Hardness Characteristics Research Articles

Unlocking the Mysteries of the Desorption-Ionization Mechanism via Separate Thermal and Charge Strategies.

Herein, a new strategy is employed to build a controllable thermal-coupled charge ionization (TCCI) device to elucidate the desorption-ionization mechanism of plasma ion sources. Efficient synergistic desorption and ionization are achieved within the TCCI device by independently controlling the desorption temperature and plasma charges. The TCCI device efficiently ionizes samples using abundant free electrons, charges, and active species from arc plasma. The coexistence of free electrons and hydroxide radicals confers redox capability to the TCCI system, implying the presence of a unified redox mechanism even when the arc plasma is transmitted through a metal conductor over a distance. In addition, molecular ions of the analytes facilitate the differentiation between primary and secondary amines during their analysis. Notably, the TCCI device enables a switch between hard and soft ionization by adjusting the thermal desorption temperature. At high temperatures (>400 °C), the TCCI device exhibits hard ionization characteristics, producing fragment ions beneficial for isomer discrimination. The TCCI mass spectrometry exhibits robust performance in terms of sensitivity and accuracy for detecting antibiotics and sterols in saline solutions, achieving linearity with correlation coefficients ≥0.99 and excellent reproducibility. The successful analysis of seven pharmaceuticals and four sterols in complex matrices using the TCCI device demonstrates its excellent salt and matrix tolerance. Overall, the TCCI device, with its independent control over thermal desorption and arc plasma, achieves efficient synergistic desorption and ionization, overcoming limitations in existing ionization technologies and contributing to the study of gas-phase ion dynamics and mechanisms.

Effect of ultrasonic shot peening on microstructure and properties of Cu-Ti alloy

Abstract Modified surface layers with refined grain size and high microhardness characteristics were prepared on Cu-Ti alloy using ultrasonic shot peening (USP) by controlling the shot diameter. The phase structure and organization morphology of the modified layer were analyzed using x-ray diffraction (XRD), optical microscopy (OM) and scanning electron microscope (SEM). The microhardness, wear resistance and corrosion resistance were systematically characterized. The results showed that the comprehensive surface properties of the sample was optimized at a shot diameter of 3.0 mm. The average grain size was refined to 12.4 nm under the high-frequency impact of steel balls. Owing to the grain refinement and work hardening, the surface microhardness, wear resistance and corrosion resistance of the sample was significantly improved. Among these, the surface microhardness of the sample was enhanced from 257.68 HV0.1 to 313.51 HV0.1, the volume wear rate was decreased from 0.3305 um2 N−1 to 0.1707 um2 N−1, and the self-corrosion current density was also decreased from 1.658 × e−5 mA μm−2 to 4.053 × e−6 mA μm−2. It is proved that USP is one of the effective methods for preparing Cu-Ti alloys with excellent surface properties.

A Critique on the Correlations Between Rock Abrasiveness, Hardness, and Mechanical Characteristics: Implication of LCPC Abrasiveness and Breakability Coefficients

A Critique on the Correlations Between Rock Abrasiveness, Hardness, and Mechanical Characteristics: Implication of LCPC Abrasiveness and Breakability Coefficients

Surface defect detection model of laser cutting polycrystalline cubic boron nitride tool based on asymptotic fusion strategy

Due to the polycrystalline cubic boron nitride tool has the characteristics of high hardness, brittleness, etc., it is easy to break the tool or produce defects in the laser cutting process, which affects the cutting performance of the tool. Traditional defect detection methods can no longer meet the needs of modern manufacturing. Aiming at the problems of low accuracy and poor real-time detection of surface defects on laser-cutting polycrystalline cubic boron nitride tools, this study proposes the surface defect detection model of laser cutting polycrystalline cubic boron nitride tool based on asymptotic fusion strategy, which fills the gap in the field. In the backbone network, the C3SE module is constructed by modeling the correlation between feature channels to improve the model’s focus on key features in order to enhance the feature extraction and processing capability of the backbone network; In the neck network, adaptive spatial fusion operation and direct interaction of non-adjacent layers are utilized for multi-scale information fusion, and the asymptotic feature pyramid network for object detection (AFPN) is used instead of the FPN structure to improve the detection performance; In the head network, a soft suppression mechanism is introduced to reduce the overlapping frame score using a decay function, thus improving the detection accuracy. The experimental results based on the self-constructed laser-cutting polycrystalline cubic boron nitride tool surface defects dataset show that the average accuracy of the AFFS-YOLO model is improved by 5.6% compared with that of the YOLOv5 model, reaching 86.1%, and the detection effect is better than that of the original network and other classical target detection networks.

TIG assisted surface modification of Ti-6Al-4V with B4C, SiC particles

This research article assesses the improved hardness and wear behaviour of Ti–6Al–4V (Titanium-6Aluminium-4Vanadium) ex-situ produced composite case on its surface by TIG Arcing. This method is recognized for its potential to modify the surface of various metallic substrates by carefully controlling the melting and solidification of the substrate using a significantly less expensive high density electric arc heat source of the widely used autogenous (without filler) gas tungsten arc welding (GTAW) process.The molten base and the hard particles in the applied coating through reinforcement led to the development of hard surface characteristics in the Ti-6Al-4V surface matrix. The hard particles that have been reinforced by using TIG arcing to develop a hard wear-resistant surface coating are boron carbide (B4C) and silicon carbide (SiC). The presence of hard particles on the surface of Ti64 has been verified by XRD Pattern and EDS examination. The effect of different reinforced particles on the wear behaviour as well as the hardness of the modified surface has been studied by comparing the Ti64 modified surface without reinforcement and the as-built Ti64 surface samples. Vickers micro hardness testing measures the hardness of the modified particulate surface composite and demonstrates a significant increase in hardness, ranging from 1.5 to 2 times that of the base metal and wear tests confirm that the surface-coated samples of B4C and SiC on the base metal, showed a reduction in wear rate of approximately 55% and 45% respectively, compared to the base metal.

Mechanisms of hardness enhancement in CrB2 thin films with varying VB2 concentrations

Transition metal borides are well-known for their high hardness, excellent wear resistance, chemical inertness, and electrical conductivity, making them promising for a wide range of applications. Understanding the interconnections between material structure, composition, and mechanical properties is essential for designing and synthesizing effective coatings. This study systematically investigates the structural and mechanical properties of CrB₂ thin films with varying concentrations of VB₂ (0–10 wt%), focusing on structure, hardness, elastic behavior and deformation characteristics mechanisms through atomic force microscopy and nanoindentation measurements. The results show that increasing VB₂ content leads to the formation of island cluster structures, which significantly strengthens atomic bonds and, in turn, enhances the hardness of the thin films. As particle size decreases, the higher proportion of surface atoms and increased surface energy have a more pronounced effect on the mechanical properties. In particular, the addition of VB₂ up to 10 wt% in CrB₂ thin films results in a marked improvement in superhard properties. 26 % increase in hardness value is also influenced directly by the changes in Young's modulus and Poisson's ratio that depend on the VB₂ concentration.

Lightweight Mutually Authenticated Key Exchange with Physical Unclonable Functions

Authenticated key exchange is desired in scenarios where two participants must exchange sensitive information over an untrusted channel but do not trust each other at the outset of the exchange. As a unique hardware-based random oracle, physical unclonable functions (PUFs) can embed cryptographic hardness and binding properties needed for a secure, interactive authentication system. In this paper, we propose a lightweight protocol, termed PUF-MAKE, to achieve bilateral mutual authentication between two untrusted parties with the help of a trusted server and secure physical devices. At the end of the protocol, both parties are authenticated and possess a shared session key that they can use to encrypt sensitive information over an untrusted channel. The PUF’s underlying entropy hardness characteristics and the key-encryption-key (KEK) primitive act as the root of trust in the protocol’s construction. Other salient properties include a lightweight construction with minimal information stored on each device, a key refresh mechanism to ensure a fresh key is used for every authentication, and robustness against a wide range of attacks. We evaluate the protocol on a set of three FPGAs and a desktop server, with the computational complexity calculated as a function of primitive operations. A composable security model is proposed and analyzed considering a powerful adversary in control of all communications channels. In particular, session key confidentiality is proven through formal verification of the protocol under strong attacker (Dolev-Yao) assumptions, rendering it viable for high-security applications such as digital currency.

Evaluation of hard tissue characteristics and calcifications in pulp tissue of hypomineralized permanent molars using micro-computed tomography

ObjectivesTo determine and compare pulp volume, dentin mineral density, presence of microcracks, pulp stones, and accessory canals, as well as their localizations in root regions for hypomineralized and healthy teeth. DesignThis study included 60 extracted permanent molar teeth, categorized into hypomineralized and healthy groups (n = 30 each). The hypomineralized group comprised molar teeth with limited white, yellow, or brown opacities, post-eruptive breakdown, or extensive restoration or crown damage. The healthy group included caries-free molar teeth without these characteristics. Using 3D micro-computed tomography images pulp volume, dentin mineral density, and the presence and locations of microcracks, pulp stones, and accessory canals were determined for each group. Statistical analyses were conducted using Independent T-test and Chi-square test, with significance set at p < 0.05. ResultsThere was no statistically significant difference between the groups regarding pulp volume and microcracks (p ≥ 0.05). The number of accessory canals was significantly greater in the cervical (p = 0.011; p < 0.05) and middle (p = 0.010; p < 0.05) regions of the hypomineralized teeth than healthy teeth. Dentin mineral density was statistically higher in the apical, middle, and cervical root regions (p < 0.001; p < 0.05); however, the number of pulp stones was found to be greater in the cervical regions of healthy teeth compared with those with hypomineralization (p = 0.026; p < 0.05). ConclusionThere were lower dentin mineral density measurements, a decreased number of pulp stones in the cervical region, and a greater number of accessory canals in the middle and cervical regions of hypomineralized teeth compared with healthy teeth.

Hard yolk characteristics and mechanism of salted duck eggs

Hard yolk (HY), commonly found in cooked, salted eggs, has recently become a great concern in the commercial production of salted eggs because of its negative impact on the taste of yolk. Herein, the chemical and structural characteristics of HY and the underlying mechanism of HY were investigated. Although there were similar nutritional compositions between HY and non-hard yolk (NHY), HY exhibited higher hardness, springiness, gumminess and chewiness than NHY, suggesting the lower acceptability of HY. In HY, a large amount of fibril-like substance was wrapped around the surface of yolk particles, whereas this was not observed in NHY. HY demonstrated higher β-sheet content and surface hydrophobicity but lower α-helices than NHY, indicating that α-helices of yolk protein change into β-sheet. In addition, HY exhibited higher disulphide bonds than NHY (13.5% vs. 11%). A higher level of protein aggregates was observed in HY compared with that in NHY, whereas a reducing agent, dithiothreitol (DTT), decreased the level. Similarly, the addition of tea polyphenols as a reducing agent in the pickling solution reduced HY formation and improved the taste texture of salted eggs. The results of this study show that the occurrence of HY compromised the taste acceptability of salted egg. Disulphide bond–mediated protein aggregation plays an important role in mediating HY formation through which the reducing agent suppresses HY formation.

INVESTIGATION OF CONVENTIONAL AND MICROWAVE COMBINED ROASTING EFFECT ON THE PHYSICOCHEMICAL, TEXTURAL AND SENSORY PROPERTIES OF SUNFLOWER SEED

In this study, conventional, microwave, and also a combination of these two methods were applied to compare the quality properties of sunflower seeds. Alternative to conventional roasting at 160°C, microwave roasting at two different powers (300W and 600W) and also microwave with conventional roasting treatment (300 W+160°C, 600 W+160°C) were applied to raw sunflower seeds during 5 and 10 min. for each group. The moisture content of roasted seeds was found to be lower than 6%. The results show that the highest protein and fat content were found in the group of combined methods as 21.09±6.64 and 40.55±0.345% respectively. Additionally, the color values were found to be higher, and hardness and sensory characteristics were protected better after roasting compared to the control (unroasted) group. Roasting of microwave at 600W power for 5 min at 160°C was found to be advantageous for the roasting process of sunflower seed via these properties.

Influence of Prosopis juliflora bark powder/fillers on the mechanical, thermal and damping properties of jute fabric hybrid composites

In recent years, the natural fiber (NF) reinforced composites have become popular as substitute material for conventional metals and alloys in a range of structural applications. The aim of this experiment is to utilize the waste of both Prosopis Juliflora (PJ) bark and Jute fabric in valuable applications for the first time. The influence of fabric stacking patterns on the mechanical characteristics (ductile, flexural, hardness and impact) and thermal stability of fabric Jute/PJ bark powder reinforced hybrid composites in the epoxy matrix is investigated in this task. The compression moulding method is used to create composite laminates of same widths that are layered in various combinations of 5%, 10% and 15% weight of PJ bark powder. The prepared reinforced test samples characteristics of tensile, flexural, impact, and hardness characteristics are experimentally investigated. The outcomes revealed an inclusion of 15 wt% of PJ bark powder reveals positive effect on tensile, flexural, impact, hardness and thermal characteristics. These composites have a diverse range of applications, including industries, automobile and civil applications.

THE MODERN AND PROSPECTIVE STRUCTURAL MATERIALS` FOR WHEELED ARMORED VEHICLES STRENGTH CHARACTERISTICS ANALYSIS

The article presents the results of research in those the modern structural materials` strength characteristics for wheeled armored vehicles (WAV) production, as well as the technical requirements for them, were analyzed. It has been established that ordinary structural steels are used for armored car frames, and special armored steels with high strength and hardness characteristics are used for armored plating. It is expedient to use new promising materials - martensitic steels, which are characterized by extremely high strength, new ceramic materials and glass, and the latest nanomaterials - for the WAV armoring. A military vehicles protection promising direction is modern modular armor protection with the use of various materials.

Fungal Biostarter and Bacterial Occurrence of Dry-Aged Beef: The Sensory Quality and Volatile Aroma Compounds after 21 Days of Aging

In this study, we decided to test the hypothesis that the fungal biostarter M. flavus used during a 21-day beef dry-aging process significantly impacts the composition of other microorganisms, the profile of volatile compounds, meat hardness characteristics, and, consequently, the sensory quality. The experiments were performed on samples derived from animals crossbred between Holstein–Fresian cows and meat breed bulls. Two groups of samples were studied, including the control group, without biostarter, and a group inoculated with the M. flavus biostarter. Both sample groups were seasoned for 21 days in the dry-aging fridge. The physicochemical parameters (pH, color parameters), the chemical composition of muscle, the determination of the shear force, the profile of volatile compounds (VOCs), and the sensory quality were evaluated after aging. During this study, classical microbiological methods were used to investigate the influence of fungal biostarters on the growth and survival of bacteria and other fungi (e.g., yeasts) during the dry-aging process of beef (DAB). The M. flavus biostarter improved the sensory quality of DAB, allowing high sensory quality to be achieved after just 21 days. This is likely due to the diverse VOCs produced by the fungus, including 1-tetradecanol, 2-nonenal, trans-2-undecenoic acid, and the following esters: formic acid hexyl ester, 10-undecenoic acid methyl ester, and 4-methylpentanoic acid methyl ester. The presence of the biostarter had no significant effect on the number of the bacteria or the survivability of the L. monocytogenes on the meat’s surface in laboratory conditions.

Development of Fe-Mg alloys with intermediate degradation kinetics as potential biodegradable bone implants

This paper reports the production and characterizations of some Fe-xMg (x=3, 5, 7 wt.%) alloys. These Fe-Mg alloys were prepared using the mechanical alloying method followed by low-temperature sintering. The influence of the addition of various Mg contents on the microstructures, hardness, and degradation characteristics of these alloys were examined. The microstructure analyses demonstrated the homogeneous distribution of Fe and Mg in the alloys with a single-phase BCC structure. The inclusion of Mg was found to affect the alloys’ porosity, particle morphology, grain size, formation of corrosion products, and degradation behaviors. The corrosion products obtained from the alloys using the electrochemical and weight loss measurements indicated that their degradation rates (in the range of 3.13–4.7 mm/year) are in-between those of pure Fe and Mg. It was asserted that the Fe-Mg can be an appealing alternative for temporary medical implants. Furthermore, this study may establish an essential foundation for the degradation control of Fe-based implants by including more active elements.

Comparison of Hardness by Electrolytic and Electroless Deposition of Nickel on Aluminium

Abstract The work deals with the hardness characteristic of substrates coated with nickel through two primary methods: electrolytic deposition and electroless Ni-P deposition. The optimised process parameters for both the process was determined by varying a particular parameter keeping the rest constant in order to obtain minimum crystallite size of Ni. The size of the crystallite were determined using Scherrer’s equation. The optimized combination of process parameter for electrolytic deposition is: 270gm/lt of Nickel Sulfate, 60gm/lt Nickel Chloride, 35gm/lt Boric Acid, current density of 90mA/cm2 bath temperature of 55°C. The optimized combination of process parameter for electroless Ni-P deposition: 34gm/lt Nickel Sulfate, 23 gm/lt Sodium Hypophosphite, 46 gm/lt of Lactic acid, 42 gm/lt of Sodium Citrate, pH 5.0 and bath temperature 85°C. The optimised deposition rate 22μm/hr. Micro-hardness (Vickers) tests were conducted on the coated samples with a 50 gf load. The cause for difference in hardness was due to buildup of residual stress during deposition of Nickel on the substrate(aluminium). The orientation and surface texture of the materials are determined.

Study on the correlation between shear wave elastography and MRI grading of meniscal degeneration

BackgroundShear Wave Elastography (SWE) offers quantitative insights into the hardness and elasticity characteristics of tissues. The objective of this study is to investigate the correlation between SWE of the menisci and MRI-assessed degenerative changes in the menisci, with the aim of providing novel reference source for improving non-invasive evaluation of meniscal degenerative alterations.MethodsThe participants in this study were selected from patients who underwent knee joint MRI scans at our hospital from February 2023 to February 2024. The anterior horns of both the medial and lateral menisci were evaluated using SWE technique. The differences in elastic values of meniscus among different MRI grades were compared. The correlation between elastic values and MRI grades, as well as various parameters, was analyzed. Using MRI Grade 3 as the gold standard, the optimal cutoff value for meniscal tear was determined. The intraclass correlation coefficient (ICC) was employed to evaluate the reliability of repeated measurements performed by the same observer.ResultsA total of 104 female participants were enrolled in this study, with 152 lateral menisci (LM) and 144 medial menisci (MM) assessed. For the male group, 83 individuals were included, with 147 LM and 145 MM evaluated. The results demonstrated statistically significant differences in the elasticity values of the menisci at the same anatomical sites across different MRI grades (P < 0.001). Within the same grade, the MM had higher elasticity values than the LM, showing a statistically significant difference (P < 0.001). The elasticity values of the menisci were higher in males compared to females. There were statistically significant positive correlations between the elasticity values of the menisci and age, BMI, and MRI grade. The ICC for repeated measurements within the observer demonstrated good reliability (> 0.79).ConclusionsThe meniscal elasticity values measured by SWE exhibit a significant positive correlation with the grades of degeneration assessed by MRI. Furthermore, the elasticity values of the meniscus are found to increase with advancing age and elevated BMI.

Investigating the Tribological Behavior of Bioinspired Surfaces in Agro-waste and Alumina Reinforced AA6063 Matrix Composites

The tribological behavior of three bioinspired (BI) agro-waste ashes—bean pod ash (BPA), cassava peel ash (CPA), and coconut husk ash (CHA)—integrated as reinforcements in an alumina-reinforced AA6063 matrix hybrid and monolithic composite was investigated. Studies utilizing agro-wastes for bioinspired surfaces are limited despite these wastes posing significant environmental challenges. Consequently, there has been a growing effort to valorize these residues for sustainable engineering applications. This study uses a two-step stir-casting methodology to engineer bioinspired materials with lightweight properties, exceptional hardness, and wear-resistant characteristics. Microstructural investigations revealed a homogeneous distribution of natural and synthetic reinforcements within the AA6063 matrix. Lightweight AMCs were successfully fabricated, exhibiting densities ranging from 2.57 to 2.74 g/cm³ and hardness values between 81.28 and 107.47 BHN. The average surface roughness of these composites varied from 2.4 to 3.4 μm, with ANOVA tests confirming a statistically significant difference (p < 0.005). Wear rates and the coefficient of friction were observed to range from 2.52 x 10-3 to 5.50 x 10-3 mm³/m and 0.2476 to 0.5403, respectively. Reinforcing the AA6063 alloy with bioinspired agro-wastes significantly enhanced the hardness and tribological performance of the as-cast BI-AMCs. Notably, the wear rates and friction coefficients were significantly reduced, with the monolithic BI-AMCs demonstrating superior results. Furthermore, adding bioinspired agro-wastes, such as BPA, CPA, and CHA, improved the surface texture of AA6063 more effectively than Al2O3, leading to slightly smoother surfaces. These nuanced bioinspired tribological behaviors present opportunities for tailored load-bearing and aesthetic applications derived from agro-waste-based composites. This study advances our understanding of bioinspired tribological phenomena and paves the way for the development of innovative materials with diverse applications and enhanced performance.

Nanoindentation behaviors of the AlCoCrFeNi2.1 eutectic high-entropy alloy: The effects of crystal structures

The AlCoCrFeNi2.1 eutectic high-entropy alloy (EHEA), as a kind of in-situ composite materials, have achieved good match of strength and plasticity due to its typical eutectic lamella structures. Although many previous studies have investigated the indentation behaviors of the AlCoCrFeNi2.1 EHEA, there are still some controversies about the hardness characteristic of different crystal structures, requiring further clarification. Accordingly, in this study, nanoindentation tests were conducted to investigate the indentation behaviors of different crystal structures (primary L12 phase, primary B2 phase, and the eutectic phase region). The residual indentation and the crystallographic orientations were characterized by the laser scanning confocal microscope, scanning electron microscope, and electron backscatter diffraction. The hardness in different crystal structures were comparatively analyzed and the material deformation mechanisms were discussed correspondingly. The statistic results showed that the eutectic phase region had the lowest hardness, and primary B2 phase had the highest hardness. Furthermore, the slip lines in the primary L12 phase were evenly distributed near the residual indentation, but the slip lines in the eutectic phase region were concentrated near the phase boundaries. These findings are expected to deepen the understanding of the microscale deformation behaviors of EHEAs.

Influence of ultrasonic power modulation on the optimisation of aluminium alloy micro-arc oxidation coating properties

Conventional micro-arc oxidation (MAO) technology, due to the randomness and transient nature of arc discharge, produces coatings with numerous defects, poor abrasion resistance, and inadequate ability to effectively block the intrusion of corrosive media. In this paper, ultrasonic-assisted technology was used to study the effect of different ultrasonic power regulation on the performance optimization of MAO coating on 6061 aluminum alloy. The coating microstructure and elemental composition were characterized by X-ray diffraction, scanning electron microscopy and energy dispersive spectrometer, and its hardness, wear resistance, corrosion resistance and other properties were tested. The results show that the prepared coating has the characteristics of high hardness, good wear resistance and excellent corrosion resistance under the assistance of ultrasonic power of 50 W. This is mainly attributed to the cavitation effect, mechanical effect and thermal effect generated by the corresponding ultrasonic power, which effectively enhances the surface quality, performance and service life of the coating. This study provides valuable insights into the interaction between ultrasound power and the resulting MAO coatings, and has important implications for optimizing ultrasound-assisted processes and improving coating properties.

Nonlinear interactions of an n-layer X-shape low-frequency vibration isolator equipped with a nonlinear vibration absorber at 1:1 internal resonance: analytical and numerical investigations

This work addresses, for the first time, the nonlinear dynamics of an n− layers bioinspired X− shape low-frequency vibration isolation system equipped with a nonlinear vibration absorber. The comprehensive mathematical model governing the two-degree-of-freedom system has been derived using Lagrangian mechanics. The method of averaging was applied to obtain an accurate analytical solution for the derived mathematical model. Utilizing the established analytical solution, the dynamical characteristics of the X− shape vibration isolator have been explored both as a single-degree-of-freedom system and after coupling with the proposed vibration absorber, as a two-degree-of-freedom system. The influence of different system parameters, including the number of structure layers, the initial inclination angle, the X− shape rod length, and the absorber stiffness and damping coefficients, on the vibration isolation performance has been investigated. The main findings indicate that while the single-degree-of-freedom X− shape low-frequency vibration isolator performs well in eliminating low-frequency vibration excitations, it exhibits strong vibration levels when the base excitation frequency exceeds the structure's natural frequency. Additionally, it was found that coupling a highly damped linear vibration absorber to the X− shape isolator not only eliminates the strong oscillations of the structure when subjected to high-frequency base excitations but also enhances the structure's low-frequency vibration isolation performance. Moreover, it was reported that integrating a nonlinear vibration absorber with either soft or hard spring characteristics instead of a linear one may degrade the vibration isolation performance of the structure rather than enhance it. Finally, numerical validation of all the analytical results was performed, which showed excellent correspondence with the analytical findings.