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Obtaining and Characterization of New Materials, Volume IV
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Obtaining and Characterization of New Materials, Volume IV

A special issue of Materials (ISSN 1996-1944). This special issue belongs to the section "Advanced Materials Characterization".

Deadline for manuscript submissions: closed (20 March 2024) | Viewed by 31196

Printed Edition Available!
A printed edition of this Special Issue is available here.

Special Issue Editor

Dr. Andrei Victor Sandu

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Guest Editor
Department of Technologies and Equipment for Materials Processing, Faculty of Materials Science and Engineering, “Gheorghe Asachi” Technical University of Iasi, 41 “D. Mangeron” Street, 700050 Iasi, Romania
Interests: materials characterizations; biomaterials; geopolymers; microscopy
Special Issues, Collections and Topics in MDPI journals

Special Issue Information

Dear Colleagues,

After our successful first three volumes Special Issue "Obtaining and Characterization of New Materials", we have decided to create the fourth volume, in order to collect and publish a series of state-of-the-art research in the field of new materials and their understanding.

This fourth volume of Special Issue, like the first three ones, covers a wide range of topics: obtaining and characterizing New Materials, from nano- to macro-scale, involving new alloys, ceramics, composites, biomaterials, polymers, as well as procedures and technologies for enhancing their structure, properties, and functions. In order to be able to select the future use of the new materials, we first must understand their structure, to know their characteristics, involving modern techniques such as microscopy (SEM, TEM, AFM, STM, etc.), spectroscopy (EDX, XRD, XRF, FTIR, XPS, etc.), mechanical tests (tensile, hardness, elastic modulus, toughness, etc.), and their behavior (corrosion, thermal—DSC, STA, DMA, magnetic properties, biocompatibility—in vitro and in vivo), among many others.

Dr. Andrei Victor Sandu
Guest Editor

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Keywords

  • new materials
  • surface analysis
  • structure analysis
  • chemical analysis
  • mechanical properties
  • behavior of materials
  • functionalization

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Related Special Issue

Published Papers (16 papers)

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Research

18 pages, 8914 KiB  
Article
Fabrication of Lead–Zinc Tailings Sintered Brick and Its Effect Factors Based on an Orthogonal Experiment
by Hang Lin, Rui Li and Su Li
Materials 2024, 17(10), 2352; https://doi.org/10.3390/ma17102352 - 15 May 2024
Cited by 4 | Viewed by 1230
Abstract
The existence of lead-zinc tailings threatens the social and ecological environment. The recycling of lead–zinc tailings is important for the all-round green transformation of economic society. In this study, the possibility of fabricating sintered ordinary bricks with lead–zinc tailings was studied based on [...] Read more.
The existence of lead-zinc tailings threatens the social and ecological environment. The recycling of lead–zinc tailings is important for the all-round green transformation of economic society. In this study, the possibility of fabricating sintered ordinary bricks with lead–zinc tailings was studied based on orthogonal experimentation, and the phase composition and micromorphology of sintered products were analyzed by X-ray diffraction (XRD) and scanning electron microscope (SEM). With lead–zinc tailings as the main material, and clay and fly ash as additives, the effect of clay content, forming pressure, sintering temperature, and holding time on physical properties of sintered bricks was analyzed. The results show that clay content and sintering temperature have a major effect on compressive strength, while sintering temperature and holding time play an important role in water absorption. During sintering, mica, chlorite, and other components in lead–zinc tailings are decomposed to form albite, hematite, maghemite, and anhydrite, which play a role in the strength of bricks. The optimal process parameters were found to be a ratio of lead–zinc tailings:clay:fly ash = 6:3:1, forming pressure of 20 MPa, firing temperature of 1080 °C, and holding time of 60 min. The corresponding compressive strength and water absorption were 34.94 MPa and 16.02%, which meets the Chinese sintered ordinary bricks standard (GB/T 5101-2017). Full article
(This article belongs to the Special Issue Obtaining and Characterization of New Materials, Volume IV)
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17 pages, 4167 KiB  
Article
Synthesis, Crystal Structure, and Optical and Magnetic Properties of the New Quaternary Erbium Telluride EuErCuTe3: Experiment and Calculation
by Anna V. Ruseikina, Maxim V. Grigoriev, Ralf J. C. Locke, Vladimir A. Chernyshev, Alexander A. Garmonov and Thomas Schleid
Materials 2024, 17(10), 2284; https://doi.org/10.3390/ma17102284 - 11 May 2024
Cited by 1 | Viewed by 1362
Abstract
This paper reports for the first time on a new layered magnetic heterometallic erbium telluride EuErCuTe3. Single crystals of the compound were obtained from the elements at 1120 K using CsI as a flux. The crystal structure of EuErCuTe3 was [...] Read more.
This paper reports for the first time on a new layered magnetic heterometallic erbium telluride EuErCuTe3. Single crystals of the compound were obtained from the elements at 1120 K using CsI as a flux. The crystal structure of EuErCuTe3 was solved in the space group Cmcm (a = 4.3086(3) Å, b = 14.3093(9) Å, and c = 11.1957(7) Å) with the KZrCuS3 structure type. In the orthorhombic structure of erbium telluride, distorted octahedra ([ErTe6]9−) form two-dimensional layers (Er(Te1)2/2e(Te2)4/2k−)∞2, while distorted tetrahedra ([CuTe4]7−) form one-dimensionally connected substructures (Cu(Te1)2/2e(Te2)2/1t5−∞1) along the [100] direction. The distorted octahedra and tetrahedra form parallel two-dimensional layers (CuErTe32−∞2) between which Eu2+ ions are located in a trigonal-prismatic coordination environment (EuTe610−). The trigonal prisms are connected by faces, forming chains (Eu(Te1)2/2(Te2)4/22−∞1) along the [100] direction. Regularities in the variations in structural parameters were established in the series of erbium chalcogenides (EuErCuCh3 with Ch = S, Se, and Te) and tellurides (EuLnCuTe3 with Ln = Gd, Er, and Lu). Ab-initio calculations of the crystal structure, phonon spectrum, and elastic properties of the compound EuErCuTe3 were performed. The types and wavenumbers of fundamental modes were determined, and the involvement of ions in the IR and Raman modes was assessed. The experimental Raman spectra were interpreted. The telluride EuErCuTe3 at temperatures below 4.2 K was ferrimagnetic, as were the sulfide and selenide derivatives (EuErCuCh3 with Ch = S and Se). Its experimental magnetic characteristics were close to the calculated ones. The decrease in the magnetic phase transition temperature in the series of the erbium chalcogenides was discovered. Full article
(This article belongs to the Special Issue Obtaining and Characterization of New Materials, Volume IV)
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13 pages, 5164 KiB  
Article
Corrosion Resistance of Fe-Based Amorphous Films Prepared by the Radio Frequency Magnetron Sputter Method
by Tai-Nan Lin, Pin-Hsun Liao, Cheng-Chin Wang, Hung-Bin Lee and Leu-Wen Tsay
Materials 2024, 17(9), 2071; https://doi.org/10.3390/ma17092071 - 28 Apr 2024
Viewed by 1410
Abstract
Amorphous thin films can be applied to increase the anti-corrosion ability of critical components. Atomized FeCrNiMoCSiB powders were hot-pressed into a disc target for R. F. magnetron sputtering on a 316L substrate to upgrade its corrosion resistance. The XRD spectrum confirmed that the [...] Read more.
Amorphous thin films can be applied to increase the anti-corrosion ability of critical components. Atomized FeCrNiMoCSiB powders were hot-pressed into a disc target for R. F. magnetron sputtering on a 316L substrate to upgrade its corrosion resistance. The XRD spectrum confirmed that the film deposited by R. F. magnetron sputtering was amorphous. The corrosion resistance of the amorphous film was evaluated in a 1 M HCl solution with potentiodynamic polarization tests, and the results were contrasted with those of a high-velocity oxy-fuel (HVOF) coating and 316L, IN 600, and C 276 alloys. The results indicated that the film hardness and elastic modulus, as measured using a nanoindenter, were 11.1 and 182 GPa, respectively. The principal stresses in two normal directions of the amorphous film were about 60 MPa and in tension. The corrosion resistance of the amorphous film was much greater than that of the other samples, which showed a broad passivation region, even in a 1 M HCl solution. Although the amorphous film showed high corrosion resistance, the original pinholes in the film were weak sites to initiate corrosion pits. After polarization tests, large, deep trenches were seen in the corroded 316L substrate; numerous fine patches in the IN 600 alloy and grain boundary corrosion in the C276 alloy were observed. Full article
(This article belongs to the Special Issue Obtaining and Characterization of New Materials, Volume IV)
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13 pages, 3474 KiB  
Article
Characterization of Interfacial Corrosion Behavior of Hybrid Laminate EN AW-6082 ∪ CFRP
by Alexander Delp, Shuang Wu, Jonathan Freund, Ronja Scholz, Miriam Löbbecke, Thomas Tröster, Jan Haubrich and Frank Walther
Materials 2024, 17(8), 1907; https://doi.org/10.3390/ma17081907 - 19 Apr 2024
Viewed by 1180
Abstract
The corrosion behavior of a hybrid laminate consisting of laser-structured aluminum EN AW-6082 ∪ carbon fiber-reinforced polymer was investigated. Specimens were corroded in aqueous NaCl electrolyte (0.1 mol/L) over a period of up to 31 days and characterized continuously by means of scanning [...] Read more.
The corrosion behavior of a hybrid laminate consisting of laser-structured aluminum EN AW-6082 ∪ carbon fiber-reinforced polymer was investigated. Specimens were corroded in aqueous NaCl electrolyte (0.1 mol/L) over a period of up to 31 days and characterized continuously by means of scanning electron and light microscopy, supplemented by energy dispersive X-ray spectroscopy. Comparative linear sweep voltammetry was employed on the first and seventh day of the corrosion experiment. The influence of different laser morphologies and production process parameters on corrosion behavior was compared. The corrosion reaction mainly arises from the aluminum component and shows distinct differences in long-term corrosion morphology between pure EN AW-6082 and the hybrid laminate. Compared to short-term investigations, a strong influence of galvanic corrosion on the interface is assumed. No distinct influences of different laser structuring and process parameters on the corrosion behavior were detected. Weight measurements suggest a continuous loss of mass attributed to the detachment of corrosion products. Full article
(This article belongs to the Special Issue Obtaining and Characterization of New Materials, Volume IV)
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12 pages, 1164 KiB  
Article
Application of Alcohols to Inhibit the Formation of Ca(II) Dodecyl Sulfate Precipitate in Aqueous Solutions
by Csaba Bús, Marianna Kocsis, Áron Ágoston, Ákos Kukovecz, Zoltán Kónya and Pál Sipos
Materials 2024, 17(8), 1806; https://doi.org/10.3390/ma17081806 - 15 Apr 2024
Cited by 2 | Viewed by 1318
Abstract
The presence of alkaline earth cations, in particular, Ca2+ and Mg2+ ions in brine, causes undesired effects in solutions containing anionic surfactants because of precipitate formation. In the present study, an anionic surfactant, sodium dodecyl sulfate (SDS), was investigated, focusing on [...] Read more.
The presence of alkaline earth cations, in particular, Ca2+ and Mg2+ ions in brine, causes undesired effects in solutions containing anionic surfactants because of precipitate formation. In the present study, an anionic surfactant, sodium dodecyl sulfate (SDS), was investigated, focusing on the determination of various properties (surface tension, critical micelle concentration, micelle size, turbidity) in the presence of alcohols and, in particular, the inhibition of the precipitation of SDS with calcium ions. The calcium ions were added to the surfactant in increasing concentrations (3.0–10.0 g/L), and short-carbon-chain alcohols (methanol, ethanol, n-propanol and n-butanol) were used to shift the onset of precipitate formation. The critical micelle concentration (CMC) of SDS in the presence of alcohols was also determined. It was established that among these alcohols, methanol and ethanol did not exert significant effects on the solubility of the Ca(DS)2 precipitate, while n-propanol and n-butanol were found to be much more efficient inhibitors. In addition, all the alcohols in the applied concentration range (up to 20 V/V%) were found to decrease the critical micelle concentration of SDS. Full article
(This article belongs to the Special Issue Obtaining and Characterization of New Materials, Volume IV)
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12 pages, 4018 KiB  
Article
Rapid Synthesis of Noble Metal Colloids by Plasma–Liquid Interactions
by Yuanwen Pang, Hong Li, Yue Hua, Xiuling Zhang and Lanbo Di
Materials 2024, 17(5), 987; https://doi.org/10.3390/ma17050987 - 21 Feb 2024
Cited by 4 | Viewed by 1440
Abstract
The interactions between plasma and liquids cause complex physical and chemical reactions at the gas–liquid contact surface, producing numerous chemically active particles that can rapidly reduce noble metal ions. This study uses atmospheric-pressure surface dielectric barrier discharge (DBD) plasma to treat ethanol aqueous [...] Read more.
The interactions between plasma and liquids cause complex physical and chemical reactions at the gas–liquid contact surface, producing numerous chemically active particles that can rapidly reduce noble metal ions. This study uses atmospheric-pressure surface dielectric barrier discharge (DBD) plasma to treat ethanol aqueous solutions containing noble metal precursors, and stable gold, platinum, and palladium colloids are obtained within a few minutes. To evaluate the mechanism of the reduction of noble metal precursors by atmospheric-pressure surface DBD plasma, the corresponding metal colloids are prepared first by activating an ethanol aqueous solution with plasma and then adding noble metal precursors. It is found that the long-lived active species hydrogen peroxide (H2O2) plays a dominant role in the synthesis process, which has distinct effects on different metal ions. When HAuCl4 and H2PdCl4 are used as precursors, H2O2 acts as a reducing agent, and AuCl4− and PdCl42− ions can be reduced to metallic Au and Pd. However, when AgNO3 is the precursor, H2O2 acts as an oxidising agent, and Ag+ ions cannot be reduced to obtain metal colloids because metallic Ag can be dissolved in H2O2 under acidic conditions. A similar phenomenon was also observed for the preparation of Pd colloid-PA with a plasma-activated ethanol aqueous solution using Pd(NO3)2 as a Pd precursor. Full article
(This article belongs to the Special Issue Obtaining and Characterization of New Materials, Volume IV)
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21 pages, 11026 KiB  
Article
Characterization of Bulgarian Copper Mine Tailing as a Precursor for Obtaining Geopolymers
by Darya Ilieva, Lyudmila Angelova, Temenuzhka Radoykova, Andriana Surleva, Georgi Chernev, Petrica Vizureanu, Dumitru Doru Burduhos-Nergis and Andrei Victor Sandu
Materials 2024, 17(3), 542; https://doi.org/10.3390/ma17030542 - 23 Jan 2024
Cited by 4 | Viewed by 1632
Abstract
Valorization of high-volume mine tailings could be achieved by the development of new geopolymers with a low CO2 footprint. Materials rich in aluminum and silicon with appropriate solubility in an alkaline medium can be used to obtain a geopolymer. This paper presents [...] Read more.
Valorization of high-volume mine tailings could be achieved by the development of new geopolymers with a low CO2 footprint. Materials rich in aluminum and silicon with appropriate solubility in an alkaline medium can be used to obtain a geopolymer. This paper presents a study of copper mine tailings from Bulgaria as precursors for geopolymers. Particle size distribution, chemical and mineralogical composition, as well as alkaline reactivity, acidity and electroconductivity of aqueous slurry are studied. The heavy metal content and their mobility are studied by leaching tests. Sequential extraction was applied to determine the geochemical phase distribution of heavy metals. The studied samples were characterized by high alkalinity, which could favor the geopolymerization process. The water-soluble sulphates were less than 4%. The Si/Al ratio in mine tailing was found to be 3. The alkaline reactivity depended more so on the time of extraction than on the concentration of NaOH solution. The main part of the heavy metals was found in the residual fraction; hence, in high alkaline medium during the geopolymerization process, they will stay fixed. Thus, the obtained geopolymers could be expected to exert low environmental impact. The presented results revealed that studied copper mine tailing is a suitable precursor for geopolymerization. Full article
(This article belongs to the Special Issue Obtaining and Characterization of New Materials, Volume IV)
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20 pages, 14829 KiB  
Article
Plasmonic Nanocomposites of ZnO-Ag Produced by Laser Ablation and Their Photocatalytic Destruction of Rhodamine, Tetracycline and Phenol
by Elena D. Fakhrutdinova, Anastasia V. Volokitina, Sergei A. Kulinich, Daria A. Goncharova, Tamara S. Kharlamova and Valery A. Svetlichnyi
Materials 2024, 17(2), 527; https://doi.org/10.3390/ma17020527 - 22 Jan 2024
Cited by 8 | Viewed by 1810
Abstract
Hydrosphere pollution by organic pollutants of different nature (persistent dyes, phenols, herbicides, antibiotics, etc.) is one of the urgent ecological problems facing humankind these days. The task of water purification from such pollutants can be effectively solved with the help of modern photocatalytic [...] Read more.
Hydrosphere pollution by organic pollutants of different nature (persistent dyes, phenols, herbicides, antibiotics, etc.) is one of the urgent ecological problems facing humankind these days. The task of water purification from such pollutants can be effectively solved with the help of modern photocatalytic technologies. This article is devoted to the study of photocatalytic properties of composite catalysts based on ZnO modified with plasmonic Ag nanoparticles. All materials were obtained by laser synthesis in liquid and differed by their silver content and preparation conditions, such as additional laser irradiation and/or annealing of produced powders. The prepared ZnO-Ag powders were investigated by electron microscopy, X-ray diffraction and UV-Vis spectroscopy. Photocatalytic tests were carried out with well- known test molecules in water (persistent dye rhodamine B, phenol and common antibiotic tetracycline) using LED light sources with wavelengths of 375 and 410 nm. The introduction of small concentrations (up to 1%) of plasmonic Ag nanoparticles is shown to increase the efficiency of the ZnO photocatalyst by expanding its spectral range. Both the preparation conditions and material composition were optimized to obtain composite photocatalysts with the highest efficiency. Finally, the operation mechanisms of the material with different distribution of silver are discussed. Full article
(This article belongs to the Special Issue Obtaining and Characterization of New Materials, Volume IV)
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21 pages, 25481 KiB  
Article
The Influence of Different Aggregates on the Physico-Mechanical Performance of Alkali-Activated Geopolymer Composites Produced Using Romanian Fly Ash
by Adrian-Victor Lăzărescu, Andreea Hegyi, Alexandra Csapai and Florin Popa
Materials 2024, 17(2), 485; https://doi.org/10.3390/ma17020485 - 19 Jan 2024
Cited by 3 | Viewed by 1217
Abstract
In light of the urgent need to develop environmentally friendly materials that, at some point, will allow the reduction of concrete and, consequently, cement consumption—while at the same time allowing the reuse of waste and industrial by-products—alkali-activated fly ash (AAFA) geopolymer composite emerges [...] Read more.
In light of the urgent need to develop environmentally friendly materials that, at some point, will allow the reduction of concrete and, consequently, cement consumption—while at the same time allowing the reuse of waste and industrial by-products—alkali-activated fly ash (AAFA) geopolymer composite emerges as a material of great interest. The aim of this study was to investigate the physico-mechanical performance of composites based on AAFA binders and the effect of different types of aggregates on these properties. The experimental results indicate variations in flexural and compressive strength, which are influenced both by the nature and particle size distribution of aggregates and the binder-to-aggregate ratio. The analysis of the samples highlighted changes in porosity, both in distribution and pore size, depending on the nature of the aggregates. This supports the evolution of physico-mechanical performance indicators. Full article
(This article belongs to the Special Issue Obtaining and Characterization of New Materials, Volume IV)
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17 pages, 6911 KiB  
Article
DyMnO3: Synthesis, Characterization and Evaluation of Its Photocatalytic Activity in the Visible Spectrum
by Miguel Ángel López-Álvarez, Pedro Ortega-Gudiño, Jorge Manuel Silva-Jara, Jazmín Guadalupe Silva-Galindo, Arturo Barrera-Rodríguez, José Eduardo Casillas-García, Israel Ceja-Andrade, Jesús Alonso Guerrero-de León and Carlos Alberto López-de Alba
Materials 2023, 16(24), 7666; https://doi.org/10.3390/ma16247666 - 15 Dec 2023
Viewed by 1970
Abstract
DyMnO3 is a p-type semiconductor oxide with two crystal systems, orthorhombic and hexagonal. This material highlights its ferroelectric and ferromagnetic properties, which have been the subject of numerous studies. Nevertheless, its photocatalytic activity has been less explored. In this work, the photocatalytic [...] Read more.
DyMnO3 is a p-type semiconductor oxide with two crystal systems, orthorhombic and hexagonal. This material highlights its ferroelectric and ferromagnetic properties, which have been the subject of numerous studies. Nevertheless, its photocatalytic activity has been less explored. In this work, the photocatalytic activity of DyMnO3 is evaluated through the photodegradation of MG dye. For the synthesis of this oxide, a novel and effective method was used: polymer-decomposition. The synthesized powders contain an orthorhombic phase, with a range of absorbances from 300 to 500 nm and a band gap energy of 2.4 eV. It is also highlighted that, when using this synthesis method, some of the main diffraction lines related to the orthorhombic phase appear at 100 °C. Regarding its photocatalytic activity, it was evaluated under visible light (λ = 405 nm), reaching a photodegradation of approximately 88% in a period of 30 min. Photocurrent tests reveal a charge carrier separation (e−,h+) at a 405 nm wavelength. The main reactive oxygen species (ROS) involved in the photodegradation process were radicals, OH•, and photo-holes (h+). These results stand out because it is the first time that the photodegradation capability of this oxide in the visible spectrum has been evaluated. Full article
(This article belongs to the Special Issue Obtaining and Characterization of New Materials, Volume IV)
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11 pages, 2549 KiB  
Article
Effect of Post-Washing on Textural Characteristics of Carbon Materials Derived from Pineapple Peel Biomass
by Chi-Hung Tsai, Wen-Tien Tsai and Li-An Kuo
Materials 2023, 16(24), 7529; https://doi.org/10.3390/ma16247529 - 6 Dec 2023
Cited by 4 | Viewed by 1412
Abstract
Porous carbon materials have been widely used to remove pollutants from the liquid-phase streams. However, their limited pore properties could be a major problem. In this work, the effects of post-washing methods (i.e., water washing and acid washing) on the textural characteristics of [...] Read more.
Porous carbon materials have been widely used to remove pollutants from the liquid-phase streams. However, their limited pore properties could be a major problem. In this work, the effects of post-washing methods (i.e., water washing and acid washing) on the textural characteristics of the resulting biochar and activated carbon products from pineapple peel biomass were investigated in the carbonization and CO2 activation processes. The experiments were set at an elevated temperature (i.e., 800 °C) holding for 30 min. It was found that the enhancement in pore property reached about a 50% increase rate, increasing from 569.56 m2/g for the crude activated carbon to the maximal BET surface area of 843.09 m2/g for the resulting activated carbon by water washing. The resulting activated carbon materials featured the microporous structures but also were characteristic of the mesoporous solids. By contrast, the enhancement in the increase rate by about 150% was found in the resulting biochar products. However, there seemed to be no significant variations in pore property with post-washing methods. Using the energy dispersive X-ray spectroscopy (EDS) and the Fourier Transform infrared spectroscopy (FTIR) analyses, it showed some oxygen-containing functional groups or complexes, potentially posing the hydrophilic characters on the surface of the resulting carbon materials. Full article
(This article belongs to the Special Issue Obtaining and Characterization of New Materials, Volume IV)
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19 pages, 7429 KiB  
Article
Characterization of Densified Pine Wood and a Zero-Thickness Bio-Based Adhesive for Eco-Friendly Structural Applications
by Shahin Jalali, Catarina da Silva Pereira Borges, Ricardo João Camilo Carbas, Eduardo André de Sousa Marques, João Carlos Moura Bordado and Lucas Filipe Martins da Silva
Materials 2023, 16(22), 7147; https://doi.org/10.3390/ma16227147 - 13 Nov 2023
Cited by 3 | Viewed by 1648
Abstract
This study investigates a sustainable alternative for composites and adhesives in high-performance industries like civil and automotive. This study pioneers the development and application of a new methodology to characterize a bio-based, zero-thickness adhesive. This method facilitates precise measurements of the adhesive’s strength [...] Read more.
This study investigates a sustainable alternative for composites and adhesives in high-performance industries like civil and automotive. This study pioneers the development and application of a new methodology to characterize a bio-based, zero-thickness adhesive. This method facilitates precise measurements of the adhesive’s strength and fracture properties under zero-thickness conditions. The research also encompasses the characterization of densified pine wood, an innovative wood product distinguished by enhanced mechanical properties, which is subsequently compared to natural pine wood. We conducted a comprehensive characterization of wood’s strength properties, utilizing dogbone-shaped samples in the fiber direction, and block specimens in the transverse direction. Butt joints were employed for adhesive testing. Mode I fracture properties were determined via compact tension (CT) and double cantilever beam (DCB) tests for wood and adhesive, respectively, while mode II response was assessed through end-loaded split (ELS) tests. The densification procedure, encompassing chemical and mechanical processes, was a focal point of the study. Initially, wood was subjected to acid boiling to remove the wood matrix, followed by the application of pressure to enhance density. As a result, wood density increased by approximately 100 percent, accompanied by substantial improvements in strength and fracture energy along the fiber direction by about 120 percent. However, it is worth noting that due to the delignification nature of the densification method, properties in the transverse direction, mainly reliant on the lignin matrix, exhibited compromises. Also introduced was an innovative technique to evaluate the bio-based adhesive, applied as a zero-thickness layer. The results from this method reveal promising mechanical properties, highlighting the bio-based adhesive’s potential as an eco-friendly substitute for synthetic adhesives in the wood industry. Full article
(This article belongs to the Special Issue Obtaining and Characterization of New Materials, Volume IV)
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13 pages, 4403 KiB  
Article
Effect of the Sintering Mechanism on the Crystallization Kinetics of Geopolymer-Based Ceramics
by Nur Bahijah Mustapa, Romisuhani Ahmad, Mohd Mustafa Al Bakri Abdullah, Wan Mastura Wan Ibrahim, Andrei Victor Sandu, Ovidiu Nemes, Petrica Vizureanu, Christina W. Kartikowati and Puput Risdanareni
Materials 2023, 16(17), 5853; https://doi.org/10.3390/ma16175853 - 26 Aug 2023
Cited by 3 | Viewed by 1673
Abstract
This research aims to study the effects of the sintering mechanism on the crystallization kinetics when the geopolymer is sintered at different temperatures: 200 °C, 400 °C, 600 °C, 800 °C, 1000 °C, and 1200 °C for a 3 h soaking time with [...] Read more.
This research aims to study the effects of the sintering mechanism on the crystallization kinetics when the geopolymer is sintered at different temperatures: 200 °C, 400 °C, 600 °C, 800 °C, 1000 °C, and 1200 °C for a 3 h soaking time with a heating rate of 5 °C/min. The geopolymer is made up of kaolin and sodium silicate as the precursor and an alkali activator, respectively. Characterization of the nepheline produced was carried out using XRF to observe the chemical composition of the geopolymer ceramics. The microstructures and the phase characterization were determined by using SEM and XRD, respectively. The SEM micrograph showed the microstructural development of the geopolymer ceramics as well as identifying reacted/unreacted regions, porosity, and cracks. The maximum flexural strength of 78.92 MPa was achieved by geopolymer sintered at 1200 °C while the minimum was at 200 °C; 7.18 MPa. The result indicates that the flexural strength increased alongside the increment in the sintering temperature of the geopolymer ceramics. This result is supported by the data from the SEM micrograph, where at the temperature of 1000 °C, the matrix structure of geopolymer-based ceramics starts to become dense with the appearance of pores. Full article
(This article belongs to the Special Issue Obtaining and Characterization of New Materials, Volume IV)
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26 pages, 5346 KiB  
Article
Research on Thermal Insulation Performance and Impact on Indoor Air Quality of Cellulose-Based Thermal Insulation Materials
by Cristian Petcu, Andreea Hegyi, Vlad Stoian, Claudiu Sorin Dragomir, Adrian Alexandru Ciobanu, Adrian-Victor Lăzărescu and Carmen Florean
Materials 2023, 16(15), 5458; https://doi.org/10.3390/ma16155458 - 3 Aug 2023
Cited by 13 | Viewed by 5795
Abstract
Worldwide, the need for thermal insulation materials used to increase the energy performance of buildings and ensure indoor thermal comfort is constantly growing. There are several traditional, well-known and frequently used thermal insulation materials on the building materials market, but there is a [...] Read more.
Worldwide, the need for thermal insulation materials used to increase the energy performance of buildings and ensure indoor thermal comfort is constantly growing. There are several traditional, well-known and frequently used thermal insulation materials on the building materials market, but there is a growing trend towards innovative materials based on agro-industrial waste. This paper analyses the performance of 10 such innovative thermal insulation materials obtained by recycling cellulosic and/or animal waste, using standardised testing methods. More precisely, thermal insulation materials based on the following raw materials were analysed: cellulose acetate, cigarette filter manufacturing waste; cellulose acetate, cigarette filter manufacturing waste and cigarette paper waste; cellulose acetate, waste from cigarette filter manufacturing, waste cigarette paper and waste aluminised paper; cellulose from waste paper (two types made by two independent manufacturers); wood fibres; cellulose from cardboard waste; cellulose from waste cardboard, poor processing, inhomogeneous product; rice husk waste and composite based on sheep wool, recycled PET fibres and cellulosic fibres for the textile industry. The analysis followed the performance in terms of thermal insulating quality, evidenced by the thermal conductivity coefficient (used as a measurable indicator) determined for both dry and conditioned material at 50% RH, in several density variants, simulating the subsidence under its own weight or under various possible stresses arising in use. The results showed in most cases that an increase in material density has beneficial effects by reducing the coefficient of thermal conductivity, but exceptions were also reported. In conjunction with this parameter, the analysis of the 10 types of materials also looked at their moisture sorption/desorption capacity (using as a measurable indicator the amount of water stored by the material), concluding that, although they have a capacity to regulate the humidity of the indoor air, under low RH conditions the water loss is not complete, leaving a residual quantity of material that could favour the development of mould. Therefore, the impact on indoor air quality was also analysed by assessing the risk of mould growth (using as a measurable indicator the class and performance category of the material in terms of nutrient content conducive to the growth of microorganisms) under high humidity conditions but also the resistance to the action of two commonly encountered moulds, Aspergillus niger and Penicillium notatum. The results showed a relative resistance to the action of microbiological factors, indicating however the need for intensified biocidal treatment. Full article
(This article belongs to the Special Issue Obtaining and Characterization of New Materials, Volume IV)
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18 pages, 2365 KiB  
Article
Electrochemical Study of Semiconductor Properties for Bismuth Silicate-Based Photocatalysts Obtained via Hydro-/Solvothermal Approach
by Anastasiia V. Shabalina, Ekaterina Y. Gotovtseva, Yulia A. Belik, Sergey M. Kuzmin, Tamara S. Kharlamova, Sergei A. Kulinich, Valery A. Svetlichnyi and Olga V. Vodyankina
Materials 2022, 15(12), 4099; https://doi.org/10.3390/ma15124099 - 9 Jun 2022
Cited by 4 | Viewed by 2316
Abstract
Three bismuth silicate-based photocatalysts (composites of Bi2SiO5 and Bi12SiO20) prepared via the hydro-/solvothermal approach were studied using electrochemical methods. The characteristic parameters of semiconductors, such as flat band potential, donor density, and mobility of their charge [...] Read more.
Three bismuth silicate-based photocatalysts (composites of Bi2SiO5 and Bi12SiO20) prepared via the hydro-/solvothermal approach were studied using electrochemical methods. The characteristic parameters of semiconductors, such as flat band potential, donor density, and mobility of their charge carriers, were obtained and compared with the materials’ photocatalytic activity. An attempt was made to study the effect of solution components on the semiconductor/liquid interface (SLI). In particular, the Mott–Schottky characterization was made in a common model electrolyte (Na2SO4) and with the addition of glycerol as a model organic compound for photocatalysis. Thus, a medium close to those in photocatalytic experiments was simulated, at least within the limits allowed by electrochemical measurements. Zeta-potential measurements and electrochemical impedance spectroscopy were used to reveal the processes taking place at the SLI. It was found that the medium in which measurements were carried out dramatically impacted the results. The flat band potential values (Efb) obtained via the Mott–Schottky technique were shown to differ significantly depending on the solution used in the experiment, which is explained by different processes taking place at the SLI. A strong influence of specific adsorption of commonly used sulfate ions and neutral molecules on the measured values of Efb was shown. Full article
(This article belongs to the Special Issue Obtaining and Characterization of New Materials, Volume IV)
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10 pages, 563 KiB  
Article
Modifier Effect in Silica-Supported FePO4 and Fe-Mo-O Catalysts for Propylene Glycol Oxidation
by Darya Y. Savenko, Mikhail A. Salaev, Valerii V. Dutov, Sergei A. Kulinich and Olga V. Vodyankina
Materials 2022, 15(5), 1906; https://doi.org/10.3390/ma15051906 - 4 Mar 2022
Cited by 3 | Viewed by 2175
Abstract
Currently, catalytic processing of biorenewable raw materials into valuable products attracts more and more attention. In the present work, silica-supported FePO4 and Fe-Mo-O catalysts are prepared, their phase composition, and catalytic properties are studied in the process of selective oxidation of propylene [...] Read more.
Currently, catalytic processing of biorenewable raw materials into valuable products attracts more and more attention. In the present work, silica-supported FePO4 and Fe-Mo-O catalysts are prepared, their phase composition, and catalytic properties are studied in the process of selective oxidation of propylene glycol into valuable mono- and bicarbonyl compounds, namely, hydroxyacetone and methylglyoxal. A comparative analysis of the main routes of propylene glycol adsorption with its subsequent oxidative conversion into carbonyl products is carried out. The DFT calculations show that in the presence of adsorbed oxygen atom, the introduction of the phosphate moiety to the Fe-containing site strengthens the alcohol adsorption on the catalyst surface with the formation of the 1,2-propanedioxy (–OCH(CH3)CH2O–) intermediate at the active site. The introduction of the molybdenum moiety to the Fe-containing site in the presence of the adsorbed oxygen atom is also energetically favorable, however, the interaction energy is found by 100 kJ/mol higher compared to the case with phosphate moiety that leads to an increase in the propylene glycol conversion while maintaining high selectivity towards C3 products. The catalytic properties of the synthesized iron-containing catalysts are experimentally compared with those of Ag/SiO2 sample. The synthesized FePO4/SiO2 and Fe-Mo-O/SiO2 catalysts are not inferior to the silver-containing catalyst and provide ~70% selectivity towards C3 products, while the main part of propylene glycol is converted into methylglyoxal in contrast to the Ag/SiO2 catalyst featuring the selective transformation of only the secondary C-OH group in the substrate molecule under the studied conditions with the formation of hydroxyacetone. Thus, supported Fe-Mo-O/SiO2 catalysts are promising for the selective oxidation of polyatomic alcohols under low-temperature conditions. Full article
(This article belongs to the Special Issue Obtaining and Characterization of New Materials, Volume IV)
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