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Obtaining and Characterization of New Materials (5th Edition)

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

Deadline for manuscript submissions: 20 December 2024 | Viewed by 13223

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 four 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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Published Papers (15 papers)

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Research

14 pages, 2370 KiB  
Article
Nd3+-Doped Scheelite-Type Multifunctional Materials—Their Thermal Stability and Magnetic Properties
by Elżbieta Tomaszewicz, Grażyna Dąbrowska, Hubert Fuks and Paweł Kochmański
Materials 2024, 17(19), 4883; https://doi.org/10.3390/ma17194883 - 4 Oct 2024
Viewed by 739
Abstract
New Nd3+-doped cadmium molybdato-tungstates with the chemical formula of Cd1−3x▯xNd2x(MoO4)1−3x(WO4)3x (where x = 0.0283, 0.0455, 0.0839, 0.1430, 0.1875, 0.2000, 0.2500, and ▯ denotes a [...] Read more.
New Nd3+-doped cadmium molybdato-tungstates with the chemical formula of Cd1−3x▯xNd2x(MoO4)1−3x(WO4)3x (where x = 0.0283, 0.0455, 0.0839, 0.1430, 0.1875, 0.2000, 0.2500, and ▯ denotes a vacant site in the crystal lattice) were successfully synthesized by the high-temperature solid state reaction method, using CdMoO4 and Nd2(WO4)3 as the initial reactants. The structure and change in their lattice parameters as a function of Nd3+ ion concentration were investigated by the XRD (X-ray diffraction) method. The surface morphology and grain size of the doped materials were characterized by SEM (scanning electron microscopy). Their thermal properties and initial reactants were analyzed by DTA-TG (differential thermal analysis coupled with thermogravimetry) techniques. The optical properties of the Nd3+-doped cadmium molybdato-tungstates, such as optical band gap, were determined by UV–vis–NIR (ultraviolet–visible–near infrared) spectroscopy. The EPR (electron paramagnetic resonance) technique provided information on the type of magnetic interactions between Nd3+ ions. Full article
(This article belongs to the Special Issue Obtaining and Characterization of New Materials (5th Edition))
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10 pages, 4719 KiB  
Article
Cu-Al-Ni Nanocrystalline Compacts Obtained by Spark Plasma Sintering of Mechanically Alloyed Powders
by Calin-Virgiliu Prica, Traian Florin Marinca, Florin Popa, Argentina Niculina Sechel, Bogdan Viorel Neamțu, Horea Florin Chicinaș and Ionel Chicinaș
Materials 2024, 17(19), 4847; https://doi.org/10.3390/ma17194847 - 1 Oct 2024
Viewed by 445
Abstract
The aim of this work is to obtain Cu-13.5Al-4Ni alloy for use as shape memory alloy by Spark Plasma Sintering (SPS) of mechanically alloyed powder. The study investigates the structural and microstructural changes in terms of crystal parameters, crystallite sizes, and phases evolution [...] Read more.
The aim of this work is to obtain Cu-13.5Al-4Ni alloy for use as shape memory alloy by Spark Plasma Sintering (SPS) of mechanically alloyed powder. The study investigates the structural and microstructural changes in terms of crystal parameters, crystallite sizes, and phases evolution during mechanical alloying and spark plasma sintering of Cu-13.5Al-4Ni powders. We obtained alloyed powders with a structure composed of α(Cu), AlNi intermetallic compound and small amounts of elemental Al through the mechanical alloying technique. After spark plasma sintering at 900 °C, the microstructure consists of an AlNi compound distributed at the edge of α(Cu) grains. The crystallite sizes of both, α(Cu) and AlNi are in nanoscale order after 16 h of milling (9 and 6.5 nm respectively). After sintering at 900 °C (in Ar atmosphere, without holding time), the crystallite sizes increase to 46 nm for α(Cu) and to 40 nm for AlNi compound. Also, the Cu-13.5Al-4Ni compacts achieve a final density after sintering at 900 °C of around 80% from the theoretical density. Full article
(This article belongs to the Special Issue Obtaining and Characterization of New Materials (5th Edition))
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11 pages, 2511 KiB  
Article
Parameters Tailoring on the Deposition of Hydroxyapatite by Pulsed Electrical Discharge
by Stefan Alexandru Laptoiu, Mihai Ovidiu Cojocaru, Marian Miculescu and Mihai Branzei
Materials 2024, 17(18), 4583; https://doi.org/10.3390/ma17184583 - 18 Sep 2024
Viewed by 488
Abstract
The creation of strong adhesive layers of hydroxyapatite-based bioceramics (with or without bioinert metals, such as Ta, Ag, and Ti) on biocompatible metallic supports enhances the local biofunctionalization of surfaces. The processing of electroconductive materials using electrical impulse discharges is versatile, enabling precise [...] Read more.
The creation of strong adhesive layers of hydroxyapatite-based bioceramics (with or without bioinert metals, such as Ta, Ag, and Ti) on biocompatible metallic supports enhances the local biofunctionalization of surfaces. The processing of electroconductive materials using electrical impulse discharges is versatile, enabling precise coating of selected areas with perfectly adherent layers of varying thicknesses. This study aims to quantify the effects of varying the electrical power from the source generating the impulse discharge and the specific processing time per unit area of the cathode (made of titanium alloy) on the relative mass increase of the cathode. The anode comprised a mixture of hydroxyapatite powder and a self-polymerizing electroconductive acrylic resin in a tantalum sheath. The effects of the parameter adjustments on single-layer deposition adherence were quantified using a central composite design to build a second-order orthogonal model. The most significant difference in relative mass was observed with a low-power source (5 W) ensuring the electrical discharge impulse, combined with the longest specified surface treatment time (17.5 s/cm2 on a 4 cm2 surface) for a single layer presenting the largest mass increase of 0.153% of the original mass. This study aimed to enhance the performance of medical implants by optimizing surface biofunctionalization through robust hydroxyapatite-based bioceramic adhesive layers on metallic supports, determining the optimal electrical power and processing time for cathode mass increase during deposition processes, and analyzing parameter adjustments using second-order statistical orthogonal central composite programming, with a focus on single-layer deposition to identify significant differences in relative mass under specific conditions. Full article
(This article belongs to the Special Issue Obtaining and Characterization of New Materials (5th Edition))
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13 pages, 10499 KiB  
Article
High Milling Time Influence on the Phase Stability and Electrical Properties of Fe50Mn35Sn15 Heusler Alloy Obtained by Mechanical Alloying
by Florin Popa, Traian Florin Marinca, Niculina Argentina Sechel, Dan Ioan Frunză and Ionel Chicinaș
Materials 2024, 17(17), 4355; https://doi.org/10.3390/ma17174355 - 3 Sep 2024
Viewed by 362
Abstract
Fe50Mn35Sn15 Heusler alloy, obtained by mechanical alloying, was subjected to larger milling times in the range of 30–50 h to study the phase stability and morphology. X-ray diffraction studies have shown that the milled samples crystallise in a [...] Read more.
Fe50Mn35Sn15 Heusler alloy, obtained by mechanical alloying, was subjected to larger milling times in the range of 30–50 h to study the phase stability and morphology. X-ray diffraction studies have shown that the milled samples crystallise in a disordered A2 structure. The A2 structure was found to be stable in the milling range studied, contrary to the computation studies performed on this composition. Using Rietveld refinements, the lattice parameter, mean crystallite size, and lattice strain were computed. The nature of the obtained phases by milling was found to be nanocrystalline with values below 50 nm. A linear increase rate of 0.00713 (h−1) was computed for lattice strain as the milling time increased. As the milling time increases, the lattice parameter of the cubic Heusler was found to have a decreasing behaviour, reaching 2.9517 Å at 50 h of milling. The morphological and elemental distribution—characterised by scanning electron microscopy and energy-dispersive X-ray spectroscopy—evidenced Mn and Sn phase clustering. As the milling time increased, the morphology of the sample was found to change. The Mn and Sn cluster size was quantified by elemental line profile. Electrical resistivity evolution with milling time was analysed, showing a peak for 40 h of milling time. Full article
(This article belongs to the Special Issue Obtaining and Characterization of New Materials (5th Edition))
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14 pages, 17420 KiB  
Article
Electrospun Polymeric Fiber Systems Inoculated with Cyanoacrylate Tissue Adhesive: A Novel Hemostatic Alternative during Open Surgery
by Victor P. Tosa, Alexandru Ilie-Ene, Septimiu C. Tripon, Amalia Mesaros, Radu Fechete, Nicoleta Tosa, Alexandra Csapai, George C. Dindelegan and Catalin O. Popa
Materials 2024, 17(17), 4318; https://doi.org/10.3390/ma17174318 - 30 Aug 2024
Viewed by 498
Abstract
Natural-based and synthetic tissue adhesives have attracted extensive attention in the last two decades for their ability to stabilize uncontrolled bleeding instances. However; these materials present several drawbacks during use that scientists have tried to minimize in order to optimize their usage. This [...] Read more.
Natural-based and synthetic tissue adhesives have attracted extensive attention in the last two decades for their ability to stabilize uncontrolled bleeding instances. However; these materials present several drawbacks during use that scientists have tried to minimize in order to optimize their usage. This study comprises the development of a novel wound dressing, combining the excellent properties of polylactic acid (PLA) non-woven textile, as substrate, obtained through electrospinning, and a cyanoacrylate-based (CA) tissue adhesive, for rapid hemostatic action. Thus, the fabrication of electrospun PLA membranes at three different PLA concentrations, the design and manufacturing of the support system and the production of surgical patches were carried out. SEM and FT-IR methods were employed for analyzing the morphology as well as the indicative markers for the shelf life evolution of the obtained patches. PLA fibers with well-defined structures and a mean diameter varying between 4.6 and 7.24 μm were obtained with the increase of the concentration of the PLA solutions. In vivo tests on a rat model as well as peeling tests for good patch adhesion on liver fragments harvested from the test animals, with a limit for the strength of the liver tissue of 1.5 N, were carried out. The devices exhibited excellent adhesion to the parenchymal tissue and a long enough shelf life to be used with success in surgical procedures, also facilitating prompt hemostatic action. Full article
(This article belongs to the Special Issue Obtaining and Characterization of New Materials (5th Edition))
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29 pages, 9700 KiB  
Article
Evaluation of Rheological Properties of Asphalt Binder Modified with Biochar from Oat Hulls
by Camila Martinez-Toledo, Gonzalo Valdes-Vidal, Alejandra Calabi-Floody, María Eugenia Gonzalez and Oscar Reyes-Ortiz
Materials 2024, 17(17), 4312; https://doi.org/10.3390/ma17174312 - 30 Aug 2024
Viewed by 656
Abstract
In this study, the effect of biochar from oat hulls (BO) on the rheological properties of a PG 64-22 asphalt binder was evaluated using a full factorial design, which included the following factors: pyrolysis temperature (PT) (300 °C and 500 °C), BO particle [...] Read more.
In this study, the effect of biochar from oat hulls (BO) on the rheological properties of a PG 64-22 asphalt binder was evaluated using a full factorial design, which included the following factors: pyrolysis temperature (PT) (300 °C and 500 °C), BO particle size (<20 µm and <75 µm), and the amount of BO (2.5%, 5%, and 7.5%). First, the morphological and physicochemical properties of BO were analyzed by comparing it with graphite powder (CFG) and commercial activated carbon (CAC). The physicochemical properties of the modified asphalt binder were then evaluated using confocal laser microscopy, scanning electron microscopy (SEM–EDX), and Fourier-transform infrared spectroscopy (FTIR). Its storage stability was also evaluated. Subsequently, the rutting parameter G*/sin(δ) and the Fraass breaking point were analyzed to select asphalt binders that extended their viscoelastic range. The asphalt binders selected were those with 2.5%, 5%, and 7.5% BO, produced at a PT of 300 °C with a particle size <20 µm (BO300S). Next, the rheological properties of the selected samples were evaluated by testing for rotational viscosity, rutting parameter G*/sin(δ), multiple stress creep recovery (MSCR), fatigue parameter G*·sin(δ), and creep stiffness by bending beam rheometry (BBR). The rheological aging index according to rutting parameter G*/sin(δ) (RAI) was also evaluated. These tests were conducted in different states of the asphalt binder: original, short-term aged, and long-term aged. According to the results, the application of BO300S significantly increased the resistance of the asphalt binder to rutting and rotational viscosity, proportional to the amount added to the asphalt binder. Moreover, low modifier percentages improved fatigue resistance, outperforming CFG and CAC. In addition, it performs well at low service temperatures, registering better resistance than the control asphalt binders. Full article
(This article belongs to the Special Issue Obtaining and Characterization of New Materials (5th Edition))
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17 pages, 5227 KiB  
Article
Experimental Study on Preparation of Inorganic Fibers from Circulating Fluidized Bed Boilers Ash
by Qingjia Wang, Tuo Zhou, Zhiao Li, Yi Ding, Qiang Song, Man Zhang, Nan Hu and Hairui Yang
Materials 2024, 17(15), 3800; https://doi.org/10.3390/ma17153800 - 1 Aug 2024
Viewed by 517
Abstract
The ash generated by Circulating Fluidized Bed (CFB) boilers is featured by its looseness and porosity, low content of glassy substances, and high contents of calcium (Ca) and sulfur (S), thus resulting in a low comprehensive utilization rate. Currently, the predominant treatment approach [...] Read more.
The ash generated by Circulating Fluidized Bed (CFB) boilers is featured by its looseness and porosity, low content of glassy substances, and high contents of calcium (Ca) and sulfur (S), thus resulting in a low comprehensive utilization rate. Currently, the predominant treatment approach for CFB ash and slag is stacking, which may give rise to issues like environmental pollution. In this paper, CFB ash (with a CaO content of 7.64% and an SO3 content of 1.77%) was used as the main raw material. The high-temperature melting characteristics, viscosity–temperature characteristics, and initial crystallization temperature of samples with different acidity coefficients were investigated. The final drawing temperature range of the samples was determined, and mechanical property tests were conducted on the prepared inorganic fibers. The results show that the addition of dolomite powder has a significant reducing effect on the complete liquid phase temperature. The final drawing temperatures of the samples with different acidity coefficients range as follows: 1270–1318 °C; 1272–1351 °C; 1250–1372 °C; 1280–1380 °C; 1300–1382 °C; and 1310–1384 °C. The drawing temperature of this system is slightly lower than that of basalt fibers. Based on the test results of the mechanical properties of inorganic fibers, the Young’s modulus of the inorganic fibers prepared through the experiment lies between 55 GPa and 74 GPa, which basically meets the performance requirements of inorganic fibers. Consequently, the method of preparing inorganic fibers by using CFB ash and dolomite powder is entirely feasible. Full article
(This article belongs to the Special Issue Obtaining and Characterization of New Materials (5th Edition))
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17 pages, 19222 KiB  
Article
Characterisation of Fe Distribution in the Liquid–Solid Boundary of Al–Zn–Mg–Si Alloy Using Synchrotron X-ray Fluorescence Microscopy
by He Tian, Dongdong Qu, Nega Setargew, Daniel J. Parker, David J. Paterson, David StJohn and Kazuhiro Nogita
Materials 2024, 17(14), 3583; https://doi.org/10.3390/ma17143583 - 19 Jul 2024
Viewed by 664
Abstract
Al–Zn–Mg–Si alloy coatings have been developed to inhibit the corrosion of cold-rolled steel sheets by offering galvanic and barrier protection to the substrate steel. It is known that Fe deposited from the steel strip modifies the microstructure of the alloy. We cast samples [...] Read more.
Al–Zn–Mg–Si alloy coatings have been developed to inhibit the corrosion of cold-rolled steel sheets by offering galvanic and barrier protection to the substrate steel. It is known that Fe deposited from the steel strip modifies the microstructure of the alloy. We cast samples of Al–Zn–Mg–Si coating alloys containing 0.4 wt% Fe and directionally solidified them using a Bridgman furnace to quantify the effect of this Fe addition between 600 °C and 240 °C. By applying a temperature gradient, growth is encouraged, and by then quenching the sample in coolant, the microstructure may be frozen. These samples were analysed using scanning electron microscopy (SEM) and energy dispersive X-ray spectroscopy (EDS) to determine the morphological effects of the Fe distribution across the experimental temperature range. However, due to the sub 1 wt% concentration of Fe, synchrotron X-ray fluorescence microscopy (XFM) was applied to quantitatively confirm the Fe distribution. Directionally solidified samples were scanned at 7.05 keV and 18.5 keV using X-ray fluorescence at the Australian Synchrotron using the Maia array detector. It was found that a mass nucleation event of the Fe-based τ6 phase occurred at 495 °C following the nucleation of the primary α-Al phase as a result of a peritectic reaction with remaining liquid. Full article
(This article belongs to the Special Issue Obtaining and Characterization of New Materials (5th Edition))
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27 pages, 17029 KiB  
Article
Influence of the Addition of TiO2 Nanoparticles on the Self-Cleaning Capacity of Cementitious Composites
by Carmen Teodora Florean, Alexandra Csapai, Horatiu Vermesan, Timea Gabor, Andreea Hegyi, Vlad Stoian, Willi Andrei Uriciuc, Cristian Petcu and Marius Cîmpan
Materials 2024, 17(13), 3098; https://doi.org/10.3390/ma17133098 - 25 Jun 2024
Viewed by 3637
Abstract
This study evaluated the potential of incorporating TiO2 nanoparticles (NT) into cementitious composites to provide self-cleaning and self-sanitising properties, as well as the partial replacement of natural aggregates with recycled glass (RGA), ceramic brick (RBA), granulated blast furnace slag (GBA), and textolite [...] Read more.
This study evaluated the potential of incorporating TiO2 nanoparticles (NT) into cementitious composites to provide self-cleaning and self-sanitising properties, as well as the partial replacement of natural aggregates with recycled glass (RGA), ceramic brick (RBA), granulated blast furnace slag (GBA), and textolite waste (RTA) from electronic equipment on these properties. Based on the research results, the addition of NT to cementitious composites led to a significant reduction in contact angle, which means an increase in surface hydrophilicity. At the same time, Rhodamine B stain fading was highlighted, with the degree of whiteness recovery of NT composites exceeding that of the control by up to 11% for natural aggregate compositions, 10.6% for RGA compositions, 19.9% for RBA compositions, 15% for GBA compositions, and 13% for RTA compositions. In a mould-contaminated environment, it was shown that the introduction of NT allowed the material to develop a biocidal surface capacity which is also influenced by the nature of the aggregates used. Furthermore, the study revealed that, under controlled conditions, certain recycled waste aggregates, such as textolite, promoted mould growth, while others, such as brick and slag, inhibited it, highlighting not just the effect of the addition of NT, but also the significant influence of the aggregate type on the microbial resistance of cementitious composites. These improvements in the performance of cementitious composites are particularly advantageous when applied to prefabricated elements intended for the finishing and decorative surfaces of institutional (schools, administrative buildings, religious structures, etc.) or residential buildings. Full article
(This article belongs to the Special Issue Obtaining and Characterization of New Materials (5th Edition))
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14 pages, 1153 KiB  
Article
Structure of Polaronic Centers in Proton-Intercalated AWO4 Scheelite-Type Tungstates
by Georgijs Bakradze, Edmund Welter and Alexei Kuzmin
Materials 2024, 17(13), 3071; https://doi.org/10.3390/ma17133071 - 22 Jun 2024
Viewed by 918
Abstract
The studies of polaronic centers in a homologous series of scheelite-type compounds AWO4 (A = Ca, Sr, Ba) were performed using the W L3-edge and Sr K-edge X-ray absorption spectroscopy combined with the reverse Monte Carlo simulations, X-ray [...] Read more.
The studies of polaronic centers in a homologous series of scheelite-type compounds AWO4 (A = Ca, Sr, Ba) were performed using the W L3-edge and Sr K-edge X-ray absorption spectroscopy combined with the reverse Monte Carlo simulations, X-ray photoelectron spectroscopy (XPS), and first-principles calculations. Protonated scheelites HxAWO4 were produced using acid electrolytes in a one-step route at ambient conditions. The underlying mechanism behind this phenomenon can be ascribed to the intercalation of H+ into the crystal structure of tungstate, effectively resulting in the reduction of W6+ to W5+, i.e., the formation of polaronic centers, and giving rise to a characteristic dark blue-purple color. The emergence of the W5+ was confirmed by XPS experiments. The relaxation of the local atomic structure around the W5+ polaronic center was determined from the analysis of the extended X-ray absorption fine structures using the reverse Monte Carlo method. The results obtained suggest the displacement of the W5+ ions from the center of [W5+O4] tetrahedra in the structure of AWO4 scheelite-type tungstates. This finding was also supported by the results of the first-principles calculations. Full article
(This article belongs to the Special Issue Obtaining and Characterization of New Materials (5th Edition))
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28 pages, 4517 KiB  
Article
Mobility of Zn and Cu in Bentonites: Implications for Environmental Remediation
by Edyta Nartowska, Anna Podlasek, Magdalena Daria Vaverková, Eugeniusz Koda, Aleksandra Jakimiuk, Robert Kowalik and Tomasz Kozłowski
Materials 2024, 17(12), 2957; https://doi.org/10.3390/ma17122957 - 17 Jun 2024
Cited by 1 | Viewed by 972
Abstract
The aim of this study was to evaluate the mobility of copper (Cu) and zinc (Zn) and their impact on the properties of bentonites and unfrozen water content. Limited research in this area necessitates further analysis to prevent the negative effects of metal [...] Read more.
The aim of this study was to evaluate the mobility of copper (Cu) and zinc (Zn) and their impact on the properties of bentonites and unfrozen water content. Limited research in this area necessitates further analysis to prevent the negative effects of metal interactions on bentonite effectiveness. Tests involved American (SWy-3, Stx-1b) and Slovak (BSvk) bentonite samples with Zn or Cu ion exchange. Sequential extraction was performed using the Community Bureau of Reference (BCR) method. Elemental content was analyzed via inductively coupled plasma optical emission spectrometry (ICP-OES). Unfrozen water content was measured using nuclear magnetic resonance (1H-NMR) and differential scanning calorimetry (DSC). Results showed a significant influence of the main cation (Zn or Cu) on ion mobility, with toxic metal concentrations increasing mobility and decreasing residual fractions. Mobile Zn fractions increased with larger particle diameters, lower clay content, and shorter interplanar spacing, while the opposite was observed for Cu. Zn likely accumulated in larger clay pores, while Cu was immobilized in the bentonite complex. The stability of Zn or Cu ions increased with higher clay content or specific surface area. Residual Zn or Cu fractions were highest in uncontaminated bentonites with higher unfrozen water content, suggesting the potential formation of concentrated solutions in sub-zero temperatures, posing a threat to the clay–water environment, especially in cold regions. Full article
(This article belongs to the Special Issue Obtaining and Characterization of New Materials (5th Edition))
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15 pages, 5388 KiB  
Article
Additively-Manufactured Broadband Metamaterial-Based Luneburg Lens for Flexible Beam Scanning
by Xuanjing Li, Rui Feng, Quilin Tan, Jianjia Yi, Shixiong Wang, Feng He and Shah Nawaz Burokur
Materials 2024, 17(12), 2847; https://doi.org/10.3390/ma17122847 - 11 Jun 2024
Viewed by 706
Abstract
Multi-beam microwave antennas have attracted enormous attention owing to their wide range of applications in communication systems. Here, we propose a broadband metamaterial-based multi-beam Luneburg lens-antenna with low polarization sensitivity. The lens is constructed from additively manufactured spherical layers, where the effective permittivity [...] Read more.
Multi-beam microwave antennas have attracted enormous attention owing to their wide range of applications in communication systems. Here, we propose a broadband metamaterial-based multi-beam Luneburg lens-antenna with low polarization sensitivity. The lens is constructed from additively manufactured spherical layers, where the effective permittivity of the constituting elements is obtained by adjusting the ratio of dielectric material to air. Flexible microstrip patch antennas operating at different frequencies are used as primary feeds illuminating the lens to validate the radiation features of the lens-antenna system. The proposed Luneburg lens-antenna achieves ±72° beam scanning angle over a broad frequency range spanning from 2 GHz to 8 GHz and presents a gain between 15.3 dBi and 22 dBi, suggesting potential applications in microwave- and millimeter-wave mobile communications, radar detection and remote sensing. Full article
(This article belongs to the Special Issue Obtaining and Characterization of New Materials (5th Edition))
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12 pages, 2780 KiB  
Article
Vapor Pressure and Enthalpy of Vaporization of Guanidinium Methanesulfonate as a Phase Change Material for Thermal Energy Storage
by Wenrong Bi, Shijie Liu, Xing Rong, Guangjun Ma and Jiangshui Luo
Materials 2024, 17(11), 2582; https://doi.org/10.3390/ma17112582 - 27 May 2024
Cited by 1 | Viewed by 648
Abstract
This paper reports the vapor pressure and enthalpy of vaporization for a promising phase change material (PCM) guanidinium methanesulfonate ([Gdm][OMs]), which is a typical guanidinium organomonosulfonate that displays a lamellar crystalline architecture. [Gdm][OMs] was purified by recrystallization. The elemental analysis and infrared spectrum [...] Read more.
This paper reports the vapor pressure and enthalpy of vaporization for a promising phase change material (PCM) guanidinium methanesulfonate ([Gdm][OMs]), which is a typical guanidinium organomonosulfonate that displays a lamellar crystalline architecture. [Gdm][OMs] was purified by recrystallization. The elemental analysis and infrared spectrum of [Gdm][OMs] confirmed the purity and composition. Differential scanning calorimetry (DSC) also confirmed its high purity and showed a sharp and symmetrical endothermic melting peak with a melting point (Tm) of 207.6 °C and a specific latent heat of fusion of 183.0 J g−1. Thermogravimetric analysis (TGA) reveals its thermal stability over a wide temperature range, and yet three thermal events at higher temperatures of 351 °C, 447 °C, and 649 °C were associated with vaporization or decomposition. The vapor pressure was measured using the isothermogravimetric method from 220 °C to 300 °C. The Antoine equation was used to describe the temperature dependence of its vapor pressure, and the substance-dependent Antoine constants were obtained by non-linear regression. The enthalpy of vaporization (ΔvapH) was derived from the linear regression of the slopes associated with the linear temperature dependence of the rate of weight loss per unit area of vaporization. Hence, the temperature dependence of vapor pressures ln Pvap (Pa) = 10.99 − 344.58/(T (K) − 493.64) over the temperature range from 493.15 K to 573.15 K and the enthalpy of vaporization ΔvapH = 157.10 ± 20.10 kJ mol−1 at the arithmetic mean temperature of 240 °C were obtained from isothermogravimetric measurements using the Antoine equation and the Clausius–Clapeyron equation, respectively. The flammability test indicates that [Gdm][OMs] is non-flammable. Hence, [Gdm][OMs] enjoys very low volatility, high enthalpy of vaporization, and non-flammability in addition to its known advantages. This work thus offers data support, methodologies, and insights for the application of [Gdm][OMs] and other organic salts as PCMs in thermal energy storage and beyond. Full article
(This article belongs to the Special Issue Obtaining and Characterization of New Materials (5th Edition))
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24 pages, 33760 KiB  
Article
Effect of the Axial Profile of a Ceramic Grinding Wheel on Selected Roughness Parameters of Shaped Surfaces Obtained in the Grinding Process with a Dual-Tool Grinding Head
by Piotr Jaskólski, Marzena Sutowska, Wojciech Zawadka, Winfried Malorny, Krzysztof Rokosz and Krzysztof Nadolny
Materials 2024, 17(10), 2434; https://doi.org/10.3390/ma17102434 - 18 May 2024
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Abstract
The use of CNC equipment that integrates several machining operations eliminates downtime due to changes in setup and clamping of workpieces in more than one machining device. A review of CNC equipment and tools known from the literature and from manufacturers’ offerings indicates [...] Read more.
The use of CNC equipment that integrates several machining operations eliminates downtime due to changes in setup and clamping of workpieces in more than one machining device. A review of CNC equipment and tools known from the literature and from manufacturers’ offerings indicates that new technical solutions are being developed to integrate two or more technological operations. However, these examples have numerous limitations and are mostly not suitable for machining surfaces with complex shapes. An example of such solutions is the use of a dual-tool grinding head, which integrates the process of rough grinding with a ceramic grinding wheel and finish grinding with a flexible grinding wheel. Unfortunately, it has the disadvantage of being limited by the angular shape of the ceramic grinding wheel, making it unable to adapt to the complex geometries of the shaped surfaces being ground. The need to overcome this limitation became the motivation for the research work described in this article. By means of experimental research, it was verified what effect the radial outline on the periphery of a ceramic grinding wheel realized by rough grinding would have on the surface roughness parameters obtained in the process of grinding shaped surfaces. For this purpose, grinding processes using a ceramic wheel with a conical and radial outline were compared. The result of the study was a summary of the surface roughness parameters Sa, St, Sq, Spk, Str, and Sds obtained after two-stage machining (rough and finish grinding). The obtained analysis results showed that changing the axial outline of the ceramic grinding wheel makes it possible to significantly expand the range of applications of the dual-tool head without negatively affecting the quality of the machined surface. Thus, such an improvement will make it possible to increase the applicability of the head by grinding shaped surfaces with a radial profile of curvature. Full article
(This article belongs to the Special Issue Obtaining and Characterization of New Materials (5th Edition))
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19 pages, 13822 KiB  
Article
Two 3D Fractal-Based Approaches for Topographical Characterization: Richardson Patchwork versus Sdr
by François Berkmans, Julie Lemesle, Robin Guibert, Michał Wieczorowski, Christopher Brown and Maxence Bigerelle
Materials 2024, 17(10), 2386; https://doi.org/10.3390/ma17102386 - 16 May 2024
Viewed by 614
Abstract
Various methods exist for multiscale characterization of surface topographies, each offering unique insights and applications. The study focuses on fractal-based approaches, distinguishing themselves by leveraging fractals to analyze surface complexity. Specifically, the Richardson Patchwork method, used in the ASME B46.1 and ISO 25178 [...] Read more.
Various methods exist for multiscale characterization of surface topographies, each offering unique insights and applications. The study focuses on fractal-based approaches, distinguishing themselves by leveraging fractals to analyze surface complexity. Specifically, the Richardson Patchwork method, used in the ASME B46.1 and ISO 25178 standards, is compared to the Sdr parameter derived from ISO 25178-2, with a low-pass Gaussian filter for multiscale characterization. The comparison is performed from the relative area calculated on topographies of TA6V samples grit blasted with different pressures and blasting materials (media). The surfaces obtained by grit blasting have fractal-like characteristics over the scales studied, enabling the analysis of area development at multiple levels based on pressure and media. The relative area is similar for both methods, regardless of the complexity of the topographies. The relevance scale for each calculation method that significantly represents the effect of grit blasting pressure on the increased value of the relative area is a tiling of 7657.64 µm² of triangle area for the Patchwork method and a 124.6 µm cut-off for the low-pass Gaussian filter of the Sdr method. These results could facilitate a standard, friendly, new fractal method for multiscale characterization of the relative area. Full article
(This article belongs to the Special Issue Obtaining and Characterization of New Materials (5th Edition))
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