Mechanical Resistance Properties Research Articles

Biological Macromolecule Hydrogel Based on Recombinant Type I Collagen/Chitosan Scaffold to Accelerate Full-Thickness Healing of Skin Wounds.

The development of biological macromolecule hydrogel dressings with fatigue resistance, sufficient mechanical strength, and versatility in clinical treatment is critical for accelerating full-thickness healing of skin wounds. Therefore, in this study, multifunctional, biological macromolecule hydrogels based on a recombinant type I collagen/chitosan scaffold incorporated with a metal-polyphenol structure were fabricated to accelerate wound healing. The resulting biological macromolecule hydrogel possesses sufficient mechanical strength, fatigue resistance, and healing properties, including antibacterial, antioxygenic, self-healing, vascularization, hemostatic, and adhesive abilities. Chitosan and recombinant type I collagen formed the scaffold network, which was the first covalent crosslinking network of the hydrogel. The second physical crosslinking network comprised the coordination of a metal-polyphenol structure, i.e., Cu2+ with the catechol group of dopamine methacrylamide (DMA) and stacking of DMA benzene rings. Double-crosslinked networks are interspersed and intertwined in the hydrogel to reduce the mechanical strength and increase its fatigue resistance, making it more suitable for clinical applications. Moreover, the biological macromolecule hydrogel can continuously release Cu2+, which provides strong antibacterial and vascularization properties. An in vivo full-thickness skin defect model confirmed that multifunctional, biological macromolecule hydrogels based on a recombinant type I collagen/chitosan scaffold incorporated with a metal-polyphenol structure can facilitate the formation of granulation tissue and collagen deposition for a short period to promote wound healing. This study highlights that this biological macromolecule hydrogel is a promising acute wound-healing dressing for biomedical applications.

Effect of Substrate Negative Bias on the Microstructural, Optical, Mechanical, and Laser Damage Resistance Properties of HfO2 Thin Films Grown by DC Reactive Magnetron Sputtering.

Hafnium oxide thin films have attracted great attention as promising materials for applications in the field of optical thin films and microelectronic devices. In this paper, hafnium oxide thin films were prepared via DC magnetron sputtering deposition on a quartz substrate. The influence of various negative biases on the structure, morphology, and mechanical and optical properties of the obtained films were also evaluated. XRD results indicated that (1¯11)-oriented thin films with a monoclinic phase could be obtained under the non-bias applied conditions. Increasing the negative bias could refine the grain size and inhibit the grain preferred orientation of the thin films. Moreover, the surface quality and mechanical and optical properties of the films could be improved significantly along with the increase in the negative bias and then deteriorated as the negative bias voltage arrived at -50 V. It is evident that the negative bias is an effective modulation means to modify the microstructural, mechanical, and optical properties of the films.

Potential improvement of clinker sand in the mechanical high temperature and transport properties with GGBS-based prepacked geopolymer composite

In this study, a new generation prepacked geopolymer composite (PGC) material that can meet different needs was obtained by combining geopolymer concrete (GPC) and prepacked aggregate concrete (PAC) technology. In the production of PGC, 5-8 mm quartz aggregates were placed in molds and, geopolymer mortar was injected between these aggregates. Aluminosilicate based blast furnace slag (GBFS) was used as binding in geopolymer mortars; sodium silicate (Na2SiO3) and sodium hydroxide (NaOH) was used as alkali activator. In addition, clinker aggregate in different proportions was used as fine aggregate (0–4 mm) in the production of mortar. Within the scope of the study, the physical, mechanical, permeability and high temperature resistance properties of PGC were investigated. The produced samples were cured at 30 and 60 °C for 6 and 8 hours. Hardened unit weights of PGC vary between 2342 and 2539 kg/m3, and sorptivity values vary between 0 and 0.04 kg/m2.min0.5. While the increase in curing temperature and curing time increases the hardened unit weight values, it decreased permeability values. While the increase of clinker aggregate in the mortar phase does not change the hardened unit weight, it significantly reduced permeability. When the PGC samples are cured at 30 °C, the compressive strengths are 20.38–39.03 MPa; when curing at 60 °C, the compressive strengths are 35.21–57.04 MPa. Flexural strengths, 2.35–6.96 MPa with 30 °C cure, achieved 4.27–9.93 MPa results with 60 °C curing. Increasing the curing time and curing temperature significantly increased the compressive and flexural strengths. The increase in the amount of clinker aggregate added to the mortar phase decreased the strength values. While the compressive strength values of PGC mixtures do not fall below 15 MPa after being exposed to 300 °C high temperature; after the application of 600 °C high temperature, it lost up to 70% of its strength. Increasing the curing time and curing temperature, increased the high temperature resistance. The increase in the amount of clinker aggregate in the mixtures, decreased the strength loss rate.

Effect of chitosan-based bio coating on mechanical, structural and physical characteristics of microfiber based paper packaging: An alternative to wood pulp/plastic packaging

Limnocharis flava is a noxious aquatic weed that poses a threat to paddy cultivation. The high cellulose and low lignin contents in this plant make it a potential raw material for papermaking. Against this backdrop, this study was taken up to develop Limnocharis flava (LF) based sheets containing natural fibres from Banana (B), Pineapple (P), and Rice Straw (RS) as reinforcing agents. The influence of carboxymethyl cellulose (CMC) as a binder on the LF-based sheets was also studied. To enhance the mechanical and moisture resistance properties, a chitosan coating was provided to the sheets. Analytical tests for mechanical properties, water barrier properties, functional groups, structure and microstructure, thermal properties and biodegradability were performed. Among the samples, LF + B showed the highest tensile strength (34.86 Mpa) and bursting strength (13.055 kg/cm2), while LF + R had higher puncture and tearing strengths. Chitosan coating was found to enhance the sheets and improve the water barrier properties mechanically. The contact angle of LF + B increased from 91.6° to 110.65°, while the water vapour transmission rate of LF reduced from 532.18 to 404.47 on providing chitosan coating. The significant interactions of reinforcing agents were confirmed by the results of FTIR and that of the coating by the SEM micrographs. The LF-based sheets were also found to have decent thermal stability. The high value of the crystallinity index in LF + R samples supported their remarkable mechanical properties. This study proclaims the notable suitability of Limnocharis flava in manufacturing paper for packaging applications.

Experimental Investigation on Comprehensive Performance of Natural Hydraulic Lime-Based Mortars: Effect of Waterproof Admixtures Addition

ABSTRACT In this study, the bulk modification method via incorporating two different types of waterproof admixtures was adopted to make natural hydraulic lime-based mortars more durable. The influence of two admixtures and their dosages on the hydration, physical, mechanical, and aggressive environment resistance properties were evaluated. The correlations between pore and water absorption characteristics, between hydration, pore characteristics, and mechanical strength were interpreted. Results showed that two waterproof admixtures changed the microscopic reaction between different components as well as internal structure of NHL-based mortar. Introduction of silane impregnant improved the workability of natural hydraulic lime-based mortars, and the appropriate dosage of silane impregnant facilitated hydration and improved mechanical strength at 28 and 90 days. Silane impregnant modified mortars were no more hydrophilic, acid resistance was improved while water absorption characteristics were not obviously improved even resulting in degraded freeze-thaw cycle resistance. Introduction of silicon-acrylic latex deteriorated the workability and retarded hydration of natural hydraulic lime-based mortars, regardless of dosage, leading to the degradation of mechanical strength. However, water absorption characteristics and freeze-thaw cycle and acid resistance can get a noticeable improvement when appropriate dosage was adopted.

A Comprehensive Review of Aluminium Matrix Composite Reinforced with hBN Particulates

Aluminum alloys are widely employed due to their advantageous combination of properties, including light weight, corrosion resistance, and mechanical strength. These alloys consist predominantly of aluminum with small additions of other elements aimed at enhancing specific characteristics. Ceramic reinforcements like hBN, SiC, Al2O3, and B4C are added to aluminum alloys to make better their mechanical and wear resistance properties. This practice is frequent and enhances the overall performance of the resulting composite materials. The addition of ceramic reinforcements, incorporated into an aluminum matrix, leads to improved strength and stiffness of the composite. This aspect is particularly advantageous in scenarios necessitating high mechanical strength, such as aerospace and automotive components. The review focuses on the effects of hexagonal boron nitride (hBN) reinforcement on composite materials, particularly aluminum alloys. It emphasizes that the properties of these composites can vary based on several factors, including particle size, weight percentage of hBN, and the processing techniques used. The key points addressed in the study include the impact of hBN reinforcement on mechanical behavior (strength and micro-hardness) and wear resistance behavior of the resulting aluminum alloy composites.

Investigating the material removal mechanism and cutting performance in ultrasonic vibration-assisted milling of carbon fibre reinforced thermoplastic

Carbon fibre reinforced thermoplastic (CFRTP) has emerged as a sustainable alternative to carbon fibre reinforced plastic (CFRP) due to its improved reparability and recyclability. CFRTP, particularly carbon fibre reinforced polyetheretherketone (CF/PEEK), is a high-performance material known for its excellent mechanical, thermal, and corrosion resistance properties, making it well-suited for extreme environments in civil aviation equipment. However, machining processes such as milling often result in defects due to the material’s high toughness and anisotropic nature. This study aims to investigate the material removal mechanism in ultrasonic-assisted milling (UAM) of CF/PEEK and compare the effects of fibre cutting angle (θ) and milling processes on milling performance. To simulate the fibre fracture mechanisms under different θ, finite element analysis (FEA) is employed. The results reveal different fracture modes, including bending, bending-shear, compression, and compression-shear, at various θ. Additionally, UAM demonstrates lower cutting forces and temperatures compared to conventional milling (CM). Notably, UAM greatly improves surface quality by reducing burr height and facilitating chip evacuation, while also enhancing surface integrity by minimizing cavity defects and fibre pull-out phenomena. These findings contribute to the development of low-damage machining methods that aim to achieve higher accuracy in CFRTP.

Structural performance of additive manufactured aluminum tubular stub columns

AbstractAluminum is gaining more popularity in the construction industry due to its light weight, mechanical resistance and corrosion properties. Although several studies covering extruded and cold‐rolled aluminium members exist, research into the structural performance of 3D printed aluminium remains scarce. With the increasing importance of digital engineering in the construction industry and the transition from traditional to digital lean, it is important to investigate whether existing design codes are suitable to design 3D printed cross‐sections. To address this, the present paper reports experimental results on additive manufactured aluminium tubular sections subjected to compression. The sections were manufactured by selective laser melting (SLM) and were made of AlSi10Mg which is a hardenable aluminium based casting alloy. The tubular sections have different thicknesses to cover a wide range of slendernesses. Tests on similar extruded aluminium tubular sections are also reported for comparison. Tensile tests were conducted on material coupons printed in different orientations (0° and 90°) to assess the potential effect of the orientation of printing on the material response. Full load‐deformation responses using digital image correlation (DIC) are reported and key experimental results are used to assess the local buckling design provisions given in EN 1999‐1‐1 for application to additive manufactured aluminum tubes.

Preparation and properties of PVC composites filled with walnut shell powder hybrid attapulgite

AbstractIn order to reveal the effect of alkali treatment of walnut shell (WS) powder and attapulgite (ATP) hybrid filling on the properties of WS/polyvinyl chloride (PVC) composites, and to compare the effects of different reinforcement methods, WS/PVC composites were prepared by single screw melt extrusion. Furthermore, analysis was conducted on the chemical composition, thermal stability, microstructure, and physical, mechanical and wear resistance properties of composites. The results showed that ATP hybrid can enhance the performance of WPC more effectively than alkali treatment, unmodified WS blended with ATP composites have the best physical, mechanical properties, abrasive wear resistance, as well as lower water absorption, compared with the untreated, the tensile strength, bending strength and impact strength increased by 24%, 8%, and 21%, respectively. In addition, the composites of ATP hybrid alkali treated WS have the best thermal stability, and its pyrolysis residue is 15.64% higher than untreated composites. The study found that ATP have a larger potential to enhance the properties of composites than alkali treatment.Highlights Chemical treatment and inorganic mineral particle filling were used to enhance the properties of the WS/PVC composites. The experimental results showed that attapulgite can maximize the properties of the composites without alkali treatment. This means that attapulgite filling is a more effective and environmentally friendly and simple method to enhance the properties of composites than alkali treatment. The wear failure modes of the composites are mainly micro‐indentation and micro‐cutting.

Effects of Additives on the Mechanical and Fire Resistance Properties of Pultruded Composites.

Under high temperatures, fiber-reinforced polymers are destroyed, releasing heat, smoke, and harmful volatile substances. Therefore, composite structural elements must have sufficient fire resistance to meet the requirements established by building codes and regulations. Fire resistance of composite materials can be improved by using mineral fillers as flame-retardant additives in resin compositions. This article analyzes the effect of fire-retardant additives on mechanical properties and fire behavior of pultruded composite profiles. Five resin mixtures based on vinyl ester epoxy and on brominated vinyl ester epoxy modified with alumina trihydrate and triphenyl phosphate were prepared for pultrusion of strip profiles of 150 mm × 3.5 mm. A series of tests have been conducted to determine mechanical properties (tensile, flexural, compression, and interlaminar shear) and fire behavior (ignitability, flammability, combustibility, toxicity, smoke generation, and flame spread) of composites. It was found that additives impair mechanical properties of materials, as they the take place of reinforcing fibers and reduce the volume fraction of reinforcing fibers. Profiles based on non-brominated vinyl ester epoxy have higher tensile, compressive, and flexural properties than those based on brominated vinyl ester epoxy by 7%, 30%, and 36%, respectively. Profiles based on non-brominated epoxy resin emit less smoke compared to those based on brominated epoxy resin. Brominated epoxy-based profiles have a flue gas temperature which is seven times lower compared to those based on the non-brominated epoxy. Mineral fillers retard the spread of flame over the composite material surface by as much as 4 times and reduce smoke generation by 30%.

Constructing lignin based nanoparticles towards flame retardant thermoplastic polyurethane composites with improved mechanical and oxidation resistant properties

A multifunctional lignin derivative nanoparticle (C-P-Lignin) was synthesized by grafting phenyl dichloro sphosphineoxid and 1, 4-dimethoxyacetylene stepwise on the lignin, then it was applied to prepare the thermoplastic polyurethane (TPU) composite with improved mechanical properties, oxidation resistance, and flame retardancy. The tensile strength, the elongation at break, and the toughness of the TPU/2C-P-Lignin sample reached 28.3 MPa, 941 %, and 139.0 MJ/m2 respectively, which were increased by 39.0 %, 3.4 %, and 33.9 % respectively compared with that of the control TPU sample. The anti-fatigue property was also improved. More importantly, the mechanism of the improved mechanical properties was also calculated and simulated by FTIR and Materials Studio software. The TPU/2C-P-Lignin sample exhibited superior oxidation resistance during the process of photoaging and thermal oxidative aging. Furthermore, the peak heat release rate and the smoke production rate for theTPU/2C-P-Lignin sample was reduced by 50.0 % and 53.8 % compared with that of the control TPU. The reason was that the C-P-Lignin is conducive to the formation of uniformly distributed carbon layers. It is expected that this work can provide a new method for expanding the utilization of waste wood as a multifunctional lignin-based filler to improve fire safety and extend the service life of TPU polymers.

Enhancement of the mechanical properties and water barrier properties of thermoplastic starch nanocomposite films by chitin nanofibers: Biodegradable coating for extending banana shelf life

Starch-based films have limited applications due to their hydrophilicity and poor mechanical performance. Herein, thermoplastic starch (TPS) nanocomposite films with chitin nanofibers (ChNFs) extracted from shrimp-shell waste were successfully fabricated using a solvent casting method. We investigated the effects of the ChNF loadings on the physical, mechanical, and water vapor barrier properties of the nanocomposite films. The well-dispersed ChNFs within the soft matrix associated with the formation of interfacial bonding between ChNFs and starch facilitated the efficient stress transfer from the soft matrix to the stiff ChNFs. Additionally, the presence of ChNFs created tortuous pathways within the films, which could impede the diffusion of water molecules. This resulted in a significant improvement in the mechanical properties, wettability, water resistance, and water vapor barrier properties of the nanocomposites. Compared to the results obtained from the neat TPS films, the TPS nanocomposites reinforced with ChNFs exhibited a 300% higher tensile stress, a 603% Young's modulus, and a considerable increase in the water contact angle, shifting from 86.2° to 98.6°. Furthermore, the ChNF-reinforced nanocomposite films showed no fragmentation after being soaked in water for 12 h under vigorous stirring, whereas the neat TPS films disintegrated under the same conditions. Interestingly, we found that coating a suspension of TPS and ChNFs on bananas effectively delayed their aging, preventing the color change from green to yellow. This promising result demonstrates the potential of the developed coating to extend the shelf life of fresh food produce, reducing food waste and the reliance on single-use petroleum-based packaging.

Evaluation of three-component boron-free glass fiber/TiO2/polyimide nanocomposite properties prepared by 3D turbula dispersion and spark plasma sintering method

Interest has grown in recent time on the development of three-component polymer nanocomposite with enhanced properties. However, the study focuses on the effect of TiO2 nanofiller on the mechanical, tribological, dielectric, and corrosion resistance properties of boron-free glass fiber (BGF) reinforced polyimide (PI) composite produced with spark plasma sintering route. Microstructure of the samples was examined using scanning electron microscopy. Mechanical, tribological, dielectric, thermal, and corrosion behaviour of the samples were characterized by nanoindenter, ball-on-disc, LCR meter, TGA, and potentiodynamic polarization test, respectively. The SEM results show that the introduction of the nanoparticles into the BGF/PI composite aids in more uniform distribution of the BGF particles within the PI matrix, and thus good interfacial interaction of the glass fiber and the PI matrix structure. Comparing the BGF/PI composite sample with BGF/TiO2/PI nanocomposite, it was observed that the nanocomposite depicted better hardness, elastic modulus, low friction coefficient and wear rate, dielectric, and enhanced corrosion properties. With TiO2 additions, hardness and modulus of the PI composite was improved by 56.6% and 10.1%, respectively. In addition, PI composites filled with TiO2 depicted a 0.07 coefficient of friction and wear rate of about 67.7% in reduction than that of neat PI and 9.0% in reduction than that of the pristine BGF/PI composites. Improved interactions between the reinforcements and the host matrix are suggested as the possible mechanism resulting to the desirable properties of the three-component PI nanocomposite recorded. Finally, the developed nanocomposite is suggested to be favourable for automobile, aerospace, and microelectronic device applications.

Electric-Field-Induced Alignment of Functionalized Carbon Nanotubes Inside Thermally Conductive Liquid Crystalline Polyimide Composite Films.

The positive liquid crystals, 4'-heptyl-4-biphenylcarbonitrile (7CB), are used to functionalize carbon nanotubes (LC-CNT), which can be aligned in the liquid crystalline polyimide (LC-PI) matrix under an alternating electric field to fabricate the thermally conductive LC-CNT/LC-PI composite films. The efficient establishment of thermal conduction pathways in thermally conductive LC-CNT/LC-PI composite films with a low amount of LC-CNT is achieved through the oriented alignment of LC-CNT within the LC-PI matrix. When the mass fraction of LC-CNT is 15 wt %, the in-plane thermal conductivity coefficient (λ∥ ) and the through-plane thermal conductivity coefficient (λ⊥ ) of the LC-CNT/LC-PI composite films reach 4.02 W/(m ⋅ K) and 0.55 W/(m⋅K), which are 90.5 % and 71.9 % higher than those of the intrinsically thermally conductive LC-PI films respectively, also 28.8 % and 5.8 % higher than those of the CNT/LC-PI composite films respectively. Meanwhile, the thermally conductive LC-CNT/LC-PI composite films also possess excellent mechanical and heat resistance properties. The Young's modulus and the heat resistance index are 2.3 GPa and 297.7 °C, respectively, which are higher than the intrinsically thermally conductive LC-PI films and the thermally conductive CNT/LC-PI composite films under the same amount of CNT.

Electric‐Field‐Induced Alignment of Functionalized Carbon Nanotubes Inside Thermally Conductive Liquid Crystalline Polyimide Composite Films

AbstractThe positive liquid crystals, 4′‐heptyl‐4‐biphenylcarbonitrile (7CB), are used to functionalize carbon nanotubes (LC‐CNT), which can be aligned in the liquid crystalline polyimide (LC‐PI) matrix under an alternating electric field to fabricate the thermally conductive LC‐CNT/LC‐PI composite films. The efficient establishment of thermal conduction pathways in thermally conductive LC‐CNT/LC‐PI composite films with a low amount of LC‐CNT is achieved through the oriented alignment of LC‐CNT within the LC‐PI matrix. When the mass fraction of LC‐CNT is 15 wt %, the in‐plane thermal conductivity coefficient (λ∥) and the through‐plane thermal conductivity coefficient (λ⊥) of the LC‐CNT/LC‐PI composite films reach 4.02 W/(m ⋅ K) and 0.55 W/(m⋅K), which are 90.5 % and 71.9 % higher than those of the intrinsically thermally conductive LC‐PI films respectively, also 28.8 % and 5.8 % higher than those of the CNT/LC‐PI composite films respectively. Meanwhile, the thermally conductive LC‐CNT/LC‐PI composite films also possess excellent mechanical and heat resistance properties. The Young's modulus and the heat resistance index are 2.3 GPa and 297.7 °C, respectively, which are higher than the intrinsically thermally conductive LC‐PI films and the thermally conductive CNT/LC‐PI composite films under the same amount of CNT.

Effect of tungsten doping on the irradiation resistance of FeCrV-based refractory medium entropy alloy for potential nuclear applications

Given the increasing demand for energy and the rising cost of fossil fuels, the development of nuclear fission and fusion reactors has become a key priority. Recently, High Entropy Alloys (HEAs) and Medium Entropy Alloys (MEAs) have emerged as promising materials for use in nuclear reactors due to their unique properties, which include significant lattice distortion, high configurational entropy, reduced diffusivity, and the cocktail effect. In this study, we designed and analysed a series of FeCrV-based Refractory Medium-entropy Alloys (RMEAs) as structural materials in fusion reactors, using Density Functional Theory. By calculating the empirical parameters, we have verified the solid solution's structure stability of the FeCrV-based RMEA. We examined the mechanical, electronic, and irradiation resistance properties of these alloys and found that the incorporation of tungsten dopants could enhance both the mechanical properties and irradiation resistance of the materials, with the optimal doping level being approximately 8% of Tungsten. Furthermore, electronic structure calculations were performed to elucidate the underlying mechanisms. This knowledge can guide the development of new HEA/MEA materials for use in nuclear reactors.

Effect of metakaolin and boron-carbide on the properties of magnetite, basalt and quartz concrete at different elevated temperatures

Nuclear buildings are important radiation-shielding structures. They must be shielded against radiation, fire, or heat during service life. Therefore, thermal properties and behaviour under elevated temperatures are essential in designing the nuclear structure. Furthermore, heavyweight concrete is essential for fire resistance in nuclear buildings. Mineral additives improve the physical, mechanical and fire resistance properties. The paper studied the influence of metakaolin and boron carbide additives on the thermal, mechanical and microstructural properties of magnetite, basalt and quartz concrete. Visual observations, residual mechanical properties and microstructural observations using (SEM) were studied at 20, 150, 300, 500 and 800 ℃. Results showed the enhancement of the compressive strength up to 300 ℃ upon using metakaolin and boron carbide additives. As well as metakaolin and boron carbide caused the spalling of magnetite concrete, where the compressive strength had shown a steep decline above 500 ℃. Furthermore, metakaolin and boron carbide positively influenced the strength properties of basalt and quartz concrete by reducing the permeability level and hindering the decomposition level of CSH. The Scanning Electron Microscopy (SEM) images associated the role of metakaolin and boron carbide in improving cement gel structure and reducing the decomposition level of the concrete.

Effect of Mg on Al-Mg Alloy and Electroless Ni-P Codeposition of nano-Al2O3: Mechanical, Wear, and Corrosion Resistance Properties

The addition of magnesium to Aluminum alloys has become increasingly popular due to their lightweight, high strength, and corrosion resistance properties. Our research on high-content Mg doped 90, Al-10 wt% Mg alloy has shown that coating it with electroless Ni-P and codepositing nano-Al2O3 (0, 2.5, 5 and 7.5 wt%) can significantly improve its mechanical properties, resistance to wear & tear, and even corrosion resistance. The electroless Ni-P-5 wt% Al2O3 composite displayed a wear rate of 0.65×10−3 g/m at 12 N, a microhardness value of 598 HV, and remarkable thermal shock resistance. A strong and uniform bond was formed between the coating and substrate, and no delamination or cracking was observed. Polarisation curves in 3.5 wt% NaCl solution showed that the corrosion potential of the 90, Al-10 wt% Mg alloy was higher than that of Ni-P and Ni-P-nano Al2O3 composites, indicating that the incorporation of nano-Al2O3 into the Ni-P electroless bath provides superior corrosion protection. This cost-effective and simple approach makes the Ni-P-5 wt% Al2O3 nanocomposite coating an ideal choice for shielding Al-Mg alloys from corrosion. HIGHLIGHTS We examine the magnesium content in Al-Mg alloy Electroless Ni-P-5 wt% Al2O3 coating could improve the anti-corrosion properties of Al-Mg alloy The thermal shock test showed that the alloy had good thermal stability Microhardness and wear resistance increase with the addition of nano Al2O3 particles The electroless Ni-P-5 wt% Al2O3 composite shows a wear rate of 0.65×10−3 g/m at 12 N GRAPHICAL ABSTRACT

Microstructural, Mechanical, and Electrochemical Characterization of CrMoNbTiZr High-Entropy Alloy for Biomedical Application.

High-entropy alloys (HEA) with superior biocompatibility, high pitting resistance, minimal debris accumulation, and reduced release of metallic ions into surrounding tissues are potential replacements for traditional metallic bio-implants. A novel equiatomic HEA based on biocompatible metals, CrMoNbTiZr, was consolidated by spark plasma sintering (SPS). The relative sintered density of the alloy was about 97% of the theoretical density, indicating the suitability of the SPS technique to produce relatively dense material. The microstructure of the sintered HEA consisted of a BCC matrix and Laves phase, corresponding to the prediction of the thermodynamic CALPHAD simulation. The HEA exhibited a global Vickers microhardness of 531.5 ± 99.7 HV, while the individual BCC and Laves phases had hardness values of 364.6 ± 99.4 and 641.8 ± 63.0 HV, respectively. Its ultimate compressive and compressive yield strengths were 1235.7 ± 42.8 MPa and 1110.8 ± 78.6 MPa, respectively. The elasticity modulus of 34.9 ± 2.9 GPa of the HEA alloy was well within the range of cortical bone and significantly lower than the values reported for commonly used biomaterials made from Ti-based and Cr-Co-based alloys. In addition, the alloy exhibited good resistance to bio-corrosion in PBS and Hanks solutions. The CrMoNbTiZr HEA exhibited an average COF of 0.43 ± 0.06, characterized mainly by abrasive and adhesive wear mechanisms. The CrMoNbTiZr alloy's mechanical, bio-corrosion, and wear resistance properties developed in this study showed a good propensity for application as a biomaterial.

Highly Enhanced Mechanical, Thermal, and Crystallization Performance of PLA/PBS Composite by Glass Fiber Coupling Agent Modification.

To improve the toughness and heat resistance of polylactic acid (PLA), polybutylene succinate (PBS) was sufficiently blended with PLA as the base matrix, and the glass fiber (GF) that was modified with 3-aminopropyltriethoxysilane (KF-GF) was added as the reinforcement. The results demonstrated a noteworthy boost in both mechanical and heat resistance properties when employing KH-GF, in comparison to pristine GF. When the content of KH-GF reached 20%, the tensile, flexural, and IZOD impact strength of the composites were 65.53 MPa, 83.43 MPa, and 7.45 kJ/m2, respectively, which were improved by 123%, 107%, and 189% compared to the base matrix, respectively. This enhancement was primarily attributed to the stronger interfacial adhesion between KH-GF and the PLA/PBS matrix. Furthermore, the Vicat softening temperature of the composites reached 128.7 °C, which was a result of increased crystallinity. In summary, the incorporation of KH-GF into PLA/PBS composites resulted in notable enhancements in their mechanical properties, crystallinity, and thermal characteristics. The high performance KH-GF-reinforced PLA/PBS composite showed a broad application potential in the field of biodegradable packaging, biodegradable textiles, and biodegradable plastic bags.