Method for Computational Estimation of Frost Resistance in Aircraft Paint Coatings

2020 ◽  
pp. 4-17
Author(s):  
A.A. Aliyev ◽  
A.Yu. Аmpilogov
Keyword(s):  
Frost Resistance ◽  
Linear Thermal Expansion ◽  
Physical And Mechanical Properties ◽  
Temperature Cycling ◽  
Operating Conditions ◽  
Computational Method ◽  
Ice Accretion ◽  
Freezing And Thawing ◽  
Paint Coating ◽  
Paint Coatings

The paper considers the issues of temperature cycling and ice accretion on external paint coatings of aircraft as well as the negative effects of these processes expressed in periodic tension-compression strain and absorption of atmospheric moisture by surface microasperities with its subsequent freezing resulting in gradual cavity wedging. We note that laboratory testing methods recreating the temperature cycling that simulates actual operating conditions of aircraft paint coatings are increasingly labour-intensive. We substantiate the feasibility of developing a computational method for frost resistance estimation in specific operating conditions. The method takes into account the combination of contraction stresses, excessive cooling and wedging caused by ice build-up. We assume the main physical and mechanical properties of ice and paint to be homogeneous and equal to cumulative average values, and the linear thermal expansion coefficients of the substrate and coating to be constant and not dependent on temperature. We disregard ice friction over the microasperity cavities and in-flight loads on the paint coating caused by incident air flows and structural deformations of the aircraft. We present a method of computing frost resistance of aircraft paint coating subjected to cyclical ice accretion, which is based on the method of equivalent stresses. We tested frost resistance of a polyesterurethane coating over a duralumin plate in the range of --50 to 25 °C for F = 2000 freezing and thawing cycles. We performed a temperature cycling computation of the factor of safety for frost resistance in the case of periodic ice accretion. The results obtained are in good agreement with experimental data

scholarly journals Concrete based on sulfur binder being modified with inorganic additives

2018 ◽  
Vol 212 ◽  
pp. 01013
Author(s):  
Vadim Balabanov ◽  
Victor Baryshok ◽  
Nikita Epishkin
Keyword(s):  
Frost Resistance ◽  
Building Materials ◽  
Physical And Mechanical Properties ◽  
High Strength ◽  
Strength Properties ◽  
Climatic Conditions ◽  
Freezing And Thawing ◽  
Concrete Mixtures ◽  
Irkutsk Region ◽  
Water Saturated

The sharply continental climate of the Irkutsk region is characterized by wide temperature intervals throughout the year. The repeated cyclicity of freezing and thawing of building materials in the water-saturated state influences the change in technical characteristics and the durability of concrete products and structures. The concrete products’ features in such climatic conditions create the need for the production of concretes with improved indicators of physical and mechanical properties. The effect of modifying additives on the technological characteristics of sulfur concrete is established. The effect of all elements of sulfur concrete on its strength and frost resistance. The composition of sulfuric concrete is obtained, which meets all the requirements and also has high strength and increased frost resistance. Formulations with a certain ratio of structural sulfuric concrete mixtures were developed. As a result of the use of technical sulfur in the composition of concrete products, the problem of utilizing annually accumulating reserves of technical sulfur is partially solved. The strength properties of sulfuric concretes easily compete with high-quality brands of concrete, special types of concretes that have in their composition additives.

scholarly journals Effect of Eco-Friendly Cellulose Nanocrystals on Physical Properties of Cement Mortars

Polymers ◽  
2019 ◽  
Vol 11 (12) ◽  
pp. 2088 ◽  
Author(s):  
Danuta Barnat-Hunek ◽  
Małgorzata Grzegorczyk-Frańczak ◽  
Monika Szymańska-Chargot ◽  
Grzegorz Łagód
Keyword(s):  
Weight Loss ◽  
Frost Resistance ◽  
Detrimental Effect ◽  
Physical And Mechanical Properties ◽  
Salt Crystallization ◽  
High Modulus ◽  
Freezing And Thawing ◽  
Low Thermal Expansion ◽  
Cement Mortars ◽  
Microstructure Examination

Nanocellulose, being a material with nanodimensions, is characterized by high tensile strength, high modulus of elasticity, low thermal expansion, and relatively low density, as well as exhibiting very good electrical conductivity properties. The paper presents the results of research on cement mortars with the addition of nanocrystals cellulose, applied in three different amounts (0.5%, 1.0%, and 1.5%) by weight of cement, including: physical and mechanical properties, frost resistance and resistance against the detrimental effect of salt, and microstructure examination (SEM). Along with an increase in amount of admixture, the weight loss following frost resistance and salt crystallization tests is reduced. Studies have shown that the addition of nanocrystalline cellulose improves the compressive and flexural strength by 27.6% and 10.9%, respectively. After 50 freezing and thawing (F–T) cycles for the mortars with 1.5% nanocellulose admixture, an improvement in frost resistance by 98% was observed. In turn, the sulfate crystallization tests indicated a 35-fold decrease in weight loss following 1.5% nanopolymer addition to the mortar.

scholarly journals Durability of Hydrophobic/Icephobic Coatings in Protection of Lightweight Concrete with Waste Aggregate

Materials ◽  
2020 ◽  
Vol 14 (1) ◽  
pp. 101
Author(s):  
Danuta Barnat-Hunek ◽  
Jacek Góra ◽  
Marcin K. Widomski
Keyword(s):  
Frost Resistance ◽  
Lightweight Concrete ◽  
Physical And Mechanical Properties ◽  
High Porosity ◽  
Freezing And Thawing ◽  
Adhesive Properties ◽  
Surface Protection ◽  
High Durability ◽  
Before And After ◽  
Freezing And Thawing Cycles

The aim of the research presented in this paper is to evaluate the feasibility of using hydrophobic agents based on organosilicon compounds for surface protection of lightweight concrete modified with waste polystyrene. The experimental part pertains to the physical and mechanical properties of polystyrene-modified lightweight concrete. The concrete samples were prepared with the following ingredients: CEM I 42.5 R cement, recycled polystyrene (0–2 mm), quartz sand (0–2 mm), coarse river aggregate (2–16 mm), and water. Silane and tetramethoxysilane were employed for surface hydrophobization. Concrete with 20% polystyrene exhibits high porosity (25.22%), which is related to an increase in absorptivity (14.75%) compared to the reference concrete. The hydrophobized concrete is characterized by the lowest surface free energy (SFE) value, which is 7 or 11 times lower than the value of reference concrete, depending on the agents. The test on the contact angle (CA) was performed before and after the frost-resistance test (F–T test). Lower SFE translates into lower adhesive properties, higher resistance of the material to the infiltration of water and corrosive compounds, e.g., salts, and higher resistance to freezing and thawing cycles. Silane and tetramethoxysilane coating raised frost resistance by 54–58% compared to the reference samples. This agent reduced absorptivity by 30%. Recycled polystyrene can be successfully used to produce lightweight concrete (LC) with high durability provided by hydrophobic/icephobic coatings.

Structure and properties of compact articles from high-alloyed iron powder with adding of boron nitride

2020 ◽  
pp. 39-48
Author(s):  
B. O. Bolshakov ◽  
◽  
R. F. Galiakbarov ◽  
A. M. Smyslov ◽  
◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Boron Nitride ◽  
Grain Boundary ◽  
Bending Strength ◽  
Physical And Mechanical Properties ◽  
Operating Conditions ◽  
Structure And Properties ◽  
Steam Turbines ◽  
Friction Forces ◽  
Wide Range

The results of the research of structure and properties of a composite compact from 13 Cr – 2 Мо and BN powders depending on the concentration of boron nitride are provided. It is shown that adding boron nitride in an amount of more than 2% by weight of the charge mixture leads to the formation of extended grain boundary porosity and finely dispersed BN layers in the structure, which provides a high level of wearing properties of the material. The effect of boron nitride concentration on physical and mechanical properties is determined. It was found that the introduction of a small amount of BN (up to 2 % by weight) into the compacts leads to an increase in plasticity, bending strength, and toughness by reducing the friction forces between the metal powder particles during pressing and a more complete grain boundary diffusion process during sintering. The formation of a regulated structure-phase composition of powder compacts of 13 Cr – 2 Mо – BN when the content of boron nitride changes in them allows us to provide the specified physical and mechanical properties in a wide range. The obtained results of studies of the physical and mechanical characteristics of the developed material allow us to reasonably choose the necessary composition of the powder compact for sealing structures of the flow part of steam turbines, depending on their operating conditions.

scholarly journals Properties and Structure of Concretes Doped with Production Waste of Thermoplastic Elastomers from the Production of Car Floor Mats

Materials ◽  
2021 ◽  
Vol 14 (4) ◽  
pp. 872
Author(s):  
Malgorzata Ulewicz ◽  
Alina Pietrzak
Keyword(s):  
Tensile Strength ◽  
Production Process ◽  
Compression Strength ◽  
Physical And Mechanical Properties ◽  
Thermoplastic Elastomer ◽  
Thermoplastic Elastomers ◽  
Production Waste ◽  
Fine Aggregate ◽  
Freezing And Thawing ◽  
Average Decrease

This article presents physical and mechanical properties of concrete composites that include waste thermoplastic elastomer (TPE) from the production process of car floor mats. Waste elastomer (2–8 mm fraction) was used as a substitute for fine aggregate in quantities of 2.5, 5.0, 7.5, and 10% of the cement weight. For all series of concrete, the following tests were carried out: compression strength, bending tensile strength, splitting tensile strength, absorbability, density, resistance to water penetration under pressure, frost resistance, and abrasion resistance, according to applicable standards. Moreover, SEM/EDS analysis was carried out on the surface microstructure of synthesized concrete composites. It was proven that the use of production waste from the production process of car floor mats in the quantity of 2.5% does not influence the change of the concrete microstructure and it does not result in the decrease of the mechanical parameters of concrete modified with waste. All concrete modified with the addition of waste meet standards requirements after carrying out 15 cycles of freezing and thawing, and the average decrease in compression strength did not exceed 20%. Adding waste in the quantity of 2.5% allows for limiting the use of aggregate by about 5%, which is beneficial for the natural environment.

scholarly journals CHANGES IN THE COMPOSITION AND PROPERTIES OF THE HOST ROCKS OF COAL DEPOSITS IN YAKUTIA UNDER THE INFLUENCE OF CRYOGENESIS

2020 ◽  
Vol 5 (443) ◽  
pp. 133-140
Author(s):  
Melnikov Andrey E., ◽  
◽  
Ze Zhang, ◽  
Grib Nikolay N., ◽  
Camil Jakub Shabo, ◽  
...  
Keyword(s):  
Ultimate Strength ◽  
Great Influence ◽  
Physical And Mechanical Properties ◽  
Strength Properties ◽  
Physicomechanical Properties ◽  
Freezing And Thawing ◽  
Coal Deposits ◽  
Host Rocks ◽  
Transformation Processes ◽  
Cryogenic Processes

The results of laboratory tests carried out on rock samples of the Kharbalakhskoye coalfield located in Central Yakutia revealed significant secondary changes having taken place in the host rocks containing the coal. Evidently, under transformation processes, it is not only the composition of the rocks that had changed, but also the nature of structural bonds that have a great influence on their physical and mechanical properties. Thus, the ultimate strength values of coal-containing sandstone and siltstone samples under uniaxial compression vary from 20 to 30 MPa, while under uniaxial tension, the ultimate strength values range from 6 to 10 MPa. These relatively low numerical values pertaining to the physicomechanical properties of rocks, which are generally atypical for long-flame coal deposits, are almost 50% lower than those of analogous rocks hosting other coal deposits in Russia. It is considered that the mechanical strength properties of the rocks of the Kharbalakhskoye field are due to significant cryogenic processes. A comparative analysis of the properties of core samples obtained from boreholes drilled in 2019 with samples from a quarry obtained several decades ago reveals signs of transformation of rocks in the Kharbalakhskoye field due to phase transitions of freezing and thawing water.

scholarly journals Effect of Polypropylene Fiber on Frost Resistance of Cemented Soil

2019 ◽  
Vol 57 (2) ◽  
pp. 78-86
Author(s):  
Lina Xu ◽  
Lei Niu
Keyword(s):  
Frost Resistance ◽  
Polypropylene Fiber ◽  
High Strength ◽  
Strength Loss ◽  
Curing Time ◽  
Freezing And Thawing ◽  
Cemented Soil ◽  
Small Cracks ◽  
The Impact ◽  
Engineering Projects

Polypropylene fiber is widely used as a reinforcing material in composite materials of various engineering projects, because it has high strength and corrosion resistance. In this study, with the purpose of examine the impact of discrete polypropylene fiber on frost resistance of cemented soil, cemented soil treated with polypropylene fiber is used as the research sample. Firstly, the impact of curing time, fiber content and length on the strength of cemented soil has been considered. And then, the frost resistance characteristics of cemented soil reinforced by polypropylene fiber with the content of 0.5% have been investigated. The results show that with the development of curing time, the strength of cemented soil increases logarithmically. By adding an appropriate amount of polypropylene fiber, the strength of the specimen may be improved. In this study, cemented soil reinforced by polypropylene fiber 0.1% in content and 3 mm in length has the best reinforcement effect. After 21 cycles of freezing and thawing processes, a sharp decline in strength of cemented soil without fiber, and the strength loss ratio is up to 45%. There are cracks in the specimens, and some of the specimens have broken off. Differently, after 21 freeze-thaw cycles, the strength of the cemented soil with fiber decreased less, and the strength loss ratios are between 1 and 13%, and there are only small cracks on the surface of specimens. The results show that adding discrete polypropylene fiber is a suitable method to prevent the generation and development of internal cracks in the cemented soil during freezing and thawing, thereby improving the frost resistance. These results can be used as a reference for the application of cemented soil reinforced with fiber in seasonal frozen regions.

scholarly journals Experimental Study on Freezing and Thawing Cycles of Shrinkage-Compensating Concrete with Double Expansive Agents

Materials ◽  
2020 ◽  
Vol 13 (8) ◽  
pp. 1850
Author(s):  
Jinjun Guo ◽  
Ting Guo ◽  
Shiwei Zhang ◽  
Yan Lu
Keyword(s):  
Frost Resistance ◽  
Large Scale ◽  
Mass Loss Rate ◽  
Test Results ◽  
Freezing And Thawing ◽  
Expansive Agent ◽  
Hydraulic Concrete ◽  
Mix Proportion ◽  
Three Stages ◽  
Freezing And Thawing Cycles

The freezing and thawing of construction concrete is becoming an increasingly important structural challenge. In this study, a shrinkage-compensating concrete based on a double expansive admixture was developed and its frost resistance was assessed through rapid freezing and thawing cycling. The frost resistance of the concrete was derived through the measurement and calculation of the relative dynamic modulus of elasticity (RDME) and the mass loss rate (MLR), and the freezing- and thawing-cycle microstructures and products of concretes with different expansive agents were analyzed using scanning electron microscopy (SEM). It was shown that changes in the properties of the concrete under freezing and thawing could be divided into three stages: slow-damage stage, fast-damage stage, and stable stage. Compared to concrete without an expansive agent, a single-expansive-agent concrete demonstrated excellent frost resistance during the slow-damage stage, but the frost resistance rapidly decreased during the fast-damage age. After 150 cycles (the stable-damage stage), the concrete with a U-type expansive agent (UEA): MgO expansive agent (MEA) mix proportion of 2:1 had the best frost resistance, with RDME and MLR values 17.35% higher and 25.1% lower respectively, than that of an expansive-agent-free concrete. These test results provide a basis for the study of frost resistance in large-scale hydraulic concrete structures.

Ice Formation as an Indicator of Frost-Resistance on the Concrete Containing Slag Cement in Conditions of Freezing and Thawing

2016 ◽  
Vol 865 ◽  
pp. 145-150
Author(s):  
Oleksandr Moskalenko ◽  
Rayisa Runova
Keyword(s):  
Frost Resistance ◽  
Ice Formation ◽  
Cement Concrete ◽  
Chemical Additives ◽  
Freezing And Thawing ◽  
Slag Cement ◽  
Mineral Supplement

The connection with the icing on the frost resistance of concrete containing slag cement and chemical additives «MC Bauchemie» under freezing and thawing.It is shown that freeze concrete samples at (-) 10°C increase in the amount of slag from 30 to 70 wt.% Of binder in the composition leads to an increase in the index of ice formation in the concrete of 1.7 ... 1.9 times compared with the concrete obtained at a slag containing slag cement with a content of 10 wt.%. Frost resistance of concrete is reduce from F450 to F400.When freezing of concrete samples at (-) 20°C increase in the amount of slag from 30 to 50 wt. % Binder in the composition leads to an increase in the index of ice formation in the concrete of 1.7 times compared with the concrete obtained on slag cement containing slag with a content of 10 wt.%. Frost resistance of concrete is reduce from F400 to F350.The concrete on the slag containing cement with slag 70 wt. % is observed a slight decrease in ice formation. However, its value is 1.4 times higher than ice formation in concretes containing slag in an amount of 10 wt. %. Mark on frost resistance remains at F350.The smallest ice formation, regardless of the content of the slag into the slag containing cement, concrete characterized in that use complex organo-mineral supplement SX (5%) + SP (0.6%) in the amount of 5.6%. According to the degree of influence of additives used to reduce ice formation in the slag in concretes, containing cements can be ranker number: SX (5%) + SP (0.6%) > NC (5%) + SP (0.6%) > SP (0.6%).

scholarly journals Moisture and Frost Resistance of the Recycled Base Rehabilitated with the Foamed Bitumen Technology / Odpornosc Na Oddziaływanie Wody I Mrozu Podbudowy W Technologii Recyklingu Z Asfaltem Spienionym

2012 ◽  
Vol 58 (2) ◽  
pp. 185-198 ◽  
Author(s):  
M. Iwanski ◽  
A. Chomicz-Kowalska
Keyword(s):  
Frost Resistance ◽  
New Technology ◽  
Physical And Mechanical Properties ◽  
Climatic Conditions ◽  
Specific Production ◽  
Central European ◽  
Road Pavement ◽  
Foamed Bitumen ◽  
Cold Recycling ◽  
Production Conditions

Abstract The technology of recycling with foamed bitumen is a new technology of road rehabilitation. Due to the climatic conditions in the Central European countries, road pavement structure should be moisture and frost resistant. Because of its specific production conditions, this is especially important for pavements rehabilitation with the cold recycling technology. Determining the physical and mechanical properties, as well as moisture and frost resistance, depends on binder and filler contents. They are the key elements before its use for road building. The tests presented here have been performed on mineral recycled base mixes with foamed bitumen. The material from the existing layers was used. The content of bitumen binder amounted to 2.0%, 2.5%, 3.0% and 3.5%, while that of cement to 1.0%, 1.5%, 2.0%, 2.5%. The results were subject to the optimization process. This allowed to state that with the use of 2.5% foamed bitumen and 2.0% of cement, the base had the required properties, as well as the moisture and frost resistance.

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