One-Pot Synthesis of Fast-Chargeable Fe₃O₄@rGO Anode for Lithium-Ion Batteries
Reset-Voltage Controlled Resistance-State and Applications of Forming-Free Fe-Doped SrTiO₃ Thin-Film Memristor
Adsorption of Atomic Hydrogen on Hydrogen Boride Sheets Studied by Photoelectron Spectroscopy
Cutting-Edge Hydrogel Technologies in Tissue Engineering and Biosensing: An Updated Review
Ge-Doped BN Nanoclusters Functionalized with Amino Acids for Bisphenol Binding

Journal Description

Materials

Materials is an international peer-reviewed, open access journal on materials science and engineering published semimonthly online by MDPI. The Portuguese Materials Society (SPM), Spanish Materials Society (SOCIEMAT), Manufacturing Engineering Society (MES) and Chinese Society of Micro-Nano Technology (CSMNT) are affiliated with Materials and their members receive discounts on the article processing charges.

Open Access— free for readers, with article processing charges (APC) paid by authors or their institutions.
High Visibility: indexed within Scopus, SCIE (Web of Science), PubMed, PMC, Ei Compendex, CaPlus / SciFinder, Inspec, Astrophysics Data System, and other databases.
Journal Rank: JCR - Q1 (Metallurgy and Metallurgical Engineering) / CiteScore - Q2 (Condensed Matter Physics)
Rapid Publication: manuscripts are peer-reviewed and a first decision is provided to authors approximately 15.5 days after submission; acceptance to publication is undertaken in 3.4 days (median values for papers published in this journal in the first half of 2024).
Recognition of Reviewers: reviewers who provide timely, thorough peer-review reports receive vouchers entitling them to a discount on the APC of their next publication in any MDPI journal, in appreciation of the work done.
Testimonials: See what our editors and authors say about Materials.
Companion journals for Materials include: Electronic Materials and Construction Materials.

Impact Factor: 3.1 (2023); 5-Year Impact Factor: 3.4 (2023)

Imprint Information Journal Flyer Open Access ISSN: 1996-1944

Latest Articles

13 pages, 2482 KiB

Open AccessArticle

Optical and Geometrical Properties from Terahertz Time-Domain Spectroscopy Data

by George Youssef, Nha Uyen T. Huynh and Somer Nacy

Materials 2024, 17(23), 5854; https://doi.org/10.3390/ma17235854 (registering DOI) - 29 Nov 2024

Abstract

Terahertz waves are nondestructive and non-ionizing to synthetic and natural materials, including polymeric and biological materials. As a result, terahertz-based spectroscopy has emerged as a suitable technique to uncover fundamental molecular mechanisms and material properties in this electromagnetic spectrum regime. In terahertz time-domain spectroscopy (THz-TDS), the material’s optical properties are resolved using the raw time-domain signals collected from the sample and air reference data depending on accurate prior knowledge of the sample geometry. Alternatively, different spectral analysis algorithms can extract the complex index of refraction of optically thick or optically thin samples without specific thickness knowledge. A THz-TDS signal without apparent Fabry–Pérot oscillations is commonly associated with optically thin samples, whereas the terahertz signal of optically thick samples exhibits distinct Fabry–Pérot oscillations. While several extraction algorithms have been reported a priori, the steps from reducing the time-domain signal to calculating the complex index of refraction and resolving the correct thickness can be daunting and intimidating while obscuring important steps. Therefore, the objective is to decipher, demystify, and demonstrate the extraction algorithms for Fabry–Pérot-absent and -present terahertz signals for various polymers with different molecular structure classifications and nonlinear optical crystal zinc telluride. The experimental results were in good agreement with previously published values while elucidating the contributions of the molecular structure to the stability of the algorithms. Finally, the necessary condition for manifesting Fabry–Pérot oscillations was delineated. Full article

(This article belongs to the Special Issue Terahertz Materials and Technologies in Materials Science)

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14 pages, 2092 KiB

Open AccessArticle

Compression Behavior of Dental Flowable Composites—Digital Image Correlation and Numerical Analysis

by Agnieszka Chojnacka-Brożek, Aneta Liber-Kneć and Sylwia Łagan

Materials 2024, 17(23), 5853; https://doi.org/10.3390/ma17235853 (registering DOI) - 28 Nov 2024

Abstract

In the development of restorative materials, it is important to evaluate the elastic properties of the material in order to achieve good clinical results. The aim of this study was to evaluate the compression behavior of two dental flowable materials (EverX Flow and Flow-Art) using experimental methods and numerical simulation. The Poisson’s ratio was determined using two methods of strain measurement: the electrical strain gauge method (ESG) and digital image correlation (DIC). Material constants determined in experimental studies were implemented in a numerical model, and displacement analysis was conducted using the finite element method (FEM). The tests showed higher compressive strength and modulus of elasticity for EverX Flow compared to Flow-Art. The values of the Poisson’s ratio were similar for both measurement methods, ranging from 0.27 to 0.28 for EverX Flow and from 0.30 to 0.32 for Flow-Art. This demonstrated the feasibility of the DIC method for obtaining the Poisson’s ratio values for this type of composites. Compression test conditions were reproduced in the numerical analysis. The obtained distributions of the displacement field on the surface of the sample from the DIC and numerical analyses were compared. A good match was observed between DIC displacement measurements and displacement values obtained in FEM analysis. The comprehensive approach used in the study allows us to analyze whether the results obtained in the numerical simulation correspond to the material response to the applied load and validate the model. Full article

(This article belongs to the Special Issue Mechanical Properties of Dental Materials)

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11 pages, 1842 KiB

Open AccessArticle

Synthesis of N-Doped Graphene Quantum Dots from Cellulose and Construction of a Fluorescent Probe for 6-Mercaptopurin Quantitative Detection

by Qiang Xu, Jiayi Dong, Guiqin Yan, Rongnan Yi and Xiaojing Yang

Materials 2024, 17(23), 5852; https://doi.org/10.3390/ma17235852 (registering DOI) - 28 Nov 2024

Abstract

With cellulose as the precursor and ethylenediamine as the N source, N-doped graphene quantum dots (N-GQDs) were synthesized by a simple and feasible one-pot hydrothermal method. The whole process did noSchemet need a strong acid or strong base and avoided interference from inorganic salt residues. The whole process lasted only 3 h and avoided any complex postprocessing. Because of the outstanding optical properties of N-GQDs, a high-efficiency 6-mercaptopurine fluorescent probe based on the inner filter effect of fluorescence was established. The detection range was 0.2–60 μM and the detection limit was 0.05 μM. This method can preliminarily detect 6-mercaptopurine in human urine and avoids any sample preparation or extraction in advance and brings satisfactory results. Full article

(This article belongs to the Special Issue Fabrication, Characteristics and Applications of Multifunctional Polymer Nanocomposites)

17 pages, 2447 KiB

Open AccessArticle

17-4 Precipitation-Hardening Stainless Steel: Soft-Tough Heat Treatment Mechanism and Thermal Fatigue Characteristics

by Ping-Yu Hsieh, Bo-Ding Wu and Fei-Yi Hung

Materials 2024, 17(23), 5851; https://doi.org/10.3390/ma17235851 (registering DOI) - 28 Nov 2024

Abstract

This study selected 17-4PH (Type 630) precipitation-hardening stainless steel as the raw material. After subjecting the material to precipitation hardening and softening heat treatments, the effects of these treatments on the microstructural characteristics and mechanical properties were investigated, along with a thermal fatigue test. The results showed that after the precipitation hardening heat treatment, the ultimate tensile strength and hardness of 17-4PH stainless steel increased. However, the ductility was around 2%, indicating a severe brittleness effect, which is unfavorable for ordnance applications. A double aging treatment for 12 h resulted in a combination of softness and ductility, with an ultimate tensile strength of 900 MPa, ductility of 26%, and hardness HRC 28. These material properties are suitable for cold forging in ordnance and other applications. In addition, a thermal fatigue test was conducted on the softened 17-4PH material from 750 °C to room temperature. After 3000 thermal cycles, there was no significant change in material properties, ensuring it can withstand 3000 rounds of gunfire in a barrel with excellent durability. Furthermore, XRD and fracture surface analysis confirmed that the softening mechanism of 17-4PH stainless steel and its high-temperature phase stability could provide a reference for cold forging and high-temperature applications. Full article

(This article belongs to the Special Issue Fatigue and Fracture of Metals and Alloys: Numerical and Experimental Study (3rd Edition))

20 pages, 5861 KiB

Open AccessArticle

Quantitative Seismic Damage Assessment of Resilient Concrete Columns Using Drift Ratio-Based Fractal Dimension

by Bunka Son, Ganggang Li, Zhiwei Luo and Yuping Sun

Materials 2024, 17(23), 5850; https://doi.org/10.3390/ma17235850 - 28 Nov 2024

Abstract

The objective of this paper is to develop assessment models to quantitatively evaluate the seismic damage caused to resilient concrete columns intended for buildings located in strong-earthquake-prone regions such as Japan and China. The proposed damage assessment models are based on the fractal analysis of crack patterns on the surface of damaged concrete columns and expressed in the form of a fractal dimension (FD) versus transient drift ratio relationship. To calibrate the proposed damage assessment models, a total of eighty images of crack patterns for eight concrete columns were utilized. All the columns were reinforced by weakly bonded ultra-high-strength (WBUHS) rebars and tested under reversed cyclic loading. The experimental variables covered the shear span ratio of the column, the concrete strength, the axial load ratio, and the amount of steel in the WBUHS rebars. A box-counting algorithm was adopted to calculate or derive the FD of the crack pattern corresponding to each transient drift ratio. The test results reveal that the FD is an efficient image-based quantitative indicator of seismic damage degree for resilient concrete columns and correlates strongly with the transient drift ratio and is subjected to the influence of the shear span ratio. The influence of the other experimental variables on the derived FDs is, if any, little. Based on the test results, a linear equation was developed to define the relationships between the FD and transient drift ratio, and a multi-linear equation was formulated to relate the transient drift ratio to the residual drift ratio, an important index adopted in current design guidelines to measure the repairability of damaged concrete structures. To further verify the efficiency of the drift ratio-based FD in seismic damage assessment, the correlation between the FD and relative stiffness loss (RSL), an indicator used to measure the overall damage degree of concrete structures, was also examined. The driven FD exhibited very strong correlation with RSL, and an empirical equation was developed to reliably assess the overall seismic damage degree of resilient concrete columns with an FD. Full article

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

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16 pages, 1295 KiB

Open AccessArticle

The Shrinking Fermi Liquid Scenario for Cuprates Under the Scrutiny of Optical Conductivity Measurements

by Sergio Caprara, Carlo Di Castro, Giovanni Mirarchi, Götz Seibold and Marco Grilli

Materials 2024, 17(23), 5849; https://doi.org/10.3390/ma17235849 - 28 Nov 2024

Abstract

In a recent paper [B. Michon et al., Nat. Commun. (2023) 14:3033], optical conductivity experiments in cuprate superconductors were shown to display scaling properties consistent with the Marginal Fermi Liquid theory. Here, we argue that the temperature regime studied in these experiments does not allow for distinguishing between Marginal Fermi Liquid and Shrinking Fermi Liquid. In the latter scenario, which we recently proposed and which applies near a quantum critical point, dynamical fluctuations of the order parameter with a short correlation length mediate a nearly isotropic scattering among the quasiparticles over the entire Fermi surface leading to strange metal behavior. If the damping of these nearly local fluctuations increases by decreasing the temperature, the Fermi liquid regime shrinks and the strange metal behavior is extended to the lowest temperatures. This Shrinking Fermi Liquid scenario has many similarities and some differences with respect to the Marginal Fermi Liquid theory. In particular, we show that the approximate scaling properties of the optical conductivity in some high-frequency regimes predicted by the Shrinking Fermi Liquid scenario account for a very good description of the experimental data. Full article

(This article belongs to the Special Issue Advances in Cuprates and Iron-Based Superconductors: Physics, Properties, and Applications)

20 pages, 1792 KiB

Open AccessArticle

The Effect of a Zeolite Addition to Modified Bitumen on the Properties of Stone Matrix Asphalt Lärmarmer Mixtures Produced as Warm Mix Asphalt

by Marta Wasilewska, Roman Pacholak, Pawel Gierasimiuk, Wladyslaw Gardziejczyk, Agnieszka Woszuk, Leslaw Bichajlo and Tomasz Siwowski

Materials 2024, 17(23), 5848; https://doi.org/10.3390/ma17235848 - 28 Nov 2024

Abstract

This paper presents the properties of an SMA LA (stone matrix asphalt Lärmarmer) mixture based on the polymer-modified binder PMB 45/80-55, formed by the addition of zeolites (synthetic zeolite type Na-P1 and natural zeolite—clinoptilolite). The compositions of the SMA 11, SMA 8 LA and SMA 11 LA mixtures based on modified bitumen with PMB 45/80-55 (reference mixture) or PMB 45/80-55 with Na-P1 or clinoptilolite were determined. Their resistance to permanent deformation, water sensitivity, water permeability and susceptibility to changes in texture and skid resistance during the period of use were verified. Adding zeolites reduced the production temperature by as much as 15 °C for the SMA 11 LA mixtures and 20 °C for SMA 8 LA. The addition of zeolites did not significantly affect the resistance to permanent deformation, the water permeability or the mass loss. The mixtures with clinoptilolite were resistant to the harmful effects of water, while the mixtures with Na-P1 proved more sensitive to water. Water permeability tests showed a higher permeability for SMA 11 LA compared to SMA 8 LA due to the higher nominal aggregate size. The Cantabro test showed greater particle loss for SMA 11 LA than for SMA 8 LA. A skid resistance and macrotexture analysis indicated that the SMA LA layers required special maintenance on the road due to the clogging of pores in the mix structure. Full article

(This article belongs to the Special Issue Advances in Asphalt Materials (Second Volume))

32 pages, 2346 KiB

Open AccessReview

Antibacterial Properties and Biocompatibility of Multicomponent Titanium Oxides: A Review

by Boris B. Straumal, Evgenii N. Kurkin, Igor L. Balihin, Elisaveta Klyatskina, Peter B. Straumal, Natalia Yu. Anisimova and Mikhail V. Kiselevskiy

Materials 2024, 17(23), 5847; https://doi.org/10.3390/ma17235847 - 28 Nov 2024

Abstract

The simple oxides like titania, zirconia, and ZnO are famous with their antibacterial (or even antimicrobial) properties as well as their biocompatibility. They are broadly used for air and water filtering, in food packaging, in medicine (for implants, prostheses, and scaffolds), etc. However, these application fields can be broadened by switching to the composite multicomponent compounds (for example, titanates) containing in their unit cell, together with oxygen, several different metallic ions. This review begins with a description of the synthesis methods, starting from wet chemical conversion through the manufacturing of oxide (nano)powders toward mechanosynthesis methods. The morphology of these multicomponent oxides can also be very different (like thin films, complicated multilayers, or porous scaffolds). Further, we discuss in vitro tests. The antimicrobial properties are investigated with Gram-positive or Gram-negative bacteria (like Escherichia coli or Staphylococcus aureus) or fungi. The cytotoxicity can be studied, for example, using mouse mesenchymal stem cells, MSCs (C3H10T1/2), or human osteoblast-like cells (MG63). Other human osteoblast-like cells (SaOS-2) can be used to characterize the cell adhesion, proliferation, and differentiation in vitro. The in vitro tests with individual microbial or cell cultures are rather far away from the real conditions in the human or animal body. Therefore, they have to be followed by in vivo tests, which permit the estimation of the real applicability of novel materials. Further, we discuss the physical, chemical, and biological mechanisms determining the antimicrobial properties and biocompatibility. The possible directions of future developments and novel application areas are described in the concluding section of the review. Full article

21 pages, 5695 KiB

Open AccessReview

Advances in the Mitigation of Microbiologically Influenced Concrete Corrosion: A Snapshot

by Husnu Gerengi, Ertugrul Kaya, Moses M. Solomon, Matthew Snape and Andrea Koerdt

Materials 2024, 17(23), 5846; https://doi.org/10.3390/ma17235846 - 28 Nov 2024

Abstract

Concrete, a versatile construction material, faces pervasive deterioration due to microbiologically influenced corrosion (MIC) in various applications, including sewer systems, marine engineering, and buildings. MIC is initiated by microbial activities such as involving sulfate-reducing bacteria (SRB), sulfur-oxidizing bacteria (SOB), etc., producing corrosive substances like sulfuric acid. This process significantly impacts structures, causing economic losses and environmental concerns. Despite over a century of research, MIC remains a debated issue, lacking standardized assessment methods. Microorganisms contribute to concrete degradation through physical and chemical means. In the oil and gas industry, SRB and SOB activities may adversely affect concrete in offshore platforms. MIC challenges also arise in cooling water systems and civil infrastructures, impacting concrete surfaces. Sewer systems experience biogenic corrosion, primarily driven by SRB activities, leading to concrete deterioration. Mitigation traditionally involves the use of biocides and surface coatings, but their long-term effectiveness and environmental impact are questionable. Nowadays, it is important to design more eco-friendly mitigation products. The microbial-influenced carbonate precipitation is one of the green techniques and involves incorporating beneficial bacteria with antibacterial activity into cementitious materials to prevent the growth and the formation of a community that contains species that are pathogenic or may be responsible for MIC. These innovative strategies present promising avenues for addressing MIC challenges and preserving the integrity of concrete structures. This review provides a snapshot of the MIC in various areas and mitigation measures, excluding underlying mechanisms and broader influencing factors. Full article

(This article belongs to the Special Issue Microbiologically Influenced Corrosion of Metallic and Non-metallic Materials: Mechanisms and Protection)

15 pages, 3830 KiB

Open AccessArticle

Preparation of Hot-Pressed Wheat Straw Board by Self-Adhesive Process: Effects of Raw Material Sizes and Acid/Alkali Pretreatment

by Jianing Wang, Ziyue Feng, Jiachen Zuo, Qinzhen Fan and Libo Zhang

Materials 2024, 17(23), 5845; https://doi.org/10.3390/ma17235845 - 28 Nov 2024

Abstract

The development of wheat straw boards utilizing intrinsic bonding mechanisms not only facilitates the high-value utilization of agricultural solid waste but also diminishes the reliance on synthetic adhesives. In this study, using wheat straw as the primary substrate, we investigated the effects of mechanical smashing combined with pretreatment using inorganic acids or alkalis on the properties of hot-pressed boards, as well as the relationship between the properties of hot-pressed boards and the physical properties and chemical composition of wheat straw raw materials. These selective pretreatments effectively degraded lignin, hemicellulose, and other components, thereby promoting fiber reorientation and resulting in a denser microstructure with improved self-bonding capabilities. The optimal board was fabricated with a granularity of 0.3 mm and underwent alkali pretreatment, achieving a tensile strength of 11.564 MPa, an internal bonding strength of 0.556 MPa, and bending strength and modulus of 24.306 MPa and 2.766 GPa, respectively. These findings have significant implications for advancing manufacturing processes and conceptualizing binder-free boards derived from agricultural residues. Full article

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19 pages, 6178 KiB

Open AccessArticle

Considering the Bottom Edge Cutting Effect of the Carbon Fiber Reinforced Polymer Milling Force Prediction Model and Optimization of Machining Parameters

by Yiwei Zhang, Mengke Yan, Yushu Lai, Guixing Wang and Yifan Yang

Materials 2024, 17(23), 5844; https://doi.org/10.3390/ma17235844 - 28 Nov 2024

Abstract

The milling force plays a pivotal role in CFRP milling. Modeling of the milling force is helpful to explore the changing law, optimize the processing parameters, and then reduce the appearance of defects. However, most of the existing models ignore the effect of the bottom edge. In this paper, the prediction of milling force in CFRP milling processes is taken as the research object. By analyzing the milling mechanism and considering the end milling cutter’s bottom cutting edge, the prediction model of milling force was established. Based on the experimental data and simulation data of milling force, the milling force coefficient was obtained by inverse calculation. Subsequently, the predicted cutting force was compared with the experimental cutting force, showing a maximum error of 14.5%, which is within a reasonable range, and the correctness of the model was verified. Furthermore, combined with the delamination damage and the milling force prediction model, a multi-objective optimization model of milling parameters was established, and the genetic algorithm was used to solve the model. The unidirectional carbon fiber plate with a fiber direction angle of 45° was selected as the optimization example. The minimum delamination damage was obtained under the cutting conditions of a spindle speed of

4903.1569 r / m i n

, feed rate per tooth of

0.01 m m / z

, and an axial depth of cut of

0.5 m m

, and the experimental verification was carried out. The feasibility of the genetic algorithm in CFRP milling parameter optimization modeling was also verified. Full article

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20 pages, 7648 KiB

Open AccessArticle

Characterization of Myrrh Extract Effect on Polylactide and Polypropylene Melt Spun Multifilament Yarn Structure and Properties

by Evaldas Bolskis, Egidijus Griškonis, Mindaugas Marksa, Lina Ragelienė and Erika Adomavičiūtė

Materials 2024, 17(23), 5843; https://doi.org/10.3390/ma17235843 - 28 Nov 2024

Abstract

Myrrh has unique medicinal properties: it is an anti-inflammatory, antifungal, and antibacterial material. The aim of this study was to assess the influence of ethanolic myrrh extract on the production and properties of modified PP and PLA melt spun yarns. In this work, multifilament yarns of polylactide (PLA) and polypropylene (PP) containing 10 wt% myrrh resin at different melt-spinning drawing ratios (DRs) were prepared. The results of scanning electron microscopy revealed that the multifilament yarns from polymers covered by myrrh resin extract had a smooth surface without cracks or visible myrrh derivatives. The influence of myrrh resin on the mechanical properties of PP and PLA multifilament yarns was analyzed, and it was found that the presence of myrrh (PP/M, PLA/M) increased tenacity (cN/tex) and decreased the tensile strain (%) of melt spun yarns obtained at different draw ratios (DRs). During optical analysis, it was found that the absorbance of yarns increased in the entire UV region of the spectra, which was most likely determined by the presence of myrrh. The degree of crystallinity and the wetting angle of PP/M and PLA/M multifilament yarns increased compared with the pure PLA and PP multifilament yarns. This study concludes that the presence of myrrh derivatives influences PLA yarns degradation rate and antibacterial effects against Gram-positive bacteria. Full article

(This article belongs to the Special Issue Design and Development of Polymer-Based Drug Carriers for Biomedical Applications)

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18 pages, 6329 KiB

Open AccessReview

Oxidation Behavior of Nanocrystalline Alloys

by Yashaswini Karanth, Saurabh Sharma, Kris Darling, Haitham El Kadiri and Kiran Solanki

Materials 2024, 17(23), 5842; https://doi.org/10.3390/ma17235842 - 28 Nov 2024

Abstract

Thermo-mechanically stabilized nanocrystalline (NC) alloys are increasingly valued for their enhanced mechanical strength and high-temperature stability, achieved through thermodynamic and kinetic stabilization methods. However, their fine-grained structure also increases susceptibility to internal oxidation due to higher atomic diffusivity associated with a greater volume fraction of grain boundaries (GBs). By incorporating solutes that form protective oxides, or the so-called thermally growing oxides (TGO), this vulnerability can be mitigated. The TGO scale acts as a diffusion barrier for oxygen that slows down the oxidation kinetics and prevents internal oxidation that impairs the structural integrity of the metal. This review examines advancements in oxidation-resistant NC alloys, focusing on the interplay between grain size and alloy chemistry. We explore how grain refinement influences diffusion coefficients, particularly the enhanced GB diffusion of Ni and Cr in Ni-Cr-based alloys, which improves oxidation resistance in NC variants like Ni-Cr and Cu-Cr compared to coarse-grained counterparts. We also analyze the role of third elements as oxygen scavengers and the impact of reactive elements such as Hf, Zr, and Y in NiAl alloys, which can slow down diffusion through early establishment of protective TGO layers and enhance oxidation resistance. The concomitant effect of grain size refinement, modifications in alloy stoichiometry, and enhanced atomic diffusion is shown to manifest via drastic reductions in oxidative mass gain, and visualization of the stable, protective oxide scales is delivered through characterization techniques such as TEM, SEM, and EDS. A brief overview is provided regarding stress effects and the role of induced stress in driving oxide scale spallation, which can negatively impact oxidation kinetics. Lastly, we propose future research directions aimed at developing micro-structurally stable NC alloys through multi-solute strategies and surface modification techniques, targeting robust materials for high-stress applications with improved oxidation resistance. Full article

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Abstract

Rock varnishes, complex structures formed by long-term deposition on rocks, exhibit unique light absorption characteristics and are widely distributed across arid environments on Earth’s surface. The varnishes possess the ability to absorb and convert photons from solar radiation into electrons, which represents a newly discovered fundamental energy form in nature, with further elucidation required regarding the underlying mechanism of how semiconductor minerals respond to light radiation. The regulations governing the photoconductive responses of samples from the Alashan region in Gobi, China, and the mechanisms exhibited by rock rock varnishes under various bias voltages and irradiation wavelengths (532 nm, 808 nm, and 1064 nm) were studied. The photoconductivity response is positively correlated with the applied external bias, and the response caused by shorter wavelengths is larger. The synergistic effect was quantitatively assessed by monitoring and fitting the correlation between photoconductivity, temperature, and time during laser irradiation. As an effective method to study the fundamental physical properties of semiconductor minerals, the photoconductivity testing will help to establish a fundamental framework for investigating the intrinsic physical characteristics of natural rock varnishes. Full article

27 pages, 38081 KiB

Open AccessArticle

Dynamic Testing of Materials for Galvanising Pot Roll Bearings with Improved Performance

by Giovanni Paolo Alparone, James Sullivan, Christopher Mills, James Edy and David Penney

Materials 2024, 17(23), 5837; https://doi.org/10.3390/ma17235837 - 28 Nov 2024

Abstract

Galvanising pot roll bearings are subjected to severe deterioration due to the corrosion of the bearing materials in liquid Zn, resulting in maintenance stops that can cost thousands of pounds per hour in downtime. Dynamic wear testing in molten Zn-Al and Zn-Al-Mg was conducted to assess the corrosion and wear resistance of three material pairs using a bespoke testing rig. The materials investigated in this study were Wallex6^TM coated with WC-Co, stainless steel 316L coated with Al₂O₃, and as-received Wallex6^TM and Wallex4^TM alloys. It was found that only the Al₂O₃ coating remained unreactive in Zn alloy, whereas the materials containing Co were corroded, as evidenced by the formation of intermetallic compounds containing Al-Co-Zn-Fe. The results also highlighted that the dissolution of the Co matrix and diffusion of Zn and Al from the bath occurred in Wallex6^TM and Wallex4^TM. However, the diffusion of Zn into the Wallex^TM alloys was reduced by approximately 60% in the Zn-Al-Mg bath compared to Zn-Al. The wear scars were analysed to determine the wear coefficient of the worn specimens. Out of the three material couplings investigated in this study, minimal wear damage in both Zn-Al and Zn-Al-Mg was only obtained by pairing Wallex6^TM with Al₂O₃ coatings. Full article

(This article belongs to the Special Issue New Trends in Mechanical and Tribological Properties of Materials and Components)

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