Surface Microstructure Research Articles

Design and optimization of a flexible fiber-conducted laser light guide plate system

As the demand for slim liquid crystal displays (LCDs) continues to rise in the lighting and visual display fields, the edge-lit backlight structure has received significant attention. However, the edge-lit backlight structure cannot function properly without a light guide plate (LGP) system. This study proposes a novel LGP system employing a laser as the light source and utilizing optical fiber as a waveguide. The design transmits a laser beam into the LGP through an optical fiber, adds microstructure and reflective surfaces, and optimizes the layout of the microstructure. Under the condition that a single point light source is used as the incident light source of the system, the illumination uniformity of the light output surface is finally realized to be as high as 95.8 %, and the light transmission efficiency is as high as 79.7 %. Next, the light output performance of the LGP was measured in the case of single-point light entry on the short side of the strip LGP, and the difference between the test results and the simulation data was within 5 %. The system adopts the fiber optic transmission method of electro-optical separation, which has certain application prospects in the fields of underwater detection, decorative lighting and urban landscape.

Self-Powered Biomimetic Pressure Sensor Based on Mn-Ag Electrochemical Reaction for Monitoring Rehabilitation Training of Athletes.

Self-powered pressure detection using smart wearable devices is the subject of intense research attention, which is intended to address the critical need for prolonged and uninterrupted operations. Current piezoelectric and triboelectric sensors well respond to dynamic stimuli while overlooking static stimuli. This study proposes a dual-response potentiometric pressure sensor that responds to both dynamic and static stimuli. The proposed sensor utilizes interdigital electrodes with MnO2/carbon/polyvinyl alcohol (PVA) as the cathode and conductive silver paste as the anode. The electrolyte layer incorporates a mixed hydrogel of PVA and phosphoric acid. The optimized interdigital electrodes and sandpaper-like microstructured surface of the hydrogel electrolyte contribute to enhanced performance by facilitating an increased contact area between the electrolyte and electrodes. The sensor features an open-circuit voltage of 0.927V, a short-circuit current of 6µA, a higher sensitivity of 14mV/kPa, and outstanding cycling performance (>5000 cycles). It can accurately recognize letter writing and enable capacitor charging and LED lighting. Additionally, a data acquisition and display system employing the proposed sensor, which facilitates the monitoring of athletes' rehabilitation training, and machine learning algorithms that effectively guide rehabilitation actions are presented. This study offers novel solutions for the future development of smart wearable devices.

Enhanced marine biofouling and corrosion resistance through springtails-inspired papillate-like micropillar arrays surface modified by antimicrobial peptide

Marine biological fouling has a serious impact on artificial facilities, and traditional antifouling coatings are not beneficial to green development, which lead to the urgent to develop green strategies that can effectively prevent fouling. In this study, an innovative confluence of physical and biological approaches was employed to mitigate the harm caused by biofouling on a material substrate. Firstly, a hierarchical microstructured morphology was prepared on an aluminum surface by reactive ion etching and characterised. The antibacterial peptide, A-2S, was surface modified with dopamine as a coupling agent to produce a physico-biological synergistic antifouling surface. X-ray photoelectron spectroscopy, fourier transform infrared spectroscopy, and electrochemical experiments were then used to analyse the binding effect and corrosion resistance performance. A-2S was successfully modified on the sample surface and exhibited good corrosion resistance with a corrosion inhibition efficiency of 86.57 %. Compared to a bare aluminum plate, the microstructure surface has a certain inhibitory effect on fouling organisms, and the antifouling performance decreases over time. In contrast, the antimicrobial peptide synergistic surfaces demonstrated superior durable antifouling performance. Compared with the 50 % of the antifouling performance on the microstructure surface, the synergistic surface has a unique contact point effect of the microstructure and excellent antibacterial and bactericidal properties of antimicrobial peptides, resulting in a surface antifouling performance of over 80 %. The synergistic modification method enhanced the corrosion resistance of the material and reduced the adhesion of fouling organisms, mitigating the harm caused by biofouling on the marine equipment substrate.

Evaluation of anti-inflammatory properties on the surface of dental implants depending on the type of processing (Part 1)

The aim. To study of the anti-inflammatory properties of the surface of commercial dental implants with different processing methods using the example of the course of the first stage of implantation. Materials and methods. Dental implants made of titanium with 3D Active and Xpeed surface treatment were used. The surface microstructure and biocompatibility of the samples, surface corrosion, elemental analysis of the surface was studied. The assessment of the severity of peri-implantitis and mucositis based on the depth of the peri-implant pocket and bleeding during probing, determination of the coefficient of stability of implants (KSI) is given. Median test (χ2), Kruskel–Wallis test (H), univariate variance analysis (F) were used for multiple comparison of samples. The difference in parameters was considered statistically significant at the p ≤ 0.05 level. Results. The surfaces of 3D Active implants are monolithic with rounded pores in the form of wells of different diameters and depths; the upper layer of the Xpeed sample consists of closely adjacent to each other fragments of a rectangular or polygonal shape, in the form of tiles, leaving rectangular faces on the outside. On the surface of the 3D Active samples, in addition to oxygen and carbon, there was phosphorus – 5.04 wt%, as well as S, Ca, Na, Zr, Zn which weight percentage did not exceed 1 wt%. A significant difference in the elemental composition of Xpeed implants was the presence of chlorine 0.07 wt% and 0.93 wt%, silicon – 0.10 wt% and 0.14 wt%, aluminum 0.06 wt% and 0.23 wt%, respectively, with the latter has a significant advantage in these elements. Xpeed had an insignificant weight percentage of iron in its composition – 0.12 wt%. The assessment of cell adhesion to the surface of the samples on the first day of incubation demonstrated that the samples with the Xpeed and 3D Active surfaces did not have a statistically significant difference between them. Also, on the 7th day of incubation, the level of reduction of resazurin in Xpeed was lower, no significant difference was observed (p > 0.05). The clinical signs of bone tissue resorption were identified in 36.4 % of 3D Active implants and 60.0 % of Xpeed implants (p = 0.3); inflammation of the mucous membrane – in the areas of installation of 54.5 % of 3D Active implants. No signs of mucositis were detected around the Xpeed implants (p = 0.23). 9.1 % of 3D Active implants were “lost”; no cases of loss of Xpeed implants have been identified. The KSI of 3D Active – 64.0 ± 5.9 units, Xpeed – 65.1 ± 3.7 units. Conclusions. According to KSI indicators, titanium implants with Xpeed coating (65.1 ± 3.7 units) and 3D Active (64.0 ± 5.9 units) showed the same capabilities. Bone tissue resorption without signs of inflammation is more common around Xpeed-coated implants than 3D Active-coated implants. Clinical signs of inflammation are more frequent and more severe around implants with a 3D Active coating, which affected both the severity of the course of the first stage of implantation and its results. Xpeed-coated implants are more reliable than 3D Active: loss among 3D Active implants was 9.1 %, Xpeed – 0.0 %.

The Effect of Tempering Temperature on Microstructure and Wear Behavior of Tungsten and Boron Alloyed Ni-Hard 4 White Cast Irons

AbstractThis study investigates the effect of tempering temperature on the microstructure and wear resistance of high-alloy white cast iron (Ni-Hard 4) with 1.15% W and 0.5% B additions. Specimens were austenitized at 850 °C for 5 h, quenched in air, and tempered at temperatures between 250 and 650 °C for 4 h. Equilibrium and non-equilibrium thermodynamic calculations were performed using Thermo-Calc software. After the microstructural investigations, hardness testing was carried out. A pin-on-disk tribometer was used to conduct wear tests under dry sliding conditions. Microstructure and worn surfaces were examined using light and scanning electron microscopes. The results showed that increasing tempering temperature resulted in a higher volume fraction of carbides. It was found that tempering at 550 °C for four hours increases resistance to wear giving the lowest measured values of weight loss and wear rate. Accordingly, tempering allows the precipitation of fine carbides in the martensitic matrix which may increase wear resistance.

The oil lubricated fretting wear behavior under different sliding displacements and frequencies of Ti6Al4V titanium alloy as affected by micro-shot peening

The fretting wear behavior under oil lubricants is of great practical significance since oil is usually used to regulate fretting regime for minimizing wear. In this study, micro-shot peening (MSP) was performed on Ti6Al4V titanium alloy, in which 0.6 MPa injection air pressure, 60 s shot time and high-speed steel particles with an average diameter of 50 μm were used. Surface topography, microstructure, hardness and compression residual stress of test samples were examined. Oil lubricated fretting wear tests were then conducted between titanium alloy sample and GCr15 counterbody under different sliding displacements and frequencies. The test results show that the surface structure of MSP treated samples experienced severe plastic deformation, the surface hardness was increased from 310.8 HV to 433.5 HV, and a compression residual stress of −303.5 MPa was introduced within surface layer. Moreover, MSP treatment reduced the coefficients of friction through producing a micro-dimpled surface. Thereby, the fretting wear resistance of MSP treated sample under oil lubricated condition was improved. By comparison, at higher sliding displacement and frequency, the ability of MSP treatment to resist fretting wear was improved more significantly since more better lubricating effect can be obtained. Fretting damage of untreated sample under oil lubrication was mainly attributed to fatigue wear, delamination wear, abrasive wear and oxidation wear, while that of MSP treated sample was mainly regional peeling off and abrasive wear.

Solution‐Processed Nanocoating of Ca2Nb3O10 and Polydopamine for Anticorrosion on Magnesium Alloy

2D materials have exhibited great potential for applications in anticorrosion nanocoatings. However, the nanocoating of prefocused graphene shows “corrosion‐promoting activity” due to its high conductivity. Metal oxide nanosheets obtained by delaminating layered oxides have been another attractive candidate. This study demonstrates a water‐based Ca2Nb3O10 (CNO) ink spray coated on magnesium alloys to form a continuous coating without complex functionalization and structural control. The composite coating of Ca2Nb3O10 (CNO) and polydopamine (PDA) is fabricated by combining spray‐ and dip‐coating methods. The surface composition and microstructure of the as‐prepared coatings are characterized by X‐ray diffractometry, Fourier transform infrared, X‐ray photoelectron spectroscopy, scanning electron microscopy, and energy‐dispersive spectrometry. The anticorrosion performance of the composite coating is evaluated by potentiodynamic polarization, electrochemical impedance spectroscopy, and salt spray tests. The electrochemical results show that the CNO/PDA heterostructure coating provides an enhanced corrosion inhibition efficiency (99.62%) with a corrosion current density of 5.49 × 10−7 A cm−2, three orders of magnitude lower than bare AZ31. The immersion tests before and after heat treatment and salt spray tests indicate that the composite coating has good stability and long‐term anticorrosion performance. Solution‐processed nanocoating and extensible materials design provide a green and facile route to anticorrosion nanotechnology for industrial demands.

Reduced osseointegration in disuse and denervation rat models results from impaired cellular responses to multiscale microstructured titanium surfaces.

Immobilization-induced skeletal unloading results in muscle atrophy and rapid bone loss, thereby increasing the risk of falling and the need for implant therapy in patients with extended bed rest or neuromuscular injuries. Skeletal unloading causes bone loss by altering bone growth and resorption, suggesting that implant performance might be affected. To test this, we focused on early events in implant osseointegration. We used the rat sciatic neurectomy-induced disuse model under two different settings. In Study 1, 16 Sprague Dawley rats (SD) were separated into control, sham operated+cast immobilization, and sciatic neurectomy+casting groups; titanium implants with multiscale microtextured topography and hydrophilic chemistry (modSLA) were inserted in the distal femoral metaphysis. Neurectomy surgeries and casting were performed at the same surgical setting as implant placement; rats were euthanized 4 weeks post-implantation. In Study 2, we established the unloaded condition before implantation. A total of 12 SD rats were divided into control and sciatic+femoral neurectomy groups. A total of 24 days after sciatic and femoral neurectomy surgery, rats received implants. Study 2 rats were euthanized at 4 weeks post-implantation. MicroCT and histomorphometry showed that trabecular bone and osseointegration were reduced when disuse was established before implantation. Osteoblasts isolated from Study 1 sciatic neurectomy tibial bones exhibited impaired differentiation on modSLA culture disks, revealing a possible mechanism responsible for the decreased osseointegration observed in the Study 2 rats. This study addressed the importance of considering the mechanical unloading and muscle function history before implant insertion and suggests that implant performance was reduced due to poor cellular ability to regenerate.

Aloe vera Gel–Reinforced Biodegradable Starch–PVA Blends for Sustainable Packaging of Green Chillies

ABSTRACTThe objective of the current study was to evaluate the feasibility of Aloe vera gel as a plasticizer and crosslinker in improving the properties of starch–polyvinyl alcohol blends that could find applications in packaging. The concentration of Aloe vera gel was varied (1%, 3%, 5% and 7% wt/wt) to produce SPA‐1, SPA‐3, SPA‐5 and SPA‐7 films, respectively. The plasticizing and crosslinking characteristics associated with Aloe vera gel had a positive influence on the mechanical properties of the films. Addition of Aloe vera gel increased the tensile strength of films from 27.45 MPa (control) to 32.98, 32.53 and 32.32, for SPA‐1, SPA‐3 and SPA‐5 films, respectively. Among all the films, highest elongation at break (20.62%) was observed for SPA‐3 films. Due to crosslinking, degree of swelling, water solubility and water vapour permeability for SPA‐3 films decreased by 5.58%, 38.29% and 21.44%, respectively, compared to control films. The contact angle of the SPA‐3 film significantly increased by 49.25% when compared to control samples. Scanning electron microscope images revealed compact and smooth surface microstructure of control films, and crosslinking was evident in presence of Aloe vera gel. The rate of degradation for SPA‐3 films in soil after 40 days was enhanced by 32.25% compared to control films. SPA‐1 and SPA‐3 films were tested for use as packaging material for storage of green chillies. Chillies under unpacked conditions, in control and SPA‐1 films, turned red in 3 days. Those stored in films with 3% Aloe vera gel began to change colour later (after 5 days) with no visual evidence of microbial or fungal growth. In summary, starch–polyvinyl alcohol matrix films with 3% Aloe vera gel (SPA‐3) were effective as a sustainable alternative in increasing shelf life of foodstuff.

Comparative studies on microstructural characteristics and wear behavior of high-speed and low-speed laser cladding graphene/CoCrFeMo0.5NiTi0.5 high-entropy alloy composite layers

To prevent the failure of curved parts due to wear under actual working conditions, a graphene/CoCrFeMo0.5NiTi0.5 high-entropy alloy composite coating was prepared on the surface of a curved part using both high-speed and low-speed laser cladding (LLC). The surface morphology, physical phases, elemental distribution, microstructure, microhardness, and wear behavior of this coating applied via high-speed and LLC were comparatively studied. The results showed that the maximum height difference on the surface of the high-speed laser cladding (HLC) layer was only 44.7 % of that of the LLC layer, and the surface powder was more completely melted. The average microhardness of the HLC layer was about 1.49 times higher than that of the LLC layer and showed a maximum hardness of 666.38 HV0.5, which was about 2.95 times higher than that of the substrate. The internal microstructure of the HLC layer was finer and the diffusion of Fe atoms from the substrate into the coating was significantly reduced. In all three wear environments, abrasive wear occurred in both the low-speed and HLC layers. The total wear rate of the LLC layer was 230.588 μm3 N−1 mm−1, which was about 3.06 times higher than that of the HLC layer (75.395 μm3 N−1 mm−1). The wear surfaces of both cladding layers were oxidized, and the wear rate increased with the oxygen content on the wear surfaces under the same wear conditions. Meanwhile, the oxygen content of the wear surfaces of both cladding layers in sodium chloride solution was significantly higher than that during dry wear.

Smart Textile Flexible MnCo2O4 Electrodes: Urea Surface Modification for Improved Electrochemical Functionality.

Surface microstructure modification of metal oxides also improves the electrochemical performance of metal oxide nanoparticles. The present investigation demonstrates how varying the urea molar content during the hydrothermal process altered the surfaces of MnCo2O4 nanoparticles. Successive increases of 0.1 M in urea concentration transformed the surface shape of MnCo2O4 nanoparticles from flower-like to sheet-like microstructures. Excellent electrochemical performance of MnCo2O4 nanoparticles was demonstrated in an aqueous 1 M KOH electrolyte. The improved MnCo2O4 nanoparticles have been employed to develop an asymmetric supercapacitor (ASC). The ASC device exhibits an energy density of 13 Wh/kg at a power density of 553 W/kg and a specific capacitance of 29 F g-1 at a current density of 4 mA/cm2. The MnCo2O4 nanoparticle electrode demonstrates remarkable electrocatalytic activity in both HER and OER. The MnCo2O4 electrode shows overpotential for HER and OER at 356 mV and 1.46 V, respectively. The Tafel slopes for HER and OER of the MnCo2O4 electrode are 356 mV/dec and 187 mV/dec, respectively.

Two-photon lithography for customized microstructured surfaces and their influence on wettability and bacterial load

BackgroundDevice-related bacterial infections account for a large proportion of hospital-acquired infections. The ability of bacteria to form a biofilm as a protective shield usually makes treatment impossible without removal of the implant. Topographic surfaces have attracted considerable attention in studies seeking antibacterial properties without the need for additional antimicrobial substances. As there are still no valid rules for the design of antibacterial microstructured surfaces, a fast, reproducible production technique with good resolution is required to produce test surfaces and to examine their effectiveness with regard to their antibacterial properties.MethodsIn this work various surfaces, flat and with microcylinders in different dimensions (flat, 1, 3 and 9 μm) with a surface area of 7 × 7 mm were fabricated with a nanoprinter using two-photon lithography and evaluated for their antibiofilm effect. The microstructured surfaces were cultured for 24 h with different strains of Pseudomonas aeruginosa and Staphylococcus aureus to study bacterial attachment to the patterned surfaces. In addition, surface wettability was measured by a static contact angle measurement.ResultsContact angles increased with cylinder size and thus hydrophobicity. Despite the difference in wettability, Staphylococcus aureus was not affected by the microstructures, while for Pseudomonas aeruginosa the bacterial load increased with the size of the cylinders, and compared to a flat surface, a reduction in bacteria was observed for one strain on the smallest cylinders.ConclusionsTwo-photon lithography allowed rapid and flexible production of microcylinders of different sizes, which affected surface wettability and bacterial load, however, depending on bacterial type and strain.

Allergenicity Modulation of Casein with the Modifications of Linearization, Cross-Linking, and Glycation via the Regulation of Th1/Th2 Homeostasis.

Casein (CN) is the primary allergenic protein in cow's milk, contributing to the worldwide escalating prevalence of food allergies. However, there remains limited knowledge regarding the effect of structural modifications on CN allergenicity. Herein, we prepared three modified CNs (mCN), including sodium dodecyl sulfate and dithiothreitol-induced linear CN (LCN), transglutaminase-cross-linked CN (TCN), and glucose-glycated CN (GCN). The electrophoresis results indicated widespread protein aggregation among mCN, causing variations in their molecular weights. The unique internal and external structural characteristics of mCN were substantiated by disparities in surface microstructure, alterations in the secondary structure, variations in free amino acid contents, and modifications in functional molecular groups. Despite the lower digestibility of TCN and GCN compared to LCN, they significantly suppressed IL-8 production in Caco-2 cells without significantly promoting their proliferation. Moreover, GCN showed the weakest capacity to induce LAD2 cell degranulation. Despite the therapeutic effect of TCN, GCN-treated mice displayed the most prominent attenuation of allergic reactions and a remarkably restored Th1/Th2 imbalance, while LCN administration resulted in severe allergic phenotypes and endotypes in both cellular and murine models. This study highlighted the detrimental effect of linear modifications and underscored the significance of glycation in relation to CN allergenicity.

S30408 stainless steel laser weld joints: Microstructure evolution, performance and surface reinforced composites

The reinforced corrosion resistance composite coating was fabricated by laser cladding (LC) on the laser weld seam (WS) of S30408. The uniform microstructure, good tensile strength of WS and the LC coating were investigated, the mechanism of this LC coating reinforced the corrosion resistance of WS was extensively researched. The results revealed that WS consisted of face-centered cubic (fcc) austenite, and body-centered cubic (bcc) ferrite. The LC coating consisted of fcc. Amounts of the granular precipitates were distributed near the ferrites in WS. The tensile strength of WS was increased due to the synergistic effect of the solution/fine grain strengthening. Corrosion resistance of the LC coating was higher than that of the weld seam. Passivation films were produced due to the chemical reaction between Co/Cr/Fe and water/oxygen.

Analysis and optimization of the heat transfer behavior in the melt-spinning process of Nd-Fe-B ribbons

Heat transfer plays a significant role on the quality of Nd-Fe-B ribbons in the melt-spinning (MS) process. In this paper, the heat transfer behavior in the MS process of Nd-Fe-B ribbons was investigated by experiment and simulation. A full flow channel heat transfer model with high accuracy is established using the “fluid-thermal” coupling method. The temperature distribution of the cooling roller and fluid field in steady-state is obtained. The simulated and experimental results of the outlet temperature are compared and the relative error is within 5%. The microstructures of the free surface and roller-sticking surface of Nd-Fe-B melt-spun ribbons are characterized by FE-SEM, and the refined grains are formed on the roller-sticking surface of Nd-Fe-B ribbons due to rapid solidification caused by the heat transfer from the roller. Moreover, a multi-nozzle structure is proposed for the MS process. The temperature distribution on the surface of the cooling roller in the axial direction is more uniform compared with the original single-nozzle structure, and the average convective heat transfer coefficient is increased by about 1.27 times after the modification of multi-nozzle structure, with a productivity of three times. Finally, the experimental design method of Latin hypercube sampling response surface design is used to obtain the response surface relationships of rotational speed, inlet flow rate, and water inlet temperature on the surface temperature of the cooling roller, respectively. NSGA-II multi-objective genetic algorithm (MOGA) is adopted for multi-objective optimization of process parameters. The optimized combination of process parameters is obtained with a relative error of about 0.41%. The research results are helpful to understand the heat transfer behaviors in the MS process of Nd-Fe-B ribbons, improve the utilization rate of the cooling roller and enhance the production efficiency in the actual application.

PH-responsive HMDS terminated m-Cresol for inhibiting the spontaneous combustion in different-rank coals

In this study, pH responsiveness of 1, 1, 1, 3, 3, 3-hexamethyldisilazane terminated m-Cresol (HTMC) in different-rank coals was investigated, and its inhibition performance regarding the spontaneous combustion of coal was explored. First, color changes in the deprotection reaction of HTMC under different acidic conditions were analyzed. Then, surface microstructures of these coals and pH values of their filtrates were tested. Subsequently, experiments were performed on different coal samples for grasping their low-temperature oxidation characteristics, weight loss rates, pore characteristics, and free radical variations. The experimental results show that HTMC can effectively protect phenolic hydroxyl groups in inhibitors, and the acidity of coal can promote the conversion rate of its deprotection reaction. For instance, in XAM coal (pH ≈ 6), sufficient H+ stimulates HTMC to release massive m-Cresol which contains highly reactive phenolic hydroxyl, thereby effectively suppressing increases of the concentration and type of free radicals. The crossing point temperature (177.2 °C) and inhibition rate at 110 °C (75.9 %) of the HTMC-inhibited XAM sample are 33.1 °C and 17.9 % higher than those of the m-Cresol-inhibited one, respectively. This study confirms the applicability of pH-responsive HTMC to different-rank coals and may lay a theoretical foundation for the design of efficient reactive inhibitors.

Study on hardness and corrosion resistance of Co-Mo-P/ZrO2 composite coating electrodeposited on Q345 steel

Co-Mo-P/ZrO2 composite coating was prepared on the surface of Q345 steel by electrodeposition technology, and the effect of different ZrO2 particle concentrations on the surface morphology, chemical composition, thickness, microstructure and mechanical properties of the composite coating was investigated. The results show that different composite coatings prepared by changing the concentration of ZrO2 particles in the bath show aggregated cellular surface morphology, which is composed of Co, Mo, P, Zr, and O elements. With the concentration of ZrO2 particles increasing from 4 g/L to 20 g/L, the average grain size and the amount of ZrO2 particles incorporated both decrease first and then increase. Moreover, along with the increase in concentration of ZrO2 particles, the hardness and scratch resistance of the composite coating both show a trend of increasing first and then decreasing. However, changing the concentration of ZrO2 particles has no obvious effect on the grain structure and growth orientation of the composite coating. When the concentration of ZrO2 particles is 12 g/L, the surface of the composite coating is relatively dense with an average grain size of 40.78 nm and (200) crystal face preferred orientation. More ZrO2 particles are incorporated on the surface and boundary of the grain aggregation, which plays an obvious dispersion strengthening effect. The hardness of the composite coating reaches 580.2 HV, showing good scratch and corrosion resistance.

Determination of Crack Resistance of the Cover and Slide Glass by Indentation Method with the Visualization Using Atomic Force Microscopy

Crack resistance of two types of glass was studied – cover glass (0.17 mm thick) and slide glass (2 mm thick) using an improved technique through the use of the probe methods, which makes it possible to increase the accuracy of determining the crack resistance of glass. Colorless silicate glass was used. Crack resistance was determined by the Vickers pyramid indentation method. Microstructure of glasses surface and deformation region after indentation were studied using an atomic force microscope. Mechanical properties of glasses were determined by nanoindentation. Surface relief of a glass slide is rougher than that one of a cover glass. Roughness Rz for a cover glass is less than for a slide glass. Specific surface energy value of 0.26 N/m is higher for the slide glass compared to the coverslip. One elastic modulus value E of the cover glass is 48 GPa, and that one of the slide glass is 58 GPa. The microhardness value H is almost the same for by the glasses and amounts to 6.7 GPa for a slide glass and 6.4 GPa for a cover glass. Atomic force microscope images of deformation region after indentation with a Vickers pyramid show that the first cracks appear at a load of 1 N on the slide glass, and at 2 N on the cover glass. At a load of 3 N, the cover glass is destroyed. Based on the results of crack resistance calculations it was found that critical stress intensity coefficient KIC values are 1.42 MPa∙m1/2 for a glass slide, and 1.10 MPa∙m1/2 for a cover glass.

The effect of laser shock peening with different power density on the microstructure evolution and mechanical properties of MAR-M247 nickel-base alloy

This study investigates the effects of laser shock peening (LSP) on the microstructural evolution and surface hardening of MAR-M247 nickel-based alloy. Experimental and numerical simulation methods are employed to analyze the influence of pulse power density and spot size. The results demonstrate that LSP significantly enhances surface hardness and yield strength. As the pulse power density increases, the magnitude and depth of plastic deformation increase. Higher power densities can implant deeper and greater compressive residual stress (CRS), but the corresponding tensile residual stress (TRS) also increases. Reducing both power density and spot size decreases the amount of plastic deformation of the surface. However, decreasing the spot size results in a decrease in the depth of the CRS. On the other side, based on the analysis of the microstructure, during the process of LSP, many dislocations accumulate in the γ matrix and evolve into subgrain boundaries, resulting in grain refinement. Additionally, LSP induces the precipitation of nanoscale carbides. This study tries to establish the influence law and action mechanism between LSP process-material property-microscopic evolution, which provides theoretical and applied data support for engineering applications.

Enhanced interfacial bonding strength of hot-pressed titanium Alloy/CFRTP joint via laser ablation and interfacial adhesive

Joining titanium alloy with carbon fiber reinforced thermoplastic (CFRTP) is one of the hot subjects in the automotive and aerospace industries. To improve the joint strength of TC4/CFRTP PA6, this study combined the surface treatment of TC4 alloy, including laser ablation, Silane Coupling Agent (SCA) treatment, and interfacial PA6 adhesive. The results showed that the pretreatment and the laser texturing induced the micro-scale porous and macro-scale groove grid structure, respectively. The superhydrophilicity of the laser texturing as well as amino polar groups induced by SCA treatment promoted the adhesion of the thermoplastic PA6 melt into the microstructure of the TC4 alloy surface. The mechanical interlocking and hydrogen bonding between TC4 alloy and CFRTP PA6 significantly improved the shear strength of the TC4/CFRTP PA6 joint (17.5 MPa). Furthermore, with the incorporation of interfacial PA6 adhesive, the joint strength was further enhanced, and the damage of the TC4/CFRTP PA6 joint was transformed from interfacial to interlaminar CFRTP PA6.