Materials

22 pages, 10893 KB

Open AccessArticle

Direct Measurement of Energy Dissipation in Nanoscale Tribomechanical Interfaces: Dissipative Transfer Steady State

by Dinh Dat Pham, Yuichi Otsuka and Yukio Miyashita

Materials 2026, 19(11), 2258; https://doi.org/10.3390/ma19112258 - 26 May 2026

This study examines the development of a steady state in the cyclic wear process for various combinations of metallic and inorganic materials. Energy dissipation is widely acknowledged as a significant parameter in wear mechanisms. However, at the nanoscale, the linear correlation between energy [...] Read more.

This study examines the development of a steady state in the cyclic wear process for various combinations of metallic and inorganic materials. Energy dissipation is widely acknowledged as a significant parameter in wear mechanisms. However, at the nanoscale, the linear correlation between energy dissipation and wear progression is not consistently applicable. In this study, experimental observations of cyclic wear between scanning probe microscopy (SPM) cantilevers and substrate displacement were conducted. Substrate vibrations were monitored using a laser Doppler vibrometer, which facilitated the direct estimation of energy dissipation at nanocontacts during cyclic loading. The wear rates of the substrates decreased with an increase in the number of cyclic loadings, indicating the formation of a transfer steady state at the interface. Symmetric contact mode, based on the viscoelastic behavior of the contact, and asymmetric mode, based on adhesion between the interfaces, are commonly observed. The asymmetric mode evolved in the later stages of cyclic wear, suggesting the transfer of the steady state between the interfaces. A linear relationship between energy dissipation and wear rates was still observed for metallic substrates, whereas a steady state was observed for inorganic materials. This difference can be attributed to material exchange at the interfaces. Full article

(This article belongs to the Special Issue Corrosion and Materials in Interacting Systems)

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41 pages, 5788 KB

Open AccessArticle

Gas Permeability of the Anisotropic Structure of a Frame Made of Concrete with the Addition of a Biocomponent—Application in Livestock Buildings

by Elżbieta Janowska-Renkas, Dariusz Fabianowski, Igor Klementowski, Kinga Borek, Adam Koniuszy and Grzegorz Wałowski

Materials 2026, 19(11), 2257; https://doi.org/10.3390/ma19112257 - 26 May 2026

Abstract

The paper presents the results of experimental studies aimed at assessing thermal conductivity, compressive strength, water absorption and capillary action of samples in the form of ordinary concrete (reference sample—B1) and lightweight concrete with the addition of a biocomponent (C100) in the range [...] Read more.

The paper presents the results of experimental studies aimed at assessing thermal conductivity, compressive strength, water absorption and capillary action of samples in the form of ordinary concrete (reference sample—B1) and lightweight concrete with the addition of a biocomponent (C100) in the range of 3–31.2% porosity with varied morphology. Gas permeability studies were conducted for porous materials with an anisotropic structure. The measurement results indicate a significant effect of the type of material on thermal conductivity for B1, which is 3.05 W·(m·K)⁻¹ and C100 equal to 0.09 W·(m·K)⁻¹. On the other hand, the highest water absorption is demonstrated by C100, which is 99%, and the lowest by B1 equal to 2%. Tests were conducted for different gas permeability conditions using oxygen (O₂), nitrogen (N₂) and carbon dioxide (CO₂). The basis for assessing gas permeability through porous beds is the gas flow resulting from the overpressure forcing this flow. The highest gas permeability coefficient at a flow resistance of 6 kPa for B1 was 2.7·10⁻⁷ m², and for C100, 2.1·10⁻⁷ m² at CO₂ flow. The following issues were identified: scientific, identifying the lack of research on gas permeability testing for anisotropic concrete structures; application, identifying reports of premature failure of concrete structures in livestock buildings due to the effects of toxic substances. The novelty in the article is the indication of the gas permeability model and the performance of a comparative analysis (multi-criteria analysis) based on diagnostic features. In the hierarchical decision-making structure, gas permeability was used as one of the evaluation criteria, which can be assessed as a stimulant or destimulant depending on the climatic zone. The permeability of gas media is one of the features that allow for assessing the suitability of materials, among others, for small-sized prefabricated wall systems—the durability of both the element itself and any reinforcing inserts depends on permeability. The aim of this article was to compare the physical and functional properties of materials, such as thermal conductivity, water absorption, capillarity and gas permeability, in relation to the material composition. The research was of an application and engineering nature, focusing on macroscale functional parameters that are important from the point of view of the practical application of the tested building composites. The scientific problem is to indicate the lack of scientific research on the study of gas permeability in anisotropic concrete structures in livestock building conditions. The engineering use of hempcrete indicates its usefulness in various structural elements of livestock buildings. Full article

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

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19 pages, 5618 KB

Open AccessArticle

Effect of Sandblasting Pressure Combined with Acid Pickling on the Microstructure and Surface Properties of Ti-6Al-4V Alloy

by Yuanyuan Xie and Lei Li

Materials 2026, 19(11), 2256; https://doi.org/10.3390/ma19112256 - 26 May 2026

Abstract

Titanium alloys are widely used in aerospace, marine engineering, and biomedical fields owing to their excellent specific strength, corrosion resistance, and biocompatibility. As an important surface modification technique, sandblasting combined with acid pickling can not only eliminate the machining defects in Ti-6Al-4V but [...] Read more.

Titanium alloys are widely used in aerospace, marine engineering, and biomedical fields owing to their excellent specific strength, corrosion resistance, and biocompatibility. As an important surface modification technique, sandblasting combined with acid pickling can not only eliminate the machining defects in Ti-6Al-4V but also improve its surface morphology, thereby playing a crucial role in enhancing its service performance. By employing advanced characterization equipment, including scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDS), a 3D profilometer, and a friction and wear tester, combined with wetting theoretical models and morphological evolution analysis, this study systematically investigated the comprehensive effects of different pressure sandblasting followed by acid pickling on the surface microstructure, wetting behavior, and tribological properties of forged Ti-6Al-4V alloy. The results indicated that the combined application of sandblasting and acid pickling exerted a significant regulatory effect on the surface and interface characteristics of the Ti-6Al-4V alloy. After the combined sandblasting and acid pickling treatment, a distinct micro-pit network structure was formed on the surface of the Ti-6Al-4V alloy, and its hydrophilicity and roughness showed a positive correlation with the increase in sandblasting pressure. Notably, the microstructural evolution exhibited a high degree of internal consistency with the macroscopic wear resistance: the hierarchical micro-pit network exposed after acid pickling exerted an excellent “debris capture” effect, thereby suppressing the severe third-body abrasive wear observed in the solely sandblasted state. This study aims to enhance the surface roughness, wear resistance, and hydrophilicity of the Ti-6Al-4V alloy, providing a cost-effective and industrially applicable method for the surface texturing of titanium alloys. Full article

(This article belongs to the Section Metals and Alloys)

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20 pages, 1463 KB

Open AccessArticle

Corrosion Behavior and Deterioration Mechanism of Ecological Concrete in Deep Water Environment

by Hua Wei, Kang Wang, Chunhe Li, Anyi Chen and Hao Lu

Materials 2026, 19(11), 2255; https://doi.org/10.3390/ma19112255 - 26 May 2026

Abstract

To elucidate the corrosion behavior of cracked reinforced concrete under pressurized permeation at 0.3 MPa, three exposure conditions were established, namely a low-concentration chloride-sulfate solution, a high-concentration chloride-magnesium sulfate solution, and a high-concentration chloride-magnesium sulfate-carbonate composite solution, and cyclic permeation tests were conducted. [...] Read more.

To elucidate the corrosion behavior of cracked reinforced concrete under pressurized permeation at 0.3 MPa, three exposure conditions were established, namely a low-concentration chloride-sulfate solution, a high-concentration chloride-magnesium sulfate solution, and a high-concentration chloride-magnesium sulfate-carbonate composite solution, and cyclic permeation tests were conducted. Based on the chloride ion (Cl⁻) content distribution, permeation behavior, and steel half-cell potential measurements, together with XRD and SEM microstructural analyses, the results showed that Cl⁻ transport was significantly enhanced. At a depth of 15 mm, the Cl⁻ content increased from 0.011% under unpressurized conditions to 0.211% at 90 d and further to 0.322% at 365 d, while it remained close to zero at depths of 35 mm and below. Under the low-concentration condition, permeation ceased after about 3 months, and the half-cell potential recovered from −550 to −580 at 46 d and stabilized at −250 to −340 in the later stage, indicating a certain self-healing capacity of the cracks. Under the high-concentration and composite conditions, permeation persisted throughout the 12-month period, and the half-cell potential dropped to −800 to −900 at 34–40 d and remained at −580 to −840 in the later stage, indicating that the steel remained in an active corrosion state for a long time. XRD and SEM results further showed that corrosion products such as AFt increased, and the internal concrete structure gradually deteriorated. Full article

(This article belongs to the Section Green Materials)

21 pages, 9332 KB

Open AccessArticle

Effect of Luanbai Glaze on the Coloration of Cobalt Pigment in Yuan Dynasty Jingdezhen Porcelains: An Experimental Study

by Jun Sun, Qijiang Li, Xiaoyan Xia, Min Tang, Yan Liang and Linxin Ouyang

Materials 2026, 19(11), 2254; https://doi.org/10.3390/ma19112254 - 26 May 2026

Abstract

This study investigates whether Yuan Dynasty Jingdezhen Luanbai glaze can support cobalt-blue coloration under conditions relevant to early blue-and-white porcelain production. Comparative analyses of archaeological Luanbai and blue-and-white specimens show that the two glaze types have similar average thicknesses, approximately 0.20 mm, and [...] Read more.

This study investigates whether Yuan Dynasty Jingdezhen Luanbai glaze can support cobalt-blue coloration under conditions relevant to early blue-and-white porcelain production. Comparative analyses of archaeological Luanbai and blue-and-white specimens show that the two glaze types have similar average thicknesses, approximately 0.20 mm, and comparable basic chemical compositions, especially in their SiO₂ and Al₂O₃ contents. These results suggest that they belong to related high-temperature calcium–alkali glaze traditions rather than completely isolated technological systems. Simulated firing experiments using five cobalt pigments of different compositions further indicate that Luanbai glaze can support cobalt-blue coloration at 1300 °C in a reducing atmosphere. Compared with unglazed controls, Luanbai-glazed samples showed a more consistent blue appearance and clearer pigment–glaze interaction. XPS and SEM-EDS line-scan analyses revealed differences in the near-surface chemical environment and cross-sectional distribution of Co, Mn, and Fe between glazed and unglazed samples, supporting the role of glaze coverage in color development. Refiring experiments on authentic Yuan sherds further supported the feasibility of cobalt-blue coloration on historical Luanbai glaze surfaces. Overall, the results suggest that the opalescent appearance of Luanbai glaze is not an inherent barrier to underglaze cobalt decoration. This work provides experimental evidence for reassessing the technological relationship between Luanbai and early blue-and-white porcelain. Full article

(This article belongs to the Section Advanced and Functional Ceramics and Glasses)

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20 pages, 13372 KB

Open AccessArticle

Comparative Study of Wear Behavior of Hypereutectic Al–Si Piston Alloys Using Experimental and Numerical Methods

by Atanasi Tashev, Valyo Nikolov, Boyan Dochev, Desislava Dimova, Mara Kandeva and Mihail Zagorski

Materials 2026, 19(11), 2253; https://doi.org/10.3390/ma19112253 - 26 May 2026

Abstract

This study presents an integrated experimental–numerical approach for evaluating the wear behavior of three non-standardized hypereutectic aluminum–silicon (Al–Si) piston alloys based on the AlSi25CuCr system, namely AlSi25Cu4Cr (M1), AlSi25Cu5Cr (M3), and AlSi25Cu5Cr (M5). The wear coefficient was determined experimentally under boundary-lubrication conditions, while [...] Read more.

This study presents an integrated experimental–numerical approach for evaluating the wear behavior of three non-standardized hypereutectic aluminum–silicon (Al–Si) piston alloys based on the AlSi25CuCr system, namely AlSi25Cu4Cr (M1), AlSi25Cu5Cr (M3), and AlSi25Cu5Cr (M5). The wear coefficient was determined experimentally under boundary-lubrication conditions, while the contact conditions in the piston–cylinder system were evaluated using Finite Element Analysis (FEA) and implemented within the Archard wear model. The results reveal a pronounced inconsistency between hardness and wear resistance. Although hardness increases from 1363 MPa (M1) to 1677 MPa (M5), the corresponding wear depth increases from 13.94 nm to 27.61 nm per engine cycle. This behavior is attributed to differences in microstructural characteristics, particularly the morphology and distribution of silicon particles and intermetallic phases, which significantly influence the tribological performance of hypereutectic Al–Si alloys. The experimentally determined wear coefficient K also shows a significant increase, rising from 12.14 × 10⁻⁵ (M1) to 29.59 × 10⁻⁵ (M5). The lowest wear is observed for alloy M1, whereas M5 exhibits the poorest tribological performance. These findings demonstrate that microstructural characteristics, particularly the morphology and distribution of silicon particles and intermetallic phases, have a dominant influence over hardness in governing wear behavior. The main scientific contribution lies in the direct coupling of experimentally determined material properties with realistically simulated contact conditions, enabling a quantitative and physically consistent comparison of piston alloys under identical operating regimes. The proposed methodology provides a reliable framework for material selection and optimization of piston alloys with enhanced wear resistance. Full article

(This article belongs to the Special Issue High-Strength Lightweight Alloys: Innovations and Advancements)

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27 pages, 3031 KB

Open AccessArticle

Recovery and Purification of Lithium Hydroxide from Spent Cathode Crucibles via Sulfation and Conversion Processes

by Jin-Seong Yoon, H. Y. Sohn and Jei-Pil Wang

Materials 2026, 19(11), 2252; https://doi.org/10.3390/ma19112252 - 26 May 2026

Abstract

This study presents an integrated process for the recovery and purification of lithium hydroxide (LiOH) from lithium sulfate (Li₂SO₄) solution obtained by sulfuric acid leaching of spent crucibles used for producing the cathodes of LIBs. The recovered leachate contains [...] Read more.

This study presents an integrated process for the recovery and purification of lithium hydroxide (LiOH) from lithium sulfate (Li₂SO₄) solution obtained by sulfuric acid leaching of spent crucibles used for producing the cathodes of LIBs. The recovered leachate contains considerable concentrations of metallic impurities, including Na, K, Mg, Ca, Al, and Ni, which hinder the direct production of high-purity LiOH. To overcome this limitation, a pretreatment step combining cation- and anion-exchange resins was introduced to control impurity levels and condition the solution prior to conversion. Under the optimized ion-exchange condition of 10 g cation-exchange resin and 50 g anion-exchange resin, the solution pH was adjusted to 6–7, resulting in effective impurity removal through combined ion-exchange and solution-conditioning effects. More than 90% of Al was removed, while Mg, Ca, Na, K, and Ni were removed by approximately 70–75%. After purification, LiOH was produced through a double-displacement conversion reaction using Ba(OH)₂. The results showed that the reaction temperature and the [OH]:[Li] molar ratio were the key parameters governing the sulfate-removal-based apparent conversion efficiency and filtrate-based LiOH purity. Excess OH⁻ promoted the formation of dissolved and complexed species, thereby lowering the purity of the LiOH-containing filtrate. In contrast, the optimum condition was identified at 70 °C and an [OH]:[Li] molar ratio of 1:1, under which SO₄²⁻ was effectively removed as solid BaSO₄. Under these conditions, the sulfate-removal-based apparent conversion efficiency reached 91.91%, and the filtrate-based LiOH purity was 98.84%. X-ray diffraction analysis confirmed the coexistence of LiOH·H₂O and LiOH phases in the final recovered product, whereas the precipitate was identified as single-phase BaSO₄, indicating effective sulfate removal. Overall, this study demonstrates the feasibility of producing high-purity LiOH from sulfation-derived Li₂SO₄ leachate through a sequential process consisting of impurity removal, conversion, and drying. The findings provide fundamental process data for the design of lithium recovery and purification routes using spent cathode crucibles as secondary lithium resources. Full article

(This article belongs to the Special Issue Technology in Lithium-Ion Batteries: Prospects and Challenges)

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16 pages, 8675 KB

Open AccessArticle

A Model for Comprehensive Material Degradation and Strength Characteristics Assessment of Historic Masonry Structures

by Czesław Miedziałowski, Romuald Szeląg and Adam Walendziuk

Materials 2026, 19(11), 2250; https://doi.org/10.3390/ma19112250 - 26 May 2026

Abstract

Historic buildings are susceptible to damage resulting from material degradation, deterioration of structural properties, changes in loads, overloading, and extraordinary events, which manifest as defects and flaws. These structures are also modernised, rebuilt, and adapted to new functions. In some cases, a rapid [...] Read more.

Historic buildings are susceptible to damage resulting from material degradation, deterioration of structural properties, changes in loads, overloading, and extraordinary events, which manifest as defects and flaws. These structures are also modernised, rebuilt, and adapted to new functions. In some cases, a rapid assessment of the structural condition is necessary. In practice, it is essential to maintain the safety of structures and their components, which is achieved by conducting an inventory and assessing the technical condition of structural elements and built-in materials. A numerical model was developed using macro-elements, and the practical applications of this model in strength analyses of degraded materials and sections of masonry structures are presented herein. The proposed approach was generalised and extended to include a classification of damaged masonry structures, which can be helpful and applied in indexing and searching databases of building structures, as well as in AI-assisted automatic pattern recognition. This resulted in a coherent and comprehensive approach to assessing the technical and structural condition of historic masonry buildings in use, as well as those undergoing repair, reconstruction, and modernisation. Full article

(This article belongs to the Special Issue Testing of Materials and Elements in Civil Engineering (4th Edition))

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20 pages, 4267 KB

Open AccessArticle

Effect of Steel Slag Content on the Performance and Hydration Mechanism of Phosphogypsum–Steel Slag–Fly Ash All-Solid-Waste Binders

by Di Liu, Yazhou Wang, Binbin Zhang and Yu Ma

Materials 2026, 19(11), 2249; https://doi.org/10.3390/ma19112249 - 26 May 2026

Abstract

To promote the synergistic utilization of phosphogypsum (PG), steel slag (SS), and fly ash (FA), a ternary all-solid-waste binder, namely PG-SS-FA cementitious material (PSA), was prepared. The effects of SS content on workability, setting behavior, mechanical properties, hydration products, pore structure, and microstructure [...] Read more.

To promote the synergistic utilization of phosphogypsum (PG), steel slag (SS), and fly ash (FA), a ternary all-solid-waste binder, namely PG-SS-FA cementitious material (PSA), was prepared. The effects of SS content on workability, setting behavior, mechanical properties, hydration products, pore structure, and microstructure were systematically investigated. The results showed that increasing SS content continuously reduced the fluidity of PSA, while the setting time first shortened and then increased. The fastest setting was observed at 40% SS, with initial and final setting times of 126 and 321 min, respectively. Increasing SS from 20% to 40% enhanced the hydration reaction, promoted the formation of AFt and C-(A)-S-H gel, reduced residual unreacted phases, and refined the pore structure, resulting in the highest compressive and flexural strengths for M40. However, further increasing SS to 60% and 80% reduced the fly ash proportion and limited the sustained supply of reactive Si/Al species, despite increasing Ca²⁺ availability and alkalinity, thereby restricting later-age gel accumulation and pore refinement and ultimately weakening mechanical performance. Overall, the performance evolution of PSA is governed by the coupled effects of alkali/Ca supply from SS, sulfate supply from PG, and reactive Si/Al supply from FA. The optimal performance at 40% SS is attributed to the synergistic construction of an AFt framework and continuous pore filling by C-(A)-S-H gel. Full article

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

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14 pages, 1957 KB

Open AccessArticle

Polarity-Dependent EDM-Type Degradation in Rolling Bearings Under Low-Speed Unipolar Excitation

by Zifan Li, Ran Cai, Tianyi Zhang and Xueyuan Nie

Materials 2026, 19(11), 2248; https://doi.org/10.3390/ma19112248 - 26 May 2026

Abstract

Bearings in electric motors are exposed to stray currents and shaft voltages, which can accelerate surface damage and reduce service life. This study examines how pulsed direct current (DC) direction affects early-stage degradation in rolling bearings under low-speed operation. A dedicated test rig [...] Read more.

Bearings in electric motors are exposed to stray currents and shaft voltages, which can accelerate surface damage and reduce service life. This study examines how pulsed direct current (DC) direction affects early-stage degradation in rolling bearings under low-speed operation. A dedicated test rig was used in which the bearing inner and outer rings were connected directly to the positive and negative terminals of a pulsed DC power supply. Unipolar excitation was applied at 20 kHz with a nominal current of 3 A and shaft-voltage peaks of about 3 V for 3 h, with current flowing in only one direction during each test. After testing, the bearings were sectioned and examined by optical microscopy, scanning electron microscopy (SEM), and X-ray photoelectron spectroscopy (XPS). The results showed that when current flowed from the outer ring to the inner ring, visible electrical discharge machining (EDM)-type damage was mainly found on the outer raceway. When the current direction was reversed, the damaged region shifted to the inner raceway. The affected areas showed crater-like discharge features and surface chemical changes, while the opposite raceway showed much less change under the same test conditions. These observations indicate that current direction influences where EDM-type damage more likely forms in the bearing under the present low-speed unipolar excitation conditions. Full article

(This article belongs to the Special Issue Alloy Strengthening Mechanisms, Microstructure Control and Performance Optimization (Second Edition))

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33 pages, 29002 KB

Open AccessArticle

Effect of Water–Solid Ratio on the Performance, Microstructure Evolution, and Low-Carbon Characteristics of Multi-Solid-Waste-Based Flowable Stabilized Soil

by Jiaojiao Ni, Qing Jiang, Qiwei Zhan, Haitao Hu and Yongqi Zhao

Materials 2026, 19(11), 2247; https://doi.org/10.3390/ma19112247 - 26 May 2026

Abstract

To promote the high-value utilization of industrial solid wastes and address the disposal of excavated soils, a novel low-carbon composite cementitious material, solid waste-based geopolymer cement (SGPC), was developed, consisting of soda residue (SR), granulated blast furnace slag (GGBS), phosphogypsum (PG), and ordinary [...] Read more.

To promote the high-value utilization of industrial solid wastes and address the disposal of excavated soils, a novel low-carbon composite cementitious material, solid waste-based geopolymer cement (SGPC), was developed, consisting of soda residue (SR), granulated blast furnace slag (GGBS), phosphogypsum (PG), and ordinary Portland cement (PC) in a mass ratio of 10:81:9:25, with industrial solid wastes accounting for 80% of the binder. The effects of water-to-solid ratio (W/S = 0.41–0.49) on the workability, mechanical performance, and microstructural evolution of SGPC-stabilized soil were systematically investigated to provide a sustainable alternative to conventional cement-based stabilizers. The results indicate that the optimum water-to-solid ratio is 0.43 (SGPC43), with a 28-day unconfined compressive strength of 1450 kPa, exceeding the engineering requirement of 0.8 MPa and reaching over 85% of that of a pure cement system (C43). The flowability remained 163 mm after 60 min, with initial and final setting times of 43 h and 58 h, respectively. Microstructural analysis revealed that the alkalinity provided by soda residue promotes the hydration of slag and phosphogypsum, forming interwoven calcium (alumino) silicate hydrate (C–(A)–S–H) and ettringite (AFt), which fill pores and form a dense structure, thereby enhancing mechanical performance. Environmental and economic assessments show that the CO₂ emission of SGPC43 per ton of binder decreases from 930 kg CO₂-e/t to 235 kg CO₂-e/t (approximately 74.7% reduction), while the material cost decreases from 110 USD/t to 53 USD/t (approximately 51.8% reduction). A simplified uncertainty analysis indicates that the carbon reduction remains at 70% ± 5% and the cost reduction at 50% ± 5%, confirming the robustness of the results. Overall, SGPC43 demonstrates excellent engineering performance, environmental benefits, and economic feasibility, highlighting its potential as a low-carbon and sustainable stabilizing material. Full article

(This article belongs to the Special Issue Sustainability and Performance of Cement-Based Materials)

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14 pages, 1719 KB

Open AccessArticle

Debonding Behavior of Resin-Cemented Attachment-Housing Denture-Base Complexes Under Cyclic Mechanical Loading

by Evangelos V. Skondras, Savvas N. Kamalakidis, Eftychia Skondra, Antonios Bouzakis, Lambrini Papadopoulou, Eleana Kontonasaki and Olga Naka

Materials 2026, 19(11), 2246; https://doi.org/10.3390/ma19112246 - 26 May 2026

Abstract

Implant-supported overdentures improve denture retention and patient satisfaction, but debonding of attachment housings from the denture base remains a frequent prosthetic complication. This in vitro study evaluated the influence of attachment-housing and denture-base materials on debonding occurrence and maximum tensile force in resin-cemented [...] Read more.

Implant-supported overdentures improve denture retention and patient satisfaction, but debonding of attachment housings from the denture base remains a frequent prosthetic complication. This in vitro study evaluated the influence of attachment-housing and denture-base materials on debonding occurrence and maximum tensile force in resin-cemented attachment housing denture-base complexes subjected to cyclic mechanical loading. Thirty standardized specimens were digitally designed and fabricated from three denture-base materials—polymethylmethacrylate (PMMA) (n = 12), polyetheretherketone (PEEK) (n = 12), and cobalt-chromium (Co-Cr) (n = 6)—and combined with either titanium or PEEK attachment housings, which were bonded with a dual-polymerized resin cement. The specimens were subjected to 1100 cycles of alternating tensile and compressive loading, and debonding occurrence and maximum tensile force were recorded. Debonding occurred in 60% of the specimens and differed significantly among denture base materials. No debond-ing was observed in the Co-Cr specimens, whereas debonding occurred in 75% of the PMMA and PEEK specimens. The Co-Cr specimens also demonstrated significantly higher maximum tensile force values than the PMMA and PEEK groups, while regarding the attachment-housing material, no significant main effect was detected. Within the limitations of this in vitro study, the denture-base material, fabrication, and surface treatment combinations significantly influenced debonding and tensile force during cyclic loading, whereas the attachment-housing material did not demonstrate a significant main effect. Full article

(This article belongs to the Special Issue Advanced Biomaterials for Dental Applications (2nd Edition))

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20 pages, 5798 KB

Open AccessArticle

Design Analysis for Controlling Spray Particle Size of Ultrasonic Nozzles Using Piezoelectric Ceramic Vibrators

by Su-Ho Lee, Sunghyun Lim, Myeong-Gwang Choi, Jae-Eun Hwang and Herie Park

Materials 2026, 19(11), 2245; https://doi.org/10.3390/ma19112245 - 26 May 2026

Abstract

This study aims to demonstrate the feasibility of controlling particle size through a mathematical model in the design of industrially applicable ultrasonic spray nozzles by utilizing the vibrational characteristics of piezoelectric ceramics. A piezoelectric ceramic composition with a low sintering temperature and excellent [...] Read more.

This study aims to demonstrate the feasibility of controlling particle size through a mathematical model in the design of industrially applicable ultrasonic spray nozzles by utilizing the vibrational characteristics of piezoelectric ceramics. A piezoelectric ceramic composition with a low sintering temperature and excellent thermal stability (Curie temperature above 300 °C) was developed and used as a ceramic vibrator. Furthermore, the resonance frequency and nozzle displacement were calculated using the COMSOL program and applied to a mathematical model to design an ultrasonic nozzle capable of producing a spray particle diameter of approximately 30 μm. The designed ultrasonic nozzle was fabricated, and its spray characteristics were analyzed. The consistency of the spray characteristics was examined by comparing them with the mathematical model based on changes in ultrasonic nozzle length, resonance frequency, and fluid viscosity. When the ultrasonic nozzle horn length was 22 mm, the resonance frequency was found to be 42.1 kHz, and at a flow rate of 65 mL/min. the average spray particle size was approximately 30–40 μm, indicating fine and uniform particles. In addition, it can be seen that as the length of the nozzle horn increases, the resonance frequency decreases, reducing the supply energy delivered to the liquid, and the particle size increases as shown in the mathematical analysis. The theoretical separation energy required to atomize pure water at a flow rate of 65 mL/min. is 2100 J, which was found to be greater than all energy loss occurring during the atomization process. However, it can be seen that as the length of the ultrasonic nozzle increases, the maximum atomization volume increases, and as viscosity increases, the energy required to separate a single atomized particle becomes greater. Full article

(This article belongs to the Special Issue Piezoelectric, Ferroelectric and Dielectric Materials: Characterization, Properties and Emerging Applications)

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24 pages, 5986 KB

Open AccessArticle

Multi-Scale Quality Evaluation of Road Markings from Glass Bead Distribution: A Novel GSMTA Framework

by Xiaosong Lu, Haoqin Guo, Rui He, Hao Wu, Liangliang Li and Jianrong Hu

Materials 2026, 19(11), 2244; https://doi.org/10.3390/ma19112244 - 26 May 2026

Abstract

Road markings constitute essential traffic control elements that ensure safety and traffic flow efficiency. The nighttime visibility of road markings, quantified through retroreflective luminance (R_L), is fundamentally governed by the distribution characteristics of embedded glass beads (GBs) within the marking [...] Read more.

Road markings constitute essential traffic control elements that ensure safety and traffic flow efficiency. The nighttime visibility of road markings, quantified through retroreflective luminance (R_L), is fundamentally governed by the distribution characteristics of embedded glass beads (GBs) within the marking matrix. Yet, three persistent limitations hinder reliable GB distribution evaluation: measurement variability, oversimplified model assumptions (fixed 50% embedment depth vs. observed 50–60% variations), and fragmented correlations between GB morphology and R_L metrics. This study proposes a granulometric–spatial–morphological triad assessment (GSMTA) framework, integrating instance segmentation with hierarchical performance analytics. The GSMTA framework achieves 15% higher segmentation accuracy over Otsu/Fast Random Forest methods, quantifying GB distribution via granulometric (size gradation), spatial (homogeneity index), and morphological (shape factor) descriptors. Through principal component analysis, the derived L³D performance indices establish statistically robust retroreflective luminance (R_L) prediction models, with PC1 and PC2 capturing 91.7% of the variance and validation errors. The model remained below 8% error across a 750 mcd·m⁻²·lx⁻¹ R_L range, ensuring reliable and precise performance evaluation. Field validation demonstrates the framework’s capacity of transforming pixel-level segmentation data into practical quality control metrics. This advancement supports lifecycle management through standardized GB distribution evaluation, overcoming prior incompatibility issues between microscopic morphology analysis and macroscale R_L measurements. Full article

(This article belongs to the Special Issue Emerging Technologies and Materials for Smart, Durable and Sustainable Construction)

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5 pages, 163 KB

Open AccessEditorial

New Cementitious Materials: Advances, Challenges, and Future Perspectives

by Mohammad Saberian

Materials 2026, 19(11), 2243; https://doi.org/10.3390/ma19112243 - 26 May 2026

Abstract

The development of cementitious materials has undergone a significant transformation in recent years, driven by the need to reduce the environmental footprint of construction while improving material performance [...] Full article

(This article belongs to the Special Issue Preparation and Properties of New Cementitious Materials (2nd Edition))

14 pages, 43226 KB

Open AccessArticle

Temperature-Dependent Microstructure Evolution and Superplastic Deformation Behavior of Cold-Deformed Cr4Mo4Ni4V Martensitic Steel: From Continuous to Discontinuous Dynamic Recrystallization

by Jiwei Wang, Wanli Yang, Jiabin Liu, Tao Li, Wei Tang, Bin Shao and Yingying Zong

Materials 2026, 19(11), 2242; https://doi.org/10.3390/ma19112242 - 26 May 2026

Abstract

To elucidate the evolution of dynamic recrystallization (DRX) mechanisms in cold-worked Cr4Mo4Ni4V martensitic steel, tensile tests were conducted on a 50% cold-deformed material at 600–850 °C at a fixed strain rate of 0.001 s⁻¹, combined with systematic microstructural characterization. Under this [...] Read more.

To elucidate the evolution of dynamic recrystallization (DRX) mechanisms in cold-worked Cr4Mo4Ni4V martensitic steel, tensile tests were conducted on a 50% cold-deformed material at 600–850 °C at a fixed strain rate of 0.001 s⁻¹, combined with systematic microstructural characterization. Under this specific strain rate, the results reveal a temperature-dependent transition from continuous dynamic recrystallization (CDRX) to discontinuous dynamic recrystallization (DDRX). At 600 °C, CDRX dominates, producing recrystallized grains with orientations close to the parent matrix and relatively strong texture. At 750 °C, CDRX and DDRX coexist, while DDRX is significantly enhanced, characterized by grain boundary nucleation and random orientations, leading to a marked reduction in texture intensity; simultaneously, the fraction of recrystallized grains and high-angle grain boundaries reaches a maximum. At 850 °C, DDRX becomes dominant. This transition in DRX mechanism governs the high-temperature plasticity, with optimal superplasticity achieved at 800 °C, corresponding to an elongation of 748%. Cavities are primarily initiated at carbide/matrix interfaces, and their growth and coalescence dominate the fracture process. These findings clarify the temperature-dependent DRX evolution and its role in regulating superplasticity, providing guidance for microstructure design and superplastic forming of martensitic steels. Full article

(This article belongs to the Special Issue Microstructure and Mechanical Properties of Alloys (2nd Edition))

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14 pages, 17519 KB

Open AccessArticle

Experimental and Theoretical Investigation of the κ-Phase (Ag₂Mg₅) in the Ag-Mg System

by Weronika Gozdur, Wojciech Gierlotka, Magdalena Bieda, Władysław Gąsior, Andrzej Budziak, Marek Polański, Magda Pęska and Adam Dębski

Materials 2026, 19(11), 2241; https://doi.org/10.3390/ma19112241 - 26 May 2026

Abstract

The present study extends the investigation of thermodynamic properties of phases in the silver–magnesium binary system, with particular emphasis on the κ-Ag₂Mg₅ phase, for which available literature data remain scarce. The work is divided into two parts. The experimental [...] Read more.

The present study extends the investigation of thermodynamic properties of phases in the silver–magnesium binary system, with particular emphasis on the κ-Ag₂Mg₅ phase, for which available literature data remain scarce. The work is divided into two parts. The experimental section comprises the synthesis of the κ phase from high-purity Ag and Mg, followed by its characterisation using scanning electron microscopy (SEM) and X-ray diffraction (XRD). The synthesised material was subsequently used for calorimetric determination of the standard enthalpy of formation employing the drop solution method. Measurements were carried out in two experimental series (A and B), using two different metallic solvents (Al and Sn), at temperatures of 1020 K and 689 K. The enthalpy of formation obtained in both series was −14.4 ± 0.32 and −14.5 ± 0.42 kJ/mol at., respectively. In addition, the limiting partial enthalpy of solution of liquid Ag in liquid Al was determined calorimetrically and its average value is equal 7.1 ± 0.7 kJ/mol. The theoretical part of the study involved ab initio calculations of defect formation energies. The obtained results show good agreement with available literature data and provide a consistent interpretation of the observed non-stoichiometry of the κ-phase. Full article

(This article belongs to the Special Issue Thermodynamic Modeling, Microstructural Design and Surface Engineering of Advanced Metal Alloys)

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17 pages, 2288 KB

Open AccessArticle

Nb₂O₅/g-C₃N₄ Composite Photocatalysts Supported on Etna-Derived Aluminosilicate for Solar H₂ Production

by Roberto Fiorenza, Roberta Chiarenza, Sebastiano Arcidiacono, Eleonora La Greca, Anna Lucia Pellegrino, Maria Teresa Armeli Iapichino, Giuliana Impellizzeri, Marisa Giuffrida, Marco Viccaro, Cristina Maria Belfiore, Salvatore Scirè and Leonarda Francesca Liotta

Materials 2026, 19(11), 2240; https://doi.org/10.3390/ma19112240 - 26 May 2026

Abstract

In this work, Etna ash-derived photocatalysts were investigated for the first time for solar H₂ production. Volcanic ash, commonly treated as a special waste in eastern Sicily (Italy), was modified through chemical treatment followed by microwave-assisted crystallization, avoiding the conventional high-temperature thermal [...] Read more.

In this work, Etna ash-derived photocatalysts were investigated for the first time for solar H₂ production. Volcanic ash, commonly treated as a special waste in eastern Sicily (Italy), was modified through chemical treatment followed by microwave-assisted crystallization, avoiding the conventional high-temperature thermal route. The obtained material was tested both as a bare photocatalyst and as a support for a Nb₂O₅/graphitic carbon nitride composite prepared by a hydrothermal method. The Etna-derived photocatalyst exhibited a solar H₂ production rate (by TEOA photoreforming) of 920 μmol/g_cat∙h. Upon incorporation of the Nb-based composite, the H₂ evolution rate increased by about 2.5 times, reaching 2370.5 μmol/gcat∙h, demonstrating a strong synergistic effect. Notably, the developed materials largely outperformed commercial TiO₂ P25 (25 μmol/g_cat∙h). The enhanced photocatalytic activity was attributed to the tailored modifications of Etna ash, which increased porosity and promoted aluminosilicate framework reorganization, favoring an optimal distribution of the photocatalytically active TiO₂ and iron oxide phases. The obtained Nb oxide/carbon nitride supported on modified Etna ash also showed a remarkable stability after six consecutive runs of solar photocatalytic H₂ production. This work demonstrates a sustainable strategy for converting volcanic waste into efficient multifunctional photocatalysts while minimizing the use of critical raw materials. Full article

(This article belongs to the Special Issue Innovative Nanostructured and Porous Materials for Advanced Photocatalysis)

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14 pages, 1923 KB

Open AccessArticle

Optimizing the Energy Product in Core–Shell Nanoparticle Magnets: General Guidelines and the FePt/CoFe System

by Ioannis Panagiotopoulos, Georgia Basina, Garyfalia Nezou, Alexandros Konstadinidis, Vasileios Alexandrakis, George Hadjipanayis and Vasileios Tzitzios

Materials 2026, 19(11), 2239; https://doi.org/10.3390/ma19112239 (registering DOI) - 25 May 2026

Abstract

The optimization of the energy product in permanent magnets presents a complicated multi-parametric problem that encompasses a large variety of intrinsic and microstructural properties. As both high remanent magnetization and coercivity are required, the main concern in optimizing a given material is often [...] Read more.

The optimization of the energy product in permanent magnets presents a complicated multi-parametric problem that encompasses a large variety of intrinsic and microstructural properties. As both high remanent magnetization and coercivity are required, the main concern in optimizing a given material is often how to deal with the trade-off between these two properties. A promising approach is to combine high-anisotropy with high-magnetization phases in chemically synthesized magnetically hard–soft nanoparticles. The magnetization reversal in such systems has been studied by micromagnetics, but most of the solutions are given for a magnetically hard shell surrounding a magnetically soft core, although the inverse configuration may be more accessible from a fabrication perspective and can even help induce tetragonicity in phases such as CoFe. Here we summarize the basic general design rules for such systems, and we present specific calculations for the FePt/CoFe system. Though in larger particles complex reversal modes that are scientifically interesting occur, these are not relevant to the problem of achieving high energy products. Optimal energy products are achieved in small particles in the homogeneous exchange spring regime. Therefore, the optimal size and phase content must be determined under the contradictory requirements of achieving homogeneous reversal and avoiding thermal fluctuations. Full article

(This article belongs to the Special Issue Advances in Magnetic Materials and Applications)

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