Defect and Diffusion Forum最新文献

{"title":"Evaluation of the Effect of Impregnation Coatings on Concrete Protection","authors":"Lukáš Sedlaček, J. Fládr, I. Broukalová","doi":"10.4028/p-gei8wj","DOIUrl":"https://doi.org/10.4028/p-gei8wj","url":null,"abstract":"The paper deals with evaluation and comparison of the effect of two substances on reduction of concrete absorbability and increasing the durability. In four tests the effect of hydrophobic impregnation of investigated substances on various properties of test specimens was examined. The penetration depth, the rate of water absorption and alkali resistance, drying ratio and weight loss after freeze-and-thaw cycles in sodium chloride solution were the followed parameters. The positive effect of both substances on the final durability of concrete was confirmed.","PeriodicalId":11306,"journal":{"name":"Defect and Diffusion Forum","volume":" 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-03-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140384642","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Composite Conductive Carbon-Polymer Paints as a Replacement for the “Faraday Cage”","authors":"V. Barsukov, I. Senyk, Borys Haliuk, Yaroslav Kuryptia, Volodymyr H Khomenko, O. Butenko, O. Chernysh, Iryna Makyeyeva, Mirella Suchea, Emmanuel Koudoumas","doi":"10.4028/p-way26a","DOIUrl":"https://doi.org/10.4028/p-way26a","url":null,"abstract":"We have developed composite paint based on graphite, carbon black and some other not expensive components, which can be used as a clay court for sustainable buildings and electronic devices. This paint can reduce sufficiently the problem, which is related to the effects of electromagnetic radiation (EMR) on human health. Cellular and radiotelephones, as well as their broadcast antennas, especially which use of the 5G, 6G communication system, may pose a high risk of cancer, reproductive disorders, memory, cellular stress, neurological and mental disorders. The medical disorders are already often experienced by servicemen working at radar stations, observation posts and other similar facilities associated with high-frequency EMR. The effect of EMR is especially dangerous for children of preschool and school age, so, it is necessary to use similar paints first of all for such buildings. Carbon-based composite paints have been developed, which can be used as a clay court for sustainable buildings and electronic devices. This paint can reduce sufficiently the problem, which is related to the effects of electromagnetic radiation (EMR) on human health. Cellular and radiotelephones, as well as their broadcast antennas, especially which use of the 5G, 6G communication system, may pose a high risk of cancer, reproductive disorders, memory, cellular stress, neurological and mental disorders. The medical disorders are already often experienced by servicemen working at radar stations, observation posts and other similar facilities associated with high-frequency EMR. The effect of EMR is especially dangerous for children of preschool and school-age, so, it is necessary to use similar paints first of all for such buildings. It is also necessary to note the significant impact of EMR on electronic equipment. First of all, this is a well-known problem of providing the so-called \"electronic compatibility\", when simultaneously operating different electronic equipment (e.g., thermal imager and radio transmitter) interfere with each other. A number of scientific developments have been implemented and work is underway under the NATO SfS international grant in this area.","PeriodicalId":11306,"journal":{"name":"Defect and Diffusion Forum","volume":" 66","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-03-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140384667","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Selected Mechanical Properties of Concrete with Regard to the Type of Steel Fibers","authors":"Radoslav Gandel","doi":"10.4028/p-ag0dte","DOIUrl":"https://doi.org/10.4028/p-ag0dte","url":null,"abstract":"Not only in the construction industry, but also in other technical areas, efforts are being made to reduce the costs or difficulty of producing a certain product and at the same time to improve some of its properties. With the development of modern technologies come new possibilities in the development and production of such products. Fiber reinforced concrete is one of them. Fiber reinforced concrete does not fully replace reinforced concrete, but even with a reduction in price and production time, it has a certain part of the properties of reinforced concrete, which can be used for structural elements with specifically required properties. The subject of the presented paper is the testing and comparison of compressive and split tensile strength of steel fiber reinforced concrete (SFRC) with steel fibers MasterFiber 482 with dosage 60 kg/m3 and 90 kg/m3 and SFRC with 5 different types of steel fibers with dosage 50 kg/m3, where dosage 0 kg/m3 represents ordinary portland concrete (OPC). Submitted paper is also focused on specific test methods of concrete, such as measurement of resistance to frost and defrosting chemicals and pressure water seepage.","PeriodicalId":11306,"journal":{"name":"Defect and Diffusion Forum","volume":"113 36","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-03-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140381324","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Replacement of Fine Aggregates in Fine-Grained Concrete by Waste Material from Cetris Boards Production","authors":"Kateřina Matýsková, Vlastimil Bílek, Lukáš Procházka, Radka Hédlová, Marie Horňáková","doi":"10.4028/p-smci67","DOIUrl":"https://doi.org/10.4028/p-smci67","url":null,"abstract":"Given the increasing amount of waste in the world, it is essential not only to reduce waste generation but also to explore potential uses for the waste produced. This includes waste generated in the production of building materials. The construction industry is a significant contributor to global waste and carbon dioxide emissions, making it crucial to address these issues for sustainable development. During the production of CETRIS boards, approximately 7 600 tons of waste are generated annually. One of the waste materials obtained during the board processing is a fine powder. This waste material can potentially be reused in two ways: it can be incorporated back into the process of producing CETRIS boards or utilized in the production of building materials. This research project focuses on examining the possibility of using this waste material as a substitute for fine aggregate in fine-grained concrete. To investigate its viability, the waste material underwent testing for dry density and absorbency. Subsequently, a reference mixture and concretes with different replacement rates (50%, and 100%) of natural fine aggregate were produced to create self-healing concrete mixtures. The study examined the density, and compressive strength of these concrete samples 28 days after concreting. The findings indicated that as the amount of waste material in the concrete increased, the measured properties decreased. However, despite the decrease, the compressive strengths of the concrete remained very high, leading to the classification as high-strength concrete. Further exploration and optimization of the replacement rates could lead to the development of environmentally friendly and sustainable building materials.","PeriodicalId":11306,"journal":{"name":"Defect and Diffusion Forum","volume":" 890","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-03-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140383064","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"High Performance and Ultra-High Performace Fibre Reinforced Concrete with Stabilized Homogeneity","authors":"L. Musil, Jan Vesecký, Jan Kubát, Jan Vodička","doi":"10.4028/p-47eirw","DOIUrl":"https://doi.org/10.4028/p-47eirw","url":null,"abstract":"This paper describes the segregation of fibres in high performance and high strength concretes. It focuses on both laboratory and practical conditions. It compares different mixtures produced and processed in the laboratory and in the precast concrete company. Two methods are chosen in the paper to avoid fibre segregation. The first method is a suitable mix design considering the water/cement ratio and the amount of superplasticizer. The second method is the addition of synthetic fibres to the mixture while maintaining sufficient workability. The paper examines the consistence of each mixture according to the concrete placement location, segregation of fibres in the fresh mixture and hardened composite. Both methods under laboratory and practical conditions have shown a positive impact on the reduction of segregation of steel fibres in the mixture. Simultaneously, the strength properties of all mixtures were compared, which depended mainly on the type of synthetic fibres used.","PeriodicalId":11306,"journal":{"name":"Defect and Diffusion Forum","volume":" 20","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-03-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140384404","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"3D Printed Cement Composites Testing","authors":"Denisa Jancarikova, I. Khongová, Petr Bibora, Halina Szklorzova","doi":"10.4028/p-qfstv6","DOIUrl":"https://doi.org/10.4028/p-qfstv6","url":null,"abstract":"Testing of the properties of cement mortars for 3D printing has not been standardized yet. Manufacturers of dry mixes declares tensile strength and compressive strength, but these properties are determined on standard beams for cement mortars, and their values may differ from the material actually formed by the 3D printing method. Another factor affecting strength is the printing process itself, where different printing machines require different consistencies and therefore different amount of water. Last but not least, it is necessary to take into account the different properties of the printed material depending on the direction of testing. Presented article brings results of determination the compressive strength, flexural tensile strength, splitting tensile strength and uniaxial tensile strength of the cement mortar from 3D printing loaded in different directions in relation to the axis of the print and comparing them with the parameters determined on standard beams made of the same material. A commercially produced dry mixture was used. Rectangular object was printed. Before the actual printing and also the fresh mixture was taken from the print head directly into the molds for the production of standard beams 40×40×160 mm. The printed object and the beams were placed in a water environment after 24 hours and the properties were determined at the age of 28 days. Cubes with dimensions of 40×40×40 mm and beams of 40×40×160 mm were subsequently cut from the printed object. The results of the testing point to a relatively large variability of the strength characteristics not only according to the direction of the load forces, but also in different places of the printed object (samples were taken in the bottom part, in the middle and in top of the printed object). Strengths of the standard beams were significantly higher than strengths of samples cut out from 3D printed object.","PeriodicalId":11306,"journal":{"name":"Defect and Diffusion Forum","volume":" 27","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-03-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140383633","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Effect of the Non-Linear Radiative Unsteady Mixed Convective Flow over a Curved Stretching Surface with Soret and Dufour Effects: A Numerical Study","authors":"Temjennaro Jamir, H. Konwar","doi":"10.4028/p-8dz1ax","DOIUrl":"https://doi.org/10.4028/p-8dz1ax","url":null,"abstract":"The subject of unsteady convective flow with non-linear thermal radiation has become an important issue of research, due to its implications in advanced energy conversion systems operating at high temperature, solar energy technology and chemical process at high operation temperature. Due to the importance of this issue, a time dependent incompressible viscous fluid flow, heat and mass transfer over a curved stretching surface has been numerically analysed by taking into account the heat flux due to concentration gradient and mass flux due to temperature gradient. Together with this the Rosseland approximation is being employed for the nonlinear thermal radiation impact in presence of thermal slip. With the aid of non-dimensional variables and the corresponding physical boundary conditions, the leading nonlinear momentum, energy, and species equations are converted into a set of coupled ordinary differential equations. These equations are then resolved using the MATLAB bvp4c solver. The stability of the numerical technique has been verified and compared with available literatures. The resultant parameters of engineering interest and the boundary layer flow field parameters and have been presented using tables and graphically plots. The study concludes that for lesser curvature parameter (0.5≤K≤0.7) the surface drag force, heat and mass transfer rates can improve by about 9.59%, 2.87% and 1.67% each respectively. The presence of the temperature ratio parameter and the non-linear thermal radiation are found to greatly influence the temperature profile and the heat transfer rate of the system. Results show that the heat transfer rate improves by about 24.39% and 16.66% for varying non-linear thermal radiation (1≤Rd≤1.5) and temperature ratio parameter (1.2≤θw≤1.4) respectively. Results obtained also show that improving the thermal slip parameter (0.4≤L≤0.6) can reduce heat transfer rate by about 13.62% and reduce the surface temperature profile.","PeriodicalId":11306,"journal":{"name":"Defect and Diffusion Forum","volume":"35 32","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-01-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139442848","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Wear of the 3D Printed Polylactic Acid Elements Sliding against the Synthetic Resins at the Higher Speed Friction","authors":"Yuh-Ping Chang, C. Liu, Jin Chi Wang, Kao Wei Chen, Mei Fen Suyeh","doi":"10.4028/p-akaa6p","DOIUrl":"https://doi.org/10.4028/p-akaa6p","url":null,"abstract":"Since the requirement of high dust-free levels, it is necessary to develop the technologies with anti-wear and low dust generation for drive elements that can be quickly printed. Polylactic acid and synthetic resins are often paired with each other for the 3D printed driven elements. To achieve \"smooth friction\", the adhesion wear under dry friction conditions should be reduced. To achieve a \"high dust-free level\", the anti-wear of the paired elements under higher speed friction should be improved to reduce the generation of abrasive dust. Therefore, wear of the 3D printed polylactic acid elements sliding against the synthetic resins at the high speed friction are investigated in this paper.","PeriodicalId":11306,"journal":{"name":"Defect and Diffusion Forum","volume":"22 17","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-01-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139443220","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Effect of Laser Surface Modification on Texture, Roughness, Wettability and Surface Energy of Hastelloy C22, C276 & X","authors":"P. Suvin, Ambesh Singh, B. D. K. Patro, Vimal Edachery, S. Kailas, J. Horng","doi":"10.4028/p-5jhop9","DOIUrl":"https://doi.org/10.4028/p-5jhop9","url":null,"abstract":"Hastelloy is a nickel-chromium-molybdenum-iron-based alloy and a member of the ‘superalloy’ family. Hastelloy has exceptional properties like high strength, wear resistance and high-temperature stress-corrosion resistance. Therefore, Hastelloy is used in gas turbines, power plants, metal injection molding, etc. Many industrial applications are related to the properties of the surface. Wettability is a key surface property that affects applications like lubrication, adhesion, coating, heat conduction, etc. Laser Texturing is an excellent method to modify the surface properties of materials like metal, polymers and ceramic. In the present study, a carbon dioxide laser created unidirectional textures on Hastelloy (C22, C276, X). Different sets of unidirectional textures were formed by changing the laser power and frequency. Various roughness parameters were compared for every laser parameter. In this paper, the effective change in wettability properties of Hastelloy (C22, C276, X) after the Laser texturing process for a range of power and frequency were studied under DI water and glycerol as test fluids. Results show that the contact angle of the test fluid increases as the laser power increases, and the contact angle decreases as the laser frequency increases for all three superalloys. The surface energy of a given set of samples was also measured using the recorded contact angle of DI water and Glycerol by the OWRK equation. Similar trends were found in surface energy for all three Hastelloy.","PeriodicalId":11306,"journal":{"name":"Defect and Diffusion Forum","volume":"31 12","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-01-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139443932","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Study on Shape Effect of MHD Radiative Ag-Water and CuO-Water Nanofluid Flow in a Semi-Porous Channel","authors":"Dhanonjoy Chandra Paul, Md. Abdul Hye, Md. Maidul Islam, Md. Zakir Hosen, M. Alam","doi":"10.4028/p-1sbxuh","DOIUrl":"https://doi.org/10.4028/p-1sbxuh","url":null,"abstract":"This paper studies the two-dimensional unsteady incompressible Ag-water and CuO-water nanofluid flow in a semi-porous expanding-contracting channel in the presence of thermal radiation effect. The continuity equation, Navier-Stokes equation, and energy equation governing the model are transformed into a set of non-dimensional ordinary differential equations using appropriate transformations. These dimensionless governing equations are solved using power series with the aid of the Hermite-Padé approximation method. The influences of physical parameters such as Reynolds number, expansion ratio, solid volume fraction, Prandtl number, Magnetic parameter, and shape factor are depicted in velocity and temperature profiles. Moreover, the average Nusselt number and skin friction coefficient are also investigated with the effect of Reynolds number, solid volume fraction, and expansion ratio. It is observed that the heat transfer rate decreases significantly as the shape factor increases.","PeriodicalId":11306,"journal":{"name":"Defect and Diffusion Forum","volume":"40 31","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-01-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139442491","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}