening of flow, appearance and mechanical characteristics of the powder coating.

scholarly journals The impact of flooding on the operational reliability of real estate in the Kursk region

2019 ◽  
Vol 17 (2) ◽  
pp. 213-216 ◽  
Author(s):  
Vladimir Khaustov ◽  
Lorina Kruglova ◽  
Natalia Bredikhina ◽  
Teimur Guseinov
Keyword(s):  
Real Estate ◽  
Operational Reliability ◽  
The Impact ◽  
Kursk Region
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