Increase In Compressive Stress Research Articles

Optimizing texture and mechanical properties: The impact of pH-modulated metal-phenolic networks on soy protein isolate gels

This study presents the initial exploration of utilizing metal-phenolic networks (MPN) to augment the structure of soy protein isolate (SPI) gels. By employing EGCG and zinc ions to create MPN at varying pH levels (5, 7, and 9), the research investigates the impact of MPN on the texture, mechanical properties, and microstructure of SPI gels. Fourier transform infrared spectroscopy and X-ray photoelectron spectroscopy demonstrated that MPN binds to SPI through hydrogen bonding and electrostatic interactions. The findings indicate that the incorporation of MPN significantly enhances the structure of SPI gels. It is noteworthy that the MPN at pH 5 is the most effective in enhancing rheological properties, showing a 4 to 5-fold increase in the storage modulus. Conversely, the MPN at pH 7 excels in strengthening the 3D network, which boosts the mechanical properties, leading to a 1.88-fold increase in compressive stress. Furthermore, the addition of MPN enhances the structural integrity, thermal stability, and water retention of SPI gels, showcasing the potential of MPN as an innovative reinforcement method for food protein gels.

Enhancing Bone Implants: Magnesium-Doped Hydroxyapatite for Stronger, Bioactive, and Biocompatible Applications.

Hydroxyapatite (HAp) with the chemical formula Ca10(PO4)6(OH)2 is an inorganic material that exhibits morphology and composition similar to those of human bone tissues, making it highly desirable for bone regeneration applications. As one of the most biocompatible materials currently in use, HAp has undergone numerous attempts to enhance its mechanical strength. This research focuses on investigating the influence of magnesium (Mg) incorporation on the structural and mechanical properties of synthesized magnesium-doped hydroxyapatite (MgHAp) samples. Apart from its biocompatibility, Mg possesses a density and elasticity comparable to those of human bone. Therefore, incorporating Mg into HAp can be pivotal for improving bone formation. Previous studies have not extensively explored the structural changes induced by Mg substitution in HAp, which motivated us to revisit this issue. Hydrothermal synthesis technique was used to synthesize MgHAp samples with varying molar concentrations (x = 0, 0.5, 1.0, and 1.5). Theoretical simulation of HAp and MgHAp for obtaining 3D structures has been done, and theoretical X-ray diffraction (XRD) data have been compared with the experimental XRD data. Rietveld analysis revealed the alteration and deviation of lattice parameters with an increase in the Mg content, which ultimately affect the structure as well the mechanical properties of prepared samples. The findings revealed an increase in compressive stress and fracture toughness as the Mg concentration in the composition increased. Furthermore, using a finite-element analysis technique and modeling of the mechanical testing data, the von Mises stress distribution and Young's modulus values were calculated, demonstrating the similarity of the prepared samples to human cortical bone. Biocompatibility assessments using NIH-3T3 fibroblast cells confirmed the biocompatible and bioactive nature of the synthesized samples. MgHAp exhibits great potential for biomedical applications in the dental, orthopedic, and tissue engineering research fields.

Study of the inhibition mechanism of sapphire subsurface damage by tangential ultrasonic vibration

Ultrasonic vibration has a certain effect on the crack propagation tendency during sapphire grinding, but the mechanism of the effect on the crack propagation tendency has not yet been elucidated. In this study, tangential ultrasonic vibratory scratching and normal scratching sapphire processes were simulated using the discrete element method, and the expansion tendency of sub-surface cracks in the scratching sapphire process was analyzed in terms of cutting forces and stresses. The results of the study show that the crack depth decreases with increasing scratch speed and increases with increasing scratch depth; The greater the variation in cutting force, the greater the number of cracks formed and the crack propagation is mainly distributed near the maximum residual tensile stress; The introduction of tangential ultrasonic vibration induces a decrease in residual tensile stresses and an increase in residual compressive stresses, thus inhibiting subsurface crack propagation; The suppression of subsurface cracks becomes more pronounced as the amplitude increases. Finally, tangential ultrasonic vibratory scratching and normal scratching sapphire experiments were comparatively studied and the experimental results were in agreement with the simulation results. This study provides some theoretical guidance for the suppression of subsurface cracks in sapphire materials during the grinding process.

Improving Wear Resistance and Corrosive Resistance of Cemented Carbide for Mud Pulser Rotor by Deep Cryogenic Treatment.

Cemented carbide used in the rotor of a mud pulser is subjected to the scouring action of solid particles and corrosive mud media for a long time, which causes abrasive wear and electrochemical corrosion. To improve the wear and corrosive resistance of cemented carbide, samples with different cobalt content (WC-5Co, WC-8Co, and WC-10Co) receive deep cryogenic treatment (DCT) at -196 °C for 2.5 h. An optical metalloscope (OM) and X-ray diffractometer (XRD) are used to observe the phase changes of cemented carbides, and the XRD is also used to observe the change in residual stress on the cemented carbide's surface. A scanning electron microscope (SEM) is used to characterize the wear and electrochemical corrosion surface microstructure of cemented carbides (untreated and DCT). The results show that the DCT promotes the precipitation of the η phase, and the diffraction peak of ε-Co tends to intensify. Compared with the untreated, the wear rates of WC-5Co, WC-8Co, and WC-10Co can be reduced by 14.71%, 37.25%, and 41.01% by DCT, respectively. The wear form of the cemented carbides is mainly the extrusion deformation of Co and WC shedding. The precipitation of the η phase and the increase in WC residual compressive stress by DCT are the main reasons for the improvement of wear resistance. The electrochemical corrosion characteristic is the dissolution of the Co phase. DCT causes the corrosion potential of cemented carbide to shift forward and the corrosion current density to decrease. The enhancement of the corrosion resistance of cemented carbide caused by DCT is due to the Co phase transition, η phase precipitation, and the increase in the compressive stress of cemented carbide.

Influence of the thickness of pyrolytic carbon interphase on the mechanical behavior of SiC/(BN/PyC)/SiC composites

The composition and thickness of the interphase are critical factors affecting the strength of SiC/SiC materials. Therefore, SiC/(BN/PyC)/SiC ceramic matrix composites with varying PyC thicknesses were fabricated, and the mechanism by which thickness influences the mechanical properties of the materials was investigated. During the fracture process of the composites, debonding and crack deflection predominantly occurred at the BN/PyC interface. The PyC interphase thickness emerged as a critical factor influencing the mechanical performance of composites. The residual stresses within the PyC and its adjacent SiC matrix were determined by analyzing shifts in Raman peak positions. The findings indicate that a reduction in PyC thickness leads to an increase in residual compressive stress within the PyC and a corresponding increase in residual tensile stress within the SiC matrix, which increases the interfacial shear stress and improves the mechanical properties of the composites.

Cyclic shear test and finite element analysis of TRC-reinforced damaged confined masonry walls

Due to the low level of seismic fortification during construction, masonry walls are highly vulnerable to earthquakes, but some walls remain in service after repair. To investigate the strengthening effect of textile-reinforced concrete (TRC) on the seismic performance of seismically damaged confined masonry (CM) walls, tests were conducted on four masonry walls, and a finite element model was established for parametric analysis. A TRC facing improves the overall performance of the wall and increases the ductility of the wall. TRC reinforcement technology increases the peak load of CM walls by 19.9%-21.7%, the ductility factor by 42.1%-52.8%, and the cumulative energy dissipation by 95%-118%. The more severe the damage to the wall is, the less effective the strengthening effect of the TRC reinforcement. As the number of layers of textile increases, the load-bearing capacity, deformation capacity and energy dissipation capacity of the walls increase. When the vertical compressive stress increases, the increase in the shear bearing capacity and energy dissipation of walls due to the TRC facings first decreases and then increases. Moreover, TRC facings have limited effectiveness in reinforcing walls with high aspect ratios and high mortar strengths.

Effect of Low to High Pressure on the Structural, Mechanical, Electrical, and Optical Properties of Inorganic Material Ca3AsBr3: An Ab Initio Investigation.

Inorganic metal halide solar cells made from perovskite stand out for having outstanding efficiency, cheap cost, and simple production processes and recently have generated attention as a potential rival in photovoltaic technology. Particularly, lead-free Ca3AsBr3 inorganic materials have a lot of potential in the renewable industry due to their excellent qualities, including thermal, electric, optoelectronic, and elastic features. In this work, we thoroughly analyzed the stress-driven structural, mechanical, electrical, and optical properties of Ca3AsBr3 utilizing first-principles theory. The unstressed planar Ca3AsBr3 compound's bandgap results in 1.63 eV, confirming a direct bandgap. The bandgap within this compound could have changed by applying hydrostatic stress; consequently, a semiconductor-to-metallic transition transpired at 50 GPa. Simulated X-ray diffraction further demonstrated that it maintained its initial cubic form, even after external disruption. Additionally, it has been shown that an increase in compressive stress causes a change of the absorption spectra and the dielectric function with a red shift of photon energy at the lower energy region. Because of the material's mechanical durability and increased degree of ductility, demonstrated by its stress-triggered mechanical characteristics, the Ca3AsBr3 material may be suitable for solar energy applications. The mechanical and optoelectronic properties of Ca3AsBr3, which are pressure sensitive, could potentially be advantageous for future applications in optical devices and photovoltaic cell architecture.

Loading Mode-Induced Enhancement in Friction for Microscale Graphite/Hexagonal Boron Nitride Heterojunction.

Classical friction laws traditionally assume that the friction between solid pairs remains constant with a given normal load. However, our study has unveiled a remarkable deviation from conventional wisdom. In this paper, we discovered that altering the loading mode of micro graphite flakes led to significant changes in the lateral friction under identical normal loads. By adding a cap onto a single graphite flake to disperse the normal load applied by an atomic force microscope (AFM) tip, we were able to distribute the concentrated force. Astonishingly, our results demonstrated a notable 4-7 times increase in friction as a consequence of load dispersion. Finite element analysis (FEA) further confirmed that the increase in compressive stress at the edges of the graphite flake, resulting from load dispersion, led to a significant increase in friction. This study underscores the critical role of the loading mode in microscale friction dynamics, challenging the prevailing notion that friction remains static with a given normal force. Importantly, our research sheds light on the potential for achieving macroscale structural superlubricity (SSL) by assembling microscale SSL graphite flakes by using a larger cap.

Effect of residual volume after surgery of the discoid lateral meniscus on tibiofemoral joint biomechanics: a finite element analysis

BackgroundThe purpose of this study was to investigate the influence of different residual meniscus volume on the biomechanics of tibiofemoral joint after discoid lateral meniscus (DLM) surgery by finite element analysis.MethodsA knee joint model was established based on CT and MRI imaging data. The DLM model was divided into five regions according to conventional meniscectomy, with volumes of 15%, 15%, 15%, 15%, 15%, and 40% for each region. Additionally, the DLM model was divided into anterior and posterior parts to obtain ten regions. The DLM was resected according to the design scheme, and together with the intact discoid meniscus, a total of 15 models were obtained. Finite element analysis was conducted to assess shear and pressure trends on the knee joint.ResultsThe study observed significant changes in peak shear stress and compressive stress in the lateral meniscus and lateral femur cartilage. As the meniscus volume decreased, there was an increase in these stresses. Specifically, when the meniscus volume reduced to 40%, there was a sharp increase in shear stress (302%) and compressive stress (152%) on the meniscus, as well as shear stress (195%) and compressive stress (157%) on the lateral femur cartilage. Furthermore, the model grouping results showed that preserving a higher frontal volume in the meniscus model provided better biomechanical advantages.ConclusionThe use of finite element analysis has demonstrated that preserving more than 55% of the meniscus volume is necessary to prevent a significant increase in joint stress, which can potentially lead to joint degeneration. Additionally, it is crucial to preserve the front volume of the DLM in order to achieve improved knee biomechanical outcomes.

Study on mechanical and degradation behavior of Zn–Mn-xMg alloys under coupling effects of stress and SBF

Zinc-based implants will be subjected to combination of physiological corrosive media and stress during service in vivo. In this study, the mechanical and degradation behavior of Zn–Mn-xMg alloys under coupling effects of stress and simulated body fluid (SBF) were investigated. As a result, the ultimate tensile strength of Zn–Mn-xMg alloys decreased and incline to brittle fracture under the condition of slow strain rate tensile test in SBF. In addition, at a slower strain rate (1 × 10−6 s−1), the stress corrosion cracking susceptibility value will increase with the rise of Mg content. The immersion test under different compressive stresses shows that the corrosion will be inhibited under high pressure stress (50 MPa) compared with the lower one (10 MPa). The residual compressive strength of Zn-0.8Mn-xMg alloys decreases after immersion. A dense oxide layer could be induced with the increase of compressive stress, and it would inhibit the corrosion of the Zn-0.8Mn-xMg matrixes. These results indicate that Zn-0.8Mn-xMg alloys are expected to be a promising biodegradable material for biomedical applications.

ZrO2/SiO2/C nanofiber aerogels with enhanced mechanical and thermal insulation properties fabricated by freeze casting

Because of the inherent high-temperature resistance, the application of ZrO2 nanofiber aerogels in thermal insulation is promising. However, the contradiction between mechanical and thermal insulation properties has limited its applications. In the present work, nanofiber aerogels of ZrO2/SiO2/C with enhanced thermal insulation and compressive strength were successfully prepared by freeze-casting using tetraethoxysilane (TEOS) as a binder. The effect of TEOS content on the microstructure, compressive and thermal insulation properties was investigated. The porosity of the fabricated aerogels is higher than 97.3 %. The pore structure exhibits hierarchical characteristics, with honeycomb pores on the micro-scale and mesopores on the nano-scale. Part of the SiO2 phases generated by TEOS hydrolysis bond ZrO2 nanofiber to form fiber junctions, while the others cover the surface of ZrO2 nanofibers forming core-shell structure. With the increase of TEOS content, ZrO2/SiO2/C nanofiber aerogels showed a slightly decrease in thermal conductivity to a lower value of 0.032 W m−1 K−1 and an increase in compressive stress to 11.9 KPa. The thermal insulation mechanism and deformation mode during compression of aerogels were analyzed. This study not only provide ZrO2/SiO2/C nanofiber aerogels with both enhanced mechanical and thermal insulation properties, but also can guide the design and fabrication of other ceramic aerogels with excellent properties.

Numerical simulation analysis of anchor pullout under radial pressurization of anchor solid

The rock structure of weak rock formation is loose with low strength, which is easy to deform. Due to insufficient elongation and bearing capacity, anchor anchorage system damage is frequent and serious. Given the above problems, this paper researches the radial increase in compressive stress anchoring mechanism and uses finite element software ABAQUS simulation algorithms to obtain different radial pressurization conditions under the deformation of the surrounding rock law and the anchor pulling the anchor and the surrounding rock displacement stress change rule. The results show that when applying the radial pressure of 1.5 MPa, the surrounding rock and the anchor stress reach their maximum value, and the displacement reaches its minimum value. Field testing and monitoring results show that radial pressurized anchors can effectively control the deformation of the roadway perimeter rock and improve the anchoring effect.

Experimental Study and Mechanism Analysis on Compression–Shear Behavior of Hydraulic Asphalt Concrete at Different Temperatures

Abstract Hydraulic asphalt concrete (HAC), typically employed as an impermeable structure in embankment dams, is increasingly recognized for its widespread engineering applications. However, investigations of the mechanical performance of HAC under combined compressive–shear stress remain limited, particularly given its temperature sensitivity. Therefore, this study investigates the mechanical behaviors of HAC under combined compressive–shear stress at diverse temperatures and normal compressive stresses. Specifically, the failure modes, stress–strain curves, peak shear stress, and strain of HAC under various temperatures and normal compressive stresses are obtained for analysis. Experimental results demonstrate that the combination of normal compressive stress and temperature induces changes in peak shear stress and correlated shear strain. Increased normal compressive stress results in vertical restriction and the emergence of horizontal cracks, with deformation amplifying at elevated temperatures. All failure modes of HAC under these conditions are absent of spalled fines and debris. It is observed that as the normal compressive stress increases, the peak shear stress progressively increases, whereas an increase in temperature yields a clear decrease in peak shear stress. The shear strength of HAC comprises the cohesion strength of the asphalt matrix and the interfacial adhesion strength between aggregates and asphalt. Finally, three modified compressive–shear failure criteria that exhibit good prediction accuracy are established for HAC at diverse temperatures. This research offers a theoretical reference for the future investigation and engineering application of HAC.

Structure and Cathodoluminescence Properties in Tb3+ and Eu3+ Doped AlN Films

For the first time, Tb3+ and Eu3+ co‐doped AlN films were prepared using ion implantation, and the crystal structure and cathodoluminescence (CL) properties of films were investigated. Raman scattering and X‐Ray diffraction (XRD) show that high‐dose Tb3+ implantation leads to an increase in internal compressive stress. The non‐radiative resonant energy transfer was suggested between the Tb3+ and defects in the AlN host. The energy transfer mechanism between Tb3+ and Eu3+ in AlN films is discussed. Adjusting the dose ratio of Eu3+ with respect to Tb3+ allows for effective control of chromaticity coordinates and color temperatures.

The mechanism of the effect of dual-sided waterjet peening on the surface integrity and fatigue performance of 12 mm thick Inconel 718

This study aims to explore the mechanisms of residual stress formation and the effects on fatigue performance of 12 mm thick Inconel 718 under single-sided one-pass, two-pass, and dual-sided two-pass waterjet peening. Finite element models for waterjet peening and fatigue analysis were established using ABAQUS and Fe-safe, respectively. The study focused on analyzing the residual stresses, surface roughness, and fatigue cycle numbers of Inconel 718 after waterjet peening. The results were validated by conducting waterjet peening experiments and post-peening fatigue tests to ensure their reliability. The research findings indicated that the induced residual compressive stress was most effective with dual-sided two-pass waterjet peening, followed by single-sided two-pass and single-sided one-pass waterjet peening. Among them, after WJP-290 mm/s peening, the maximum residual compressive stresses for dual-sided two-pass, single-sided two-pass, and single-sided one-pass were 718.6, 906.4, and 1042.7 MPa, respectively. The maximum residual compressive stress depth after WJP-230 ∼ 290 mm/s peening was positively correlated with the jet velocity. Surface deterioration occurred after WJP-350 mm/s peening, leading to a significant reduction in the induced residual stress effect. After WJP-230 mm/s peening, the specimen exhibited an overall residual compressive stress of about 507.7 MPa at a depth of approximately 13.1 μm, with a total residual compressive stress depth of about 34.8 μm. Increasing the jet velocity to 290 mm/s shifted the maximum residual compressive stress depth to about 27.2 μm, with a maximum residual compressive stress increase of about 535 MPa, reaching 1042.7 MPa. At the same time, the overall residual compressive stress depth also increased to 39.9 μm. After increasing the jet velocity to 350 mm/s, a maximum residual compressive stress of about 708.7 MPa was induced at a depth of approximately 11.9 μm. The surface roughness, average roughness, and maximum roughness of the specimens were positively correlated with the jet velocity, with the most significant morphological changes occurring at the edges of the waterjet peened area, which coincided with the region prone to fatigue fracture in the cyclic fatigue tests. Increasing the number of jet impacts had a “peak-to-valley” effect on the surface of the peened specimens, making the surface flatter. The specimens peened with dual-sided waterjet showed significantly higher fatigue cycle numbers than those peened with single-sided waterjet. After WJP-230 mm/s peening, the fatigue life at stress levels of 93, 132, and 150 MPa was approximately 2,182,922, 258,000, and 56,575 cycles, respectively, which increased by about 399 %, 274 %, and 218 % compared to single-sided one-pass peening and by about 165 %, 139 %, and 125 % compared to single-sided two-pass peening.

Digital-image based performance analysis of CFRP–concrete interface bond under anchorage

This study investigated the bonding performance of Carbon fiber reinforced polymer (CFRP)-reinforced concrete interface under anchorage. The effect of positive compressive stress on the bonding performance of the interface was analysed using a single-sided shear test of the interface. The strain distribution on the CFRP surface during interface debonding was obtained using digital image technology. The shear-stress transfer law of the CFRP-concrete interface under anchorage was analyzed, and the bond-slip curve of the interface was obtained. Results showed that the increase in interfacial compressive stress improves the interfacial bearing capacity and slip behavior. After the interfacial compressive stress increases to a certain extent, the maximum strain of the CFRP specimens does not change with the positive stress. The principal model of bond slip in the anchorage zone under the anchoring action of the compressive steel plate was obtained; the models were tested and found to be consistent with the test results. The analytical solutions of the characteristic points of the interfacial load-slip curve in the anchorage zone under positive pressure were compared with the experimental values to prove the reliability of the fitted bond–slip intrinsic model.

Hybrid thrust sequences – A new structural perspective

Thrust sequences show a range of geometric and kinematic characteristics in cross-sections and in map view. Two types of thrust sequences are commonly observed in thrust systems – forward-breaking and break-back thrust sequences. For nearly half a century, it has been hypothesized that forward-breaking and break-back thrust sequences represent end-members of a continuous spectrum of brittle and ductile structures. Many natural and experimental observations of transitional thrust sequences display both forward-breaking and break-back (hybrid) thrust sequences within the same thrust system. An explanation of hybrid thrust sequence development has neither been provided conceptually nor experimentally. We present geometric and kinematic results of natural observations and numerical experiments that show a transition from forward-breaking to break-back thrust sequences caused by the effects of stratigraphic variations, sedimentary environment, surface processes, critical-wedge effects, progressive deformation with an increase in compressive stress, presence of detachments and their frictional properties, and strain rate. We also discuss numerous geometric, kinematic, chronological and mechanical criteria to identify the characteristic signatures of hybrid thrust sequences. This study provides a template to distinguish different thrust sequences and to characterize the deformation conditions under which hybrid thrust sequences develop in contractional settings. Mechanical and field criteria, displacement patterns imaged on seismic reflection sections across onshore and offshore thrust systems, and the way that thrusts interact in terms of geometry, kinematics and strain, are used to illustrate thrust development.

Comparative Studies of the Confined Effect of Shear Masonry Walls Made of Autoclaved Aerated Concrete Masonry Units.

Confined walls are popular in areas exposed to seismic action. The advantage of such structures is increased load-bearing capacity, ductility, and energy dissipation. Confined masonry walls are also used to restrain the intensity of cracking and improve load-bearing capacity in areas exposed to seismic action. This paper describes the research on 18 confined walls and presents a comparison with research on unconfined walls (referenced models). The confined models were classified into three series: HOS-C-AAC-without openings and with confining elements around the perimeter; HAS-C1-AAC with a centrally positioned opening and circumferential confinement; and HAS-C2-AAC with a centrally positioned window opening and additional confinement along the vertical edges of the opening. The area of the window opening was 1.5 m2. All walls were made of autoclaved aerated concrete (AAC) masonry units of the nominal density class of 600. The walls were tested under initial compressive stresses σc = 0.1; 0.75; and 1.0 N/mm2. The reference models without confinement (six models of the series HOS-AAC without openings and the series HAS-AAC with openings) were prepared from the same masonry units, had almost the same outer dimensions, and were tested under the same initial compressive stresses σc. The analysis was performed for the morphology of cracks, stress values at the moment of cracking and failure, stiffness, and angles of shear strain. The morphology of cracks was found to depend on initial compressive stresses and the presence of an opening. A significant increase in compressive stress leading to cracks and failure stresses was observed with increasing values of initial compressive stresses. As the wall behavior was clearly non-linear, the bilinear relationship described by energy dissipation E, stiffness at the moment of cracking Kcr, and maximum displacement uu was proposed to be included in the engineering description of the relationship between horizontal load and displacement of confined walls. Confinement along the vertical edges of the opening having an area of 1.5 m2 (acc. to EN 1996-1-1) increased the maximum forces Pmax by ca. 45% and marginally affected the ductility of the wall when compared to the elements with circumferential confinement.

Experimental study on permeability of spun high strength concrete material during mechanical loading

The pretensioned spun high strength concrete pipe pile (PHC pipe pile) is widely applied in important infrastructures of off-shore zones due to its low permeability and high capacity. During the construction process and the whole service period of PHC pipe piles, the damage is inevitably caused by many reasons, which may eventually cause the early durability failure of piles. Many researches have been conducted to study the change in permeability of normal concrete due to mechanical damage. However, the relation between permeability and damage of spun high strength concrete (SHSC) is still not been studied. To quantitively investigate the change of permeability of SHSC, a series of specimens of PHC pipe piles were tested for the change of permeability during mechanical loading process in this study. As a result, the relation of stress and permeability of spun high strength concrete as well as the crack roughness of the SHSC is obtained for efficient application in engineering. Before the 40% stress ratio, the permeability of the SHSC is slightly decreased as the compressive stress increases. The mean value and standard deviation of the intrinsic permeability of the SHSC are increased as the compressive stress loading reaches the peak stress. The order of magnitude of the crack roughness ξ can be taken as 10- 4 for engineering application. Compared with the vibrate-casted concrete, the crack roughness ξ is smaller, indicating that the crack surface of SHSC is rougher than the vibrate-casted concrete.

Sputtering by inverted magnetrons: influence on the texture and residual stresses in four layer Ta/W/Ta/W coatings

The aim of the study is to examine the possibilities of sputtering of multilayer coatings at a high rate of deposition on products of complex shape using inverted magnetrons. The formation of texture and residual stresses in magnetron four-layer Ta/W/Ta/W coatings deposited at voltages from 0 to –200 V on cylindrical and flat copper substrates imitating elements of the surface of complex shape products was evaluated using the X-ray method of inverse pole figures and the sin2Ψ method. The patterns of texture formation in coatings depend mainly on the bias voltage on the substrate (Us), while at Us = –200 V they differ for W and Ta layers. At Us = –100 V, the epitaxial mechanism of texture formation is realized. In the case of a cylindrical substrate, this leads to intense texture (111) of all four layers. In the case of a flat substrate, this can lead to the formation of a single-crystal texture (111) in all layers with a texture maximum width of 12°–14°. The presence of a single-crystal (111) tantalum texture corresponds to the maximum Young moduli and, accordingly, the interatomic bonding forces normal to the coating plane. This suggests that multilayer coatings with an external Ta layer have high tribological characteristics. Increasing the voltage on a flat substrate from 0 to –200 V leads to an increase in residual compressive stresses from 0.5 to 2.7 GPa for the four-layer coating under study.