Materials

15 pages, 1710 KB

Open AccessArticle

Study of Extensional Rheology Behavior of Sodium Alginate/Polyethylene Oxide Solutions for Blow Spinning

by Biao Yang, Xue Wang and Cong Du

Materials 2025, 18(24), 5491; https://doi.org/10.3390/ma18245491 - 5 Dec 2025

Blow spinning is a low-cost and versatile method that permits the large-scale production of fibrous membranes. However, polysaccharides that show numerous merits such as biocompatibility and biodegradability often have a low spinnability due to their high chain rigidity and low ability to form [...] Read more.

Blow spinning is a low-cost and versatile method that permits the large-scale production of fibrous membranes. However, polysaccharides that show numerous merits such as biocompatibility and biodegradability often have a low spinnability due to their high chain rigidity and low ability to form sufficient entanglements. Here, we report the fabrication of polysaccharide micro-fibrous membranes from sodium alginate/polyethylene oxide solutions formulated in solvent mixtures of water and ethanol. The shear and extensional rheological responses of the solutions are characterized, and parameters including specific shear viscosity, reptation time, extensional relaxation time, and maximum stretch ratio are correlated with the concentrations of polymer, polyethylene oxide, and ethanol. It is found that flexible polyethylene oxide and poorer solvent ethanol can synergistically delay the chain relaxation during stretch and increase the stretchability of the solutions. A processability map of the solutions for blow spinning is constructed, enabling the fabrication of fibrous membranes with a fiber diameter of ~1 μm, tensile strength of 4.89 MPa, elongation at break of 15.24%, and Young’s modulus of 45.43 MPa. This study presents a new strategy to fabricate sodium alginate-based membranes, which should provide insights into the design of other polysaccharide membranes with specific functions and applications. Full article

(This article belongs to the Section Polymeric Materials)

24 pages, 1954 KB

Open AccessArticle

Role of Laser Powder Bed Fusion Process Factors in Determining the Porosity Formation in 3D Printing of Stainless Steel 316L: Theoretical Modeling and Experimental Verification

by Andrzej Stwora, Reza Teimouri and Jacek Habel

Materials 2025, 18(24), 5490; https://doi.org/10.3390/ma18245490 - 5 Dec 2025

Abstract

In this study, an analytical model was developed to evaluate the influence of laser powder bed fusion (LPBF) process parameters on process-induced porosity during the 3D printing of stainless steel 316L. First, the temperature distribution, governed by a moving point heat source model [...] Read more.

In this study, an analytical model was developed to evaluate the influence of laser powder bed fusion (LPBF) process parameters on process-induced porosity during the 3D printing of stainless steel 316L. First, the temperature distribution, governed by a moving point heat source model of the laser, was used to predict the melt pool geometry during the melting stage. This prediction was then refined to account for the formation of the solidified cap. By analyzing the interaction between melt pool size and other process parameters, such as hatch spacing and layer thickness, criteria were established to distinguish between porosity caused by lack of fusion, porosity due to keyhole formation, and defect-free samples. A series of experiments were conducted, and porosity was measured using micro-CT analysis. The results showed that the porosity predicted by the model remained within an acceptable error range compared with the experimental measurements, with errors ranging from 10.5% to 24.78% and a mean error of 16.48%, demonstrating the accuracy of the developed model. Full article

(This article belongs to the Special Issue Advanced Additive Manufacturing and Its Application—2nd Edition)

17 pages, 10053 KB

Open AccessArticle

Cyclic Superelasticity, Elastocaloric Effect, and Shape Memory Effect of Solution-Treated Ti₅₀Ni₄₁Cu₇Co₂ Alloy

by Niranjan Kumar Choudhry, Da-Syuan Chou and Chih-Hsuan Chen

Materials 2025, 18(24), 5489; https://doi.org/10.3390/ma18245489 - 5 Dec 2025

Abstract

In recent years, there has been an increasing interest in studying multi-component alloys. A bulk solution-treated Ti₅₀Ni₄₁Cu₇Co₂ SMA was prepared and investigated. The functional properties, including phase transformation temperature, shape memory effect, cyclic superelasticity, and elastocaloric [...] Read more.

In recent years, there has been an increasing interest in studying multi-component alloys. A bulk solution-treated Ti₅₀Ni₄₁Cu₇Co₂ SMA was prepared and investigated. The functional properties, including phase transformation temperature, shape memory effect, cyclic superelasticity, and elastocaloric response, were systematically evaluated. The alloy exhibited a M_s temperature of around 250 K, which is beneficial for applications at room temperature. Shape memory effect with a maximum recoverable strain of 6.21% was obtained under a biased stress of 300 MPa. The superelasticity rapidly became stable during the cyclic test, reducing irrecoverable strain from 2.8% to 0.01% by the 10th cycle. After 250th superelastic cycles, the alloy exhibited a stable recoverable strain of 1.3%, and a lower critical stress for transformation (270 MPa, down from 405 MPa). The elastocaloric cooling effect reached −4.9 K at the 50th cycle and stabilized at −4.3 K thereafter. With an increase in operating temperature, the elastocaloric effect diminished and disappeared above 383 K, and the SMA retained a notable recoverable strain of ~0.5% up to 443 K. Full article

(This article belongs to the Section Metals and Alloys)

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20 pages, 4056 KB

Open AccessArticle

Experimental Study and Regression Modeling of Sound Absorption Coefficient for Wood Panels

by Miljenko Krhen, Marin Hasan, Franjo Bolkovac and Kristijan Radmanović

Materials 2025, 18(24), 5488; https://doi.org/10.3390/ma18245488 - 5 Dec 2025

Abstract

This study presents a predictive model for estimating the sound absorption coefficient of perforated and non-perforated wooden panels, based on experimental data. Measurements were conducted on four wood species: fir wood (Abies alba), pine wood (Pinus sylvestris), pedunculate oak [...] Read more.

This study presents a predictive model for estimating the sound absorption coefficient of perforated and non-perforated wooden panels, based on experimental data. Measurements were conducted on four wood species: fir wood (Abies alba), pine wood (Pinus sylvestris), pedunculate oak (Quercus robur), and sessile oak (Quercus petraea) in three panel thicknesses (11 mm, 18 mm and 25 mm), with perforation ratios of 0%, 10%, and 20%. The normal-incidence absorption coefficient was measured using the impedance tube method in accordance with ISO 10534-2. Measurements were performed in a 100 mm impedance tube, selected to match the specimen dimensions; therefore, the analysis is limited to the valid plane-wave frequency range of this tube, between 250 and 1600 Hz. Previous studies have shown that both panel thickness and perforation ratio significantly influence mid- and high-frequency absorption. Our results confirm that increased panel thickness and perforation enhance absorption, consistent with findings reported for micro-perforated and porous wood panels. Based on the measured values, we developed first-order regression functions linking the absorption coefficient to material density, thickness, and perforation percentage. The resulting equations allow reverse estimation of one or more physical parameters to meet target acoustic performance requirements. This data-driven approach provides a practical tool for designing wooden absorbers with predictable behavior and complements existing analytical models for acoustic optimization. Full article

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

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17 pages, 7472 KB

Open AccessArticle

Hydrogen Damage Behavior of X80 Pipeline Steel Under AC Interference

by Tong Li, Zhihui Li, Kejun Jiang, Yuxiang Cai, Wan Sun, Ziyong He, Jun Zhao, Tao Cao, Junjun Jin, Wenjing Chen and Guoqing Gou

Materials 2025, 18(24), 5487; https://doi.org/10.3390/ma18245487 - 5 Dec 2025

Abstract

X80 pipeline steel is a key material in the field of oil and gas transportation. Its damage behavior in a hydrogen-filled environment directly affects pipeline safety. In this study, through hydrogen permeation experiments and slow strain rate tensile tests, the electrochemical responses and [...] Read more.

X80 pipeline steel is a key material in the field of oil and gas transportation. Its damage behavior in a hydrogen-filled environment directly affects pipeline safety. In this study, through hydrogen permeation experiments and slow strain rate tensile tests, the electrochemical responses and hydrogen-induced cracking behaviors of X80 base metal and welded joints under hydrogen filling conditions in both AC and DC were systematically compared. The results show that when the base material is filled with hydrogen at 20 mA/cm² AC, the hydrogen permeation flux is the largest, and the overall hydrogen permeation parameter of the welded joint is lower than that of the base material. High-frequency polarization promotes hydrogen permeation, but anodic corrosion products at high current densities can impede hydrogen entry. The slow strain rate tensile test further confirmed that the mechanical properties of the material declined more significantly under direct current hydrogen charging, and the sensitivity to stress corrosion cracking was higher. Under alternating hydrogen charging conditions, due to the alternating effects of hydrogen charging at the cathode and corrosion at the anode, a relatively low hydrogen embrittlement sensitivity is exhibited. Full article

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

12 pages, 23393 KB

Open AccessArticle

Crystal-Plasticity-Based Micro-Mechanical Model for Simulating Plastic Deformation of TC4 Alloy

by Huanhuan Chen, Wei Li, Zhengming Qian, Dong Mi, Yangyang Wu, Siqi Zhang, Can Wu, Keke Li, Tiezheng Tang and Dongfeng Li

Materials 2025, 18(24), 5486; https://doi.org/10.3390/ma18245486 - 5 Dec 2025

Abstract

Ti-6Al-4V (TC4) alloy is widely used in aerospace and biomedical applications due to its excellent strength-to-weight ratio and corrosion resistance. Its plastic deformation behavior is strongly influenced by its microstructural characteristics, particularly grain size. In this study, a crystal plasticity model incorporating a [...] Read more.

Ti-6Al-4V (TC4) alloy is widely used in aerospace and biomedical applications due to its excellent strength-to-weight ratio and corrosion resistance. Its plastic deformation behavior is strongly influenced by its microstructural characteristics, particularly grain size. In this study, a crystal plasticity model incorporating a Hall–Petch relationship was developed to simulate the plastic deformation of TC4, with explicit consideration of the effect of grain size on slip resistance. The model employs a thermally activated flow rule to describe the kinetics of slip systems, enabling accurate prediction of flow stress and strain hardening across different microstructural conditions. The model is calibrated and validated using experimental stress–strain data from uniaxial tensile tests on specimens with varying grain sizes. Simulation results demonstrate that the model successfully captures the grain-size-strengthening effect and predicts the corresponding evolution of local strain heterogeneity. Furthermore, a critical local equivalent plastic strain criterion was established, which effectively predicts the dependence of macroscopic failure strain on grain size. This work provides a physically based computational tool for optimizing TC4 processing parameters and predicting deformation under service conditions. Full article

(This article belongs to the Section Metals and Alloys)

19 pages, 4580 KB

Open AccessArticle

Synergistic Influence of Multi-Walled Carbon Nanotubes and Nanosilica Powder on Mechanical Performance of Mortar with Demolished Concrete Waste Aggregate and Polypropylene Fibers Addition Using Taguchi Design of Experiment

by Daniel Lepadatu, Loredana Emanuela Judele, Dana Roxana Bucur, Isabela Maria Simion, Ioana Sorina Entuc, Eduard Proaspat, Razvan Ionut Teodorescu, Abdessamad Kobi and Santiago Garcia-Granda

Materials 2025, 18(24), 5485; https://doi.org/10.3390/ma18245485 - 5 Dec 2025

Abstract

This study investigates the synergistic influence of multi-walled carbon nanotubes (MWC-NTs), nanosilica powder (NSP), and polypropylene fiber waste (PFW) on the mechanical performance of mortar incorporating demolished concrete waste aggregates (DCWA). The replacement of natural aggregates with DCWA typically results in strength reductions [...] Read more.

This study investigates the synergistic influence of multi-walled carbon nanotubes (MWC-NTs), nanosilica powder (NSP), and polypropylene fiber waste (PFW) on the mechanical performance of mortar incorporating demolished concrete waste aggregates (DCWA). The replacement of natural aggregates with DCWA typically results in strength reductions and weak interfacial transition zones; therefore, the combined use of nanomaterials and microfibers is proposed as a mitigation strategy. A Taguchi Design of Experiments (DOE) approach was employed to optimize mix parameters, including MWCNT dosage, NSP content, PFW volume fraction, and DCWA replacement level. Mortar mixtures were prepared with MWCNTs (0–0.1% by binder weight), NSP (0–2% by binder weight), PFW (0–0.3% by volume), and DCWA (0–20% replacement of fine sand). Mechanical performance was assessed through compressive and flexural strength tests. A combined statistical approach using the Pareto chart and ANOVA identified the most influential parameters and their respective contributions to the response variable. The innovative aspect of this research lies in the synergistic integration of MWCNTs, NSP, demolished concrete waste, and polypropylene fiber waste within the mortar matrix, with the incorporation of nanomaterials specifically intended to compensate for the strength reduction typically induced by the use of demolition concrete waste aggregates. Although a potential nano-scale synergy between MWCNTs and NSP was initially considered, the experimental results indicated that the most relevant synergistic effects occurred among broader mix parameters rather than specifically between the two nanomaterials. Even so, when assessed individually, both nanomaterials contributed to improving the mechanical characteristics of the mortar—particularly nanosilica, which demonstrated a more pronounced effect—yet these individual enhancements did not translate into a distinct synergistic interaction between MWCNTs and NSP. The Taguchi DOE proved to be an efficient tool for multiple factor analysis, enabling reliable identification of the most influential parameters with a minimum number of tests. Its application facilitated the development of mortar mixtures that effectively integrate demolition waste while achieving enhanced mechanical performance through nano- and micro-scale reinforcement. Full article

(This article belongs to the Special Issue Advances in Sustainable Construction and Building Materials (3rd Edition))

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13 pages, 4571 KB

Open AccessArticle

Preparation and Application of Porous Metallic Glasses via Aging-Assisted Ultrasonic Vibration and Compression

by Jiaqing Lin, Heting Zhang, Zhe Chen, Jihan Jiang, Xingran Zhao, Xiaodi Liu, Wenqing Ruan and Jiang Ma

Materials 2025, 18(24), 5484; https://doi.org/10.3390/ma18245484 - 5 Dec 2025

Abstract

The quest for enhanced energy efficiency is inextricably linked to advancements in energy storage and conversion, with porous metallic glasses (MGs) serving as catalysts that hold significant potential in this area. In this study, we report the preparation of uniform porous structures by [...] Read more.

The quest for enhanced energy efficiency is inextricably linked to advancements in energy storage and conversion, with porous metallic glasses (MGs) serving as catalysts that hold significant potential in this area. In this study, we report the preparation of uniform porous structures by aging-assisted ultrasonic vibration (AAUV). The results indicate that ultrasonic treatment effectively enhances the energy state while preserving the amorphous structure of Zr₆₂Cu_15.5Ni_12.5Al₁₀ MGs. The results demonstrate that UV treatment effectively elevates the energy state while maintaining the amorphous structure. Electrochemical tests reveal significantly improved chemical activity after UV treatment, with a reduced corrosion potential and over 200-fold increase in electrochemical surface area after dealloying. The dealloyed UV-treated samples develop uniform porous structures with Cu-enriched zones, exhibiting exceptional catalytic performance in alkaline media (oxygen evolution reaction: 350 mV, hydrogen evolution reaction: 163 mV), comparable to commercial catalysts. This work provides new insights into developing high-performance MGs through energy-state engineering. Full article

(This article belongs to the Topic Electrocatalytic Advances for Sustainable Energy)

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15 pages, 3193 KB

Open AccessArticle

Mechanical and Self-Healing Performance of Cement Composites Containing Bacteria Extracted from Waste Concrete

by Se-Jin Choi, Jeong-Yeon Park, Jung-Mi Kim, Ha-Yeon Song and Jae-In Lee

Materials 2025, 18(24), 5483; https://doi.org/10.3390/ma18245483 - 5 Dec 2025

Abstract

Cracks can reduce the durability of concrete structures. To mitigate the damage caused, self-healing technologies using bacteria and cement-based materials can be utilized. For self-healing, bacteria contained within the matrix are advantageous because they can heal cracks upon introducing oxygen and water under [...] Read more.

Cracks can reduce the durability of concrete structures. To mitigate the damage caused, self-healing technologies using bacteria and cement-based materials can be utilized. For self-healing, bacteria contained within the matrix are advantageous because they can heal cracks upon introducing oxygen and water under favorable conditions. To our knowledge, this is the first study showing that Lysinibacillus fusiformis isolated from waste concrete induces calcite precipitation in a cement-based material. Replacing 5–20% of the mixing water with the bacterial solution increased mortar flow, and the initial compressive strength increased with the bacterial content. After long-term aging, the compressive strength of the sample with 20% bacterial solution was ~45.6 MPa, the highest among all samples. In terms of durability, the bacterial solution reduced the carbonation depth compared with that of a control sample without added bacteria, and the 20% sample showed 53% higher carbonation resistance than the control. In terms of the self-healing performance, the bacteria-loaded samples showed higher compressive strength recovery rates than the control sample, with the 20% sample showing the highest rate of approximately 131%. Therefore, L. fusiformis derived from waste concrete is a promising candidate bacterium for enhancing the durability and self-healing efficiency of cement composites. Full article

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

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14 pages, 9461 KB

Open AccessArticle

C15-Structured Zr-Ti-Fe-Ni-V Alloys for High-Pressure Hydrogen Compression

by Jie Xu, Changsheng Qin and Hui Wang

Materials 2025, 18(24), 5482; https://doi.org/10.3390/ma18245482 - 5 Dec 2025

Abstract

Metal hydride hydrogen compressors (MHHC) offer unique advantages over conventional mechanical compressors in high-pressure hydrogen refueling. In this study, we developed C15-structured Zr-Ti-Fe-Ni-V single-phase alloys for high-pressure hydrogen compression. By designing the alloy compositions—high Ni and low V—and employing a quenching process, the [...] Read more.

Metal hydride hydrogen compressors (MHHC) offer unique advantages over conventional mechanical compressors in high-pressure hydrogen refueling. In this study, we developed C15-structured Zr-Ti-Fe-Ni-V single-phase alloys for high-pressure hydrogen compression. By designing the alloy compositions—high Ni and low V—and employing a quenching process, the resulting ZrFe₂-based alloys exhibit reduced hydriding/dehydriding plateau hysteresis and slope, along with a narrow hydrogen solid solution zone. Notably, the Zr_0.8Ti_0.2Fe_1.2Ni_0.7V_0.1 alloy elevates the hydrogen pressure from 128.3 atm to 334.5 atm within 283–353 K, delivering an effective hydrogen capacity of 1.02 wt.%. Similarly, the Zr_0.9Ti_0.1Fe_1.2Ni_0.7V_0.1 alloy increases the hydrogen pressure from 60.4 atm to 221.8 atm across 283–363 K, with a capacity of 0.81 wt.%. This work provides a rational strategy for designing ZrFe₂-based alloys for efficient hydrogen compression and storage applications. Full article

(This article belongs to the Special Issue Hydrides for Energy Storage: Materials, Technologies and Applications)

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15 pages, 2982 KB

Open AccessArticle

Binderless Thermal Insulation Boards from Rapeseed Straw: Optimization and Performance Analysis

by Miloš Jerman, Martin Böhm, Jakub Vrzáň, Jitka Krejsová, Klára Kobetičová and Robert Černý

Materials 2025, 18(24), 5481; https://doi.org/10.3390/ma18245481 - 5 Dec 2025

Abstract

The development of sustainable thermal insulation materials is crucial for reducing the environmental impact of the construction sector. This study investigates the potential of binderless insulation boards made from rapeseed fibers, utilizing the natural adhesive properties of lignin. The effects of fiber fineness [...] Read more.

The development of sustainable thermal insulation materials is crucial for reducing the environmental impact of the construction sector. This study investigates the potential of binderless insulation boards made from rapeseed fibers, utilizing the natural adhesive properties of lignin. The effects of fiber fineness and processing temperature (160 °C and 180 °C) on basic physical, hygric and thermal properties were examined. The influence of temperature on thermal conductivity was minimal, while higher temperature slightly reduced moisture content and swelling. Finer fibers and higher temperature increased the water vapor diffusion resistance factor. Microscopy and thermal analyses confirmed sufficient lignin softening and fiber bonding at 160 °C, whereas higher temperatures caused partial fiber degradation. Overall, the results demonstrate that rapeseed straw boards provide a sustainable and vapor-permeable alternative for roof and general insulation applications, with processing conditions and fiber fineness influencing hygric properties more than thermal performance. Full article

(This article belongs to the Special Issue New Thermal Insulation Materials in Green Buildings)

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19 pages, 5801 KB

Open AccessArticle

Analysis of Post-Bonding Crack-Induced Double Cantilever Bending (PDC-DCB) Method for Hybrid Bonding Strength Measurement

by Cong Mei, Tianze Zheng, Qiuhan Hu, Yingjie Chen, Yuan Xu, Huiyao Zhao, Liu Chang, Yuan Yuan, Zongguang Yu and Liyi Li

Materials 2025, 18(24), 5480; https://doi.org/10.3390/ma18245480 - 5 Dec 2025

Abstract

The quantitative measurement of bonding strength in hybrid bonding (HB) is an indispensable metrology for process and reliability evaluation. Methods currently used such as blade insertion (BI) and double cantilever bending (DCB) have suffered from a wafer edge-only capability and limited repeatability due [...] Read more.

The quantitative measurement of bonding strength in hybrid bonding (HB) is an indispensable metrology for process and reliability evaluation. Methods currently used such as blade insertion (BI) and double cantilever bending (DCB) have suffered from a wafer edge-only capability and limited repeatability due to a lack of precise interface crack initiation. This study reports an improved DCB method by introducing a post-bonding crack (PBC) to avoid undesired cracking in a wafer substrate during DCB propagation. This method is firstly applied to measure the bonding strength of SiCN-SiCN under O₂ and N₂ activation. The test data shows that the bonding strengths are 3.53 J/m² and 2.93 J/m² with the deviations less than 3.84% and 1.84%. Based on the experimental data, finite element analysis (FEA) methods are used to simulate the crack propagation process of the PBC-DCB method. The results show that the bonding interface crack propagation can be accurately described by an optimized viscoelastic exponential model. The accuracy of simulation increased from 16.06% to 1.77%. Finally, it was found that the PBC-DCB method can solve the issue in conventional DCB where the crack may be initiated away from the target interface, therefore measuring the wrong interface. This advantage is further validated by simulations considering the offset of the PBC away from the bonding interface. Full article

(This article belongs to the Special Issue Advanced Electronic Packaging Technology: From Hard to Soft (Second Edition))

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26 pages, 9810 KB

Open AccessArticle

The Use of the Gliding Arc Plasma Technique to Deposit Fe or Mn Oxides on Fibrous Ceramic Supports for Reactions of Environmental Interest

by Sabrina Antonela Leonardi, Maximiliano Rodriguez, Eduardo Ernesto Miró, Eric M. Gaigneaux and Viviana Guadalupe Milt

Materials 2025, 18(24), 5479; https://doi.org/10.3390/ma18245479 - 5 Dec 2025

Abstract

The gliding arc plasma technique (glidarc) was used for the precipitation and deposition of Mn or Fe oxides on zirconia fibers. Two types of fibers were used: commercial (Fib Zr(C)) and biomorphic (Fib Zr(B)) ZrO₂ fibers, the latter produced using cotton as [...] Read more.

The gliding arc plasma technique (glidarc) was used for the precipitation and deposition of Mn or Fe oxides on zirconia fibers. Two types of fibers were used: commercial (Fib Zr(C)) and biomorphic (Fib Zr(B)) ZrO₂ fibers, the latter produced using cotton as a biotemplate. Both series of supported catalysts were characterized physicochemically and morphologically. Scanning Electron Microscopy (SEM) analyses showed that Fib Zr(B) largely retained the morphology of cotton. Fib Zr(B) presented the tetragonal phase (t-ZrO₂), while Fib Zr(C) exhibited the monoclinic phase (m-ZrO₂). Using X-ray Diffraction (XRD), the cryptomelane phase (K_xMn₈O₁₆) was identified only for Mn-Fib Zr(B). In the case of Fe-supported samples, the α-Fe₂O₃ phase appeared clearly in both biomorphic and commercial fibers. SEM and Transmission Electron Microscopy (TEM) images revealed that the precipitated iron oxides appeared to be better distributed than the manganese oxides, covering the outer surface of the fibrous supports more homogeneously. X-ray Photoelectron Spectroscopy (XPS) confirmed that Mn has an average oxidation state between 3+ and 4+, consistent with the cryptomelane phase detected by XRD. The synthesized supported systems were tested as catalysts in soot and CO oxidation, with the Mn-supported fibers proving to be more active than their Fe-containing counterparts in both reactions. Full article

(This article belongs to the Special Issue Advancements in Thin Film Deposition Technologies)

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22 pages, 10256 KB

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Comparative Study on the Wear Resistance of C&B-Type Polymer Materials for Temporary Crowns Manufactured Using 3D DLP Printing Technology

by Marcel Firlej, Daniel Pieniak, Andrzej Snarski-Adamski, Barbara Biedziak, Agata Niewczas, Jana Petru, Jonas Matijošius, Zbigniew Krzysiak and Katarzyna Zaborowicz

Materials 2025, 18(24), 5478; https://doi.org/10.3390/ma18245478 - 5 Dec 2025

Abstract

DLP (Digital Light Processing) 3D printing enables precise fabrication of temporary crowns. Tribological properties of these materials affect clinical durability, wear resistance, and masticatory function. This study compared three C&B-type photopolymers for DLP-printed temporary crowns: Gr-17.1 temporary It, Gr-17 temporary (Pro3dure), and VarseoSmile [...] Read more.

DLP (Digital Light Processing) 3D printing enables precise fabrication of temporary crowns. Tribological properties of these materials affect clinical durability, wear resistance, and masticatory function. This study compared three C&B-type photopolymers for DLP-printed temporary crowns: Gr-17.1 temporary It, Gr-17 temporary (Pro3dure), and VarseoSmile Temp (BEGO). Samples were printed, post-processed, and polished. Surface topography (Sa, Sz) was measured via white light interferometry, and scratch resistance was evaluated with a Rockwell indenter. Sliding wear tests under wet conditions (37 °C, 90% RH) were conducted using an SRV 4 tester at 25 N for 20,000 cycles. VarseoSmile Temp showed the highest scratch and sliding wear resistance, with the lowest mean volumetric wear (0.025 mm³) and residual scratch depth, reflecting its higher inorganic filler content (30–50 wt%). Gr-17.1 had the most stable coefficient of friction (~0.3), while Gr-17 experienced the greatest wear (0.235 mm³). No direct correlation between friction and wear was observed. These findings indicate that wear resistance depends on microstructure and filler content, supporting tribological testing as a tool to evaluate the durability of 3D-printed temporary crowns. Full article

(This article belongs to the Special Issue Evaluation of the Surface Topography, Abrasive Processing, and Precision Machining Technology and Applications)

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12 pages, 1648 KB

Open AccessArticle

Influence of Niobium Content on the Chemical Composition, Microstructure, and Microhardness of Hardfacing Coatings Applied by SMAW

by Jaime Perez, Jesus Gutierrez, Jhon Olaya, Oscar Piamba and Americo Scotti

Materials 2025, 18(24), 5477; https://doi.org/10.3390/ma18245477 - 5 Dec 2025

Abstract

This study investigates the chemical composition, microstructural evolution, and mechanical behavior of hardfacing coatings produced by Shielded Metal Arc Welding (SMAW) using electrodes with varying niobium (Nb) contents (0%, 2%, 4%, 6%, and 8%), deposited at a constant current of 120 A and [...] Read more.

This study investigates the chemical composition, microstructural evolution, and mechanical behavior of hardfacing coatings produced by Shielded Metal Arc Welding (SMAW) using electrodes with varying niobium (Nb) contents (0%, 2%, 4%, 6%, and 8%), deposited at a constant current of 120 A and employing two- and three-layer configurations. Optical Emission Spectroscopy (OES) revealed a significant reduction in niobium transfer efficiency, with the Nb content in the coatings reaching up to 3.5 wt%, approximately 50% lower than in the electrodes. Chromium (Cr) content also decreased with increasing Nb additions due to the higher thermochemical affinity of niobium for oxygen, which promotes the formation of Nb oxides during welding. X-ray diffraction (XRD) analyses confirmed the presence of complex carbides, primarily NbC and M₇C₃-type Cr carbides, embedded in eutectic austenitic matrices. The incorporation of niobium promoted grain refinement and the precipitation of primary NbC carbides, particularly in multilayer coatings where dilution effects were reduced. Scanning Electron Microscopy (SEM) and Energy-Dispersive Spectroscopy (EDS) provided additional evidence, revealing an increased density of NbC particles and a concomitant reduction in CrC particle size with higher Nb contents. Microhardness testing showed a slight increase in hardness with increasing niobium, attributed to the higher intrinsic hardness and finer size of NbC particles. Overall, these findings highlight the role of niobium as an effective grain refiner and hard-phase promoter in SMAW-applied coatings, providing a foundation for optimizing wear-resistant overlays for demanding industrial environments. Full article

(This article belongs to the Special Issue Microstructural and Mechanical Characteristics of Welded Joints)

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26 pages, 8789 KB

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Study on Preparation and Properties of Phosphogypsum-Based Lightweight Thermal Insulation Materials

by Yunpeng Chu, Tianyong Jiang, Han Huang, Gangxin Yi and Binyang Huang

Materials 2025, 18(24), 5476; https://doi.org/10.3390/ma18245476 - 5 Dec 2025

Abstract

At present, phosphogypsum, as an industrial by-product, is a solid waste in phosphoric acid production, and its accumulation has caused serious environmental pollution. Furthermore, due to the insufficient insulation properties of traditional wall materials, the issue of a rising proportion of building energy [...] Read more.

At present, phosphogypsum, as an industrial by-product, is a solid waste in phosphoric acid production, and its accumulation has caused serious environmental pollution. Furthermore, due to the insufficient insulation properties of traditional wall materials, the issue of a rising proportion of building energy consumption in total social energy consumption has become increasingly pressing. The study investigated vitrified beads as a light aggregate and phosphogypsum, mineral powder, and quicklime as an inorganic composite cementitious system to prepare the phosphogypsum-based lightweight thermal insulation material. The effect mechanism of the initial material ratio on the mechanical properties and micro-morphology of insulation materials was studied by macroscale mechanical property testing, X-ray diffraction, and scanning electron microscopy. Meanwhile, in order to meet the performance indexes specified in relevant standards, insulation materials were modified by adding sulfate aluminate cement, basalt fibers, and a waterproof agent to improve the strength, toughness, and water resistance. Based on the single-factor experimental design, the optimal dosage of various admixtures was obtained. The results indicated that the optimal properties of the sample were achieved when the binder–bead ratio was 1:4, the water–binder ratio was 1.6, the dosage of hydroxypropyl methylcellulose was 0.1%, and the solid content of waterborne acrylic emulsion was 24%. The optimal dosages of cement and fibers were 8% and 0.9%, respectively. The cement hydration products and gypsum crystals lapped through each other, filling the pores in the matrix and increasing the strength of the sample. In addition, the fibers could form a disordered network structure inside the matrix, disperse external force, weaken the stress concentration at the tip of internal cracks, and significantly improve the toughness of the modified sample. By incorporating 2.0% paraffin emulsion in the mortar and spraying 5 dilutions of sodium methyl silicate on the external surface, dense protective layers were formed both inside and outside the modified sample. The water absorption rate reduced from 30.27% to 23.30%, and the water resistance was increased to satisfy the specified requirement for the insulation material. Full article

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

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Materials, Volume 18, Issue 24 (December-2 2025) – 16 articles

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