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Five high entropy carbide ceramics, (Hf0.2,Nb0.2,Ta0.2,Ti0.2,Zr0.2)C, (Cr0.2,Hf0.2,Ta0.2,Ti0.2,Zr0.2)C, (Hf0.2,Mo0.2,Ta0.2,Ti0.2,Zr0.2)C, (Hf0.2,Ta0.2,Ti0.2,W0.2,Zr0.2)C, and (Hf0.2,Mo0.2,Ti0.2,W0.2,Zr0.2)C, were synthesized by carbothermal reduction of oxides and direct current sintering. The five high entropy carbide ceramics were determined to be nominally phase-pure with relative densities of more than 98.9% and mean grain sizes of less than 5 μm. Average Vickers hardness values ranged from 19.2 ± 0.4 GPa for (Hf0.2,Nb0.2,Ta0.2,Ti0.2,Zr0.2)C at a load of 2 kgf to 43.5 ± 0.4 GPa for (Hf0.2,Mo0.2,Ti0.2,W0.2,Zr0.2)C at a load of 0.05 kgf. Hardness generally increased with increasing the valence electron concentration and strain as measured by the Williamson–Hall analysis. However, neither correlation was conclusive enough to be a clear indicator of hardness. Instead, it was determined that a combination of effects that includes the valence electron concentration, lattice strain, and grain size all contribute to the hardness of high entropy carbide ceramics. [ABSTRACT FROM AUTHOR]

Atomistic simulations performed with a family of model potential with tunable hardness have proven to be a great tool for advancing the understanding of wear processes at the asperity level. They have been instrumental in finding a critical length scale, which governs the ductile to brittle transition in adhesive wear, and further helped in the understanding of the relation between tangential work and wear rate or how self-affine surfaces emerge in three-body wear. However, so far, the studies were mostly limited to adhesive wear processes where the two surfaces in contact are composed of the same material. Here, we propose to study the transition from adhesive to abrasive wear by introducing a contrast of hardness between the contacting surfaces. Two wear processes emerge: one by gradual accretion of the third body by detachment of chips from both surfaces and the other being a more erratic mixed process involving large deformation of the third body and removal of large pieces from the soft surface. The critical length scale was found to be a good predictor of the ductile to brittle transition between both processes. Furthermore, the wear coefficients and wear ratios of soft and hard surfaces were found to be consistent with experimental observations. The wear particle is composed of many concentric layers, an onion-like structure, resulting from the gradual accretion of matter from both surfaces. The distribution of sizes of these layers was studied, and it appears that the cumulative distribution of hard surface's chip sizes follows a power law. [ABSTRACT FROM AUTHOR]

Boron-based compounds have triggered substantial attention due to their multifunctional properties, incorporating excellent hardness and superconductivity. While tetragonal metal borides LiB4 and NaB4 with BaAl4-type structure and striking clathrate boron motif have been induced under compression, there is still a lack of deep understanding of their potential properties at ambient pressure. We herein conduct a comprehensive study on I4/mmm-structured LiB4 and NaB4 under ambient pressure via first-principles calculations. Remarkably, both LiB4 and NaB4 are found to possess high Vickers hardness of 39 GPa, which is ascribed to the robust boron framework with strong covalency. Furthermore, their high hardness values together with distinguished stability make them highly potential superhard materials. Meanwhile, electron–phonon coupling analysis reveals that both LiB4 and NaB4 are conventional phonon-mediated superconductors, with critical temperatures of 6 and 8 K at 1 atmosphere pressure (atm), respectively, mainly arising from the coupling of B 2p electronic states and the low-frequency phonon modes associated with Li-, Na-, and B-derived vibrations. This work provides valuable insights into the mechanical and superconducting behaviors of metal borides and will boost further studies of emergent borides with multiple functionalities. [ABSTRACT FROM AUTHOR]

Al2O3 has emerged as the surface passivation material of choice for p-type silicon in photovoltaics and has also become a candidate for passivating Si-based radiation sensors. However, the surface passivation of Al2O3 has been shown to degrade when exposed to gamma-radiation, making it of interest to determine methods of depositing Al2O3 that minimize the radiation-induced degradation on the surface passivation. In this study, we investigate the long-term stability and gamma-radiation hardness of Al2O3 prepared using the TMA+H2O+O3 precursor combination and how the pretreatment, the deposition temperature, and the film thickness affect the density of interface states, Dit, and fixed oxide charge, Qfix, before and after gamma-irradiation. We find that the surface saturation current density, J0s, of silicon passivated by Al2O3 increases after annealing but stabilizes over time depending on the Al2O3 thickness. Samples with thicknesses of <20 nm stabilize within hours, while those with >60 nm stabilize over days. J0s stabilizes at lower values with increased Al2O3 thickness. After exposure to 1 Mrad gamma-radiation, the samples still exhibit low Dit and high Qfix, with the best performing sample having a Dit of 1.5 × 1010 eV−1 cm−2 and a Qfix of −3.1 × 1012 cm−2. The deposition temperature appears to indirectly affect radiation hardness, owing to its impact on the hydrogen concentration in the film and at the Si–SiOx–Al2O3 interface. Lifetime measurements after irradiation indicate that Al2O3 still passivates the surface effectively. The carrier lifetime and Qfix can largely be recovered by annealing samples in O2 at 435 °C. [ABSTRACT FROM AUTHOR]

In this research, hollow inorganic microsphere (Q-cel) reinforced unsaturated polyester composite is produced, and its thermophysical properties have been characterized. The thermal decomposition kinetics of the composite obtained at different heating rates and various compositions are modeled using artificial neural networks. Also, the production optimization of the polyester composite has been evaluated using response surface methodology. The study has been repeated for certain heating rates (5, 10, and 20 K/min). Activation energies of polyester composites have been calculated using thermogravimetric data and kinetic methods. Changes in activation energy during the thermal decomposition (4 wt.% Q-cel, 94 wt.% UP, 580–660 K, and 20 K/min) of the composite are compared using FWO (129.4 kJ/mol), KAS (127.6 kJ/mol), and CR (126.5 kJ/mol). According to the results, it is seen that the activation energy goes up as the temperature and Q-cel ratio by the mass increase. When the amount of the filler in the polyester composite increases, the thermal conductivity coefficient also rises. As well as, it is determined that as Q-cel ratio in the mixture raises, the density of the composite decreases and Shore D hardness goes up. A new and original composite has been produced with Qcel-reinforced unsaturated polyester. The density of the composite is low, its thermal stability is high, and its easy processability will provide a great convenience. Modeling the Qcel ratio of the composite with RSM and the activation energy with ANN have been provided fast, efficient and optimum results. With the composite obtained, both lightweight and thermally stable polymer materials will be produced. [ABSTRACT FROM AUTHOR]

A series of high-entropy carbide ceramics with high-performance were successfully prepared by SPS using self-synthesized fine high-entropy carbides powders as hard phase and metal Co as the binder. The effects of Ti and/or Mo addition on densification, grain size and mechanical properties of (ZrHfTaNb)C–10Co ceramic were investigated. The results showed that the addition of Mo improved the wettability between the ceramic phase and Co phase, and significantly increased the densification degree of the ceramics. In addition, the average grain size decreased and the microstructure became more uniform after adding Ti and/or Mo. Compared with the mechanical properties of (ZrHfTaNb)C–10Co ceramic, those of (ZrHfTaNbTiMo)C–10Co ceramic were greatly enhanced under the action of high-entropy effect and solid solution strengthening. The hardness and fracture toughness of the (ZrHfTaNbTiMo)C–10Co ceramic achieved the satisfactory values of 20.37 GPa and 8.59 MPa m1/2, respectively. [ABSTRACT FROM AUTHOR]

To date, the thermal and electrical properties of three‐phase ceramics containing a boride phase, silicon carbide, and boron carbide have not been studied in detail. Further, the effect of the source of the boride powder has also not been investigated. This study produced three‐phase ceramics containing titanium diboride, silicon carbide, and boron carbide using three different TiB2 sources: commercial powder, TiB2 synthesized by boro/carbothermal reduction, or (Ti,Cr)B2 synthesized by boro/carbothermal reduction to address the effect of the TiB2 source. Ceramics containing synthesized TiB2 or (Ti,Cr)B2 reached >99% relative density, while the ceramic produced from commercial powder reached ∼93% relative density. The addition of Cr reduced both the thermal and electrical conductivities, but had little effect on the Vickers hardness. The (Ti,Cr)B2–SiC–B4C ceramic had a thermal conductivity of ∼33 W/m K, an electrical conductivity of ∼105 S/m, and a hardness of ∼61 GPa at 0.49 N. The highest hardness of ∼66 GPa at a load of 0.49 N was for the TiB2–SiC–B4C ceramic made with synthesized TiB2 powder. [ABSTRACT FROM AUTHOR]

The effects of annealing temperature on the microstructure, mechanical properties, and tribological properties of TiAlSiCN coatings with C contents of 9.24 at.% and 19.45 at.% are systematically investigated. The results show that all coatings maintain cubic structures with strongly preferential orientation of (200) planes, and the microstructure transforms from amorphous embedded in (Ti, Al)(C, N) nanocrystalline to amorphous encapsulated nanocrystalline with increasing C content. Elevating annealing temperature to 800 °C leads to a continuous decline in hardness, whereas the elastic strain resistance H/E increases first and then decreases. Release of H 2 formed by the breaking of the C–H bonds at 400 °C induces a local stress transformation from compressive to tensile. The toughness and hardness decreases dramatically at 600 °C by conversion of sp3 to sp2. The wear mechanisms of the coating against Si 3 N 4 counterballs are adhesive and oxidative wear. The coefficient of friction (COF) and wear rate initially decrease followed by an increase. The coatings with a-C structure exhibit lower COF and the wear process is smoother, but showing higher wear rate. Thus, the annealed TiAlSiCN coatings with preferred C content could improve the mechanical and tribological properties. [ABSTRACT FROM AUTHOR]

This article investigates the plasma‐enhanced chemical vapor deposition of a‐C:H:SiOx coatings in a non‐self‐sustaining arc discharge plasma with a hot cathode in combination with a low‐frequency (200 kHz) inductively coupled plasma. It is shown that increasing the inductor power from 0 to 600 W leads to a twofold increase in the ion current density on the substrate. An increase in ion bombardment intensity results in a 1.3‐fold reduction in the coating's growth rate due to the resputtering phenomenon, a 1.5‐fold reduction in surface roughness, and an improvement in the mechanical properties of the coatings. The hardness of the coating is increased by 9–11%, the plasticity index by 10–17%, and the resistance to plastic deformation by 32–49%. [ABSTRACT FROM AUTHOR]

This study aims to investigate the effects of the case depth and hardness distribution of carburizing on the rolling contact fatigue (RCF) properties of G20CrNi2MoA steel under deeper carburizing conditions. Four groups of specimens of different case depths are prepared and subjected to RCF tests. A 2D finite element model based on continuum damage mechanics is developed to further analyze these two factors. As the depth of the carburized case increases, the RCF life first increases and then decreases. The optimum case depth is approximately one‐quarter of the thickness of the specimen. A gentler hardness distribution due to a change in the diffusion process parameters ensures a minimal increase (8%) in the RCF performance. The proper case depth has a more notable effect on the RCF life compared with those of the gentle or steep hardness distribution. It is expected that the results can help to promote a better understanding of the heat treatment process of carburized bearings and ensure more reliable carburized bearings are produced. [ABSTRACT FROM AUTHOR]

Gamma-Al 2 O 3 ceramics can hardly be densified by conventional sintering methods because of the low surface energy of gamma-Al 2 O 3 powder and phase transformation at elevated temperature. Here, we report the preparation of translucent gamma-Al 2 O 3 ceramics by cold sintering process at merely 350 °C via using the gamma-Al 2 O 3 as starting powder. Due to the enhanced solubility and reaction of gamma-Al 2 O 3 in alkaline solution, the nanocrystalline particles can be densified to ∼92% of full density via adding 10 M NaOH solution as the transient liquid. It is proved that the high concentration of alkaline solution can greatly accelerate the dissolution-precipitation process, leading to the activation energy as low as 16.9 kJ/mol. Consequently, a translucent ceramic with in-line transmittance reaching 16% around 800 nm can be obtained, despite the residual porosity. Considering the stable hardness and translucency after water leaching or heating to 1000 °C, the cold sintered gamma-Al 2 O 3 ceramic may have the potential application as optical windows under extreme environments. [ABSTRACT FROM AUTHOR]

In the present paper, magnetic Barkhausen noise (MBN) measurements have been carried out to evaluate the hardness and ferrite grain size of API X70 steel. All samples were austenitized at 900–1200 °C for 0.5 h followed by air-cooling identically to develop different ferrite grain size. The microstructure examinations were determined by Scanning Electron Microscope (SEM). The average ferrite grain size in each sample was estimated using ImageJ open-source software. Hardness measurements were performed using durometer device. Measurements of MBN were conducted using MikroMach (Micromagnetic Materials Characterization) system. The microstructure observation shows that the increase in the austenization temperature (AUT) causes an increase in the ferrite grain size as well as their change in shape from polygonal to acicular. The results of mechanical tests showed that the increase in the austenization temperature leads to an increase in the hardness of the X70 steel. Actually, MBN method can be used to evaluate the changes in hardness and ferrite grain size in ferromagnetic materials. The sample with the lowest austenitic temperature has the highest Barkhausen noise amplitude (BNA); in contrast, the sample which contains the highest austenitic temperature has the lowest BNA; furthermore, when the austenization temperatures increases, the signal of the coercive field Hc shifts to the higher values of magnetic field. Additionally, BNA decreases, and Hc increases whenever hardness and ferrite grain size increases. In this way, a good correlation was found between MBN parameters, ferrite grain size, and hardness values. The realized experimental setup can be used for online evaluate steel microstructures and quality control of ferromagnetic materials in some industrial applications. [ABSTRACT FROM AUTHOR]

The new brake disc was evaluated for microstructure and hardness by the conventional destructive tests and non-destructive Barkhausen noise method (BNM). Ten non-destructive measurements were carried out in different areas of a brake disc, which were then cut out and made into metallographic test samples. Qualitative and quantitative analysis of graphite precipitates was performed to assess their volume in material matrix, anisotropy and size. Subsequently, graphs showing the relationships between selected stereological parameters of graphite precipitates and parameters determined from the RMS envelope of Barkhausen noise were elucidated. Similar relationships between hardness and parameters coming from non-destructive tests were carried out. Magnetic parameters that specified the size of a graphite precipitate was selected. In addition, repeatability studies using BNM were carried out in the areas of the material with the smallest and largest average size of graphite precipitates. A linear relationship between amplitude of BN and length of graphite flakes was found. The paper presents the possibilities of assessing the volume and size of graphite precipitates, as well as cast iron hardness using BNM. [ABSTRACT FROM AUTHOR]

In current research, Makrofol HS polymeric films have been utilized to evaluate the alterations in the surface properties under an atmospheric-pressure dielectric barrier discharge (DBD) plasma source. Upon DBD plasma exposure with various exposure durations ranging from 10 min to 120 min, the structural, surface wettability, surface free energy, surface roughness, and hardness features of Makrofol HS films have been studied and analyzed using different techniques. The FTIR spectra demonstrated that small changes in the band intensities correspond to the C-O-C as well as C=O bonds. Further, the changes in the absorption bands are correlated to the treatment time, leading to two critical processes, degradation, and crosslinking. The results of surface wettability displayed that the liquids' contact angle decreased from 84 ± 3o, 77 ± 3o and 62 ± 2o for water, glycerol, and dimethyl to 45 ± 1o, 42 ± 1o, and 36 ± 1o for untreated and treated samples at the highest treatment time, respectively. Also, the surface free energy significantly amended with increasing plasma exposure time. This modification in the treated surface indicates the increase in the polar groups on the treated surfaces, which then become hydrophilic surfaces. The samples' surface roughness parameters Ra, Rq, and Rz increased from 0.057 ± 0.003, 0.084 ± 0.004 and 0.366 ± 0.02 mm for untreated samples to 1.463 ± 0.073, 1.707 ± 0.085, and 6.839 ± 0.34 mm for treated samples at the highest treatment time, respectively. The Vickers hardness measurements showed an increase in the Vickers hardness from 12.31 ± 0.61 kgf/mm2 for the untreated sample to 44.89 ± 2.24 kgf/mm2 for the treated sample at the highest duration. [ABSTRACT FROM AUTHOR]

Electromagnetic welding, also referred to as magnetic pulse welding, is a solid-state welding method utilized for joining two distinct materials through high velocity impact. The direct fusion of stainless steel with titanium poses various difficulties owing to the absence of metallurgical compatibility and the occurrence of brittle intermetallic compounds such as FeTi and CrTi. To tackle these challenges, a sustainable, low heat input method like impact welding was applied to address the metallurgical compatibility of the two metals. In this study, a new technique involving aluminum foil, silver foil, and nitinol powder as intermediary materials was investigated to establish a fresh bimetallic structure between Ti-SS304L. Thorough analysis of microstructures, interface formations, and reactions was conducted using scanning electron microscopy and X-ray diffraction. The outcomes showcased successful prevention of intermetallic phase formation through the incorporation of these intermediary materials. Microhardness measurements indicated the absence of brittle FeTi and CrTi phases at the welding interface. Additionally, the weld interface was observed to be situated amid two intermetallic layers at the Ti-SS304L interface, ensuring resistance against corrosion. This inventive method not only averted the creation of harmful intermetallic compounds but also bolstered the overall strength and corrosion resilience of the joint between titanium and stainless steel. The micro hardness obtained at Ti-SS304L interface is 305 Hv and also improved 20% at interface of interlayer materials. [ABSTRACT FROM AUTHOR]

Multi-alloy-modified film is used to protect the surface of tools and components. MoN/ZrMoN bi-layer films are deposited by sputtering. The effect of the MoN deposition time and the DC power for the Zr target on the structure and mechanical performance of the coated films is studied. The ZrMoN films correspond to the (111), (200) and (220) crystal planes of the FCC (NaCl) structures. The diffraction peaks for the (111) plane gradually shift to lower 2θ values as the Zr content is increased. For a MoN buffer layer with a thickness of ~393 nm, the ZrMoN film has a hardness of 12.53 GPa and a coefficient of friction of 0.42. As the DC power for the Zr target is increased to 200 W, the e hardness and elastic recovery for the MoN/ZrMoN bi-layer films are 15.65 GPa and 67.70%, respectively, which are the maximum respective values. The experimental results show that these bi-layer films have good mechanical performance and adhesive strength. [ABSTRACT FROM AUTHOR]

In this study, a NiCoCrAlY + lanthanum zirconate multilayer thermal barrier coating was deposited on Inconel 738 through the thermal plasma spray technique. The coated samples subjected to hot corrosion testing at 900 °C for 240 h after coating them with 90 wt.% Na2SO4 + 5 wt.% NaCl + 5 wt.% V2O5. The corroded samples were evaluated using SEM, SED, XRD, microhardness and electrochemical study. The dominance of vanadium was observed in the form of LaVO4 phase formation at the plates on the coating surface. The as-received coating sample, sample after the electrochemical test, sample after hot corrosion and hot-corroded sample after electrochemical test were tested for hardness. A significant decrease of 23.8% in hardness was measured after the electrochemical test of the corroded sample. [ABSTRACT FROM AUTHOR]

DLC coatings are well known for their high fracture toughness, however, often exhibit poor adhesion properties on metallic substrates. The use of interlayers and metallic doping can be used to overcome such challenge. In this study duplex CrN/DLC and nano-multilayer DLC-W coatings were both deposited on hydraulic valve tappet using a hybrid PVD/PECVD deposition system. Microhardness measurements were taken for the uncoated valve tappet, duplex CrN/DLC and nano-multilayer DLC-W coated valve tappet at loads of 0.98 N, 1.96 N, 2.94 N, 4.9 N, 9.8 N and 19.6 N for 15 seconds using a Shimadzu hardness tester. The fracture toughness was evaluated using the Vickers indentation method from microhardness indents on the surface of the coatings. The fracture toughness for duplex CrN/DLC and nano-multilayer DLC-W coatings indented at 4.9 N, 9.8 N and 19.6 N, reveals that the fracture toughness for the duplex CrN/DLC were 20.24 ± 0.97 MPa.m1/2, 17.18 ± 0.86 MPa.m1/2 and 6.6 ± 0.28 MPa.m1/2 respectively. While the fracture toughness for nano-multilayer DLC-W was calculated as 3.75 ± 0.41 MPa.m1/2 and 4.67 ± 0.38 MPa.m1/2 at 9.8 N and 19.6 N respectively. [ABSTRACT FROM AUTHOR]

In this work, glass samples were obtained by melt-quenching in the binary system (100-x)KPO 3 -xNb 2 O 5 with x = 20, 30, 40, and 50 mol%. Thermal properties investigated by DSC together with structural investigations by Raman spectroscopy allowed to understand the structural effect of Nb 2 O 5 incorporation in the potassium phosphate glass network. A transparent glass-ceramic has also been produced by heat treatment of the 50KPO 3 –50Nb 2 O 5 glass sample. Density, molar volume, atomic packing, and refractive index were determined and increased with Nb 2 O 5 content. Chemical resistance in several corrosive aqueous solutions was found to increase with Nb 2 O 5 content and crystallization. Vickers hardness as well as elastic modulus and hardness obtained from nanoindentation experiments also strongly increased with higher niobium contents, indicating that not only optical properties but also chemical and mechanical properties are improved with niobium incorporation in the phosphate glass network. [ABSTRACT FROM AUTHOR]

Nanoindentation is one of the most widely used methods to investigate the characteristics of metallic materials. Thus, in this work, molecular dynamics simulation is employed to investigate the effects of the number of grains, the indenter radius and the indenter velocity on the indentation performance of the FeCrNiCoCu. The results show that when the number of grains increases from 4 to 16, the Young’s modulus and hardness gradually decrease, showing an inverse Hall-Petch phenomenon. With the increase of the indenter radius, the Young’s modulus increases, the hardness is greatly affected by the contact area, and the larger indenter radius is conducive to the generation and expansion of dislocation in the model. The effect of pressing speed on Young’s modulus the hardness is weak. The higher the pressing speed, the lower the dislocation density and the slower the dislocation propagation. The purpose of this paper is to provide theoretical guidance for the study of FeCrNiCoCu. [ABSTRACT FROM AUTHOR]

Electrodialysis (ED) and the continuous evolution of ion exchange membranes are one of the reasons behind its diverse applications. Known to be a high-water recovery process with limited uses of chemicals gives it the advantage of sustainable treatment technology. Water softening plays a major role in water industry; it can ensure clean, safe, and efficient water use but it affects water equilibrium. Mainly the lack of calcium carbonate causes a real issue in water distribution networks made of concrete, pipes, and reservoirs by decreasing their lifetime. This paper addresses the selectivity of softening using ED to reduce the negative impact of water hardness and to maintain both the quality and equilibrium of water. This latter should be neither too hard nor too soft, and the calco-carbonic equilibrium is of major interest. In this work, ED operations were carried out at a laboratory scale using different water initial concentrations. The propensity of the water towards calcium carbonate scaling was addressed by monitoring the Langelier saturation index (LSI) generally used to assess water scaling potential. At a demineralization rate (DR) of 80%, all the dilutes obtained from all the feed water reached the status of soft water. ED gave good results in terms of hardness reduction, and LSI corresponded to the equilibrium state at a DR of 40% in all the cases studied. [ABSTRACT FROM AUTHOR]

In this investigation, Ultra-high Hard Armor (UHA) steel plate by Shielded Metal Arc Welding (SMAW) process using the Austenitic Stainless Steel (ASS) electrode. In the first part of this investigation, using the finite element method (FEM), thermal analysis parameters were optimized using bead on plate welds in software code, known as SYSWELD. In the second part, using optimized parameters, a coupled thermo-mechanical analysis on multipass welded fabrication was carried out. Weld thermal cycles were analyzed by simulation and compared with experimentally measured temperature profiles. A double ellipsoidal heat source model was used to simulate the SMAW process. The heating rate and cooling rate were calculated along with residual stresses. This range of heating and cooling rate resulted in untempered martensite in the heat-affected zone (HAZ), confirmed by microstructure analysis and hardness mapping. Good validation was found between the measured and simulated 2D model with a 4–10% variation. This study suggests that numerical simulation is the capable technique in understanding the thermal and mechanical properties that influence the welding of ultra-high hard armor steels joints. [ABSTRACT FROM AUTHOR]

A ZrB2-B4C functionally graded composite (FGM) tile with 100 mm diameter and 6 mm thickness with ZrB2 content varying from 70% in the top layer to 10% in the bottom layer was fabricated using vacuum hot pressing. The density of the fabricated FGM is ~ 35% lower than monolithic ZrB2. To the best of our knowledge, ultra high temperature ceramic FGMs of such large dimensions have never been reported in the published literature. The FGM showed a smooth compositional transition without defects in the interlayer regions. Young's modulus of the FGM and its individual layers was determined using non-destructive ultrasound phase spectroscopy and overall Young's modulus of the FGM was correlated to the volume fraction averaged weighted sum of Young's modulus of each layer. The good interparticle bonding and lack of residual porosity in the top and middle layers resulted in high hardness and excellent wear resistance. The flexural strength of the FGM is approx. 400 MPa and the fracture mode displays a transition with composition along the thickness direction. Even under flexural loading, the interlayer regions remain intact, rendering excellent structural stability to the FGM. The fracture mechanism of the FGM has been discussed in light of the processing-induced thermal residual stress present in each layer and the presence of residual porosity and compositional gradient. The combination of low density, smooth interlayer transition, high flexural strength, as well as excellent hardness and wear resistance at the top layer renders the developed FGM potentially very attractive for thermal protection applications in hypersonic aircraft and re-entry vehicles. [ABSTRACT FROM AUTHOR]

Polyetheretherketone is a thermoelastic biopolymer that has good properties for use in medical implants. The paper presents the results of experimental research on the influence of some machining conditions (feed per tooth and cutting strategy) on the size of the temperature in the milling area, the size of the components of the cutting force, the roughness of the machined surface, the hardness of the surface layer resulting from the milling application. The working feeds had values in two ranges (0.0167–0.025 mm/tooth and, respectively, 0.05–0.15 mm/tooth). Different zig, zig-zag, and follow periphery machining strategies were applied to evaluate their effects on the values of some milling parameters of interest and, respectively, on the quality and integrity of the surface resulting from milling. The experimental research was carried out using modern research equipment, such as the confocal microscope and an interferometer, for the observation and analysis of the surface texture. It was found that a movement of the tool along a zig-zag type strategy leads to smoother surfaces compared to those obtained by zig-zag and follow periphery strategies. Higher cutting feeds (0.05–0.15 mm/tooth) determine lower values of the roughness parameter Sa. When feed values are in the range of 0.05–0.15 mm/tooth, the cutting temperature reaches values of 160–183 °C. In accordance with the higher temperature values, an increase in the hardness of the superficial layer resulting from milling is also observed. A consequence of the temperature increase in the cutting zone was a reduction in the sizes of the components of the cutting force, the material becoming more ductile and easier to cut. [ABSTRACT FROM AUTHOR]

Low plasticity burnishing (LPB) is a non-metal removal surface finishing process that enhances the surface integrity and fatigue life of engineering material by using surface sever plastic deformation. However, in some metallic material, the efficiency of process is limited because of excessive work hardening. In this case, plasticity enhancement can be enhanced by applying the electric current following the concept of electro plasticity. However, addition of current density as a new parameter to low plasticity burnishing which itself includes many factors will make the comprehensive optimization of process challenging. To effectively address this issue, in the present work, a study based on the design of experiment was carried out to identify effect of current density as main parameter of electric current-assisted burnishing (ECAB) through its interaction with other LPB parameters like spindle speed, feed rate, current density, pass number, and static force to surface roughness. The experiment was carried out on Inconel 718 fabricated by laser powder bed fusion (LPBF). Correlation between the process factors and surface hardness, roughness, and compressive residual stress as responses was developed using regression analysis followed by analysis of variances. The obtained results showed the current density, followed by pass number and static force have greater contribution on performance measures. Moreover, it was obtained that the pass number plays key role in determining trade-off between process time and products quality characteristics in ECAB. Decision-making based on service performance showed that while applying high density current, a single pass burnishing process (which leads to reduction of process time to one third) can be used for processing of material which is used in high cycle fatigue application, while for low cycle fatigue purpose, the pass number of three secures the service performance. [ABSTRACT FROM AUTHOR]

AbstractIn this paper, the dissimilar joining of Poly Lactic Acid (PLA) with Cork Wood (CW) particles reinforced Poly Lactic Acid (CW/PLA) was made by using an Ultrasonic Welding (UW) process. The single lap joint was made to analyse the better joining with good adhesion between the neat polymer and Cork PLA polymer composite. The objective of this study is to formulate a good bonding of neat biodegradable polymeric material with Cork wood particles reinforced composite with concern to the UW factors like Ultrasonic Amplitude (UA), Welding Pressure (WP), and Welding Time (WT). The experimental trial was carried out by altering the levels of UW factors such as UA (25, 28 and 31 µm), WP (0.10, 0.15 and 0.20 MPa), and WT (1, 1.3 and 1.5 sec) with respect to attainment the higher lap shear strength. The statistical optimization methods, including Taguchi and Analysis of Variance, are employed to identify the optimum factors for the welding process and evaluate the proportional impact of the UW factors. The results revealed that the UA of 28 µm, WP of 0.15 MPa, and WT of 1.5 sec exhibits the higher lap shear strength of 24.16 MPa. For the optimized condition, the interface hardness was measured using the Shore D hardness method. The results imply that the maximum interface hardness of 75 was observed at the weld centre. Fractured samples clearly show that interfacial failure is absent, this dictates the weld regions are strong enough to hold the applied load. The developed regression model for the present UW process on the PLA and Cork wood PLA composite is significant and has an R2 value of 92.8%. So, the developed model is suitable for converting into large-scale industrial production and applications. [ABSTRACT FROM AUTHOR]

In this paper, the research hypothesis of conservation of hardness coefficient is put forward, and a mathematical formula for describing and analyzing the relationship between hardness coefficient and bond energy is established in this model. The binding process of two heteronuclear atoms can be represented by Cassini oval in dynamic form, every molecular state corresponds to one of these graphs; then the critical phenomena of molecular deformation are discovered and the calculated potential energy at the critical point is consistent with the experimental dissociation energy of molecules (R is 0.99999, P < 0.0001). [ABSTRACT FROM AUTHOR]

In the production of cement, raw materials can be partially substituted by regenerable waste provided from glasses, construction and demolition waste in order to reduce the environmental problem and burden of landfills. In this study, limestone–silicate composites were synthesized using starting materials such as glass waste and lime, brick, autoclaved aerated concrete (ACC), mortar or plaster waste. The structure and mechanical properties of the nano-composite materials have been studied. The mean CaCO3 crystallite sizes are higher for composites containing ACC and brick than for doping with lime, mortar and plaster. Cement-based materials are formed by replacing 2.5% of the Portland cement with limestone–silicate composites. The results indicate new possibilities for introducing 2.5%of composites in cement paste because they promote the formation of the C-S-H network, which provides strength and long stability for the cement paste. The influence of varied types of mix composites in the expired cement on the initial cracking strain and stress, tensile strength and compressive strength were investigated. The compressive strength values of composite-expired cement specimens are situated between 11.8 and 15.7 MPa, respectively, which reflect an increase from 22.9 up to 63.54% over the compressive strength of expired cement matrix. [ABSTRACT FROM AUTHOR]

Hot-rolled backup rolls are widely used in steel rolling and usually need to be repaired by arc hardfacing after becoming worn. However, a corrugated-groove defect commonly occurs on the roll surface due to the uneven hardness distribution in the hardfacing layers, affecting the proper usage of the roll. Accordingly, a new swing-arc submerged arc welding (SA-SAW) process is proposed to attempt to solve this drawback. The microstructure and hardness are then investigated experimentally for both SAW and SA-SAW hardfacing layers. It is revealed that a self-tempering effect occurs in the welding pass bottom and the welding pass side neighboring the former pass for both processes, refining the grain in the two areas. In all the zones, including the self-tempering zone (STZ), heat-affected zone (HAZ), and not-heat-affected zone in the welding pass, both SAW and SA-SAW passes crystallize in a type of columnar grain, where the grains are the finest in STZ and the coarsest in HAZ. In addition, the arc swing improves the microstructure homogeneity of the hardfacing layers by obviously lowering the tempering degree in HAZ while promoting the even distribution of the arc heat. Accordingly, the hardness of the SA-SAW bead overall increases and distributes more uniformly with a maximum difference of < 80 HV0.5 along the horizontal direction of the bead. This hardness difference in SA-SAW is accordingly decreased by ~38.5% compared to that of the SAW bead, further indicating the practicability of the new process. [ABSTRACT FROM AUTHOR]

The precipitation-hardenable nickel-based superalloy Rene 41 exhibits remarkable mechanical characteristics and high corrosion resistance at high temperatures, properties that allow it to be used in high-end applications. This research paper presents findings on the influence of thermal shocks on its microstructure, hardness, and thermal diffusivity at temperatures between 700 and 1000 °C. Solar energy was used for cyclic thermal shock tests. The samples were characterized using microhardness measurements, optical microscopic analysis, scanning electron microscopy coupled with EDS elemental chemical analysis, X-ray diffraction, and flash thermal diffusivity measurements. Structural transformations and the variation of properties were observed with an increase in the number of shocks applied at the same temperature and with temperature variation for the same number of thermal shocks. [ABSTRACT FROM AUTHOR]

Summary Parboiled rice is well known for its high nutritional value, while its firm texture is still challenging to accept by consumers. In this study, the effects of starch gelatinisation and water migration on the increased hardness of parboiled rice were investigated. The hardness of parboiled rice was affected by starch gelatinisation, displaying an increasing trend with an increasing degree of starch gelatinisation (DSG). Examination of the water migration characteristics during soaking showed that the water uptake capacity of parboiled rice was significantly enhanced. Compared to white rice soaked at 90 °C, the water molecules in parboiled rice were restricted to the outer layer of starch. Significant correlations between rice hardness, DSG and moisture absorption‐related parameters were established, indicating that gelatinised starch limits the migration of water to the inside of the rice kernel, resulting in a firm rice grain. These results enhance the understanding of starch gelatinisation by parboiling and water migration properties during the cooking process of parboiled rice. This study provided new insights into the regulation of hardness by parboiled rice processing. [ABSTRACT FROM AUTHOR]

Zr x Ta 2 O 2x+5 (ZTOx) was systematically studied to determine ideal solid-state synthesis and pressureless sintering conditions. For Zr 6 Ta 2 O 17 (ZTO6) and other compositions with values of x in ZTOx the optimal synthesis temperature of 1100 °C with 1 h dwell time was optimal. XRD phase analysis of the homologous series indicated that for ZTOx, x = 5, 6, 7, and 8 were within the phase stability field while x = 4 and x = 9 were outside the phase stability field. Unit cell lattice parameters changed anisotropically with Zr:Ta ratio with an overall <0.1% change in unit cell volume across the solid solution. Some Raman modes red shifted while others blue shifted, indicating competing tensile and compressive strains. Sintering of ZTOx required a progressively higher temperature as Zr-content increased despite the same starting powder grain sizes and synthesis temperature. Higher Vickers hardness for Zr-rich (12.7–12.8 GPa) than Ta-rich Zr x Ta 2 O 2x+5 (11.6–11.7 GPa) disappeared when accounting for different sintering temperatures. Indentation toughness was similar for all compositions (1.2–1.4 MPa m1/2). Properties of Zr x Ta 2 O 2x+5 series indicate tunability of Zr:Ta composition ratio while maintaining the structure and room temperature mechanical properties comparable to Hf 6 Ta 2 O 17 and 8 mol% yttria stabilized zirconia ceramics. [ABSTRACT FROM AUTHOR]

Here Mo2FeB2 cermet coating was prepared on the surface of the furrow opener tip using plasma cladding. The microstructure, phase composition, microhardness and wear resistance of the coating were investigated to improve the wear resistance and to address the susceptibility to failure in the tillage process. Firstly, cladding current, cladding speed, powder delivery rate and cladding distance were set as the experimental parameters. The optimal combination of process parameters was obtained using orthogonal test: cladding current 80 A, cladding distance 10 mm and cladding speed 20 cm/min. Subsequently, the wear-resistant cladding coatings was prepared under the optimal conditions. The microstructure and phase composition of the cladding coatings were characterized by scanning electron microscope (SEM), energy dispersive spectrometer (EDS) and X-ray diffractometer (XRD). The results revealed that excellent metallurgical bonding was achieved between the cladding coatings and the substrate. The microstructure consisted of square, butterfly, cross darts, dendritic structures as well as irregular long strips of hard phase along with network eutectic microstructure and iron-based bonding phase. The phase composition included Mo2FeB2, M3B2(M: Mo, Fe, Cr), (Cr, Fe)7C3, MoB, CrB, Fe2B and Fe-Cr solid solutions. The hardness and wear resistance of cladding coatings were characterized using microhardness tester and the reciprocating friction and wear tester. An outstanding decreasing trend in microhardness from the surface to the substrate was observed for the cladding coatings, indicating a smooth transition in stress between cladding coatings and the substrate. The average microhardness of the cladding coating reached 9618 MPa, which was 2.79 times higher than that of the furrow opener tip. The wear test showed that the average wear amount (19.20 mg) and the average friction coefficient (0.294) of the cladding coating were reduced by 52.9% and 42.4%, respectively, compared with the substrate. Wear tests under various loads revealed that the friction coefficient between the cladding coating and the substrate gradually decreased with the increasing load, yet overall remained lower than that of the substrate. The wear morphology of the cladding coating under different loads was found to be lighter compared to the substrate. This was attributed to the presence of terterine borides with the high hardness, which acted as a wear-resistant skeleton, accompanying with the eutectic microstructure and bonding. The Mo2FeB2 cladding coating exhibited improved anti-plowing and anti-falling properties, leading to better wear resistance when compared with grade 45 steel substrate. The soil tank test was conducted using self-made friction and wear testing machine. The average wear of the tip of the coated layer was reduced by 70.4% (4.60 g), compared with the conventional tip (15.54 g). Field test demonstrated that the average wear amount (34.34 g) of the coated furrow opener tip was only 43.4% of that of the conventional one (79.06 g) in real soil conditions. The wear morphology revealed that the presence of the coating was effectively resisted the soil wear. The original appearance of furrow opener tip was maintained after a long time of wear, thus demonstrating the exceptional wear resistance. The results of this study can provide theoretical reference and feasible technical solutions for improving the wear resistance of agricultural machinery's soil-engaging parts. [ABSTRACT FROM AUTHOR]

Noisy trapdoor claw-free function (NTCF) is a powerful post-quantum cryptographic tool that can efficiently constrain actions of untrusted quantum devices within a classical–quantum interactive cryptographic model. Although NTCF is powerful, its essence remains a 2-to-1 one-way function (NTCF 2 1 ), which is inefficient in some cryptographic tasks. This raises an intriguing question: Can NTCF be extended to higher dimensions based on standard cryptographic hardness assumptions? Inspired by the extrapolated dihedral cosets, this work focuses on developing many-to-one trapdoor claw-free functions with polynomially bounded preimage sizes. The main results can be summarized as follows: Firstly, we introduce the definition of κ -to-1 NTCF κ 1 where κ is a polynomial integer, and present an efficient construction of NTCF κ 1 assuming quantum hardness of the learning with errors (LWE) problem. Secondly, we illustrate a key application of NTCFs in establishing a reduction from the LWE problem to the dihedral coset problems (DCPs). Specifically, our approach, leveraging NTCF 2 1 (resp. NTCF κ 1 ), reveals a new quantum reduction pathway from the LWE problem to the DCP (resp. an extrapolated version of DCP). This reduction is the core cryptographic analysis tool for studying the resistance of lattice problems against quantum attacks. Finally, we demonstrate that NTCF κ 1 can be further reduced to NTCF 2 1 , thus preserving its usefulness in proofs of quantumness. [ABSTRACT FROM AUTHOR]

High fracture toughness at cryogenic temperature and radiation hardness can be conflicting requirements for the resins for the impregnation of superconducting magnet coils. The fracture toughness of different epoxy-resin systems at room temperature (RT) and at 77 K was measured, and their toughness was compared with that determined for a polyurethane, polycarbonate (PC) and poly(methyl methacrylate) (PMMA). Among the epoxy resins tested in this study, the MY750 system has the highest 77 K fracture toughness of KIC = 4.6 MPa√m, which is comparable to the KIC of PMMA, which also exhibits linear elastic behaviour and unstable crack propagation. The polyurethane system tested has a much higher 77 K toughness than the epoxy resins, approaching the toughness of PC, which is known as one of the toughest polymer materials. CTD101K is the least performing in terms of fracture toughness. Despite this, it is used for the impregnation of large Nb3Sn coils for its good processing capabilities and relatively high radiation resistance. In this study, the fracture toughness of CTD101K was improved by adding the polyglycol flexibiliser Araldite DY040 as a fourth component. The different epoxy-resin systems were exposed to proton and gamma doses up to 38 MGy, and it was found that adding the DY040 flexibiliser to the CTD101K system did not significantly change the irradiation-induced ageing behaviour. The viscosity evolution of the uncured resin mix is not significantly changed when adding the DY040 flexibiliser, and at the processing temperature of 60 °C, the viscosity remains below 200 cP for more than 24 h. Therefore, the new resin referred to as POLAB Mix is now used for the impregnation of superconducting magnet coils. [ABSTRACT FROM AUTHOR]

Fe‐0.3C‐15Cr‐1Ni high hardness corrosion‐resistant alloy coating is prepared on the surface of 3Cr13 by laser cladding technology. The effects of scanning speeds on the microstructure, microhardness, and corrosion resistance of the coating are studied. The results show that the microstructure of the cladding layer is mainly composed of intracrystalline martensite and carbides distributed along the grain boundaries. When scanning speed increases from 3 to 5 mm s−1, the grain is obviously fined, and the number of carbides increases, further increasing scanning speed, the grain refinement degree decreases and the carbide quantity decreases gradually. When scanning speed is 5 mm s−1, the microhardness reaches the maximum, the corrosion resistance is significantly improved at 5 and 7 mm s−1, and the pitting potential and passivation zone width increase by 180–219% and 69–78%, respectively, compared with 3 mm s−1 sample, but further increases scanning speed to 9 mm s−1, the hardness and corrosion resistance significantly reduce. This is because scanning rate affects the component undercooling degree of the dynamic molten pool and the temperature gradient at the solidification interface front, which affects the growth of dendrites, the number of carbides, and further affects the alloying elements in the carbide and matrix. [ABSTRACT FROM AUTHOR]

Aluminium whose Silicon as its main alloying element, i. e. Silumin, is widely applied in engineering due to its novel properties. For particular application, e. g. as block engine of seawater vessel, Silumin's properties must be enhanced, e. g. strength at elevated temperature, hardenability and corrosion resistance. For those purposes, Nickel and Copper is added to Silumin in this work. As a result, Copper addition by 4.1 % wt increases Silumin density by 13.9 % from 2.95 to 3.36 g/cm³, decreases grain size by 35.3 % from 39.4 to 25.5 μm, increases hardness by 178.8 % from 21.66 to 60.38 HR30T and increases the corrosion rate by 24.5 % from 0.354 to 0.441 mmpy. Meanwhile, addition of Nickel by 6.35 % wt increases Silumin density by 14.9 % from 2.95 to 3.39 g/cm³, decreases grain size by 29.7 % from 39.4 to 27.7 μm, increases hardness by 161.8 % from 21.66 to 56.71 HR30T and decreases the corrosion rate by 41.2 % from 0.354 to 0.2211 mmpy. To investigate the influence of Copper and Nickel addition on Silumin's microstructure, micrograph is also taken by using an optical microscope and a scanning electron microscope. The micrograph shows dendrite presence only for the case of Copper added Silumin which deleterious for mechanical properties of Silumin. This dendrite is predicted due to slower cooling rate of the cast Silumin after Copper addition. In addition, the needle-like β-precipitate is sharper after Copper addition. This circumstance is responsible for higher hardness increase for the case of Copper addition compared to Nickel addition. The micrograph shows the existence of CuAl2 intermetallic phase. This intermetallic phase is nobler than Aluminium which is responsible for higher galvanic corrosion in Silumin after Copper addition. On the other hand, the dendrite cannot be observed in the case of Silumin after Nickel addition. The intermetallic phases after Nickel addition, i. e. AlxNiy contribute to the hardness increase. These phases also remain stable at elevated temperature which then then contributes to better mechanical properties of Silumin at the elevated temperature. [ABSTRACT FROM AUTHOR]

This study investigated how process parameters of laser cladding affect the microstructure and mechanical properties of WC-12Co composite coating for use as a protective layer of continuous caster rolls. WC-Co powders, WC-Ni powders, and Ni-Cr alloy powder with various wear resistance characteristics were evaluated in order to determine their applicability for use as cladding materials for continuous caster roll coating. The cladding process was conducted with various parameters, including laser powers, cladding speeds, and powder feeding rates, then the phases, microstructure, and micro-hardness of the cladding layer were analyzed in each specimen. Results indicate that, to increase the hardness of the cladding layer in WC-Co composite coating, the dilution of the cladding layer by dissolution of Fe from the substrate should be minimized, and the formation of the Fe-Co alloy phase should be prevented. The mechanical properties and wear resistance of each powder with the same process parameters were compared and analyzed. The microstructure and mechanical properties of the laser cladding layer depend not only on the process parameters, but also on the powder characteristics, such as WC particle size and the type of binder material. Additionally, depending on the degree of thermal decomposition of WC particles and evolution of W distribution within the cladding layer, the hardness of each powder can differ significantly, and the wear mechanism can change. [ABSTRACT FROM AUTHOR]

In this paper, an iron–aluminide intermetallic compound with cerium addition was subjected to Vickers microhardness testing. A full range of Vickers microhardness loadings was applied: 10, 25, 50, 100, 200, 300, 500, and 1000 g. Tests were conducted in two areas: 0.5 mm under the surface of the rolled specimen and in the center. The aim was to find the optimal loading range that gives the true material microhardness, also deemed load-independent hardness, HLIH. The results suggest that in the surface area, the reverse indentation size effect (RISE) occurred, similar to ceramics and brittle materials, while in the center, indentation size effect (ISE) behavior was obtained, more similar to metals. This clearly indicated an optimal microhardness of over 500 g in the surface region and over 100 g in the central region of the specimen. Load dependencies were quantitatively described by Meyer's law, proportional specimen resistance (PSR), and the modified PSR model. The modified PSR model proved to be the most adequate. [ABSTRACT FROM AUTHOR]

Cladding with a stick electrode is one of the oldest arc processes for adding a deposit on a base material. The process is suitable for outdoor working, but the disadvantages are low productivity and large dilution rates. In this work, a simple solution is proposed, which would enable cladding of a larger area with one pass and decrease the dilution rate at the same time—a new type of electrode was developed, exhibiting a rectangular cross-section instead of a round one. Hardfacings, welded with E Fe8 electrodes according to EN 14 700 Standard were welded on mild steel S355 J2 base material with three different coated stick electrodes. The first one was a commercially available, standard, round hardfacing electrode, the second was the same, but with a thinner coating, and the third one was a newly developed rectangular electrode. All three types had equal cross-sections of the metallic core and the same type of coating. Manufacturing of the rectangular electrodes in the laboratory is explained briefly. One- and multi-layer deposits were welded with all three types. Differences were observed in the arc behavior between the round and rectangular electrodes. With the rectangular electrode, the microstructure of the deposit was finer, penetration was shallower, and dilution rates were lower, while the hardness was higher, residual stresses predominantly compressive, and the results of instrumented Charpy impact tests and fracture mechanics tests were better. [ABSTRACT FROM AUTHOR]

In the present work, the influence of a corrosive environment and temperature on the corrosion resistance properties of duplex stainless steel S31803 was evaluated. The corrosive process was carried out using solutions of 1.5% HCl (m/m) and 6% FeCl3 (m/m), at temperatures of 25 and 50 °C. The microstructure of UNS S31803 duplex stainless steel is composed of two phases, ferrite and austenite, oriented in the rolling direction, containing a ferrite percentage of 46.2% in the rolling direction and 56.1% in the normal direction. Samples, when subjected to corrosive media and temperature, tend to decrease their mechanical property values. It was observed, in both corrosive media, that with increasing test temperature, there is an increase in the corrosion rate, both uniform and pitting. The sample in HCl solution obtained a uniform corrosion rate of 0.85% at 25 °C and 0.92% at 50 °C and pitting rates of 0.77% and 1.47% at the same temperatures, respectively. When tested in FeCl3 solution, it obtained uniform corrosion of 0.0006% and 0.93% and pitting of 0.53% and 18.5%, at the same temperatures. A reduction in dissolution potentials is also noted, thus characterizing greater corrosion in the samples with increasing temperature. [ABSTRACT FROM AUTHOR]

Currently, previous studies of low‐temperature sintering of high‐entropy carbide ceramics (HECCs) have followed the traditional approach to use the low‐melting‐point metals, such as Co, Ni, and so forth, as sintering additives. However, metallic binders can cause adverse impacts on hardness of HECCs. This study reported an innovation processing method for low‐temperature sintering of HECCs, which involved the use of various contents of CrN as sintering additive and spark plasma sintering at 1600°C to obtain dense HECCs. In comparison to the grain size of pure (Ti, Zr, Nb, Ta, Mo)C bulk sintered at 2000°C (3.29 ± 1.02 μm), the grain size of samples with the addition of 5–15 wt.% CrN sintered at 1600°C was significantly smaller, ranging from 0.32 to 0.48 μm. By using only 5 wt.% CrN, dense (Ti, Zr, Nb, Ta, Mo)C ceramics with a high hardness value of 26.73 ± 0.43 GPa could be obtained. Furthermore, increasing the amount of CrN to 15 wt.% resulted in a fracture toughness of 3.78 ± 0.10 MPa·m1/2. It is anticipated that the (Ti, Zr, Nb, Ta, Mo)C ceramic with an ideally combined hardness and toughness can be achieved at low sintering temperatures by the proper control of CrN content. [ABSTRACT FROM AUTHOR]

Although the hardness of sapphire is very high, in some applications, for example, working as panels in mobile phones and watches as well as optical windows in various military optical sensors, it still suffers from the destruction of being scratched and marked as well as mechanical failure by fracture. Here we reported that the technique of high‐temperature rolling we developed recently could be exploited to sapphire to enhance its hardness and fracture toughness. After rolling at 1200°C, Vickers' hardness and fracture toughness of sapphire increase by 4%–6% and 13%–27%, respectively. The enhancement of fracture toughness was explained by the residual compressive stress layer that was introduced in sapphire during rolling. The improvement of hardness was thought to be related to the hardening effect of dislocations. This work provides a new strategy for the mechanical property enhancement of sapphire in further applications. [ABSTRACT FROM AUTHOR]

The mechanical properties of Al2O3–LaPO4 composites with varying microstructures produced by flash sintering and conventional sintering are evaluated. Specifically, Vickers and Knoop hardness values were measured and calculated for different resultant microstructures, including eutectic microstructures with varying layer thickness, polycrystalline (noneutectic) microstructures, and single‐phase samples of Al2O3, LaPO4, and 8YSZ. The findings indicate that eutectic microstructures exhibited higher hardness values than polycrystalline counterparts on the flash‐sintered sample. However, the hardness values of eutectic microstructures with varying layer thicknesses show no significant or systematic variation. The grain size, indentation size, eutectic colony size, indentation shape (elastic recovery in Knoop indentations), and crack propagation pathways in the indented samples are also discussed. Overall, the results suggest that Al2O3–LaPO4 eutectic composites have higher hardness than their polycrystalline counterparts and have great potential as abradable coatings with high machinability and durability. [ABSTRACT FROM AUTHOR]

High leakage power consumption has become one of the main concerns of data security protection with CMOS device scaling. Spintronic technology is one of the efficient solutions to control circuit leakage power consumption by benefiting from its non-volatility property. Spintronic devices such as magnetic tunnel junctions (MTJs) are also compatible with CMOS transistors and suitable for designing hybrid MTJ/CMOS circuits. Hybrid MTJ/CMOS circuits can be used in many applications, such as logic-in-memory (LiM) and high-security structures. These circuits demonstrate enhanced data security compared to CMOS-based circuits by leveraging their non-volatile feature, making information leakage and data access more challenging. However, these circuits are not completely immune to attacks, and information can be revealed by potent power analysis attacks such as differential power analysis (DPA) and correlation power analysis (CPA). This paper investigates the resistance to side-channel attacks, especially DPA and CPA, for the magnetoresistive RAM (MRAM) and hybrid MTJ/CMOS AND, OR, XOR gates, hybrid MTJ/CMOS full-adder, and multiplexer circuits. Comprehensive post-layout simulation results using 40 nm TSMC CMOS technology, Monte-Carlo results, and values of normalized energy deviation (NED), normalized standard deviation (NSD)), and normalized power deviation (NPD) of PCSA-based MRAM indicate that the power consumption pattern remains constant in circuits with symmetrical structures in the reading phase even in the presence of inevitable process variation, so these circuits are resilient to power attacks and are competent for use in high-security applications such as hardware implementation of encryption algorithms. [ABSTRACT FROM AUTHOR]