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Materials (Basel, Switzerland) Jun 2024Microstructural heterogeneities of an ASTM A128 grade C steel subjected to heat treatments and their effect on abrasive wear behavior were investigated. The...
Microstructural heterogeneities of an ASTM A128 grade C steel subjected to heat treatments and their effect on abrasive wear behavior were investigated. The heat-treatment process involved different austenization times at 1050 °C and quenching media. To characterize the effects of heat treatment on the material's microstructure and mechanical behavior, two microscopy techniques were used: optical microscopy (OM), and scanning electron microscopy (SEM). The chemical composition of the material was obtained using X-ray fluorescence (XRF) optical emission spectrometry. The variation in carbide composition was evaluated using X-ray Energy Dispersive Spectroscopy (EDS). To characterize the mechanical behavior of the steel, hardness measurements and abrasive wear tests were performed after homogenization annealing and quenching treatments. The results showed that the heat-treated samples developed a heterogeneous microstructure, with the presence of austenitic grains and Martensite around the surface of the samples induced by decarburization in both the protected and unprotected specimens. The specimens with lower decarburization presented less formation of Martensite and precipitated carbides, resulting in lower hardness values and higher abrasion resistance (solution treatment at 1080 °C for 1 h + sand protection + brine quenching).
PubMed: 38930254
DOI: 10.3390/ma17122884 -
Materials (Basel, Switzerland) Jun 2024Braking systems are extremely important in any vehicle. They convert the kinetic energy of motion into thermal energy that is dissipated into the atmosphere. Different...
Braking systems are extremely important in any vehicle. They convert the kinetic energy of motion into thermal energy that is dissipated into the atmosphere. Different vehicle groups have different nominal and maximum speeds and masses, so the amount of thermal energy that needs to be absorbed by the friction pads and then dissipated can vary significantly. Conventional friction materials are composite materials capable of withstanding high temperatures (in the order of 500-600 °C) and high mechanical loads resulting from braking intensity and vehicle weight. In small vehicles traveling at low speeds, where both the amount of thermal energy and its density are limited, the use of slightly weaker friction materials with better ecological properties can be considered. This work proposes a prototype composite friction material using flax fibers as reinforcement instead of the commonly used aramid. A number of samples were prepared and subjected to laboratory tests. The samples were prepared using components of plant origin, specifically flax fibers. This component acted as reinforcement in the composite friction material, replacing aramid commonly used for this purpose. The main tribological characteristics were determined, such as the values of the coefficients of friction and the coefficients of abrasive wear rate. For this purpose, an authorial method using ball-cratering contact was used. The results were analyzed using statistical methods. It was found that the composite material using flax fibers does not differ significantly in its tribological properties from conventional solutions; so, it can be assumed that it can be used in the vehicle's braking system.
PubMed: 38930230
DOI: 10.3390/ma17122861 -
Materials (Basel, Switzerland) Jun 2024This article presents the effect of the conditions of abrasive compounds on the wear of samples made by different methods. The 28MnB5 steel was used, which is intended...
This article presents the effect of the conditions of abrasive compounds on the wear of samples made by different methods. The 28MnB5 steel was used, which is intended for agricultural components, to which two arc and laser coatings were applied. The study included the analysis of microstructure, microhardness, roughness, and tribological experiments on a dedicated stand. The arc coating was found to significantly improve the tribological properties compared to the samples without the coating. Varied wear results were obtained for the laser coating depending on the parameters of the abrasive compound. Studies of the surface roughness of the samples showed that the concentration and pH of the abrasives have a significant effect on the changes in the surface parameters after the tribological tests. The results of the tribological experiments indicated that wear resistance for some of the abrasive mass conditions was improved by the application of heat-applied coatings. In addition, it was found that the power consumption on the stand was the highest for abrasive mass conditions of a 10% moisture content and a pH of 10. For these test conditions, the mass loss was four times higher than for the parameter with W0% and pH7. The energy consumption of the stand was 60 kWh lower for this variant than for the parameter with W10% and pH10. The results of the study have important practical applications that can help in the selection of materials for agricultural machinery components, depending on the abrasive mass conditions.
PubMed: 38930218
DOI: 10.3390/ma17122849 -
Materials (Basel, Switzerland) Jun 2024Ultra-thin 304 stainless steel can be used to flexibly display substrates after they have been subjected to chemical mechanical polishing (CMP). The thickness of the...
Ultra-thin 304 stainless steel can be used to flexibly display substrates after they have been subjected to chemical mechanical polishing (CMP). The thickness of the chemical oxide layer directly affects the polishing efficiency and surface quality of 304 stainless steel. In the study presented in the following paper, the thickness variation of the chemical oxide layer of 304 stainless steel was analyzed following electrochemical corrosion under different oxidant concentration conditions. Furthermore, the impact of the oxidant concentration on the grooves, chips, and scratch depth-displacement-load curves was investigated during a nano-scratching experiment. Through this process, we were able to reveal the chemical reaction mechanism between 304 stainless steel materials and oxidizers. The corrosion rate was found to be faster at 8% oxidant content. The maximum values of the scratch depth and elastic-plastic critical load were determined to be 2153 nm and 58.47 mN, respectively.
PubMed: 38930186
DOI: 10.3390/ma17122816 -
ACS Applied Materials & Interfaces Jun 2024Transparent, hard, and flexible multifunctional coatings have a wide range of applications; however, most of them need organic solvents. Here, we present a solvent-free...
Transparent, hard, and flexible multifunctional coatings have a wide range of applications; however, most of them need organic solvents. Here, we present a solvent-free and UV-cured coating made from fluorinated epoxy MTQ silicone resin combined with branched triepoxy siloxane as the reactive diluent. After UV-initiated ring-opening polymerization in the presence of a triarylsulfonium hexafluoroantimonate catalyst, the resultant cured coating exhibits high transparency (∼92%, 550 nm), pencil hardness (7H), and flexibility (1 mm bending diameter) due to the formed organic-inorganic nanostructures in a highly cross-linked network. The triepoxy siloxane significantly reduces the viscosity before curing and increases cross-link density of the coating. The coating without any volatile content shows a smooth surface with low roughness ( = 0.46 nm) and delivers an anti-smudge ability owing to perfluorinated chains inherited from the MTQ resin. Furthermore, even after 3000 abrasion cycles, the coating still has a water contact angle greater than 90°, displaying excellent wear resistance. Our work provides a promising way to access high-performance multifunctional coatings in a more sustainable manner.
PubMed: 38924769
DOI: 10.1021/acsami.4c03775 -
Journal of Oral Rehabilitation Jun 2024Noncarious cervical lesions (NCCLs) are multifactorial and can be caused by the anatomical structure of the teeth, erosion, abrasion and abnormal occlusion. The aim of...
OBJECTIVES
Noncarious cervical lesions (NCCLs) are multifactorial and can be caused by the anatomical structure of the teeth, erosion, abrasion and abnormal occlusion. The aim of this case-control study was to explore the risk factors for NCCLs.
METHODS
Cone-beam computed tomography was used to determine whether a wedge-shaped defect existed at the cementoenamel junction. We compared 63 participants with NCCLs with 63 controls without NCCLs, matched for sex, age (±1 year) and toothbrushing-related factors (e.g., type of bristle and brushing patterns, frequency and strength). All participants were asked to complete a questionnaire about self-administered daily diet habits and health condition. Univariate and multivariate logistic regression analyses were conducted to determine the risk factors for NCCLs.
RESULTS
Significant variables in the univariate analysis (i.e., p < .2) included frequency of carbonated beverage consumption, sella-nasion-point B angle (SNB) and Frankfort-mandibular plane angle (FMA). Multivariate logistic regression demonstrated that the consumption frequency of carbonated beverages (odds ratio [OR] = 3.147; 95% confidence interval [CI], 1.039-9.532), FMA (OR = 1.100; 95% CI, 1.004-1.204) and SNB (OR = 0.896; 95% CI, 0.813-0.988) was independent influencing factors. The area under the receiver operating characteristic curve (AUC) value of regression Model 1 (established with the frequency of carbonated beverage consumption, FMA, SNB and sleep bruxism) was 0.700 (95% CI, 0.607-0.792; p < .001), and that of regression Model 2 (established using the frequency of carbonated beverage consumption, FMA and SNB) was 0.704 (95% CI, 0.612-0.796; p < .001).
CONCLUSIONS
The consumption frequency of carbonated beverages and FMA was risk factors for NCCLs; the higher the frequency of carbonated beverage consumption and FMA, the higher was the probability of NCCLs. SNB was a protective factor for NCCL occurrence; the larger the SNB, the lower was the probability of NCCL occurrence. These findings have further clarified the aetiology of NCCLs and provided clinicians with valuable insights into strategies for preventing the loss of dental tissue.
PubMed: 38924570
DOI: 10.1111/joor.13772 -
Biomimetics (Basel, Switzerland) May 2024The propulsion system is the core component of unmanned underwater vehicles. The flapping propulsion method of marine animals' flippers, which allows for flexibility,...
The propulsion system is the core component of unmanned underwater vehicles. The flapping propulsion method of marine animals' flippers, which allows for flexibility, low noise, and high energy utilization at low speeds, can provide a new perspective for the development of new propulsion technology. In this study, a new experimental flapping propulsion apparatus that can be installed in both directions has been constructed. The guide rail slider mechanism can achieve the retention of force in the direction of movement, thereby decoupling thrust, lift, and torque. Subsequently, the motion parameters of frequency-amplitude related to the thrust and lift of a bionic flapping-foil are scrutinized. A response surface connecting propulsion efficiency and these motion parameters is formulated. The highest efficiency of the flapping-foil propulsion is achieved at a frequency of 2 Hz and an amplitude of 40°. Furthermore, the impact of the installation mode and the aspect ratio of the flapping-foil is examined. The reverse installation of the swing yields a higher thrust than the forward swing. As the chord length remains constant and the span length increases, the propulsive efficiency gradually improves. When the chord length is extended to a certain degree, the propulsion efficiency exhibits a parabolic pattern, increasing initially and then diminishing. This investigation offers a novel perspective for the bionic design within the domain of underwater propulsion. This research provides valuable theoretical guidance for bionic design in the underwater propulsion field.
PubMed: 38921204
DOI: 10.3390/biomimetics9060324 -
BioRxiv : the Preprint Server For... Jun 2024A. Numerous studies have been trying to create nanomaterials based antimicrobial surfaces to combat the growing bacterial infection problems. Mechanical durability has...
A. Numerous studies have been trying to create nanomaterials based antimicrobial surfaces to combat the growing bacterial infection problems. Mechanical durability has become one of the major challenges to applying those surfaces in real life. In this study, we demonstrate the Durable Antimicrobial Microstructures Surface (DAMS) consisting of DLP 3D printed microstructures and zinc oxide (ZnO) nanoflowers. The microstructures serve as a protection armor for the nanoflowers during abrasion. The antimicrobial ability was tested by immersing in 2E8 CFU/mL ( ) suspension and then evaluated using electron microscopy. Compared to the bare control, our results show that the DAMS reduces bacterial coverage by more than 90% after 12 hrs of incubation and approximately 50% after 48 hrs of incubation before abrasion. Importantly, bacterial coverage is reduced by approximately 50% after 2 min of abrasion with a tribometer, and DAMS remains effective even after 6 min of abrasion. These findings highlight the potential of DAMS as an affordable, scalable, and durable antimicrobial surface for various biomedical applications.
PubMed: 38915492
DOI: 10.1101/2024.06.11.598554 -
Heliyon Jun 2024This study aims to prevent ice accumulation on the surface of drilling tools by investigating the effectiveness of hydrophobic coatings, which is one of the most...
This study aims to prevent ice accumulation on the surface of drilling tools by investigating the effectiveness of hydrophobic coatings, which is one of the most promising methods to solve drilling difficulties in warm ice. Herein, four types of hydrophobic organic coatings that can be used on metal surfaces were tested to evaluate their anti-icing performance, service durability, and friction properties. All of them possess rough surfaces with microstructure characteristics such as pores, stripes, or micropapillae. They also exhibit hydrophobicity, with water contact angles of 101.6°, 100.0°, 103.1°, and 108.5°. They can significantly prolong the required freezing time of water droplets on their surfaces, effectively reduce ice adhesion, and decrease the friction between ice and their surface. The ice adhesion in the axial, tensile, and tangential directions can be reduced by 65.64 %, 56.31 %, and 72.11 %, respectively, for the coating with silicon (Si)-based and fluorine (F)-containin compounds (coating-) at -30 °C; while it can be reduced by 85.05 %, 73.9 %, and 94.2 %, respectively, for the coatings with Si-based and polytetrafluoroethylene (PTFE) compounds (coating-). The two coatings mentioned above lose their anti-icing performance after 20 icing and de-icing cycles, and their hydrophobicity after 120 abrasion cycles under a load of 6 N.
PubMed: 38912511
DOI: 10.1016/j.heliyon.2024.e32319 -
Orthopaedic Journal of Sports Medicine Jun 2024While prevention protocols have been implemented, skiing-related musculoskeletal injuries and concussions continue to present to emergency departments in the United...
BACKGROUND
While prevention protocols have been implemented, skiing-related musculoskeletal injuries and concussions continue to present to emergency departments in the United States. Previous literature has suggested the pediatric population may constitute up to 40% of skiing-related injuries.
PURPOSE
To assess injury trends and the underlying mechanisms of skiing injuries in pediatric patients seen at emergency departments in the United States.
STUDY DESIGN
Descriptive epidemiology study.
METHODS
The National Electronic Injury Surveillance System (NEISS) was queried for pediatric (age ≤18 years) skiing injuries between January 1, 2012, and December 31, 2022. Injury mechanism, location, disposition, and diagnosis were recorded, and the statistical sample weight assigned by NEISS by hospital was used to calculate national estimates (NEs). Injury trends were evaluated with linear regression analysis.
RESULTS
Overall, 2951 pediatric skiing injuries were included (NE = 123,386). The mean age of the patients was 12.4 ± 3.5 years, with 61.3% of the injuries occurring in male patients. Impact with the ground was the most common injury mechanism (NE = 87,407; 70.8%). Fractures were the most common diagnosis (NE = 38,527, 31.2%), followed by strains/sprains (NE = 22,562, 18.3%), contusions/abrasions (NE = 16,257, 13.2%), and concussions (NE = 12,449, 10.1%). The lower leg was the most common fracture site (NE = 9509, 24.7%), followed by the shoulder (NE = 7131, 18.5%) and lower arm (NE = 5876, 15.3%). Analysis of annual injuries revealed no significant trend between 2012 and 2022 ( = .17), with fluctuations apparent throughout the study period. Significant decreases were seen in strains/sprains ( < .01) and contusions/abrasions ( < .01), but not in concussions ( = .57) or fractures ( = .70).
CONCLUSION
Impacts with the snow/ground made up 70.8% of all injuries. Fractures were the most common injury diagnosis, followed by strains/sprains, with the lower leg being most frequently fractured. While strains/sprains and contusions/abrasions showed a significant decline, there were no significant trends in fractures and concussions between 2012 and 2022.
PubMed: 38911123
DOI: 10.1177/23259671241255704