Resistance Performance Research Articles

Direct shear test on the interface between tunnel linings

AbstractThe lining interfaces of composite linings typically include two interfaces: the primary lining–secondary lining interface and the primary lining–waterproof layer–secondary lining interface. These interfaces are observed in Chinese highway tunnels with weak surrounding rock. In order to ascertain more effective measures to accommodate the deformations between tunnel linings, it is necessary to investigate the shear resistance performance of the interfaces and the factors that influence this performance. The samples are classified according to the presence or absence of waterproof layers, cohesive interfaces, and rough interfaces. Subsequently, direct shear tests are conducted under constant normal stress. The shear rate is 1 mm/min, and the normal stress is 0.5, 1.0, and 2.0 MPa, respectively. The results of the tests demonstrate that the shear properties are influenced by the normal stress, the waterproof layer, the cohesive interface and the rough interface. The shear resistance performance of the lining interface in the absence of a waterproof layer is observed to be superior to that observed with a waterproof layer. The normal compressive stiffness range for the primary lining‐secondary lining interface is observed to be between 0.69 and 3.17 GPa, with a pre‐peak shear stiffness range of 0.12–1.88 GPa. The effective cohesion range is found to be between 0 and 0.29 MPa, while the internal friction angle range is observed to be between 22.62° and 29.43°. In contrast, the normal compressive stiffness for the primary lining–waterproof layer–secondary lining interface is observed to be within the range of 1.24–9.78 GPa, the pre‐peak shear stiffness range is 0.45–39.68 GPa, the effective cohesion range is 0.07–1.98 MPa, and the internal friction angle range is 34.92°–52.24°. In conclusion, this investigation presents a number of potential measures that could be employed to enhance the shear resistance performance of tunnel lining interfaces. Furthermore, it furnishes a set of parameters derived from the test results that could serve as a foundation for subsequent research and design endeavors.

Effects of Laser Oscillation Frequency on the Microstructure and Properties of TiC/Fe‐Based Alloy Composite Coatings

Herein, TiC/Fe‐based alloys are melted and deposited on a 45‐steel substrate by using an oscillating laser with an 8‐shaped trajectory. Four samples are prepared to investigate the phase changes and microstructure characteristics using laser cladding under different oscillation frequencies. The microhardness, wear resistance, and electrochemical corrosion performance on both substrate and coatings are thoroughly evaluated. The results show that with TiC particles uniformly distributed throughout the coatings, the cladded coatings primarily composed of α‐Fe, (Cr, Fe)7C3, M2B (Cr, Fe), and TiC phases contribute to refined grains and enhanced mechanical strength; additionally, an increase in oscillation frequency leads to further grain refinement, which significantly improves the microhardness of coatings; however, higher hardness does not guarantee better wear resistance; the presence of cracks can actually decrease the coating's durability against wear. It is found that the coating with an oscillation frequency of 200 Hz not only achieves the best wear resistance, but also exhibits excellent electrochemical performance.

Effect of Different Surface Treatments on the Performance of Earth Plasters

Earth plasters have several advantages. Nevertheless, they are vulnerable when in contact with liquid water. For that reason, they have low durability when applied as an outdoor coating or in indoor areas with potential contact with water. In this study, the influence of six different surface treatments (traditional and innovative, based on raw materials and on waste) applied on a pre-mixed earth plaster, applied by a roller (r) or as a spray (s), was assessed. The treatments were: limewash (L), beeswax (BW), linseed oil (LO), graphene oxide dispersion (GO), water from paper immersion (WP) and water from gypsum plasterboard paper immersion (WPG). The application of L, BW and LO, despite the color change, improved the water resistance and the surface performance of the earth plaster (less than 80%–86%, 93%–98% and 97%–99% of mass loss from surface cohesion, from water erosion by dripping action and from dry abrasion, respectively, compared to the reference untreated plaster). However, the application of BW and LO had a negative effect on the hygroscopic capacity of the plaster (less than 28%–38% of water vapor adsorbed after 24 h and the MBV decreased 29%–50% compared to the reference plaster). Finally, the application of the remaining surface treatments did not significantly improve the characteristics of the plaster, having even worsened it in certain cases (more than 42%–149% of mass loss from water erosion, compared to the reference plaster). These results demonstrated that, among the treatments analyzed, the L, BW and LO treatments are the best options to apply on an earth plaster. In particular, the application of BW and LO are recommended in situations where it is necessary to improve water resistance and surface performance, and the hygroscopic capacity is not a conditioning characteristic, such as outdoor applications.

The Influence of Ti and Ni on the Microstructure, Wear Resistance, and Thermal Fatigue Performance of Laser Cladded Stellite 6 Coatings

The Influence of Ti and Ni on the Microstructure, Wear Resistance, and Thermal Fatigue Performance of Laser Cladded Stellite 6 Coatings

Unraveling Genetic Variation and Inheritance Patterns in Newly Developed Maize Hybrids for Improving Late Wilt Disease Resistance and Agronomic Performance Under Artificial Inoculation Conditions

Unraveling Genetic Variation and Inheritance Patterns in Newly Developed Maize Hybrids for Improving Late Wilt Disease Resistance and Agronomic Performance Under Artificial Inoculation Conditions

Transformation of Arsenic from Poison into Active Site by Construction of Unique AsOx/CeO2 Interface for Stable NOx Removal.

Arsenic in the flue gas has been widely reported as a common poison for SCR catalysts; however, an appropriate coping strategy is still lacking to improve the arsenic resistance performance. Herein, a unique AsOx/CeO2 interface is constructed to transform arsenic from poison into active site with balanced acid-redox property, successfully achieving efficient NOx removal. The optimized AsOx/CeO2 exhibits high NOx removal efficiency, four times that of the As-poisoned V2O5/TiO2 catalyst, and even comparable to the state-of-the-art SCR catalysts. It was found that the As-O-Ce interfacial sites in oxygen-bridged As dimers on CeO2 can provide both Lewis acid sites and active lattice oxygen species, enhancing the adsorption and activation of NH3 to form key -NH2 intermediates, thereby facilitating the NH3-SCR reaction. More surprisingly, a thin CeO2 layer on the top of V2O5/TiO2 can capture arsenic to protect catalysts from arsenic attacking, which improves the catalytic activity to 2.8 × 10-7 mol g-1 s-1, even higher than that of fresh V2O5/TiO2 (2.0 × 10-7 mol g-1 s-1). Therefore, this strategy provides new ideas not only for designing antipoisoning SCR catalysts but also a feasible solution for the stable operation of commercial SCR catalysts in arsenic-containing flue gas.

High-temperature resistance and thermal insulation performance of continuous SiMOC ceramic fibers fabricated by the modified sol-gel method combined with dry spinning

High-temperature resistance and thermal insulation performance of continuous SiMOC ceramic fibers fabricated by the modified sol-gel method combined with dry spinning

Enhanced performance of self-selective RRAM devices in V/TaOx/Pt structure

Abstract The performance of resistive random-access memory devices with vanadium as the top electrode and different TaOx insulating layer is investigated in this paper. The results indicate that the VO2 oxide layer generated by the oxidation of the vanadium electrode can serve as inherent selector, without the need for additional series selectors required in conventional methods. A large amount of oxygen vacancy migration was limited in the double insulating layers, enabling the device to achieve stable Self-Selective resistive random-access memory performance. This indicated that the advantage of the double insulation layers lay in manipulating the migration of oxygenions and vacancies. Endurance tests showed no degradation over 103 cycles, and the device maintained stability after 20,000 pulse applications. The subthreshold swing of the selector was less than 42 mV/dec, and the switching time was less than 2 μs. This research presents a promising advancement in resistive random-access memory technology with potential for high-density memory integration and reliable performance.

Graphene origami with enhanced impact resistance and energy absorption performance

The ancient art of origami has recently shown its potential in engineering intricate three-dimensional graphene structures with unique properties. This study employs molecular dynamics simulations to investigate the dynamic mechanical behavior of graphene origami structures (GOS) under hypervelocity ballistic impact. The analysis of residual velocity, kinetic energy loss, and specific penetration energy shows that GOS exhibit superior impact resistance and energy absorption performance compared with pristine graphene. One reason for the enhancements is that highly flexible GOS can unfold to produce a conical impact zone with larger out-of-plane deformation. Another reason is that three-dimensional folded regions possess more mass, enabling them to dissipate more kinetic energy from the projectile. The impact behavior of GOS is further analyzed concerning projectile size, impact position, and surface roughness. It is found that the impact resistance and energy absorption capacity of GOS can be adjusted by altering the surface roughness, specifically the folding degree and pattern geometry. This GOS holds promise for diverse applications in impact protection, such as combat armor and spacecraft shields.

Fabrication of Novel Polyurethane matrix-based Functional Composites with Enhanced Mechanical Performance

Thermoplastic polyurethane (TPU) has gained significant interest in several fields, including automobile steering wheels, and the electronics sector due to their easier processability, abrasive resistance, and self-lubricating performances. However, their strong inherent flammability and significant smoke and heat production during burning limit their industrial applications. Therefore, its applicability can be enhanced with the addition of high-strength reinforcement and making them antibacterial and flame-retardant. This research is designed to examine the influence of zirconium phosphate (ZrP) and zinc oxide (ZnO) nanoparticles on the novel polyurethane/glass fiber reinforced composites for flame retardant and antibacterial applications with improved mechanical performance. Three different types of novel polyurethane (PU1, PU2, PU3) matrices were prepared using different recipes, and 7% ZrP and 5% ZnO nanoparticles were added to the polyurethane matrices separately, and their corresponding composite samples were fabricated using glass reinforcement. Mechanical i.e., Charpy impact, hardness and tensile, and functional i.e., flame retardancy (FR) and antibacterial tests were performed to compare their performance. Mechanical testing results showed that PU3-based composite samples showed the highest values of impact force, hardness, and tensile strength in both ZrP and ZnO nanoparticle-based composite samples. Furthermore, 7% ZrP-PU3 composite exhibited the best performance of flame retardancy due to the presence of hexamethylene diisocyanates (HDI) content. Likewise, the 5% ZnO-PU3-based composite exhibited the highest antibacterial activity along with enhanced mechanical performance.

Preparation of a novel laser cladding Ni-based alloy with promising applications in high-temperature conditions: Genetic design, multi-phase evolution, and synergy mechanism

Developing novel Ni-based alloys is crucial for remanufacturing key friction parts at 800-1200 ℃ in metallurgical industry with multiple failure mechanisms, such as wear, corrosion, and adhesion. This paper adopts genetic algorithm to design high-temperature Ni-based alloy with three genetic structures of wear resistance, anti-corrosion, and self-lubricating. By combining simulation calculation and experimental methods, the evolution of the three genetic structures of the laser cladding alloy and the performance strengthening mechanism were deeply studied. The laser clad Ni17Cr10Co7Al5Ti3W2C1S sample of optimized composition had three genetic structures: Cr7C3/TiC wear resistance phases, γ/γ′ anti-oxidation and anti-corrosion phases, Ti2SC/TiS self-lubricating phases. Compared with Cr28Ni48W5 superalloy, the wear rate of the optimal sample was 2.31×10-5 mm3/(N·m) under 800 ℃ friction condition, and reduced by 97%. The friction coefficient of the sample at high temperature was 0.2, approximately half of the substrate alloy, and the self-lubricating performance was significantly improved. Electrochemical tests indicated that the polarizing potential of the sample was -0.16 VSCE in 3.5wt. % NaCl solution. The mechanism of three genetic structures evolution and synergistic enhanced wear resistance, anti-corrosion, and self-lubricating properties were elaborated. Specifically, the key gene of Ti2SC plays a profound role in improving the high-temperature wear resistance and self-lubricating performance of the novel laser clad Ni-based alloy sample. These findings present a novel avenue of material design and preparation for laser additive manufacturing and remanufacturing of key friction parts with high-performance at 800-1200 ℃ in complex metallurgical working conditions.

Promising honeycombed cork activated carbon for high desalination performance brackish water treatment

Cork activated carbon (CAC), derived from natural cork, was successfully prepared through two steps of carbonation and activation, and used for desalinating brackish water. The CAC presents a uniform honeycomb structure composed of porous carbon nanoflakes (200–300 nm) and large specific surface area (SSA) (2680 m2 g−1), offering transport channels and a large number of adsorption sites to NaCl solution. The CAC showed excellent capacitance (116 F g−1), small internal resistance and better charge-discharge performance. Moreover, the optimized CAC showed high desalting capacity (9.44 mg g−1), charge efficiency (46.72 %), and lower energy consumption (54.19 Wh m−3) in the desalination process, superior to that of the reported biomass-based activated carbons, which can be attributed to the stable honeycomb structure, high microporous volume (0.86 cm3·g−1) and large pore size (2.43 nm). This investigation demonstrates the potential application of cork granules-based CAC electrodes in the field of desalination.

Lightweight, thermally insulating SiBCN/Al2O3 ceramic aerogel with enhanced high-temperature resistance and electromagnetic wave absorption performance

Owing to tunable dielectric properties, light weight and high porosity, polymer-derived SiBCN ceramic aerogels possess significant application prospects in electromagnetic wave (EMW) absorption and thermal insulation. However, due to inadequate oxidation resistance, the structural collapse and performance deterioration of SiBCN aerogels will easily occur in high-temperature aerobic environments, limiting their application. Herein, to address this issue, a novel and straightforward strategy based on typical polymer-derived-ceramic (PDC) aerogel method and impregnation with boehmite sol was proposed for synthesizing SiBCN/Al2O3 composite ceramic aerogels. The microstructure, phase composition, thermal insulation, oxidation resistance and EMW absorption properties of SiBCN/Al2O3 ceramic aerogels were investigated. The resulting SiBCN/Al2O3 composite aerogel demonstrates superior high-temperature structural stability, exhibiting an ultra-low linear shrinkage of only 6.5 % following heat treatment at 1200 °C for 2 h in air. Additionally, the composite aerogel shows a low thermal conductivity of 0.039 W/mK and a low density of 0.112 g/cm3. The SiBCN/Al2O3 composite aerogel, composed of dielectric SiBCN, conductive free carbon, and insulating alumina, demonstrates outstanding EMW absorption properties with a minimum reflection loss of −48.6 dB and an effective bandwidth of 5.8 GHz. The enhanced microwave absorption performance is mainly attributed to the improved impedance matching, multiple reflection, and enhanced interfacial polarization resulting from the introduction of Al2O3. Given prominent oxidation resistance, thermal insulation and EMW absorption properties, the SiBCN/Al2O3 composite aerogel paves the way for developing microwave absorption and thermal insulation integrated material in high-speed vehicles.

HfC–HfO 2modified high/superhigh temperature thermal protection coating for superior hot corrosion resistance and anti-oxidation performance

HfC–HfO ₂modified high/superhigh temperature thermal protection coating for superior hot corrosion resistance and anti-oxidation performance

Effect of aged treatment on improving the performance of HVAF WC–Cr3C2–Ni coating on crystallization roller

The thermal shock resistance and high-temperature performance of WC–Cr3C2–Ni coatings on the surface of the crystallization roll after aged treatment were investigated in this study. The aging treatment at 320 ℃ for 2.5 h facilitated the diffusion of Cu element from the C17200 beryllium copper substrate toward the coating side of WC–Cr3C2–Ni coating, thereby enhancing the bonding between the coatings and substrates. After the aged treatment, the internal structure of the C17200 substrate changed from a dendritic structure to an equiaxed crystal structure, the hardness increased from 225.71 Hv0.5 to 406.52 Hv0.5 (80.4 % increased), and the wear resistance increased.Although the aging treatment reduced the hardness of the coating slightly (from 1257.58 Hv0.5 to 1155.16 Hv0.5, a decrease of 8.1%) and wear resistance (the coefficient of friction, from 0.335 to 0.312, a decrease of 6.9%). However, in the thermal shock test, the thermal shock resistance of the coating after aging treatment was increased from 19 times to 20 times (5.3% increased). However, the thermal shock failure cracks between the coatings and the substrates were transferred from the substrate part to the joint part of the two, which effectively avoided the waste of the crystallization roller substrate in the maintenance process. This research effectively reduces the purchase and maintenance costs of steel mills in actual production and provides theoretical support for cost reduction and efficiency increase in other HVAF (high-velocity air fuel) coating applications.

Tannin-based non-isocyanate polyurethane wood adhesive rich in complicated cross-linked networks with ultra-strong bonding property and excellent water resistance by introducing poly-urea structure

Developing of bio-based wood adhesives is an inevitable common topic in the development at top speed of wood industry. Herein, a bio-based tannin wood adhesive, named as tannin-based non-isocyanate polyurethane-urea (TNIPU-U), was designed which showing a ultra-strong adhesion and water resistance performance by two-step approach. A plausible mechanism was proposed, which implied that urea acted as the crosslinker to connect with derived intermediates containing free amino groups rooted from the reaction of tannin, dimethyl carbonate (DMC), and HMDA, to introduce urea linkages in traditional TNIPU. Furthermore, addition of urea to act as a trapping agent to capture excessive free HMDA in TNIPU adhesive, promoting additional polyurea formation, leading to avoidance of its emission during the hot-pressing process. This will convert the imperfection of TNIPU to a superiority by a eco-friendly strategy. The complicated cross-linked networks will be obtained that are rich in physical entanglement, covalent bonds, and hydrogen bonds. Compared with the TNIPU, the shear strength of TNIPU-U adhesive, after soaked in hot water and boiling water for 3 h, exhibited increase by 17.88 % and 34 %, respectively, indicating the potential for use under harsher conditions. Moreover, the TNIPU-U adhesive exhibits an excellent bonding performance (1.93 MPa) that greatly exceeds the China National Standard (GB/T 9846–2015, ≥ 0.7 MPa) requirement for exterior-grade plywood type I. It is comparable to commercial phenol-formaldehyde resin on the aspect of water tolerance. It can be applied to particleboard preparation and bamboo bonding as well, showing a well-adopted feature. This study provides an efficient, low-cost, and sustainable strategy for high performance bio-based wood adhesives.

Enhanced mechanical properties and oxidation resistance in Ti-rich medium entropy alloy via Al2O3 addition

Lightweight high/medium entropy alloys (H/MEAs) have attracted significant attention for their potential applications in lightweight high-temperature materials. Incorporation of oxides or oxygen atoms is an effective strategy for enhancing the mechanical and oxidation resistance performance of H/MEAs. Therefore, this work investigated the microstructure, phase compositions, mechanical properties, and oxidation resistance of Ti-V-Cr medium entropy alloys with varying Al2O3 oxide content. The results showed a notable improvement in mechanical performance and enhanced oxidation resistance with the addition of Al2O3. The incorporation of Al2O3 oxides contributed to fine grain strengthening, interstitial strengthening, phase separation and transformation, collectively enhancing performance of the alloy. The 0.6 wt.% Al2O3-added Ti-25V-15Cr alloy achieved a balance between strength and ductility, with a density of 5.111 g/cm3, a yield strength of 1371 MPa, and a plasticity exceeding 40%, even in the as-cast state. The 1.2 wt.% Al2O3 alloy exhibited a high yield strength of 1471 MPa and plasticity over 15%. Additionally, the 0.6 wt.% Al2O3-added alloy displayed superior oxidation resistance at 700 °C. The incorporation of Al2O3 did not change the oxidation mechanism of the Ti-25V-15Cr alloy but reduced the oxidation extent on the surface by forming oxides of the same type with varying morphologies.

Skid Resistance Performance Analysis and Driving Safety Evaluation in the Full Life Cycle of Asphalt Pavement

Skid Resistance Performance Analysis and Driving Safety Evaluation in the Full Life Cycle of Asphalt Pavement

Research on thermal resistance Performance: Broadband solar absorber based on laminated circular ring − disk microstructure

This paper presents a laminated circular-ring-disk (CRDS) solar microstructure absorber constructed based on heat-resistant metals. This absorber achieves an ultra-broadband absorption with a bandwidth of 2171.68 nm in the near-ultraviolet to mid-infrared band, and has three absorption peaks with absorption rates exceeding 96 %, with peak wavelengths of 342.09 nm, 1215.40 nm, and 2032.86 nm respectively. With the finite-difference time-domain method (FDTD), we detected that the average absorption efficiency of this absorber under Atmospheric mass of 1.5(AM 1.5) conditions is as high as 96.05 %, and the average energy loss is only 3.95 %. Meanwhile, the research results of the electric field distribution of the CRDS microstructure show that CRDS effectively promotes the surface plasmon resonance effect between the laminated metal materials. Combined with the research on the top micro-absorption structure materials, we finally determined the structural parameters of the CRDS structure absorber and selected heat-resistant metals nickel (Ni), chromium (Cr), and titanium (Ti). On this basis,we focused on the thermal radiation performance of the absorber and found that it has good adaptability to high-temperature environments. Finally, by comparing the Transverse Electric Wave(TE) and Transverse Magnetic Wave(TM) polarization conditions with the sweep parameter diagrams of 0°-60°, we found that the absorber has excellent angle insensitivity. In view of the above discussions, the CRDS microstructure absorber has good thermal stability, angle insensitivity, and can achieve ultra-broadband perfect absorption from the near-ultraviolet to the mid-infrared band, and has broad application prospects.

A simple strategy to significantly improve the anticorrosion and aging resistance of epoxy coatings by adding polyaniline modified multi-walled carbon nanotubes

Epoxy coatings are widely used for corrosion protection of metals, but under extremely harsh environments, the epoxy polymer chains such as the C-O bonds of epoxy ether and aromatic ether, and the -OH in the epoxy chain structure can also undergo aging and degradation, leading to the failure of the coating in service. How to extend the anti-aging capability of epoxy resins while maintaining their other properties unchanged has become a major challenge in the practical application of epoxy coatings. In this study, the polyaniline (PANI) modified multi-walled carbon nanotubes (MWCNT@PANI) were synthesized by polymerization in-situ and added to epoxy resin as an anti-aging filler. The various measurements have been adopted to characterize the composition and structure of MWCNT@PANI, and the anticorrosive performance of the composite coating for carbon steel were evaluated via salt spray, chemical aging and UV light aging. Results showed that the impedance value of the blank epoxy coating decreases by at least two orders of magnitude after the salt spray tests, and the contact angle decreases by about 30° and gradually changes from hydrophobic to hydrophilic, indicating a significant decline in corrosion resistance. In contrast, the composite coating confirmed the excellent anti-aging performance, while the impedance values increased by approximately 2-5 orders of magnitude compared to that in blank epoxy coatings, and remained around 1010 Ω·cm2. Given the dense encapsulation of MWCNT@PANI, the dispersion stability between the filler and EP can be improved, and the effective corrosion resistance performance was also supported by molecular dynamic simulation. Besides that, the ability of free radical quenching along with the labyrinth effect and hydrophobic interaction have also been investigated to explain the anticorrosion and anti-aging mechanism.