Materials

22 pages, 9011 KiB

Open AccessArticle

Using Fumed Silica to Develop Thermal Insulation Cement for Medium–Low Temperature Geothermal Wells

by Lan Shen, Huijing Tan, You Ye and Wei He

Materials 2022, 15(14), 5087; https://doi.org/10.3390/ma15145087 - 21 Jul 2022

Cited by 4 | Viewed by 1806

During geothermal energy development, the bottom high-temperature fluid continuously exchanges heat with the upper low-temperature wellbore and the stratum during its rising process. Thermal insulation cement (TIC) can increase the outlet temperature, thus effectively reducing the heat loss of the geothermal fluid and [...] Read more.

During geothermal energy development, the bottom high-temperature fluid continuously exchanges heat with the upper low-temperature wellbore and the stratum during its rising process. Thermal insulation cement (TIC) can increase the outlet temperature, thus effectively reducing the heat loss of the geothermal fluid and improving energy efficiency. In this study, vitrified microbubbles (VMB) were screened out by conducting an orthogonal test of compressive strength (CS) and thermal conductivity (TC) on three inorganic thermal insulation materials (VMB, expanded perlite (EP), and fly-ash cenosphere (FAC)). Fumed silica (FS) was introduced into the cement with VMBs, as its significant decreasing effect on the TC. Moreover, a cement reinforcing agent (RA) and calcium hydroxide [CH] were added to further improve the CS of TIC at 90 °C. The fresh properties, CS, TC, hydration products, pore-size distribution, and the microstructure of the cement were investigated. As a result, a TIC with a TC of 0.1905 W/(m·K) and CS of 5.85 MPa was developed. The main conclusions are as follows: (1) Increasing the mass fraction of the thermal insulation material (TIM) is an effective method to reduce TC. (2) The CH content was reduced, but the C–S–H gel increased as FS content increased due to the pozzolanic reaction of the FS. (3) As the C–S–H gel is the main product of both the hydration and pozzolanic reactions, the matrix of the cement containing 60% FS and VMBs was mainly composed of gel. (4) The 10% RA improved the cement fluidity and increased the CS of TIC from 3.5 MPa to 5.85 MPa by promoting hydration. Full article

(This article belongs to the Special Issue Advanced and Sustainable Low Carbon Cement and Concrete Materials)

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20 pages, 9407 KiB

Open AccessReview

Effect of Sn Grain Orientation on Reliability Issues of Sn-Rich Solder Joints

by Yu-An Shen and John A. Wu

Materials 2022, 15(14), 5086; https://doi.org/10.3390/ma15145086 - 21 Jul 2022

Cited by 10 | Viewed by 2415

Abstract

Sn-rich solder joints in three-dimensional integrated circuits and their reliability issues, such as the electromigration (EM), thermomigration (TM), and thermomechanical fatigue (TMF), have drawn attention related to their use in electronic packaging. The Sn grain orientation is recognized as playing an important role [...] Read more.

Sn-rich solder joints in three-dimensional integrated circuits and their reliability issues, such as the electromigration (EM), thermomigration (TM), and thermomechanical fatigue (TMF), have drawn attention related to their use in electronic packaging. The Sn grain orientation is recognized as playing an important role in reliability issues due to its anisotropic diffusivity, mechanical properties, and coefficient of thermal expansion. This study reviews the effects of the Sn grain orientation on the EM, TM, and TMF in Sn-rich solder joints. The findings indicate that in spite of the failure modes dominated by the Sn grain orientation, the size and shape of the solder joint, as well as the Sn microstructures, such as the cycling twining boundary (CTB), single crystals, and misorientations of the Sn grain boundary, should be considered in more detail. In addition, we show that two methods, involving a strong magnetic field and seed crystal layers, can control the Sn grain orientations during the solidification of Sn-rich solder joints. Full article

(This article belongs to the Special Issue Novel Materials and Processes for Electronic Packaging)

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22 pages, 8605 KiB

Open AccessArticle

Predicting the Tensile Behaviour of Ultra-High Performance Fibre-Reinforced Concrete from Single-Fibre Pull-Out Tests

by Konstantin Hauch, Kasem Maryamh, Claudia Redenbach and Jürgen Schnell

Materials 2022, 15(14), 5085; https://doi.org/10.3390/ma15145085 - 21 Jul 2022

Cited by 5 | Viewed by 1837

Abstract

In this paper, a prediction model for the tensile behaviour of ultra-high performance fibre-reinforced concrete is proposed. It is based on integrating force contributions of all fibres crossing the crack plane. Piecewise linear models for the force contributions depending on fibre orientation and [...] Read more.

In this paper, a prediction model for the tensile behaviour of ultra-high performance fibre-reinforced concrete is proposed. It is based on integrating force contributions of all fibres crossing the crack plane. Piecewise linear models for the force contributions depending on fibre orientation and embedded length are fitted to force–slip curves obtained in single-fibre pull-out tests. Fibre characteristics in the crack are analysed in a micro-computed tomography image of a concrete sample. For more general predictions, a stochastic fibre model with a one-parametric orientation distribution is introduced. Simple estimators for the orientation parameter are presented, which only require fibre orientations in the crack plane. Our prediction method is calibrated to fit experimental tensile curves. Full article

(This article belongs to the Special Issue Mathematical Modeling of Building Materials)

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21 pages, 7222 KiB

Open AccessArticle

Numerical Simulation of Intelligent Fuzzy Closed-Loop Control Method for Radial–Axial Ring Rolling Process of Super-Large Rings

by Ke Zhang, Xiaokai Wang, Lin Hua, Xinghui Han and Xiangjin Ning

Materials 2022, 15(14), 5084; https://doi.org/10.3390/ma15145084 - 21 Jul 2022

Cited by 1 | Viewed by 1671

Abstract

During the radial–axial ring rolling (RARR) process of super-large rings, abnormal deformation states such as instability and out of circularity often lead to rolling termination and quality fluctuation of ring products. In this work, an intelligent fuzzy closed-loop control method for RARR process [...] Read more.

During the radial–axial ring rolling (RARR) process of super-large rings, abnormal deformation states such as instability and out of circularity often lead to rolling termination and quality fluctuation of ring products. In this work, an intelligent fuzzy closed-loop control method for RARR process of super-large rings is proposed, i.e., the ring’s offset adaptive fuzzy control (ROAFC) based on the regulation of the axial roll’s rotational speed and the ring’s circularity fuzzy control (RCFC) based on the regulation of the mandrel’s feed speed. In addition, a recursive average filtering algorithm is added to smooth the axial roll’s rotational speed and the mandrel’s feed speed according to the actual situation. Using the ABAQUS/Explicit software and its subroutine VUAMP, the intelligent fuzzy controller of the ring’s offset and circularity in the RARR process is designed, and the finite element (FE) model for RARR process of a Φ10 m super-large ring with an integrated intelligent fuzzy control algorithm is established. The variation laws of the ring’s offset and circularity error in the RARR process are studied with regard to different control methods such as conventional planning control (CPC), ROAFC, RCFC, and comprehensive control of ROAFC combined with RCFC (ROAFC + RCFC). The results obtained show that, compared with the CPC, the ring’s offset is reduced by 84.6% and the circularity error is decreased by 51.9% in the RARR process utilizing comprehensive control of ROAFC + RCFC. The research results provide methodological guidance for realizing the intelligent forming of super-large rings. Full article

(This article belongs to the Special Issue Feature Papers in "Metals and Alloys" Section)

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18 pages, 10109 KiB

Open AccessArticle

Comparative Analysis of the Influence of Chemical Composition and Microstructure on the Abrasive Wear of High-Strength Steels

by Martyna Zemlik, Łukasz Konat and Jerzy Napiórkowski

Materials 2022, 15(14), 5083; https://doi.org/10.3390/ma15145083 - 21 Jul 2022

Cited by 7 | Viewed by 1779

Abstract

The paper discusses the microstructural, chemical and tribological properties of the selected low-alloy, high-strength martensitic boron steels with a hardness of 500–600 HBW. These materials, due to their increased strength, and thus resistance to abrasive wear, are widely used in the mining, agricultural [...] Read more.

The paper discusses the microstructural, chemical and tribological properties of the selected low-alloy, high-strength martensitic boron steels with a hardness of 500–600 HBW. These materials, due to their increased strength, and thus resistance to abrasive wear, are widely used in the mining, agricultural or building industries. Grades such as XAR, TBL and Creusabro were subjected to a comparative analysis. As a result of the conducted research, an attempt was made to determine the relation between the microstructural properties, chemical composition, hardness and abrasive wear resistance of the above-mentioned metallic materials belonging to the same material group. The scope of work involved a metallographic analysis, including the examination of the microstructure with an analysis of the prior austenite grain size. Tribological tests were carried out with the use of a T-07 tester, which is designed for testing abrasive wear resistance in the presence of a loose abrasive. As a result, it was found that the coefficient of relative abrasion resistance k_bAV in relation to as-normalized C45 steel is equal to 0.9–1.25 and may even have the same value among materials of different hardness in the as-delivered state. Full article

(This article belongs to the Special Issue The Abrasive Wear Processes of Modern Materials Used in Working Elements)

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9 pages, 2355 KiB

Open AccessArticle

Normally-off Hydrogen-Terminated Diamond Field-Effect Transistor with SnO_x Dielectric Layer Formed by Thermal Oxidation of Sn

by Shi He, Yanfeng Wang, Genqiang Chen, Juan Wang, Qi Li, Qianwen Zhang, Ruozheng Wang, Minghui Zhang, Wei Wang and Hongxing Wang

Materials 2022, 15(14), 5082; https://doi.org/10.3390/ma15145082 - 21 Jul 2022

Cited by 1 | Viewed by 1410

Abstract

SnO_x films were deposited on a hydrogen-terminated diamond by thermal oxidation of Sn. The X-ray photoelectron spectroscopy result implies partial oxidation of Sn film on the diamond surface. The leakage current and capacitance–voltage properties of Al/SnO_x/H-diamond metal-oxide-semiconductor diodes were investigated. [...] Read more.

SnO_x films were deposited on a hydrogen-terminated diamond by thermal oxidation of Sn. The X-ray photoelectron spectroscopy result implies partial oxidation of Sn film on the diamond surface. The leakage current and capacitance–voltage properties of Al/SnO_x/H-diamond metal-oxide-semiconductor diodes were investigated. The maximum leakage current density value at −8.0 V is 1.6 × 10⁻⁴ A/cm², and the maximum capacitance value is measured to be 0.207 μF/cm². According to the C–V results, trapped charge density and fixed charge density are determined to be 2.39 × 10¹² and 4.5 × 10¹¹ cm⁻², respectively. Finally, an enhancement-mode H-diamond field effect transistor was obtained with a V_TH of −0.5 V. Its I_DMAX is −21.9 mA/mm when V_GS is −5, V_DS is −10 V. The effective mobility and transconductance are 92.5 cm²V⁻¹ s⁻¹ and 5.6 mS/mm, respectively. We suspect that the normally-off characteristic is caused by unoxidized Sn, whose outermost electron could deplete the hole in the channel. Full article

(This article belongs to the Special Issue Diamond Material and Its Applications)

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15 pages, 6804 KiB

Open AccessArticle

Laser Direct Joining of Steel to Polymethylmethacrylate: The Influence of Process Parameters and Surface Mechanical Pre-Treatment on the Joint Strength and Quality

by Fábio A. O. Fernandes, José P. Pinto, Bruno Vilarinho and António B. Pereira

Materials 2022, 15(14), 5081; https://doi.org/10.3390/ma15145081 - 21 Jul 2022

Cited by 3 | Viewed by 1620

Abstract

The search for lightweight structures increases the demand for non-metallic materials, such as polymers, composites, and hybrid structures. This work presents the dissimilar joining through direct laser joining between polymethylmethacrylate (PMMA) and S235 galvanised steel using a pulsed Nd:YAG laser. The main goal [...] Read more.

The search for lightweight structures increases the demand for non-metallic materials, such as polymers, composites, and hybrid structures. This work presents the dissimilar joining through direct laser joining between polymethylmethacrylate (PMMA) and S235 galvanised steel using a pulsed Nd:YAG laser. The main goal is to determine the influence of processing parameters on joint strength and quality. In addition, the impact of surface conditions on the joint quality was also analysed. Overall, the optimum ranges of process parameters were found, and some are worth highlighting, such as the laser beam diameter and pulse duration, which significantly influenced the joint strength. Failure of the welded samples occurred in PMMA component, demonstrating good joint efficiency. Additionally, a maximum increase of 5.1% of the tensile shear strength was achieved thanks to the mechanical pre-treatment. It is possible to conclude that the joining between PMMA and the S235 galvanised steel can be performed by optimising the process parameters. Additionally, it can be enhanced through surface pre-treatments by exploring the mechanical interlock between both materials. Full article

(This article belongs to the Special Issue Laser Machining Technology in Materials Science)

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21 pages, 8448 KiB

Open AccessArticle

Stability Study of the Irradiated Poly(lactic acid)/Styrene Isoprene Styrene Reinforced with Silica Nanoparticles

by Ana Maria Lupu (Luchian), Marius Mariş, Traian Zaharescu, Virgil Emanuel Marinescu and Horia Iovu

Materials 2022, 15(14), 5080; https://doi.org/10.3390/ma15145080 - 21 Jul 2022

Cited by 1 | Viewed by 1605

Abstract

In this paper, the stability improvement of poly(lactic acid) (PLA)/styrene-isoprene block copolymer (SIS) loaded with silica nanoparticles is characterized. The protection efficiency in the material of thermal stability is mainly studied by means of high accurate isothermal and nonisothermal chemiluminescence procedures. The oxidation [...] Read more.

In this paper, the stability improvement of poly(lactic acid) (PLA)/styrene-isoprene block copolymer (SIS) loaded with silica nanoparticles is characterized. The protection efficiency in the material of thermal stability is mainly studied by means of high accurate isothermal and nonisothermal chemiluminescence procedures. The oxidation induction times obtained in the isothermal CL determinations increase from 45 min to 312 min as the polymer is free of silica or the filler loading is about 10%, respectively. The nonisothermal measurements reveal the values of onset oxidation temperatures with about 15% when the concentration of SiO₂ particles is enhanced from none to 10%. The curing assay and Charlesby–Pinner representation as well as the modifications that occurred in the FTIR carbonyl band at 1745 cm⁻¹ are appropriate proofs for the delay of oxidation in hybrid samples. The improved efficiency of silica during the accelerated degradation of PLA/SIS 30/n-SiO₂ composites is demonstrated by means of the increased values of activation energy in correlation with the augmentation of silica loading. While the pristine material is modified by the addition of 10% silica nanoparticles, the activation energy grows from 55 kJ mol⁻¹ to 74 kJ mol⁻¹ for nonirradiated samples and from 47 kJ mol⁻¹ to 76 kJ mol⁻¹ for γ-processed material at 25 kGy. The stabilizer features are associated with silica nanoparticles due to the protection of fragments generated by the scission of hydrocarbon structure of SIS, the minor component, whose degradation fragments are early converted into hydroperoxides rather than influencing depolymerization in the PLA phase. The reduction of the transmission values concerning the growing reinforcement is evidence of the capacity of SiO₂ to minimize the changes in polymers subjected to high energy sterilization. The silica loading of 10 wt% may be considered a proper solution for attaining an extended lifespan under the accelerated degradation caused by the intense transfer of energy, such as radiation processing on the polymer hybrid. Full article

(This article belongs to the Special Issue Advances in Polymer Blends and Composites)

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13 pages, 4557 KiB

Open AccessArticle

Bending Strength of Polyamide-Based Composites Obtained during the Fused Filament Fabrication (FFF) Process

by Michał Mazurkiewicz, Janusz Kluczyński, Katarzyna Jasik, Bartłomiej Sarzyński, Ireneusz Szachogłuchowicz, Jakub Łuszczek, Janusz Torzewski, Lucjan Śnieżek, Krzysztof Grzelak and Marcin Małek

Materials 2022, 15(14), 5079; https://doi.org/10.3390/ma15145079 - 21 Jul 2022

Cited by 2 | Viewed by 1484

Abstract

The research shows the comparison between two types of polyamide-based (PA) composites and pure, base material. The conducted analysis describes how the additions of carbon fibers and glass microbeads affect the material’s properties and its behavior during the bending tests. All samples have [...] Read more.

The research shows the comparison between two types of polyamide-based (PA) composites and pure, base material. The conducted analysis describes how the additions of carbon fibers and glass microbeads affect the material’s properties and its behavior during the bending tests. All samples have been tested in the three main directions available during the FFF process. To extend the scope of the research, additional digital-image-correlation tests and fracture analyses were made. The obtained results indicated a positive influence of the addition of carbon fibers into the material’s volume (from 81.39 MPa in the case of pure PA to 243.62 MPa in the case of the PA reinforced by carbon fibers). Full article

(This article belongs to the Special Issue Mechanical Properties of Polymeric, Metallic, and Composite Materials)

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21 pages, 2582 KiB

Open AccessReview

Forecasting the Post-Pandemic Effects of the SARS-CoV-2 Virus Using the Bullwhip Phenomenon Alongside Use of Nanosensors for Disease Containment and Cure

by Mohammed S. Alqahtani, Mohamed Abbas, Mohammed Abdulmuqeet, Abdullah S. Alqahtani, Mohammad Y. Alshahrani, Abdullah Alsabaani and Murugan Ramalingam

Materials 2022, 15(14), 5078; https://doi.org/10.3390/ma15145078 - 21 Jul 2022

Cited by 2 | Viewed by 2160

Abstract

The COVID-19 pandemic has the tendency to affect various organizational paradigm alterations, which civilization hasyet to fully comprehend. Personal to professional, individual to corporate, and across most industries, the spectrum of transformations is vast. Economically, the globe has never been more intertwined, and [...] Read more.

The COVID-19 pandemic has the tendency to affect various organizational paradigm alterations, which civilization hasyet to fully comprehend. Personal to professional, individual to corporate, and across most industries, the spectrum of transformations is vast. Economically, the globe has never been more intertwined, and it has never been subjected to such widespread disruption. While many people have felt and acknowledged the pandemic’s short-term repercussions, the resultant paradigm alterations will certainly have long-term consequences with an unknown range and severity. This review paper aims at acknowledging various approaches for the prevention, detection, and diagnosis of the SARS-CoV-2 virus using nanomaterials as a base material. A nanostructure is a material classification based on dimensionality, in proportion to the characteristic diameter and surface area. Nanoparticles, quantum dots, nanowires (NW), carbon nanotubes (CNT), thin films, and nanocomposites are some examples of various dimensions, each acting as a single unit, in terms of transport capacities. Top-down and bottom-up techniques are used to fabricate nanomaterials. The large surface-to-volume ratio of nanomaterials allows one to create extremely sensitive charge or field sensors (electrical sensors, chemical sensors, explosives detection, optical sensors, and gas sensing applications). Nanowires have potential applications in information and communication technologies, low-energy lightning, and medical sensors. Carbon nanotubes have the best environmental stability, electrical characteristics, and surface-to-volume ratio of any nanomaterial, making them ideal for bio-sensing applications. Traditional commercially available techniques have focused on clinical manifestations, as well as molecular and serological detection equipment that can identify the SARS-CoV-2 virus. Scientists are expressing a lot of interest in developing a portable and easy-to-use COVID-19 detection tool. Several unique methodologies and approaches are being investigated as feasible advanced systems capable of meeting the demands. This review article attempts to emphasize the pandemic’s aftereffects, utilising the notion of the bullwhip phenomenon’s short-term and long-term effects, and it specifies the use of nanomaterials and nanosensors for detection, prevention, diagnosis, and therapy in connection to the SARS-CoV-2. Full article

(This article belongs to the Special Issue Opportunities for Nanomaterials to Address the Challenges of COVID‐19)

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12 pages, 8775 KiB

Open AccessArticle

Life Prediction Method of Dissimilar Lightweight Materials Welded Joints with Precrack under Coupled Impact-Fatigue Loading

by Zhengshun Ni, Tao Xiong, Jie Lei, Liuping Wang, Tong Gao, Jianwu Yu and Chengji Mi

Materials 2022, 15(14), 5077; https://doi.org/10.3390/ma15145077 - 21 Jul 2022

Cited by 1 | Viewed by 1401

Abstract

This paper aims to explore the fatigue life estimation approach of welded joints with precrack under coupled impact and fatigue loading, and the base metal is dissimilar 5083H111 and 5754 aluminum alloy. Impact tests are first carried out on the dissimilar lightweight materials [...] Read more.

This paper aims to explore the fatigue life estimation approach of welded joints with precrack under coupled impact and fatigue loading, and the base metal is dissimilar 5083H111 and 5754 aluminum alloy. Impact tests are first carried out on the dissimilar lightweight materials welded joint with precrack located in the middle of the specimen, and a stress and strain field is obtained to determine the fatigue damage model parameters by using finite element dynamic analysis to simulate the impact process. Based, on the S-N curve of welded joints, the predicted life expectancy is found to be inconsistent with the experimental results. According to the continuum damage mechanics, the lifetime assessment model is presented to calculate both impact and fatigue damage. The estimated results agree well with the experimental ones. Full article

(This article belongs to the Special Issue Fatigue Behavior, Lifetime Prediction and Modeling of Welding Process)

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25 pages, 1379 KiB

Open AccessReview

Selective Oxidation of Cellulose—A Multitask Platform with Significant Environmental Impact

by Ioana A. Duceac, Fulga Tanasa and Sergiu Coseri

Materials 2022, 15(14), 5076; https://doi.org/10.3390/ma15145076 - 21 Jul 2022

Cited by 14 | Viewed by 3444

Abstract

Raw cellulose, or even agro-industrial waste, have been extensively used for environmental applications, namely industrial water decontamination, due to their effectiveness, availability, and low production cost. This was a response to the increasing societal demand for fresh water, which made the purification of [...] Read more.

Raw cellulose, or even agro-industrial waste, have been extensively used for environmental applications, namely industrial water decontamination, due to their effectiveness, availability, and low production cost. This was a response to the increasing societal demand for fresh water, which made the purification of wastewater one of the major research issue for both academic and industrial R&D communities. Cellulose has undergone various derivatization reactions in order to change the cellulose surface charge density, a prerequisite condition to delaminate fibers down to nanometric fibrils through a low-energy process, and to obtain products with various structures and properties able to undergo further processing. Selective oxidation of cellulose, one of the most important methods of chemical modification, turned out to be a multitask platform to obtain new high-performance, versatile, cellulose-based materials, with many other applications aside from the environmental ones: in biomedical engineering and healthcare, energy storage, barrier and sensing applications, food packaging, etc. Various methods of selective oxidation have been studied, but among these, (2,2,6,6-tetramethylpiperidin-1-yl)oxyl) (TEMPO)-mediated and periodate oxidation reactions have attracted more interest due to their enhanced regioselectivity, high yield and degree of substitution, mild conditions, and the possibility to further process the selectively oxidized cellulose into new materials with more complex formulations. This study systematically presents the main methods commonly used for the selective oxidation of cellulose and provides a survey of the most recent reports on the environmental applications of oxidized cellulose, such as the removal of heavy metals, dyes, and other organic pollutants from the wastewater. Full article

(This article belongs to the Special Issue Surface Modifications for Advanced Polymer Composites)

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14 pages, 1405 KiB

Open AccessArticle

Exploring the Physicochemical, Mechanical, and Photocatalytic Antibacterial Properties of a Methacrylate-Based Dental Material Loaded with ZnO Nanoparticles

by Patricia Comeau, Julia Burgess, Niknaz Malekafzali, Maria Luisa Leite, Aidan Lee and Adriana Manso

Materials 2022, 15(14), 5075; https://doi.org/10.3390/ma15145075 - 21 Jul 2022

Cited by 7 | Viewed by 1680

Abstract

While resin-based materials meet the many requirements of a restorative material, they lack adequate, long-lasting antimicrobial power. This study investigated a zinc oxide nanoparticle (ZnO NP)-loaded resin-blend (RB) toward a new antimicrobial photodynamic therapy (aPDT)-based approach for managing dental caries. The results confirmed [...] Read more.

While resin-based materials meet the many requirements of a restorative material, they lack adequate, long-lasting antimicrobial power. This study investigated a zinc oxide nanoparticle (ZnO NP)-loaded resin-blend (RB) toward a new antimicrobial photodynamic therapy (aPDT)-based approach for managing dental caries. The results confirmed that up to 20 wt% ZnO NPs could be added without compromising the degree of conversion (DC) of the original blend. The DC achieved for the 20 wt% ZnO NP blend has been the highest reported. The effects on flexural strength (FS), shear bond strength to dentin (SBS), water sorption (WS), solubility (SL), and viability of Streptococcus mutans under 1.35 J/cm² blue light or dark conditions were limited to ≤20 wt% ZnO NP loading. The addition of up to 20 wt% ZnO NPs had a minimal impact on FS or SBS, while a reduction in the bacteria count was observed. The maximum loading resulted in an increase in SL. Furthermore, 28-day aging in 37 °C water increased the FS for all groups, while it sustained the reduction in bacteria count for the 20 wt% resin blends. Overall, the ZnO NP-loaded resin-based restorative material presents significant potential for use in aPDT. Full article

(This article belongs to the Special Issue Advances in Antimicrobial Strategies Based on Nanoparticles)

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22 pages, 5734 KiB

Open AccessArticle

Microstructure and Wear Characterization of the Fe-Mo-B-C—Based Hardfacing Alloys Deposited by Flux-Cored Arc Welding

by Michał Bembenek, Pavlo Prysyazhnyuk, Thaer Shihab, Ryszard Machnik, Olexandr Ivanov and Liubomyr Ropyak

Materials 2022, 15(14), 5074; https://doi.org/10.3390/ma15145074 - 21 Jul 2022

Cited by 35 | Viewed by 2882

Abstract

An analysis of common reinforcement methods of machine parts and theoretical bases for the selection of their chemical composition were carried out. Prospects for using flux-cored arc welding (FCAW) to restore and increase the wear resistance of machine parts in industries such as [...] Read more.

An analysis of common reinforcement methods of machine parts and theoretical bases for the selection of their chemical composition were carried out. Prospects for using flux-cored arc welding (FCAW) to restore and increase the wear resistance of machine parts in industries such as metallurgy, agricultural, wood processing, and oil industry were presented. It is noted that conventional series electrodes made of tungsten carbide are expensive, which limits their widespread use in some industries. The scope of this work includes the development of the chemical composition of tungsten-free hardfacing alloys based on the Fe-Mo-B-C system and hardfacing technology and the investigation of the microstructure and the mechanical properties of the developed hardfacing alloys. The composition of the hardfacing alloys was developed by extending the Fe-Mo-B-C system with Ti and Mn. The determination of wear resistance under abrasion and impact-abrasion wear test conditions and the hardness measurement by means of indentation and SEM analysis of the microstructures was completed. The results obtained show that the use of pure metal powders as starting components for electrodes based on the Fe-Mo-B-C system leads to the formation of a wear-resistant phase Fe(Mo,B)₂ during FCAW. The addition of Ti and Mn results in a significant increase in abrasion and impact-abrasion wear resistance by 1.2 and 1.3 times, respectively. Full article

(This article belongs to the Special Issue Advanced Designs of Materials, Machines and Processes in a Circular Economy)

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14 pages, 2941 KiB

Open AccessArticle

Structure, Martensitic Transformation, and Damping Properties of Functionally Graded NiTi Shape Memory Alloys Fabricated by Laser Powder Bed Fusion

by Hao Jiang, Rui Xi, Xiaoqiang Li, Sergey Kustov, Jan Van Humbeeck and Xiebin Wang

Materials 2022, 15(14), 5073; https://doi.org/10.3390/ma15145073 - 21 Jul 2022

Cited by 5 | Viewed by 1781

Abstract

Besides the unique shape memory effect and superelasticity, NiTi alloys also show excellent damping properties. However, the high damping effect is highly temperature-dependent, and only exists during cooling or heating over the temperature range where martensitic transformation occurs. As a result, expanding the [...] Read more.

Besides the unique shape memory effect and superelasticity, NiTi alloys also show excellent damping properties. However, the high damping effect is highly temperature-dependent, and only exists during cooling or heating over the temperature range where martensitic transformation occurs. As a result, expanding the temperature range of martensite transformation is an effective approach to widen the working temperature window with high damping performance. In this work, layer-structured functionally graded NiTi alloys were produced by laser powder bed fusion (L-PBF) alternating two or three sets of process parameters. The transformation behavior shows that austenite transforms gradually into martensite over a wide temperature range during cooling, and multiple transformation peaks are observed. A microstructure composed of alternating layers of B2/B19′ phases is obtained at room temperature. The functionally graded sample shows high damping performance over a wide temperature range of up to 70 K, which originates from the gradual formation of the martensite phase during cooling. This work proves the potential of L-PBF to create NiTi alloys with high damping properties over a wide temperature range for damping applications. Full article

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15 pages, 1412 KiB

Open AccessArticle

Effect of Aggregate Type on Properties of Ultra-High-Strength Concrete

by Anna Szcześniak, Jarosław Siwiński and Adam Stolarski

Materials 2022, 15(14), 5072; https://doi.org/10.3390/ma15145072 - 21 Jul 2022

Cited by 3 | Viewed by 1733

Abstract

In this work, we present an analysis of natural fine aggregates’ influence on the properties of ultra-high-strength concrete. The reference concrete mix was made of natural sand with the addition of fly ash and microsilica. It was assumed to obtain concrete with a [...] Read more.

In this work, we present an analysis of natural fine aggregates’ influence on the properties of ultra-high-strength concrete. The reference concrete mix was made of natural sand with the addition of fly ash and microsilica. It was assumed to obtain concrete with a very high strength without the addition of fibers and without special curing conditions, ensuring the required workability of the concrete mix corresponding to the consistency of class S3. The reference concrete mix was modified by replacing sand with granite and basalt aggregate in the same fractions. Five series of concrete mixes made with CEM I 52.5R cement were tested. Experimental investigations were carried out regarding the consistency of the concrete mix, the compressive strength, the flexural strength and the water absorption by hardened concrete. A comparative analysis of the obtained results indicated significant improvement in the concrete strength after the use of basalt aggregate. The strength of the concrete series based on basalt aggregate, BC1, allowed it to be classified as ultra-high-performance concrete. Concrete based on sand, SC1, was characterized by the lowest compressive and flexural strength but obtained the best workability of the mix and the lowest water absorption. The results presented in the paper, show a significant influence of the type of aggregate used on the mechanical and physical properties of ultra-high strength concrete. Full article

(This article belongs to the Special Issue Advanced and Sustainable Low Carbon Cement and Concrete Materials)

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11 pages, 18961 KiB

Open AccessArticle

Horizontal Oxidation Diffusion Behavior of MEMS-Based Tungsten-Rhenium Thin Film Thermocouples

by Yong Ruan, Meixia Xue, Jiao Teng, Yu Wu and Meng Shi

Materials 2022, 15(14), 5071; https://doi.org/10.3390/ma15145071 - 21 Jul 2022

Cited by 4 | Viewed by 1726

Abstract

Tungsten-rhenium thin film thermocouples (TFTCs) are well suited for the surface temperature monitoring of hot components due to their small size, rapid response and low cost. In this study, a tungsten-rhenium TFTC with SiC protective film on all parts except the pads was [...] Read more.

Tungsten-rhenium thin film thermocouples (TFTCs) are well suited for the surface temperature monitoring of hot components due to their small size, rapid response and low cost. In this study, a tungsten-rhenium TFTC with SiC protective film on all parts except the pads was fabricated by a microelectromechanical system (MEMS) process. During the low to medium temperature (−40 °C to 500 °C) repeatability test phase, the thermal voltage from the TFTC agreed well with that of the standard tungsten-rhenium thermocouple. However, during the high temperature test phase, the TFTC lost electronic response at around 620 °C. Failure analysis of the TFTC tested at 620 °C was performed by microscopy, scanning electron microscope (SEM), energy dispersive spectroscopy (EDS), laser scanning confocal microscope (LSCM) and statistics. The results showed that the pads were oxidized without the protective layer, the number of oxidized protrusions distributed in this TFTC from the pad to the node decreases more and more slowly and the size of the oxidized protrusions also becomes smaller and smaller. This demonstrates the presence of horizontal oxidation diffusion in TFTCs, further illustrating the importance of pad protection and provides a direction for the subsequent structural optimization and the extension of the service life of TFTCs and other sensors. Full article

(This article belongs to the Section Thin Films and Interfaces)

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15 pages, 16607 KiB

Open AccessArticle

Failure Mechanism of the Fire Control Computer CPU Board inside the Tank under Transient Shock: Finite Element Simulations and Experimental Studies

by Xiangrong Li, Guohui Wang, Yongkang Chen, Bo Zhao and Jianguang Xiao

Materials 2022, 15(14), 5070; https://doi.org/10.3390/ma15145070 - 21 Jul 2022

Cited by 1 | Viewed by 1368

Abstract

The electronic components inside a main battle tank (MBT) are the key components for the tank to exert its combat effectiveness. However, breakdown of the inner electronic components can easily occur inside the MBT due to the strong transient shock and large vibration [...] Read more.

The electronic components inside a main battle tank (MBT) are the key components for the tank to exert its combat effectiveness. However, breakdown of the inner electronic components can easily occur inside the MBT due to the strong transient shock and large vibration during artillery fire. As a typical key electronic component inside an MBT, the fault mechanism and fault patterns of the CPU board of the fire control computer (FCC) are discussed through numerical simulation and experimental research. An explicit nonlinear dynamic analysis is performed to study the vibration features and fault mechanism under instantaneous shock load. By using finite element modal analysis, the first six nature frequencies of the CPU board are calculated. Meanwhile, curves of stress–frequency and strain–frequency of the CPU board under different harmonic loads are obtained, which are applied to further identify the peak response of the structure. Validation of the finite element model and simulation results are performed by comparing those obtained from the modal with experiments. Based on the dynamic simulation and experimental analysis, fault patterns of CPU board are discussed, and some optimization suggestions were proposed. The results shown in this work can provide a potential technical basis and reference for the optimization design of the electronic components that are commonly used in the modern weapon equipment and wartime support. Full article

(This article belongs to the Special Issue Materials under High Pressure)

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18 pages, 4223 KiB

Open AccessArticle

Investigation into Thermomechanical Response of Polymer Composite Materials Produced through Additive Manufacturing Technologies

by Raluca Maier, Anca Mihaela Istrate, Alexandra Despa, Andrei Cristian Mandoc, Sebastian Bucaciuc and Romică Stoica

Materials 2022, 15(14), 5069; https://doi.org/10.3390/ma15145069 - 21 Jul 2022

Cited by 5 | Viewed by 2037

Abstract

This paper presents the static mechanical behavior and the dynamic thermomechanical properties of four market-available reinforced and non-reinforced thermoplastics and photopolymer materials used as precursors in different additive manufacturing technologies. This article proposes a characterization approach to further address development of aeronautic secondary [...] Read more.

This paper presents the static mechanical behavior and the dynamic thermomechanical properties of four market-available reinforced and non-reinforced thermoplastics and photopolymer materials used as precursors in different additive manufacturing technologies. This article proposes a characterization approach to further address development of aeronautic secondary structures via 3D-printed composite materials replacing conventional manufactured carbon fiber reinforced polymer (CFRP) composites. Different 3D printing materials, technologies, printing directions, and parameters were investigated. Experimental results showed that carbon-reinforced ONYX_R material exhibits a transition point at 114 °C, a 600 MPa tensile strength, and an average tensile strain of 2.5%, comparable with conventional CFRP composites manufactured via autoclave, making it a suitable candidate for replacing CFRP composites, in the aim of taking advantage of 3D printing technologies. ONYX material exhibits higher stiffness than Acrylonitrile-Butadiene-Styrene Copolymer (ABS), or conventional Nylon 6/6 polyamide, the flexural modulus being 2.5 GPa; nevertheless, the 27 °C determined transition temperature limits its stability at higher temperature. Daylight High Tensile (further called HTS) resin exhibits a tensile strength and strain increase when shifting the printing direction from transversal to longitudinal, while no effect was observed in HighTemp DL400 resin (further called HTP). Full article

(This article belongs to the Special Issue Advanced Composites: From Materials Characterization to Structural Application (Second Volume))

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10 pages, 1556 KiB

Open AccessArticle

Effect of Different Cleaning Methods on Shear Bond Strength of Resin Cement to Contaminated Zirconia

by Maher Saeed Hajjaj and Saeed Jamaan Alzahrani

Materials 2022, 15(14), 5068; https://doi.org/10.3390/ma15145068 - 21 Jul 2022

Cited by 5 | Viewed by 2258

Abstract

The aim of this study was to evaluate the effect of different cleaning methods on the shear bond strength (SBS) of resin cement to contaminated zirconia specimens. Eighty rectangular-shaped specimens (2 × 5 × 10 mm) were fabricated from Zirconia blocks (IPS e.max [...] Read more.

The aim of this study was to evaluate the effect of different cleaning methods on the shear bond strength (SBS) of resin cement to contaminated zirconia specimens. Eighty rectangular-shaped specimens (2 × 5 × 10 mm) were fabricated from Zirconia blocks (IPS e.max ZirCAD) and randomly divided into 8 groups (n = 10). Group A (control) was not exposed to contaminants. The following tests specimens were contaminated with saliva and silicone indicating paste. Group B was coated with ceramic primer, then subjected to contamination. Groups C, D, E, F, G, and H were contaminated; cleaned with water rinse, Ivoclean, air particle abrasion, hydrofluoric acid, KATANA^TM Cleaner and ZirClean^TM, respectively, and then coated with ceramic primer and bonded to dual cure resin cement cylinders. All the specimens were subjected to artificial aging and surviving specimens were subjected to the SBS test. For statistical analysis, ANOVA and multiple comparison methods at the 0.05 significance level were used. There was no statistically significant difference among Ivoclean (21.48 ± 2.90 MPa), air particle abrasion (21.92 ± 2.85 MPa), and the control group (24.68 ± 5.46). The application of ceramic primer before contamination did not preserve the SBS of resin cement to zirconia. Cleaning the contaminated zirconia surface with hydrofluoric acid (15.03 ± 3.63) or KATANA^TM Cleaner (17.27 ± 7.63) did not restore SBS to the uncontaminated state, but it was significantly higher than simply rinsing with water (12.46 ± 5.17) or the use of ZirClean^TM (11.59 ± 5.53). The bond strength of resin cement to zirconia was influenced by cleaning methods. Full article

(This article belongs to the Special Issue Advanced Restorative and Dental Materials: Biological, Physical, and Chemical Properties)

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11 pages, 3723 KiB

Open AccessArticle

1 × 4 Wavelength Demultiplexer C-Band Using Cascaded Multimode Interference on SiN Buried Waveguide Structure

by Jonathan Menahem and Dror Malka

Materials 2022, 15(14), 5067; https://doi.org/10.3390/ma15145067 - 21 Jul 2022

Cited by 17 | Viewed by 1974

Abstract

Back reflection losses are a key problem that limits the performances of optical communication systems that work on wavelength division multiplexing (WDM) technology based on silicon (Si) Multimode Interference (MMI) waveguides. In order to overcome this problem, we propose a novel design for [...] Read more.

Back reflection losses are a key problem that limits the performances of optical communication systems that work on wavelength division multiplexing (WDM) technology based on silicon (Si) Multimode Interference (MMI) waveguides. In order to overcome this problem, we propose a novel design for a 1 × 4 optical demultiplexer based on the MMI in silicon nitride (SiN) buried waveguide structure that operates at the C-band spectrum. The simulation results show that the proposed device can transmit four channels with a 10 nm spacing between them that work in the C-band with a low power loss range of 1.98–2.35 dB, large bandwidth of 7.68–8.08 nm, and good crosstalk of 20.9–23.6 dB. Thanks to the low refractive index of SiN, a very low back reflection of 40.57 dB is obtained without using a special angled MMI design, which is usually required, using Si MMI technology. Thus, this SiN demultiplexer MMI technology can be used in WDM technique for obtaining a high data bitrate alongside a low back reflection in optical communication systems. Full article

(This article belongs to the Special Issue Photonic Materials for Optical Waveguide Application)

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18 pages, 6624 KiB

Open AccessArticle

The Time-Dependent Effect in Ultra High-Performance Concrete According to the Curing Methods

by Kwangmo Lim, Kyongchul Kim, Kyungtaek Koh and Gumsung Ryu

Materials 2022, 15(14), 5066; https://doi.org/10.3390/ma15145066 - 21 Jul 2022

Cited by 2 | Viewed by 1646

Abstract

Ultra-high-performance concrete (UHPC) is required to develop multifunctional concrete structures such as long-span bridges. During the construction of long-span bridges, girders exhibit significant differences in age because they use different curing days in the precast process. In this study, the performances of UHPC [...] Read more.

Ultra-high-performance concrete (UHPC) is required to develop multifunctional concrete structures such as long-span bridges. During the construction of long-span bridges, girders exhibit significant differences in age because they use different curing days in the precast process. In this study, the performances of UHPC were compared when subjected to long-term storage under various conditions after 3-day steam curing. At 365 days, the compressive strength of steam curing is 197 MPa, moist is 191 MPa, and the air is 169 MPa. Based on these differences, prediction models were proposed for long-term performances. Furthermore, the development characteristics of compressive strength, modulus of elasticity (MOE), and flexural strength until 365 days of age were analyzed under air, moist, and steam conditions. Steam curing exhibited the highest level of strength development while air curing showed the lowest. Flexural strength showed no significant difference depending on age because steel fibers were mixed with UHPC; they significantly contributed to flexural performance. The results would contribute to recognizing differences in strength between members at sites where UHPC is applied and to managing high-quality structures constructed using precast members. These research results are expected to contribute to efficient member production and process management during the construction of large structures such as super-long-span bridges. Full article

(This article belongs to the Section Construction and Building Materials)

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16 pages, 3833 KiB

Open AccessArticle

Characterizing the Mechanical Behavior of Bone and Bone Surrogates in Compression Using pQCT

by Johannes D. Pallua, David Putzer, Elias Jäger, Gerald Degenhart, Rohit Arora and Werner Schmölz

Materials 2022, 15(14), 5065; https://doi.org/10.3390/ma15145065 - 20 Jul 2022

Cited by 3 | Viewed by 1469

Abstract

Many axial and appendicular skeleton bones are subjected to repetitive loading during daily activities. Until recently, the structural analysis of fractures has been limited to 2D sections, and the dynamic assessment of fracture progression has not been possible. The structural failure was analyzed [...] Read more.

Many axial and appendicular skeleton bones are subjected to repetitive loading during daily activities. Until recently, the structural analysis of fractures has been limited to 2D sections, and the dynamic assessment of fracture progression has not been possible. The structural failure was analyzed using step-wise micro-compression combined with time-lapsed micro-computed tomographic imaging. The structural failure was investigated in four different sample materials (two different bone surrogates, lumbar vertebral bodies from bovine and red deer). The samples were loaded in different force steps based on uniaxial compression tests. The micro-tomography images were used to create three-dimensional models from which various parameters were calculated that provide information about the structure and density of the samples. By superimposing two 3D images and calculating the different surfaces, it was possible to precisely analyze which trabeculae failed in which area and under which load. According to the current state of the art, bone mineral density is usually used as a value for bone quality, but the question can be raised as to whether other values such as trabecular structure, damage accumulation, and bone mineralization can predict structural competence better than bone mineral density alone. Full article

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11 pages, 5136 KiB

Open AccessArticle

Strained Lattice Gold-Copper Alloy Nanoparticles for Efficient Carbon Dioxide Electroreduction

by Fangfang Chang, Chenguang Wang, Xueli Wu, Yongpeng Liu, Juncai Wei, Zhengyu Bai and Lin Yang

Materials 2022, 15(14), 5064; https://doi.org/10.3390/ma15145064 - 20 Jul 2022

Cited by 2 | Viewed by 1678

Abstract

Electrocatalytic conversion of carbon dioxide (CO₂) into specific renewable fuels is an attractive way to mitigate the greenhouse effect and solve the energy crisis. Au_nCu_100-n/C alloy nanoparticles (Au_nCu_100−n/C NPs) with tunable compositions, a [...] Read more.

Electrocatalytic conversion of carbon dioxide (CO₂) into specific renewable fuels is an attractive way to mitigate the greenhouse effect and solve the energy crisis. Au_nCu_100-n/C alloy nanoparticles (Au_nCu_100−n/C NPs) with tunable compositions, a highly active crystal plane and a strained lattice were synthesized by the thermal solvent co-reduction method. Transmission electron microscopy (TEM) and X-ray diffraction (XRD) results show that Au_nCu_100−n/C catalysts display a subtle lattice strain and dominant (111) crystal plane, which can be adjusted by the alloy composition. Electrochemical results show that Au_nCu_100−n/C alloy catalysts for CO₂ reduction display high catalytic activity; in particular, the Faradaic efficiency of Au₇₅Cu₂₅/C is up to 92.6% for CO at −0.7 V (vs. the reversible hydrogen electrode), which is related to lattice shrinkage and the active facet. This research provides a new strategy with which to design strong and active nanoalloy catalysts with lattice mismatch and main active surfaces for CO₂ reduction reaction. Full article

(This article belongs to the Special Issue Properties of Interfaced Materials and Films)

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15 pages, 4236 KiB

Open AccessArticle

Tenebrio molitor Larvae-Based Magnetic Polyurea Employed as Crude Oil Spill Removal Tool

by Mostafa Aboelkheir, Fernando Gomes, Cintia Meiorin and Tiago Galdino

Materials 2022, 15(14), 5063; https://doi.org/10.3390/ma15145063 - 20 Jul 2022

Cited by 2 | Viewed by 1569

Abstract

Renewable resources constitute an extremely rich and varied set of molecules and polymers produced by natural biological activities. Within the applications of these polymers, a very important application is the use of these materials as a sorber for oils or oil spills. The [...] Read more.

Renewable resources constitute an extremely rich and varied set of molecules and polymers produced by natural biological activities. Within the applications of these polymers, a very important application is the use of these materials as a sorber for oils or oil spills. The advantage of these nanocomposites is the fact that they integrate different component materials and their properties into a single component material. They have several applications, ranging from environmental remediation to the development of advanced medical applications. This work proposed using magnetic polyurea composites based on an animal substrate from Tenebrio molitor larvae to perform oil spill clean-up operations under a magnetic field in the presence of 1% and 3% of magnetite to be tested as magnetic crude oil sorber. The obtained materials were characterized by Fourier transform infrared (FTIR) spectroscopy, X-ray Diffraction (XRD), Thermogravimetric Analysis (TGA), Scanning Differential Calorimetry (DSC), and Low-Field Nuclear Magnetic Resonance (LF-NMR 1H). The sorber material is simple to prepare and inexpensive. The use of magnetite as a magnetic charge allowed for the efficient removal of oil from water with about 28 g of oil per gram of sorber. These results are very promising and encouraging for future environmental recovery studies involving magnetite and sustainable polymers. Full article

(This article belongs to the Special Issue Advances in Nanomaterials and Molecules and Their Applications on Environment Recovery and Release Systems)

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18 pages, 5812 KiB

Open AccessArticle

A Damage Model of Concrete including Hysteretic Effect under Cyclic Loading

by Zhi Liu, Li Zhang, Lanhao Zhao, Zihan Wu and Bowen Guo

Materials 2022, 15(14), 5062; https://doi.org/10.3390/ma15145062 - 20 Jul 2022

Cited by 3 | Viewed by 1709

Abstract

A novel damage model for concrete has been developed, which can reflect the complex hysteresis phenomena of concrete under cyclic loading, as well as other nonlinear behaviors such as stress softening, stiffness degradation, and irreversible deformation. The model cleverly transforms the complex multiaxial [...] Read more.

A novel damage model for concrete has been developed, which can reflect the complex hysteresis phenomena of concrete under cyclic loading, as well as other nonlinear behaviors such as stress softening, stiffness degradation, and irreversible deformation. The model cleverly transforms the complex multiaxial stress state into a uniaxial state by equivalent strain, with few computational parameters and simple mathematical expression. The uniaxial tensile and compressive stress–strain curves matching the actual characteristics are used to accommodate the high asymmetry of concrete in tension and compression, respectively. Meanwhile, an unloading path and a reloading path that can reflect the hysteresis effect under cyclic loading of concrete are established, in which the adopted expressions for the loading and unloading characteristic points do not depend on the shape of the curve. The proposed model has a concise form that can be easily implemented and also shows strong generality and flexibility. Finally, the reliability and correctness of the model are verified by comparing the numerical results with the three-point bending beam test, cyclic loading test, and a seismic damage simulation of the Koyna gravity dam. Full article

(This article belongs to the Section Construction and Building Materials)

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18 pages, 1941 KiB

Open AccessArticle

Selected Physical and Spectroscopic Properties of TPS Moldings Enriched with Durum Wheat Bran

by Maciej Combrzyński, Agnieszka Wójtowicz, Anna Oniszczuk, Dariusz Karcz, Jarosław Szponar and Arkadiusz P. Matwijczuk

Materials 2022, 15(14), 5061; https://doi.org/10.3390/ma15145061 - 20 Jul 2022

Cited by 3 | Viewed by 1506

Abstract

The impact of the amount of durum wheat bran additive used on the selected structural, mechanical, and spectroscopic properties of thermoplastic starch moldings was examined in this study. Bran was added to corn starch from 10 to 60% by weight in the blends. [...] Read more.

The impact of the amount of durum wheat bran additive used on the selected structural, mechanical, and spectroscopic properties of thermoplastic starch moldings was examined in this study. Bran was added to corn starch from 10 to 60% by weight in the blends. Four temperature settings were used for the high-pressure injection: 120, 140, 160, and 180 °C. The highest value of elongation at break (8.53%) was observed for moldings containing 60% bran. Moreover, for these moldings, the tensile strength and flexural strength were lower (appropriately 3.43 MPa and 27.14 MPa). The highest deformation at break (1.56%) were obtained for samples with 60% bran and injection molded at 180 °C. We saw that higher bran content (50 and 60%) and a higher injection molding temperature (160 °C and 180 °C) significantly changed the color of the samples. The most significant changes in the FTIR spectra were observed at 3292 and 1644 cm⁻¹ and in the region of 1460–1240 cm⁻¹. Moreover, notable changes were observed in the intensity ratio of bands at 1015 and 955 cm⁻¹. The changes observed correspond well with the amount of additive used and with the injection temperature applied; thus it may be considered as a marker of interactions affecting plasticization of the material obtained. Full article

(This article belongs to the Special Issue Bio-Based Materials and Their Environmental Applications)

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8 pages, 664 KiB

Open AccessCommunication

Thermodynamic Modeling Study of Carbonation of Portland Cement

by Kamasani Chiranjeevi Reddy, Nahom S. Melaku and Solmoi Park

Materials 2022, 15(14), 5060; https://doi.org/10.3390/ma15145060 - 20 Jul 2022

Cited by 3 | Viewed by 1823

Abstract

The assessment of the extent of carbonation and related phase changes is important for the evaluation of the durability aspects of concrete. The phase assemblage of Portland cements with different clinker compositions is evaluated using thermodynamic calculations. Four different compositions of cements, as [...] Read more.

The assessment of the extent of carbonation and related phase changes is important for the evaluation of the durability aspects of concrete. The phase assemblage of Portland cements with different clinker compositions is evaluated using thermodynamic calculations. Four different compositions of cements, as specified by ASTM cements types I to IV, are considered in this study. Calcite, zeolites, and gypsum were identified as carbonation products. CO₂ content required for full carbonation had a direct relationship with the initial volume of phases. The CO₂ required for portlandite determined the initiation of carbonation of C-S-H. A continual decrease in the pH of pore solution and a decrease in Ca/Si is observed with the carbonation of C-S-H. Type II cement exhibited rapid carbonation at relatively less CO₂for full carbonation, while type III required more CO₂ to carbonate to the same level as other types of cement. The modeling of carbonation of different Portland cements provided insights into the quantity of CO₂ required to destabilize different hydrated products into respective carbonated phases. Full article

(This article belongs to the Special Issue Science and Technology for Silicate-Based Construction and Building Materials)

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20 pages, 7491 KiB

Open AccessArticle

Experimental and Numerical Investigation on the Shear Behavior of Engineered Cementitious Composite Beams with Hybrid Fibers

by Jeyaprakash Maheswaran, Maheswaran Chellapandian, Madappa V. R. Sivasubramanian, Gunasekaran Murali and Nikolai Ivanovich Vatin

Materials 2022, 15(14), 5059; https://doi.org/10.3390/ma15145059 - 20 Jul 2022

Cited by 5 | Viewed by 1612

Abstract

The shear behavior of innovative engineered cementitious composites (ECC) members with a hybrid mix of polyvinyl alcohol (PVA) and polypropylene (PP) fibers is examined. The overall objective of the investigation is to understand the shear behavior of ECC beams with different mono and [...] Read more.

The shear behavior of innovative engineered cementitious composites (ECC) members with a hybrid mix of polyvinyl alcohol (PVA) and polypropylene (PP) fibers is examined. The overall objective of the investigation is to understand the shear behavior of ECC beams with different mono and hybrid fiber combinations without compromising the strength and ductility. Four different configurations of beams were prepared and tested, including 2.0% of PP fibers, 2.0% of PVA fibers, 2.0% of steel fibers and hybrid PVA and PP fibers (i.e., 1% PP and 1% PVA). In addition to the tests, a detailed nonlinear finite element (FE) analysis was accomplished using the commercial ABAQUS software. The validated FE model was used to perform an extensive parametric investigation to optimize the design parameters for the hybrid-fiber-reinforced ECC beams under shear. The results revealed that the use of hybrid PVA and PP fibers improved the performance by enhancing the overall strength and ductility compared to the steel and PP-fiber-based ECC beams. Incorporating hybrid fibers into ECC beams increased the critical shear crack angle, indicating the transition of a failure from a brittle diagonal tension to a ductile bending. Full article

(This article belongs to the Special Issue Recent Innovations in Fibrous Concrete with Superior Mechanical Properties and Evolution in 2022)

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14 pages, 4037 KiB

Open AccessArticle

Technogenic Fiber Wastes for Optimizing Concrete

by Sergey Klyuev, Roman Fediuk, Marina Ageeva, Ekaterina Fomina, Alexander Klyuev, Elena Shorstova, Linar Sabitov, Oleg Radaykin, Sergey Anciferov, Diana Kikalishvili, Afonso R. G. de Azevedo, Nikolai Ivanovich Vatin and Mugahed Amran

Materials 2022, 15(14), 5058; https://doi.org/10.3390/ma15145058 - 20 Jul 2022

Cited by 13 | Viewed by 1852

Abstract

A promising method of obtaining mineral fiber fillers for dry building mixtures is the processing of waste that comes from the production of technogenic fibrous materials (TFM). The novelty of the work lies in the fact that, for the first time, basalt production [...] Read more.

A promising method of obtaining mineral fiber fillers for dry building mixtures is the processing of waste that comes from the production of technogenic fibrous materials (TFM). The novelty of the work lies in the fact that, for the first time, basalt production wastes were studied not only as reinforcing components, but also as binder ones involved in concrete structure formation. The purpose of the article is to study the physical and mechanical properties of waste technogenic fibrous materials as additives for optimizing the composition of raw concrete mixes. To assess the possibility of using wastes from the complex processing of TFM that were ground for 5 and 10 min as an active mineral additive to concrete, their chemical, mineralogical, and granulometric compositions, as well as the microstructure and physical and mechanical characteristics of the created concretes, were studied. It is established that the grinding of TFM for 10 min leads to the grinding of not only fibers, but also pellets, the fragments of which are noticeable in the total mass of the substance. The presence of quartz in the amorphous phase of TFM makes it possible to synthesize low-basic calcium silicate hydrates in a targeted manner. At 90 days age, at 10–20% of the content of TFM, the strength indicators increase (above 40 MPa), and at 30% of the additive content, they approach the values of the control composition without additives (above 35 MPa). For all ages, the ratio of flexural and compressive strengths is at the level of 0.2, which characterizes a high reinforcing effect. Analysis of the results suggests the possibility of using waste milled for 10 min as an active mineral additive, as well as to give better formability to the mixture and its micro-reinforcement to obtain fiber-reinforced concrete. Full article

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