Topic Editors

Prof. Dr. Filippo Berto
Renowned Chair and Distinguished Professor of Mechanics of Materials, Sapienza University of Rome, Rome, Italy
Dr. Ricardo Branco
Department of Mechanical Engineering, CEMMPRE, University of Coimbra, 3030-788 Coimbra, Portugal
Dr. Yanxin Qiao
School of Materials Science and Engineering, Jiangsu University of Science and Technology, Jiangsu 212003, China

Surface Treatments for Protecting from Fracture and Fatigue Damage

Abstract submission deadline
closed (10 April 2022)
Manuscript submission deadline
closed (10 July 2022)
Viewed by
36494

Topic Information

Dear Colleagues,

The present topic intends to promote research in the field of protection against fatigue and fracture by employing conventional and innovative surface treatments or coatings. Particularly in critical environments, this allows mitigation of the problems related to the initiation and subsequent propagation of cracks that can decrease the life of structural components. The aim of the Special Issue is to update on the state of the art in this regard, providing readers with useful information on recent technologies. The effect of these surface treatments at different scales is also of interest.

Prof. Dr. Filippo Berto
Prof. Dr. Ricardo Branco
Prof. Dr. Yanxin Qiao
Topic Editors

Keywords

  • fatigue
  • fracture
  • microstructure
  • surface treatments
  • advanced coatings

Participating Journals

Journal Name Impact Factor CiteScore Launched Year First Decision (median) APC
Coatings
coatings
3.236 3.9 2011 13.5 Days 2200 CHF
Materials
materials
3.748 4.7 2008 13.9 Days 2300 CHF
Polymers
polymers
4.967 5.7 2009 12.4 Days 2400 CHF
Metals
metals
2.695 3.8 2011 16.9 Days 2000 CHF

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Published Papers (27 papers)

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Article
Fatigue and Life Prediction of S135 High-Strength Drill Pipe Steel under Tension–Torsion Multiaxial Loading
Coatings 2022, 12(8), 1222; https://doi.org/10.3390/coatings12081222 - 21 Aug 2022
Viewed by 737
Abstract
This paper investigates the fatigue behavior of S135 high-strength drill pipe steel under tension–torsion multiaxial loading. Based on the concept of critical plane during fatigue, the fatigue model under the combined loading of tension–torsion is established. The proposed model is validated, and the [...] Read more.
This paper investigates the fatigue behavior of S135 high-strength drill pipe steel under tension–torsion multiaxial loading. Based on the concept of critical plane during fatigue, the fatigue model under the combined loading of tension–torsion is established. The proposed model is validated, and the predicted results are in good agreement with the experimental testing results. The maximum relative errors between the estimation and the experiment are mostly within the range of factor two to three for proportional, and 90° non-proportional tension–torsion loading. Meanwhile, the failure mechanism is also discussed through fracture analysis. Full article
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Article
Effects of Deep Rolling on the Microstructure Modification and Fatigue Life of 35Cr2Ni4MoA Bolt Threads
Metals 2022, 12(7), 1224; https://doi.org/10.3390/met12071224 - 20 Jul 2022
Cited by 3 | Viewed by 739
Abstract
Stress concentration on a bolt thread, resulting from its own special shape, poses a threat to the fatigue strength of the bolt, which directly affects the safety and reliability of aircraft. In this paper, deep rolling was applied to a bolt thread to [...] Read more.
Stress concentration on a bolt thread, resulting from its own special shape, poses a threat to the fatigue strength of the bolt, which directly affects the safety and reliability of aircraft. In this paper, deep rolling was applied to a bolt thread to improve its fatigue resistance. The properties of the plastic deformation layer, including the surface morphology, microstructure, hardness, and residual stress, as well as the fatigue life of the bolt, were characterized by means of SEM, white light interferometer, EBSD, and fatigue tests. The results showed that the surface roughness of the bottom of the thread was reduced to 0.255 μm, and a plastic deformation layer of about 300 μm in depth was formed after rolling. A more compact streamlined fibrous microstructure, composed of refined grains, with increased dislocation density and hardness and decreased tensile residual stress, was formed in the plastic deformation layer. The fatigue life of the bolts after rolling increased by about 113%, evidencing the comprehensive result of these microstructure modifications. Full article
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Article
Laboratory Assessment of Selected Protective Coatings Applied on Two Sandstone Types
Coatings 2022, 12(6), 761; https://doi.org/10.3390/coatings12060761 - 01 Jun 2022
Cited by 1 | Viewed by 846
Abstract
The efficiency of three commercial hydrophobic coatings applied on two types of sandstones was subjected to the tests of water absorption by capillarity, water absorption by complete immersion, and frost resistance. Two days of the curing time of coatings on samples were chosen [...] Read more.
The efficiency of three commercial hydrophobic coatings applied on two types of sandstones was subjected to the tests of water absorption by capillarity, water absorption by complete immersion, and frost resistance. Two days of the curing time of coatings on samples were chosen for the laboratory tests. The effects of the used coatings were different (ambiguous). Two coatings proved their effectiveness and thus, relevance of their use, but different coatings were effective on each type of sandstone. The coating F showed the best efficiency for the Hořice sandstone and coating A for the Malé Skalky sandstone. The third testing coating H was ineffective on both types of sandstone. The water absorption tests by capillarity showed a loss of the coating effectiveness over time. By completely immersing the samples in water, all three coatings lost their effectiveness and the hydrophobic effects disappeared. Applied protective coatings helped to preserve the frost resistance of the Hořice sandstone when looking at the uniaxial compressive strength after 25 freeze–thaw cycles, regardless of their fading hydrophobic effect. In addition, a penetration depth test for Hořice sandstone was performed. The impregnation depth reflects the effectiveness of the coatings and confirmed the results obtained by the water absorption tests by capillarity. The findings presented in the article are also useful in practice, as Hořice sandstone will be mined and frequently used in the future as well. Full article
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Article
The Effect of Temperature Cycling on the Magnetic Degradation and Microstructure of a Zn-Coated NdFeB Magnet
Coatings 2022, 12(5), 660; https://doi.org/10.3390/coatings12050660 - 12 May 2022
Cited by 1 | Viewed by 899
Abstract
Temperature cycling tests in various temperature ranges were carried out to investigate the magnetic degradation of the Zn-coated NdFeB magnet. The losses of the surface magnetic field and magnetic flux were well fitted by using an index model. Compared with the lower limit [...] Read more.
Temperature cycling tests in various temperature ranges were carried out to investigate the magnetic degradation of the Zn-coated NdFeB magnet. The losses of the surface magnetic field and magnetic flux were well fitted by using an index model. Compared with the lower limit temperature, the upper limit temperature had more obvious effect on the magnetic degradation. Once the upper limit temperature exceeded ≥160 °C, the magnetic degradation mainly occurred during the first cycle, which was different from the gradual decline with an increase in cycle number at a temperature of ≤140 °C. Moreover, the temperature cycling with a maximum upper limit temperature of 180 °C led to a loss of the remanence intensity, while the coercivity remained stable. Microstructure and element distribution analysis revealed that the oxidation of the Zn coating layer during the temperature cycling causes its cracking and an insertion of the oxygen element into the NdFeB substrate. The Nd-, Pr-rich phase at grain boundaries provided diffusion channels for oxygen elements, leading to a surface oxidation of NdFeB grains. Full article
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Article
Enhanced Erosion Resistance of an Ultrafine-Grained Ti Alloy with a PVD Coating
Metals 2022, 12(5), 818; https://doi.org/10.3390/met12050818 - 09 May 2022
Viewed by 863
Abstract
This paper presents the results of a comprehensive study of the erosive wear resistance, strength, and adhesive characteristics of the high-temperature structural titanium alloy Ti-5.7Al-3.8Mo-1.2Zr-1.3Sn (the Russian grade VT8M-1) with coarse-grained and ultrafine-grained (UFG) structures and a protective erosion-resistant TiVN coating produced by [...] Read more.
This paper presents the results of a comprehensive study of the erosive wear resistance, strength, and adhesive characteristics of the high-temperature structural titanium alloy Ti-5.7Al-3.8Mo-1.2Zr-1.3Sn (the Russian grade VT8M-1) with coarse-grained and ultrafine-grained (UFG) structures and a protective erosion-resistant TiVN coating produced by physical vapor deposition (PVD), deposited on the alloy surface. A microscopic analysis of the areas subjected to the action of abrasive particles was performed, and different characters of erosive wear were revealed depending on the structural state of the alloy. The obtained results convincingly demonstrate that by means of refining the grain structure of alloys and depositing a protective ion-plasma TiVN coating on the alloy surface, it is possible to significantly increase the erosion resistance of materials operating under high loads and in aggressive environments. Full article
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Article
Aging Analysis of Thermally Aged Asphalt Using Peak-Fitting Method: Its Pattern and Statistical Prediction
Coatings 2022, 12(5), 582; https://doi.org/10.3390/coatings12050582 - 24 Apr 2022
Viewed by 904
Abstract
In this study, the peak fitting method was proposed to deal with and analyze the thermally aged pattern and statistical prediction of asphalt in order to reduce the calculation accuracy caused by overlapping and partial overlapping of infrared spectrum peaks. The aromatic functional [...] Read more.
In this study, the peak fitting method was proposed to deal with and analyze the thermally aged pattern and statistical prediction of asphalt in order to reduce the calculation accuracy caused by overlapping and partial overlapping of infrared spectrum peaks. The aromatic functional group index, aliphatic branch chain index, aliphatic functional group index, butadiene functional group index, styrene index and carbonyl functional group index were used to evaluate the aged asphalt. The piecewise fitting method of OriginPro 9.0 was proposed to investigate the thermally aged pattern of asphalt based on the peak fitting method. From the testing results, after the process of thermal aging, the aromatic functional group index and carbonyl functional group index increased, the aliphatic branch chain index, aliphatic functional group index and butadiene functional group index decreased, and the styrene index was stable. Taking the carbonyl functional group index as the research object, the thermally aged pattern of asphalt based on the peak fitting method conformed to the two-reaction kinetic model and the aging process consists of a fast-rate reaction period and constant-rate reaction period, where the coefficients of determination are all above 0.91. These results show that the pattern and statistical prediction of thermally aged asphalt by infrared spectrum illustrate rapidly for a time and then develop at a relatively constant speed, which corresponds to the road performance of asphalt aging. Therefore, the aging condition of asphalt can be evaluated, which has important theoretical significance to predict the aging state of asphalt and accurately grasping the road aging state. Full article
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Article
Research on Meshing Gears CIMT Design and Anti-Thermoelastic Scuffing Load-Bearing Characteristics
Materials 2022, 15(6), 2075; https://doi.org/10.3390/ma15062075 - 11 Mar 2022
Viewed by 1221
Abstract
In the process of gear meshing, it is an inevitable trend to encounter failure cases such as contact friction thermal behavior and interface thermoelastic scuffing wear. As one of the cores influencing factors, the gear meshing contact interface micro-texture (CIMT) significantly restricts the [...] Read more.
In the process of gear meshing, it is an inevitable trend to encounter failure cases such as contact friction thermal behavior and interface thermoelastic scuffing wear. As one of the cores influencing factors, the gear meshing contact interface micro-texture (CIMT) significantly restricts the gear transmission system (GTS) dynamic characteristics. This subject suggests the contact characteristic model and interface friction dynamics coupling model of meshing gear pair with different CIMT. Considering the influence of gear meshing CIMT on distribution type of hydrodynamic lubricating oil film, contact viscous damping and frictional thermal load, the aforementioned models have involved transient meshing stiffness (TMS) and static transmission accumulated error (STAE). Based on the proposed models, an example verification of meshed gear pair (MGP) is analyzed to reveal the influence of CIMT on the dynamic characteristics of GTS under a variety of micro-texture configurations and input branch power and rated speed/shaft torque conditions. Numerical simulation results indicate that the influence of CIMT on gear dynamic response is extremely restricted by the transient contact regularity of the meshing gear surface. Meshing gears’ dynamic characteristics (especially vibration and noise) can be obviously and effectively adjusted by setting a regular MGP with CIMT instead of random gear surfaces. Full article
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Article
Research on Dynamic Performance of CRTSⅢ Type Slab Ballastless Track under Long-Term Service
Materials 2022, 15(6), 2033; https://doi.org/10.3390/ma15062033 - 10 Mar 2022
Cited by 3 | Viewed by 1097
Abstract
To fill the blank in the research on the dynamic performance of track structure under long-term service, the dynamic response study of China Railway Track System Ⅲ type slab ballastless track (CRTSIII SBT) under the action of fatigue for 30 million times and [...] Read more.
To fill the blank in the research on the dynamic performance of track structure under long-term service, the dynamic response study of China Railway Track System Ⅲ type slab ballastless track (CRTSIII SBT) under the action of fatigue for 30 million times and the parting between track slab and self-compacting concrete (SCC) was carried out. By establishing the finite element model of the CRTSIII SBT structure and taking the stiffness change of isolation layer and fastener under fatigue state and the parting during service as the research objects, combined with the full-scale model test, the dynamic response amplitude and vibration law of track structure was analyzed based on the finite element model of axle falling test method. The results show the following: (1) Under the fatigue load, the acceleration of rail and base increases obviously, the longitudinal tensile stress of SCC surface decreases, the longitudinal tensile stress of base surface increases, and the vertical stress of each layer of track structure increases as well. (2) Under the action of the parting, the dynamic response of each structural layer increases, and the change of acceleration and stress of each layer under the action point of axle falling is the most obvious. (3) The fatigue load will weaken the vibration damping performance of the track, and the parting will continue to develop under the action of the falling axle, resulting in partial or total failure of the SCC layer. Both of them will aggravate the dynamic response of the track structure and affect driving safety, which should be paid attention to during maintenance. Full article
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Article
The Effect of Surface Substrate Treatments on the Bonding Strength of Aluminium Inserts with Glass-Reinforced Poly(phenylene) Sulphide
Materials 2022, 15(5), 1929; https://doi.org/10.3390/ma15051929 - 04 Mar 2022
Cited by 2 | Viewed by 1064
Abstract
Materials composed of a polymer matrix reinforced with carbon/glass fibres providing lightweight and superior mechanical properties are widely used as structural components for automotive and aerospace applications. However, such parts need to be joined with various metal alloys to obtain better mechanical performance [...] Read more.
Materials composed of a polymer matrix reinforced with carbon/glass fibres providing lightweight and superior mechanical properties are widely used as structural components for automotive and aerospace applications. However, such parts need to be joined with various metal alloys to obtain better mechanical performance in many structural elements. Many studies have reported enhancements in polymer–metal bonding using adhesives, adhesive/rivet combined joints, and different surface treatments. This study investigated the influences of various surface treatments on the adhesion between glass-reinforced poly(phenylene) sulphide (PPS) and aluminium alloy during the injection over-moulding process. Adhesion strength was evaluated via the shear test. Correlations for the shear strength of the polymer–metal with different metal–substrate treatments were studied. Since the strongest bonding was attained in the treatment with the highest roughness, this value, as it determines the level of micromechanical interlocking of connected materials, seems to be a critical factor affecting the adhesion strength. Three-dimensional (3D) topographic images characterized with a 3D optical microscope indicated that there was a meaningful influence exerted by the interface topologies of the aluminium substrates used for the over-moulding process. The results further indicated that increases in a substrate’s surface energy in connection with atmospheric plasma treatments negatively influence the final level of the bonding mechanism. Full article
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Article
Corrosion Inhibition Coating Based on the Self-Assembled Polydopamine Films and Its Anti-Corrosion Properties
Polymers 2022, 14(4), 794; https://doi.org/10.3390/polym14040794 - 18 Feb 2022
Cited by 3 | Viewed by 1417
Abstract
Metal corrosion is becoming increasingly serious in oil and gas production, and one way to solve this problem is to modify the metal surface. Thus, a corrosion inhibition coating on the N80 steel was constructed via the self-polymerization and assembling of the dopamine. [...] Read more.
Metal corrosion is becoming increasingly serious in oil and gas production, and one way to solve this problem is to modify the metal surface. Thus, a corrosion inhibition coating on the N80 steel was constructed via the self-polymerization and assembling of the dopamine. The optimum reaction condition of polydopamine films was determined by the corrosion rate assessment of the films coated N80 steel, which was the reaction at 60 °C and 5 g/L dopamine in the Tris-HCl buffer solution (pH = 8.5) for 1 h. The spectral results confirmed the existence of the polydopamine coating on the surface of N80 steel, and high stability of the coating in the oil well produced water was observed. The anti-corrosion performance of the polydopamine-coated N80 steel confirmed that high temperature accelerated the anti-corrosion effect of the coating, and the corrosion rate of N80 plate in 90 °C oil well produced water was 0.0591 mm·a−1, lower than the standard value. The corrosion rates of the polydopamine coated N80, A3 and J55 plates at 90 °C were 0.0541 mm·a−1, 0.0498 mm·a−1 and 0.0455 mm·a−1, respectively. No significant effects of the categories of corrosive medium and steel plate on the performance of the coating were observed. Full article
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Article
A New Type of Coating Brush Plating Solution and Its Application Performance
Coatings 2022, 12(2), 134; https://doi.org/10.3390/coatings12020134 - 24 Jan 2022
Viewed by 1695
Abstract
A new type of coating brush plating solutioncontaining stannous sulfate and potassium pyrophosphate was prepared by solution mixing method.Its structures, physicochemical properties, and the application effect in power equipment contact were also investigated by electrochemical workstation, X-ray photoelectron spectroscopy (XPS), scanning electron microsco [...] Read more.
A new type of coating brush plating solutioncontaining stannous sulfate and potassium pyrophosphate was prepared by solution mixing method.Its structures, physicochemical properties, and the application effect in power equipment contact were also investigated by electrochemical workstation, X-ray photoelectron spectroscopy (XPS), scanning electron microsco (SEM), Mapping, and infrared thermometer. The results showed that the tin coating has good adaptability to the ambient temperature and good adhesion with the copper substrate. Cerium nitrate was evenly distributed over the tin plating layer, reduced the crystal refinement of tin and lead to a uniform distribution of microdefects. When the cerium nitrate content, the amount of additives, the amount of complex agent, and the number of brush plating operations are 0.1%, 10.0%, 8.0%, and 5 times, respectively, the tin plating layer has the best electrochemical performance. For application, the damaged contacts of power equipment can fully meet the demand of power use after being treated by the new brush plating solution. Full article
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Article
Microstructure and Fracture Toughness of Nitrided D2 Steels Using Potential-Controlled Nitriding
Metals 2022, 12(1), 139; https://doi.org/10.3390/met12010139 - 11 Jan 2022
Cited by 2 | Viewed by 1076
Abstract
Potential-controlled nitriding is an effective technique for enhancing the life of steel molds and dies by improving their surface hardness and toughness against fatigue damage. In this study, the effect of the nitriding potential on the microstructure and fracture toughness of nitrided AISI [...] Read more.
Potential-controlled nitriding is an effective technique for enhancing the life of steel molds and dies by improving their surface hardness and toughness against fatigue damage. In this study, the effect of the nitriding potential on the microstructure and fracture toughness of nitrided AISI D2 steels was investigated. The nitrided layers were characterized by microhardness measurements, optical microscopy, and scanning electron microscopy, and their phases were identified by X-ray and electron backscatter diffraction. As the nitriding potential increased to 2.0 atm−1/2, an increase in the surface hardness and fracture toughness was observed with the growth of the compound layer. However, both the surface hardness and the fracture toughness decreased at the higher nitriding potential of 5.0 atm−1/2 owing to the increased porosity in the compound layers, which mainly consist of the ε (Fe2–3N) phase. Additionally, by observing crack growth behavior, the fracture toughness was analyzed considering the material characteristics of the diffusion and compound layers. The fracture toughness was influenced by the location of the initial Palmqvist cracks due to the localized plastic deformation of the diffusion layer and increased crack length due to the porous compound layer. Full article
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Article
[email protected]5O7I Heterojunction Derived from [email protected] for Enhanced Photocatalytic Activity under Visible Light
Materials 2022, 15(2), 508; https://doi.org/10.3390/ma15020508 - 10 Jan 2022
Cited by 1 | Viewed by 1099
Abstract
In the study, [email protected] composites were synthesized by the hydrothermal method and then calcined to acquire the [email protected]5O7I composite as a novel composite for the photocatalytic deterioration of the antibiotic tetracycline (TC). The prepared [email protected]5O7I [...] Read more.
In the study, [email protected] composites were synthesized by the hydrothermal method and then calcined to acquire the [email protected]5O7I composite as a novel composite for the photocatalytic deterioration of the antibiotic tetracycline (TC). The prepared [email protected]5O7I composites were physically and chemically characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), Brunauer–Emmet–Teller (BET) surface area, UV–Vis diffuse reflectance spectroscopy (DRS), emission fluorescence spectra, transient photocurrent response, electrochemical impedance spectra and Mott–Schottky. Among the composites formed an n–n heterojunction, which increased the separation efficiency of electrons and holes and the efficiency of charge transfer. After the photocatalytic degradation test of TC, it showed that [email protected]5O7I (2:1) had the best photodegradation effect with an 86.2% removal rate, which provides a new approach to the treatment of antibiotics such as TC in wastewater. Full article
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Article
Improvement in Bending Strength of Silicon Nitride through Laser Peening
Materials 2022, 15(1), 315; https://doi.org/10.3390/ma15010315 - 02 Jan 2022
Viewed by 958
Abstract
This study aimed to improve the bending strength and reliability of ceramics using laser peening (LP). In the experiment, LP without coating (LPwC) and with coating (LPC) were applied to silicon nitride (Si3N4) under various conditions. The surface roughness, [...] Read more.
This study aimed to improve the bending strength and reliability of ceramics using laser peening (LP). In the experiment, LP without coating (LPwC) and with coating (LPC) were applied to silicon nitride (Si3N4) under various conditions. The surface roughness, residual stress, and bending strength were then measured for the non-LP, LPwC, and LPC specimens. The results show that the LPwC specimen had a greater surface roughness but introduced larger and deeper compressive residual stress when compared with the non-LP and LPC specimens. In addition, the bending strength of the LPwC specimen was higher and scatter in bending strength was less compared with the non-LP and LPC specimens. This may be attributed to the transition of the fracture initiation point from the surface to the interior of the LPwC specimen because of the compressive residual stress introduced near the surface. Thus, it was demonstrated that the application of LP is effective in improving the strength and reliability of ceramics. Full article
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Article
Insights on the Formation Mechanism of Ultra-Low Friction of Phenolic Resin Graphite at High Temperature
Coatings 2022, 12(1), 6; https://doi.org/10.3390/coatings12010006 - 22 Dec 2021
Cited by 1 | Viewed by 1824
Abstract
In the present paper, the influences of high temperature on the tribological properties of phenolic resin graphite (PRG) sliding against tungsten carbide-nickel (WC-Ni) alloy in ambient air were investigated systematically. Results demonstrated that the antifriction behaviors of PRG was sensitive to high temperature [...] Read more.
In the present paper, the influences of high temperature on the tribological properties of phenolic resin graphite (PRG) sliding against tungsten carbide-nickel (WC-Ni) alloy in ambient air were investigated systematically. Results demonstrated that the antifriction behaviors of PRG was sensitive to high temperature and PRG exhibits ultra-low coefficient of friction (CoF) of about 0.01–0.015. The low CoF is attributed to the formation of graphite tribofilms, which shows different formation processes on the contact interface at different temperatures (room temperature, 200, 300 and 400 °C). These findings provide insight into the formation mechanism of graphite tribofilms, and provide an important basis for improving the tribological properties of graphite-based friction materials and manufacturing new graphite for seal applications. Full article
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Article
Hydrogen Absorption during Case Hardening of Steels EN20MnCr5 (SAE5120) and EN18CrNiMo7-6 (SAE4820)
Metals 2022, 12(1), 6; https://doi.org/10.3390/met12010006 - 21 Dec 2021
Cited by 2 | Viewed by 1825
Abstract
Damages to case-hardened components are often associated with the phenomenon of hydrogen embrittlement due to their specific fracture pattern. In the present work, the effects of the case hardening process on the hydrogen content in the material were investigated and the effects of [...] Read more.
Damages to case-hardened components are often associated with the phenomenon of hydrogen embrittlement due to their specific fracture pattern. In the present work, the effects of the case hardening process on the hydrogen content in the material were investigated and the effects of hydrogen on the mechanical properties were examined. In order to determine not only the influence of the heat treatment process but also the influence of the material, the case-hardening steels EN20MnCr5 (SAE5120) and EN18CrNiMo7-6 (SAE4820) with different degrees of purity were investigated. From the results it can be deduced that the sulphidic and oxidic inclusions have no significant influence on the hydrogen content. When checking the mechanical properties, it was shown in the incremental step loading technique according to ASTM F1624 that a purely case-hardened condition only has a slight tendency to hydrogen embrittlement. However, if the material is additionally loaded with hydrogen, the material fails significantly below the maximum expected load in the incremental step loading test, which is to be interpreted as a clear indication of failure due to hydrogen embrittlement. However, the fracture patterns of these two states do not show any significant differences. Therefore, it does not seem possible to attribute damage to a case-hardened component to hydrogen embrittlement on the basis of the fracture pattern alone. Full article
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Article
Fatigue Behavior of an AM50 Die-Casting Alloy Anodized by Plasma Electrolytic Oxidation
Materials 2021, 14(24), 7795; https://doi.org/10.3390/ma14247795 - 16 Dec 2021
Cited by 1 | Viewed by 1480
Abstract
While an anodizing process is essential for magnesium alloys to be used under corrosive environments, it sometimes stimulates a fatigue fracture that initiates at the interface between the coating layer and the substrate. In this study, a plasma electrolyte oxidation (PEO) technique was [...] Read more.
While an anodizing process is essential for magnesium alloys to be used under corrosive environments, it sometimes stimulates a fatigue fracture that initiates at the interface between the coating layer and the substrate. In this study, a plasma electrolyte oxidation (PEO) technique was employed to provide excellent adhesion between the anodizing layer and the AM50 die-cast by applying an extremely high dielectric discharge in an alkaline phosphate electrolyte, and its effect on corrosion and fatigue behaviors was investigated. The stress intensity factor at the fatigue limit was estimated to be 0.28 MPam0.5. The specimen anodized using the PEO technique exhibits enhanced strength and corrosion resistance compared to the unanodized counterpart. Furthermore, it shows a relative fatigue life in spite of the thick anodizing layer because the crack initiates from the interface, not from the pore near the interface. Full article
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Article
In Situ Reduction of Silver Nanoparticles on the Plasma-Induced Chitosan Grafted Polylactic Acid Nonwoven Fabrics for Improvement of Antibacterial Activity
Coatings 2021, 11(12), 1517; https://doi.org/10.3390/coatings11121517 - 09 Dec 2021
Viewed by 1748
Abstract
An eco-friendly approach for improvement of antibacterial properties of polylactic acid (PLA) nonwoven fabrics was obtained by in situ reduction of silver nanoparticles (Ag NPs) on dielectric barrier discharge (DBD) plasma-induced chitosan grafted (DBD-CS-Ag NPs) PLA nonwoven fabrics. The surface morphology, surface element [...] Read more.
An eco-friendly approach for improvement of antibacterial properties of polylactic acid (PLA) nonwoven fabrics was obtained by in situ reduction of silver nanoparticles (Ag NPs) on dielectric barrier discharge (DBD) plasma-induced chitosan grafted (DBD-CS-Ag NPs) PLA nonwoven fabrics. The surface morphology, surface element composition and the chemical state of silver of the PLA surfaces after the treatment were evaluated through scanning electron microscopy (SEM), energy dispersive X-ray (EDX), Fourier transform infrared spectroscopy (FTIR), X-ray photoelectron spectroscopy (XPS) and X-ray diffraction (XRD), respectively. The antibacterial activity of DBD-CS-Ag NPs treated PLA against Escherichia coli (E. coli) and Staphylococcus aureus (S. aureus) was tested. The uniform dispersion of silver nanoparticles on the DBD-CS-Ag NPs treated PLA surface were confirmed by SEM images. The results of XPS and XRD showed that the concentration of silver element on the surface of PLA nonwoven fabrics was significantly improved after DBD-CS-Ag NPs treatment. The DBD-CS-Ag NPs treated PLA nonwoven fabrics also exhibited excellent antibacterial properties. Full article
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Article
Influence of 3D Printing Topology by DMLS Method on Crack Propagation
Materials 2021, 14(23), 7483; https://doi.org/10.3390/ma14237483 - 06 Dec 2021
Cited by 2 | Viewed by 1272
Abstract
The presented text deals with research into the influence of the printing layers’ orientation on crack propagation in an AlSi10Mg material specimen, produced by additive technology, using the Direct Metal Laser Sintering (DMLS) method. It is a method based on sintering and melting [...] Read more.
The presented text deals with research into the influence of the printing layers’ orientation on crack propagation in an AlSi10Mg material specimen, produced by additive technology, using the Direct Metal Laser Sintering (DMLS) method. It is a method based on sintering and melting layers of powder material using a laser beam. The material specimen is presented as a Compact Tension test specimen and is printed in four different defined orientations (topology) of the printing layers—0°, 45°, 90°, and twice 90°. The normalized specimen is loaded cyclically, where the crack length is measured and recorded, and at the same time, the crack growth rate is determined. The evaluation of the experiment shows an apparent influence of the topology, which is essential especially for possible use in the design and technical preparation of the production of real machine parts in industrial practice. Simultaneously with the measurement results, other influencing factors are listed, especially product postprocessing and the measurement method used. The hypothesis of crack propagation using Computer Aided Engineering/Finite Element Method (CAE/FEM) simulation is also stated here based on the achieved results. Full article
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Article
Mutual Effects of Components of Protective Films Applied on Steel in Octadecylamine and 1,2,3-Benzotriazole Vapors
Materials 2021, 14(23), 7181; https://doi.org/10.3390/ma14237181 - 25 Nov 2021
Cited by 6 | Viewed by 1191
Abstract
In this work, we used a combination of corrosion, electrochemical, and physical methods to determine the properties of nanoscale films obtained by treatment with octadecylamine (ODA), benzotriazole (BTA) vapors, and their mixtures at elevated temperatures. The mixture of ODA + BTA surpasses its [...] Read more.
In this work, we used a combination of corrosion, electrochemical, and physical methods to determine the properties of nanoscale films obtained by treatment with octadecylamine (ODA), benzotriazole (BTA) vapors, and their mixtures at elevated temperatures. The mixture of ODA + BTA surpasses its components in protective aftereffect, but an analysis of their mutual effects shows that there is antagonism between them. Electrochemical impedance spectroscopy data indicate that the protection of steel by a mixture of ODA + BTA and its components is characterized by a mixed blocking activation mechanism. The processing of steel in hot vapors of the ODA + BTA mixture leads to hydrophobization of the surface and super-hydrophobization if a polymodal surface is created on the steel before processing in vapors. Full article
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Article
Mechanical and Dynamic Mechanical Properties of the Amino Silicone Oil Emulsion Modified Ramie Fiber Reinforced Composites
Polymers 2021, 13(23), 4083; https://doi.org/10.3390/polym13234083 - 24 Nov 2021
Cited by 2 | Viewed by 1422
Abstract
The mechanical and dynamic mechanical properties, interface adhesion and microstructures of the amino silicone oil emulsion (ASO) modified short ramie fiber reinforced polypropylene composites (RFPCs) with different fiber fractions were investigated. The RFPCs were made through a combined process of extrusion and injection [...] Read more.
The mechanical and dynamic mechanical properties, interface adhesion and microstructures of the amino silicone oil emulsion (ASO) modified short ramie fiber reinforced polypropylene composites (RFPCs) with different fiber fractions were investigated. The RFPCs were made through a combined process of extrusion and injection molding. Mechanical property tests of the RFPCs revealed enhancements in tensile and flexural strengths with increase of the fiber fraction due to the high stiffness of the fiber filler and a better interfacial bonding from ASO treatment. The dynamic mechanical analysis (DMA) results indicated that fiber incorporation plays an important role in DMA parameters (storage modulus, loss modulus, and damping ratio) at Tg by forming an improved interfacial adhesion and providing more effective stress transfer rate and energy dissipation between matrix and fiber. The phase behavior analysis suggests all the RFPCs are a kind of heterogeneity system based on the Cole-Cole plot analysis. Full article
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Review
Arsenic Removal from Contaminated Water Using Natural Adsorbents: A Review
Coatings 2021, 11(11), 1407; https://doi.org/10.3390/coatings11111407 - 19 Nov 2021
Cited by 8 | Viewed by 1961
Abstract
More than 170 million individuals have been influenced by arsenic (As) because of the ingestion of As-polluted groundwater. The presence of As in water bodies, particularly groundwater, has been found to become a widespread issue in the past few decades. Because arsenic causes [...] Read more.
More than 170 million individuals have been influenced by arsenic (As) because of the ingestion of As-polluted groundwater. The presence of As in water bodies, particularly groundwater, has been found to become a widespread issue in the past few decades. Because arsenic causes extreme wellbeing impacts, even at a low concentration in drinking water, the innovations of As removal from contaminated water are of significant importance. Traditional strategies, for example, reverse osmosis, ion exchange, and electro-dialysis are generally utilized for the remediation of As-polluted water; however, the high cost and/or sludge production restricts their application in less-developed areas. The utilization of adsorbents acquired from natural materials has been explored as an alternative for the costly techniques for As removal. This paper aims to review the past and current developments in using naturals adsorbents or modified natural materials for arsenic removal and show the different parameters, which may influence the As removal effectiveness of the natural adsorbent, such as contact time, adsorbent dosage, flow rate, pH, reusability, temperature, and influence of others ions. Full article
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Article
Effect of Carbon Partition and Precipitation on Wear Resistance of Carburized Layer in Heavy-Duty Gear
Materials 2021, 14(22), 6958; https://doi.org/10.3390/ma14226958 - 17 Nov 2021
Viewed by 1138
Abstract
The carburizing–quenching–tempering process is generally conducted on heavy-duty gear in order to obtain favorable comprehensive mechanical performance. Different mechanical properties could be produced by carbon partition and precipitation. In this study, the carburizing–quenching–tempering process was carried out on low-carbon alloy steel in order [...] Read more.
The carburizing–quenching–tempering process is generally conducted on heavy-duty gear in order to obtain favorable comprehensive mechanical performance. Different mechanical properties could be produced by carbon partition and precipitation. In this study, the carburizing–quenching–tempering process was carried out on low-carbon alloy steel in order to investigate the influence of microstructure evolution and precipitate transition on mechanical behavior and wear resistance under different carburizing/tempering durations. Favorable comprehensive mechanical property and wear resistance could be obtained in favor of long durations of carburizing/tempering. A fatigue-wear model was proposed to describe fatigue crack evolution and damage mechanism on the basis of wear features. Full article
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Article
Chloride Transport Behaviour and Service Performance of Cracked Concrete Linings in Coastal Subway Tunnels
Materials 2021, 14(21), 6663; https://doi.org/10.3390/ma14216663 - 04 Nov 2021
Cited by 1 | Viewed by 1360
Abstract
The concrete lining in subway tunnels often undergoes cracking damage in coastal cities. The combination of cracked tunnel lining structures and high concentrations of corrosive ions in the groundwater (e.g., chlorine) can accelerate concrete erosion, reduce the mechanical performance of the lining structures [...] Read more.
The concrete lining in subway tunnels often undergoes cracking damage in coastal cities. The combination of cracked tunnel lining structures and high concentrations of corrosive ions in the groundwater (e.g., chlorine) can accelerate concrete erosion, reduce the mechanical performance of the lining structures and shorten the tunnel service life. This paper investigates the chloride ion concentration in the groundwater of several subway tunnels in the coastal city of Qingdao, China. Indoor experiments and numerical simulations are conducted to investigate the chloride ion transport behaviour and service performance of cracked concrete linings. The results are applied to predict the service life of lining structures. The crack depth in concrete linings is found to have the most significant effect on the transport rate of chloride ions, followed by the crack width. The numerical simulations are carried out using COMSOL software to study the chloride transport behaviour in cracked specimens and predict the service lifetimes of lining structures of different thicknesses, and the results correspond well with the experimental data. The durability of a concrete lining can be enhanced by increasing the thickness of the protective concrete layer. Additional measures are proposed for treating cracked concrete linings to resist chloride ion attack in subway tunnels. Full article
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Article
Preparation and Characterization of Water-Insoluble Gardenia Blue Pigment
Materials 2021, 14(21), 6594; https://doi.org/10.3390/ma14216594 - 02 Nov 2021
Cited by 1 | Viewed by 1363
Abstract
Based on molecular simulations, the synthetic route of water-insoluble gardenia blue pigment was prepared by the reaction of genipin and L-Phenylalanine methyl ester hydrochloride. A highly purified pigment was obtained after extraction by chloroform and purification by silica gel column chromatography, and the [...] Read more.
Based on molecular simulations, the synthetic route of water-insoluble gardenia blue pigment was prepared by the reaction of genipin and L-Phenylalanine methyl ester hydrochloride. A highly purified pigment was obtained after extraction by chloroform and purification by silica gel column chromatography, and the value of color is up to 288. A study on the structural characteristics of the pigment was implemented with a scanning electron microscope, ultraviolet-visible spectrophotometer, Fourier transform infrared spectrometer, X-ray photoelectron spectrometer, and quatropde-time of flight mass spectrometer. The results showed that the surface of the pigment was largely smooth and spherical; The λmax was 607 nm, and the main functional groups include O-C=O, C=O, C-N, C=C, OH, and benzene ring; We detrained six different molecular weight and chemical structures of pigments and speculated the particular structures and formation mechanisms of three kinds of pigment, whose molecular weights are 690.1156, 720.1226, and 708.1246 Da, respectively. The pigment was only able to be dissolved in ethanol, methanol, acetone, ethyl acetate, and other strong polar organic solvents, but was not able to be dissolved in water, ethyl ether, petroleum ether, and other weak polar organic solvents. In terms of light and thermal stabilities, water-insoluble gardenia blue pigment is significantly better than water-soluble gardenia blue pigment (p < 0.05). When it is under direct light for 7 days or incubated at 80–120 °C for 24 h, the pigment residual rates were 74.90, 95.26, 88.27, and 87.72%, respectively. Full article
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Article
Thermal, Mechanical and Chemical Analysis of Poly(vinyl alcohol) Multifilament and Braided Yarns
Polymers 2021, 13(21), 3644; https://doi.org/10.3390/polym13213644 - 22 Oct 2021
Cited by 4 | Viewed by 1647
Abstract
Poly(vinyl alcohol) (PVA) in multifilament and braided yarns (BY) forms presents great potential for the design of numerous applications. However, such solutions fail to accomplish their requirements if the chemical and thermomechanical behaviour is not sufficiently known. Hence, a comprehensive characterisation of PVA [...] Read more.
Poly(vinyl alcohol) (PVA) in multifilament and braided yarns (BY) forms presents great potential for the design of numerous applications. However, such solutions fail to accomplish their requirements if the chemical and thermomechanical behaviour is not sufficiently known. Hence, a comprehensive characterisation of PVA multifilament and three BY architectures (6, 8, and 10 yarns) was performed involving the application of several techniques to evaluate the morphological, chemical, thermal, and mechanical features of those structures. Scanning electron microscopy (SEM) was used to reveal structural and morphological information. Differential thermal analysis (DTA) pointed out the glass transition temperature of PVA at 76 °C and the corresponding crystalline melting point at 210 °C. PVA BY exhibited higher tensile strength under monotonic quasi-static loading in comparison to their multifilament forms. Creep tests demonstrated that 6BY structures present the most deformable behaviour, while 8BY structures are the least deformable. Relaxation tests showed that 8BY architecture presents a more expressive variation of tensile stress, while 10BY offered the least. Dynamic mechanical analysis (DMA) revealed storage and loss moduli curves with similar transition peaks for the tested structures, except for the 10BY. Storage modulus is always four to six times higher than the loss modulus. Full article
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Article
Application of the Electrochemical Permeation Method for Hydrogen Diffusion Coefficient Determination in Pipeline Steel 10G2
Coatings 2021, 11(10), 1260; https://doi.org/10.3390/coatings11101260 - 16 Oct 2021
Viewed by 1583
Abstract
In this article, we conduct research on the effect of corrosion tests on the hydrogen diffusion process in gas steel in electrochemical permeability tests. This tests show that a long corrosion test time reduces the hydrogen diffusion coefficient by an order of magnitude, [...] Read more.
In this article, we conduct research on the effect of corrosion tests on the hydrogen diffusion process in gas steel in electrochemical permeability tests. This tests show that a long corrosion test time reduces the hydrogen diffusion coefficient by an order of magnitude, indicating the formation of aging defects in the steel. During operation, the diffusion coefficient decreases by two orders of magnitude, which also indicates the formation of a large number of defects in the steel. Consequently, based on the change in the diffusion coefficient in the material, it is possible to assess the degree of material failure. Full article
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