scholarly journals An Effective Method for Hybrid CNT/GNP Dispersion and Its Effects on the Mechanical, Microstructural, Thermal, and Electrical Properties of Multifunctional Cementitious Composites

2020 ◽  
Vol 2020 ◽  
pp. 1-20
Author(s):  
Mohammadmahdi Abedi ◽  
Raul Fangueiro ◽  
Antonio Gomes Correia
Keyword(s):  
Mechanical Performance ◽  
Aqueous Suspension ◽  
Research Work ◽  
Cementitious Composites ◽  
Sodium Dodecylbenzene Sulfonate ◽  
Dodecylbenzene Sulfonate ◽  
Dispersion Mechanism ◽  
Optical Microscopic Image ◽  
Thermal And Electrical Properties ◽  
Quality Dispersion

This paper reports a study undertaken to achieve a compatible and affordable technique for the high-quality dispersion of carbon nanotubes (CNTs) and graphene nanoplatelets (GNPs) in an aqueous suspension to be used in multifunctional cementitious composites. In this research work, two noncovalent surfactants with different dispersion mechanisms (Pluronic F-127 (nonionic) and sodium dodecylbenzene sulfonate (SDBS) (ionic)) were used. We evaluated the influences of various factors on the dispersion quality, such as the surfactant concentration, sonication time, and temperature using UV-visible spectroscopy, optical microscopic image analysis, zeta potentials, and particle size measurement. The effect of tributyl phosphate (TBP) used as an antifoam agent was also evaluated. The optimum suspensions of each surfactant were used to produce cementitious composites, and their mechanical, microstructural, electrical, and thermal behaviors were assessed and analyzed. The best dispersed CNT+GNP aqueous suspensions using Pluronic and SDBS were obtained for concentrations of 10% and 5%, respectively, with 3 hours of sonication, at 40°C, with TBP used for both surfactants. The results also demonstrate that cementitious composites reinforced with CNT+GNP/Pluronic showed better mechanical performance and microstructural characteristics due to the higher quality of the dispersion and the increasing hydration rate. Composites prepared with an SDBS suspension demonstrated lower electrical and thermal conductivities compared to those of the Pluronic suspension due to changes in the intrinsic properties of CNTs and GNPs by the SDBS dispersion mechanism.

Microstructural and Mechanical Behaviour Evaluation of Mg-Al-Zn Alloy Friction Stir Welded Joint

2020 ◽  
Vol 17 (3) ◽  
pp. 8150-8159
Author(s):  
Kulwant Singh ◽  
Gurbhinder Singh ◽  
Harmeet Singh
Keyword(s):  
Heat Treatment ◽  
Friction Stir Welding ◽  
Magnesium Alloys ◽  
Mechanical Performance ◽  
Fuel Efficiency ◽  
Research Work ◽  
Grain Structure ◽  
Tensile Fracture ◽  
Friction Stir ◽  
The Impact

The weight reduction concept is most effective to reduce the emissions of greenhouse gases from vehicles, which also improves fuel efficiency. Amongst lightweight materials, magnesium alloys are attractive to the automotive sector as a structural material. Welding feasibility of magnesium alloys acts as an influential role in its usage for lightweight prospects. Friction stir welding (FSW) is an appropriate technique as compared to other welding techniques to join magnesium alloys. Field of friction stir welding is emerging in the current scenario. The friction stir welding technique has been selected to weld AZ91 magnesium alloys in the current research work. The microstructure and mechanical characteristics of the produced FSW butt joints have been investigated. Further, the influence of post welding heat treatment (at 260 °C for 1 h) on these properties has also been examined. Post welding heat treatment (PWHT) resulted in the improvement of the grain structure of weld zones which affected the mechanical performance of the joints. After heat treatment, the tensile strength and elongation of the joint increased by 12.6 % and 31.9 % respectively. It is proven that after PWHT, the microhardness of the stir zone reduced and a comparatively smoothened microhardness profile of the FSW joint obtained. No considerable variation in the location of the tensile fracture was witnessed after PWHT. The results show that the impact toughness of the weld joints further decreases after post welding heat treatment.

Pneumatic Microextrusion-Based Additive Biofabrication of Polycaprolactone Bone Scaffolds: Part II – Investigation of the Influence of Polymer Flow Parameters

2021 ◽  
Author(s):  
Mohan Yu ◽  
Logan Lawrence ◽  
Pier Paolo Claudio ◽  
James B. Day ◽  
Roozbeh (Ross) Salary
Keyword(s):  
Mechanical Performance ◽  
Research Work ◽  
Biological Tissues ◽  
Direct Write ◽  
Bone Scaffolds ◽  
Flow Parameters ◽  
Material Deposition ◽  
Flow Pressure ◽  
Physical Phenomena ◽  
Head Temperature

Abstract Pneumatic micro-extrusion (PME), a direct-write additive manufacturing process, has emerged as a high-resolution method for the fabrication of a broad range of biological tissues and organs. However, the PME process is intrinsically complex, governed by complex physical phenomena. Hence, investigation of the effects of consequential parameters would be an inevitable need. The goal of this research work is to fabricate biocompatible, porous bone tissue scaffolds for the treatment of osseous fractures, defects, and eventually diseases. In pursuit of this goal, the objective of this study is to investigate the influence of material deposition factors — i.e., (i) deposition head temperature, (ii) flow pressure, and (iii) infill pattern — on the mechanical performance of PME-fabricated bone scaffolds. It was observed that the deposition head temperature as well as the flow pressure significantly affected scaffold diameter (unlike scaffold height). In addition, material deposition rate increased significantly as a result of an increase in the deposition temperature; this phenomenon stems from a reduction in Polycaprolactone (PCL) viscosity. Furthermore, there was a direct correlation between the amount of deposited mass and scaffold stiffness. Overall, the results of this study pave the way for future investigation of PME-deposited PCL scaffolds with optimal functional properties for incorporation of stem cells toward the treatment of osseous fractures and defects.

scholarly journals Efecto del dióxido de titanio en las propiedades mecánicas y autolimpiantes del mortero

2021 ◽  
Vol 25 (109) ◽  
pp. 88-97
Author(s):  
Carlos Magno Chavarry Vallejos ◽  
Liliana Janet Chavarría Reyes ◽  
Xavier Antonio Laos Laura ◽  
Andrés Avelino Valencia Gutiérrez ◽  
Enriqueta Pereyra Salardi ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Tio2 Nanoparticles ◽  
Low Temperatures ◽  
Mechanical Performance ◽  
Cement Mortar ◽  
Physical And Mechanical Properties ◽  
Cementitious Composites ◽  
Palabras Clave ◽  
Self Cleaning

El presente artículo tiene como objetivo determinar la influencia de la adición del dióxido de titanio (TiO2) en el mortero de cemento Pórtland Tipo I. La investigación es descriptiva, correlacional, explicativo, con diseño experimental, longitudinal, prospectivo y estudio de cohorte. Se elaboró una mezcla patrón y tres mezclas de mortero con 5%, 7.5% y 10% de contenido de TiO2 como reemplazo del volumen de cemento para las propiedades autolimpiantes se realizó el ensayo de rodamina e intemperismo. La incorporación de dióxido de titanio disminuyó la resistencia a la compresión, incrementó la fluidez y tasa de absorción de agua; la prueba de rodamina dio que el mortero sin actividad fotocatalítico no contenía TiO2 porque no cumple con los factores de fotodegradación R4 y R26. Mediante la exposición de paneles al intemperismo favoreciendo la propiedad autolimpiante de los morteros con adición de TiO2 (5%). Palabras Clave: Actividad foto catalítico, dióxido de titanio, factores de fotodegradación, propiedades mecánicas y autolimpiante. Referencias [1]E. Medina and H. Pérez, “Influencia del fotocatalizador dióxido de titanio en las propiedades autolimpiables y mecánicas del mortero de cemento - arena 1:4 - Cajamarca,” Universidad Nacional de Cajamarca, 2017. [2]G. Abella, “Mejora de las propiedades de materiales a base de cemento que contienen TiO 2 : propiedades autolimpiantes,” Universidad Politécnica de Madrid, 2015. [3]J. Gonzalez, “El Dióxido de titanio como material fotocatalitico y su influencia en la resistencia a la compresión en Morteros,” Universidad de San Buenaaventura Seccional Bello, 2015. [4]D. Jimenez and J. Moreno, “Efecto del reemplazo de cemento portland por el dioido de titanio en las propiedades mecanicas del mortero,” Pontificia Universidad Javeriana, 2016. [5]L. Wang, H. Zhang, and Y. Gao, “Effect of TiO2 nanoparticles on physical and mechanical properties of cement at low temperatures,” Adv. Mater. Sci. Eng., 2018, doi: 10.1155/2018/8934689. [6]Comisión de Normalización y de Fiscalización de Barreras Comerciales no Arancelares, Norma Técnica Peruana. Perú, 2013, p. 29. [7]ASTM Internacional, “ASTM C150,” 2021. https://www.astm.org/Database.Cart/Historical/C150-07-SP.htm. [8]M. Issa, “( current astm c150 / aashto m85 ) with limestone and process addition ( ASTM C465 / AASHTO M327 ) on the performance of concrete for pavement and Prepared By,” 2014. [9]S. Zailan, N. Mahmed, M. Abdullah, A. Sandu, and N. Shahedan, “Review on characterization and mechanical performance of self-cleaning concrete,” MATEC Web Conf., vol. 97, pp. 1–7, 2017, doi: 10.1051/matecconf/20179701022. [10]C. Chavarry, L. Chavarría, A. Valencia, E. Pereyra, J. Arieta, and C. Rengifo, “Hormigón reforzado con vidrio molido para controlar grietas y fisuras por contracción plástica,” Pro Sci., vol. 4, no. 31, pp. 31–41, 2020, doi: 10.29018/issn.2588-1000vol4iss31.2020pp31-41. [11]D. Tobaldi, “Materiali ceramici per edilizia con funzionalità fotocatalitica,” Università di Bologna, 2009. [12]Norme UNI, “Norma Italiana UNI 11259,” 2016. http://store.uni.com/catalogo/uni-11259-2008?josso_back_to=http://store.uni.com/josso-security-check.php&josso_cmd=login_optional&josso_partnerapp_host=store.uni.com. [13]E. Grebenisan, H. Szilagyi, A. Hegyi, C. Mircea, and C. Baera, “Directory lines regarding the desing and production of self-cleaning cementitious composites,” Sect. Green Build. Technol. Mater., vol. 19, no. 6, 2019. [14]M. Kaszynska, “The influence of TIO2 nanoparticles on the properties of self-cleaning cement mortar,” Int. Multidiscip. Sci. GeoConference SGEM, pp. 333–341, 2018.

scholarly journals Attempts to Improve the Subsurface Properties of Horizontally-Formed Cementitious Composites Using Tin(II) Fluoride Nanoparticles

Coatings ◽  
2020 ◽  
Vol 10 (1) ◽  
pp. 83 ◽  
Author(s):  
Kamil Krzywiński ◽  
Łukasz Sadowski ◽  
Jacek Szymanowski ◽  
Andrzej Żak ◽  
Magdalena Piechówka-Mielnik
Keyword(s):  
Tensile Strength ◽  
Compressive Strength ◽  
Abrasion Resistance ◽  
Mechanical Performance ◽  
Reference Sample ◽  
Ultrasonic Pulse Velocity ◽  
Ultrasonic Pulse ◽  
Pulse Velocity ◽  
Cementitious Composites ◽  
Fluoride Nanoparticles

This article presents studies that were performed in order to improve the subsurface properties of horizontally-formed cementitious composites using tin(II) fluoride nanoparticles. The main aim of the study was to solve the problem of the decrease in subsurface properties caused by mortar bleeding and the segregation of the aggregate along the height of the overlay. The article also aims to highlight the patch grabbing difficulties that occur during the process of forming horizontally-formed cementitious composites. Four specimens were analyzed: one reference sample and three samples modified with the addition of 0.5, 1.0, and 1.5% of tin(II) fluoride nanoparticles in relation to the cement mass. To analyze the mechanical properties of the specimens, non-destructive (ultrasonic pulse velocity) and destructive tests (flexural tensile strength, compressive strength, abrasion resistance, pull-off strength) were performed. It was indicated that due to the addition of the tin(II) fluoride, it was possible to enhance the subsurface tensile strength and abrasion resistance of the tested cementitious composites. To confirm the obtained macroscopic results, the porosity of the subsurface was measured using SEM. It was also shown that the addition of the tin(II) fluoride nanoparticles did not reduce its flexural and compressive strength. The results show that horizontally-formed cementitious composites with the addition of 1.0% of tin(II) fluoride nanoparticles in relation to the cement mass obtained the most effective mechanical performance, especially with regard to subsurface properties.

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