Search Results (44)

This paper investigates the influence of substrate grain size on the behavior of a multilayer CrN/CrAlN coating, with the bilayer thickness varying across the cross-section in the range of 200–1000 nm. The substrate tools were made of WC-Co sintered carbide with three different grain sizes. The coatings were subjected to mechanical and tribological tests to assess their performance, including nanohardness, scratch resistance, and tribological testing. The coating’s roughness was measured using a 2D profilometer. Additionally, the chemical composition and surface morphology were analyzed using Scanning Electron Microscopy (SEM) and Energy Dispersive X-Ray Spectroscopy (EDX). The durability tests were performed on an industrial CNC machine tool on the particleboard. The results revealed that tools with ultra-fine nano-grain (S) and micro-grain (T) WC-Co substrates exhibited a significant increase in tool durability by 28% and 44%, respectively. Significant differences in the microgeometry of the substrate U, especially in relation to the tool based on substrate S, explain the lack of improvement in its durability despite the use of a multilayer coating. Full article

Nano- and micro-indentation have become essential tools for quantifying the micromechanical behavior of rocks beyond traditional macroscopic tests. This review summarizes the historical evolution, experimental methodologies, and interpretation models (e.g., Oliver–Pharr, Doerner–Nix, energy-based methods, Hertz/ECM/Lawn), with a particular focus on rock-specific challenges such as heterogeneity, anisotropy, and surface roughness. A structured literature survey (1980–August 2025) covers representative studies on shale, limestone, marble, sandstone, claystone, and granite. The transition from classical hardness measurements to advanced instrumented indentation has enabled more reliable determination of localized properties, including hardness, elastic modulus, fracture toughness, and creep. Special attention is given to the applicability and limitations of different interpretation models when applied to heterogeneous and anisotropic rocks. Current challenges include high sensitivity to surface conditions and difficulties in capturing the full complexity of natural rock behavior. Looking forward, promising directions involve intelligent systems that integrate AI-driven data analytics, robotic automation, and multiscale modeling (from molecular dynamics to continuum FEM) to enable predictive material design. This review aims to provide geoscientists and engineers with a comprehensive foundation for the effective application and further development of indentation-based testing in rock mechanics and geotechnical engineering. Full article

To investigate the influence patterns and underlying mechanisms of solid waste-derived Nano-Micro-Powder (NMP) materials on asphalt performance, this study selected nano-sized silica fume (a typical industrial solid waste) along with conventionally used hydrated lime and cement powders as representative modifiers. Based on material type, dosage, and particle size, the high-temperature rheological properties, low-temperature rheological behavior, and nano-scale mechanical characteristics of NMP-modified asphalt were systematically evaluated through dynamic shear frequency tests, Multiple Stress Creep Recovery (MSCR) tests, Bending Beam Rheometer (BBR) tests, and Atomic Force Microscopy (AFM) measurements. Additionally, the grey relational analysis method was employed to quantify the impact of key nanoparticle characteristics on modified asphalt performance. The results demonstrate the following: (1) With increasing NMP dosage and decreasing particle size, the complex modulus (G*) of modified asphalt increases significantly, while the creep recovery rate (R) rises and non-recoverable creep compliance (J_nr) decreases. The creep stiffness slope (m-value) diminishes under low-temperature conditions. (2) Among different NMP types, silica fume-modified asphalt exhibits the highest G*, R, and m-value parameters. (3) At the nanoscale, adhesion force, modulus, and surface roughness all increase with higher NMP dosage and smaller particle size. Silica fume demonstrates superior performance in these nano-mechanical properties compared to hydrated lime and cement powders. (4) Grey relational analysis reveals that specific surface area shows the strongest correlation with the overall performance of NMP-modified asphalt. Full article

Titanium–aluminum–vanadium (Ti6Al4V) is a material chosen for spine, orthopedic, and dental implants due to its combination of desirable mechanical and biological properties. Lasers have been used to modify metal surfaces, enabling the generation of a surface on Ti6Al4V with distinct micro- and nano-scale structures. Studies indicate that topography with micro/nano features of osteoclast resorption pits causes bone marrow stromal cells (MSCs) and osteoprogenitor cells to favor differentiation into an osteoblastic phenotype. This study examined whether the biological response of human MSCs to Ti6Al4V surfaces is sensitive to laser treatment-controlled micro/nano-topography. First, 15 mm diameter Ti6Al4V discs (Spine Wave Inc., Shelton, CT, USA) were either machined (M) or additively manufactured (AM). Surface treatments included no laser treatment (NT), nanosecond laser (Ns), femtosecond laser (Fs), or nanosecond followed by femtosecond laser (Ns+Fs). Surface wettability, roughness, and surface chemistry were determined using sessile drop contact angle, laser confocal microscopy, X-ray photoelectron spectroscopy (XPS), and scanning electron microscopy (SEM). Human MSCs were cultured in growth media on tissue culture polystyrene (TCPS) or test surfaces. On day 7, the levels of osteocalcin (OCN), osteopontin (OPN), osteoprotegerin (OPG), and vascular endothelial growth factor 165 (VEGF) in the conditioned media were measured. M NT, Fs, and Ns+Fs surfaces were hydrophilic; Ns was hydrophobic. AM NT and Fs surfaces were hydrophilic; AM Ns and Ns+Fs were hydrophobic. Roughness (Sa and Sz) increased after Ns and Ns+Fs treatment for both M and AM disks. All surfaces primarily consisted of oxygen, titanium, and carbon; Fs had increased levels of aluminum for both M and AM. SEM images showed that M NT discs had a smooth surface, whereas AM surfaces appeared rough at a higher magnification. Fs surfaces had a similar morphology to their respective NT disc at low magnification, but higher magnification revealed nano-scale bumps not seen on NT surfaces. AM Fs surfaces also had regular interval ridges that were not seen on non-femto laser-ablated surfaces. Surface roughness was increased on M and AM Ns and Ns+Fs disks compared to NT and Fs disks. OCN was enhanced, and DNA was reduced on Ns and Ns+Fs, with no difference between them. OPN, OPG, and VEGF levels for laser-treated M surfaces were unchanged compared to NT, apart from an increase in OPG on Fs. MSCs grown on AM Ns and Ns+Fs surfaces had increased levels of OCN per DNA. These results indicate that MSCs cultured on AM Ns and AM Ns+Fs surfaces, which exhibited unique roughness at the microscale and nanoscale, had enhanced differentiation to an osteoblastic phenotype. The laser treatments of the surface mediated this enhancement of MSC differentiation and warrant further clinical investigation. Full article

Background: Traditional sandblasted large-grit acid-etched (SLA) surface treatments frequently utilize alumina (Al₂O₃) blasting, which may leave residual particles embedded in implant surfaces, potentially compromising biocompatibility and osseointegration. This study investigates a contamination-free alternative: titanium dioxide particle (TiO₂) blasting followed by hydrochloric acid (HCl) etching, aimed at generating a cleaner, hierarchical micro–nano-textured surface. Methods: Grade IV titanium disks were treated either with TiO₂ sandblasting alone or with an additional HCl etching step. Surfaces were analyzed via atomic force microscopy (AFM), scanning electron microscopy (SEM), contact angle measurements, and profilometry. hFOB osteoblasts were cultured to assess adhesion, proliferation, metabolic activity, and morphology. Results: The combination treatment produced a more homogeneous micro–nano structure with significantly increased roughness and a cleaner surface chemistry. Osteoblast proliferation and metabolic activity were notably improved in the TiO₂ and HCl group. SEM imaging showed a more organized cytoskeletal structure and pronounced filopodia at 72 h. Conclusions: Titanium blasting combined with HCl etching yields a cost-effective, contamination-free surface modification with promising early-stage cellular responses. This approach represents a safer and effective alternative to conventional SLA treatment. Full article

The dust generated during the sandblasting process of the sandblasted and acid-etched (SLA) method, commonly used to treat the surface of Ti dental implants, poses significant challenges in maintaining a clean manufacturing environment and ensuring safe working conditions. Nevertheless, surface modification remains crucial for improved performance of Ti dental implants. To address this problem and propose a clean and simple surface modification process to potentially replace SLA modification, this study aimed to characterize the surfaces of commercially pure Ti (cp-Ti) samples treated by acid etching and compare them with SLA-treated samples in terms of surface roughness (R_q), wettability (assessed through contact angle measurements), mineralized matrix deposition (evaluated through simulated body fluid [SBF] soaking), cell viability, cell differentiation (assessed based on alkaline phosphatase activity), and mineralization (assessed using MTT assay). Acid-etched surfaces exhibited nano- and micro-roughness and higher hydrophilicity than SLA surfaces, which is conducive to forming a highly bioactive TiO₂ surface. Moreover, acid-etched samples exhibited earlier hydroxyapatite deposition after SBF soaking than SLA samples. Furthermore, the acid-etched surfaces were nontoxic and displayed significantly higher cell viability and differentiation after seven days than SLA surfaces. These findings suggest that acid etching is a viable alternative to the SLA method, likely offering superior surface bioactivity and biocompatibility. Full article

Background: The physicochemical changes of the surface aim to improve cell adhesion, proliferation, and differentiation, that is, better biological interaction with the cells and, consequently, with the peri-implant tissues. In the present study, implants with the same macrogeometry were compared in vitro and in vivo, but with two different surfaces: micro-rough and a new micro-nano-rough surface. Materials and Methods: A total of 90 implants were used, 10 of which were used for in vitro surface characterization (n = 5 per group) through scanning electron microscopy (SEM), atomic force microscopy (AFM), and surface roughness measurements. For in vivo tests, 80 implants (n = 40 per group) were used in 20 rabbits (n = 2 implants per tibia). Two experimental groups were created: a control group, where the implants had a surface treated by sandblasting with titanium oxide microparticles, and a test group, where the implants were sandblasted using the same process as the previous group plus acid conditioned. The implant stability quotient (ISQ) was measured by resonance frequency (initially and at both euthanasia times). Animals were euthanized 3 and 5 weeks after implantation (n = 10 animals per time). Ten samples from each group at each time point were evaluated by removal torque (RTv). Another ten samples from each group were evaluated histologically and histomorphometrically, measuring the percentage of bone-to-implant contact (%BIC) and the bone area fraction occupancy (%BAFO). Results: In vitro, it was possible to observe a more homogeneous surface for the test group compared to the control group. ISQ values showed statistical differences at both 3 and 5 weeks (test > control). For RTv, the values were: 44.5 ± 4.25 Ncm (control group) and 48.6 ± 3.17 Ncm (test group) for the time of 3 weeks; 64.3 ± 4.50 Ncm (control group) and 76.1 ± 4.18 Ncm (test group) at 5 weeks. The %BIC and %BAFO values measured in both groups and at both times did not show significant differences (p > 0.05). Conclusions: The higher removal torque and ISQ values presented in the samples from the test group compared to the control group indicate that there was an acceleration in the mineralization process of the newly formed bone matrix. Full article

In past decades, the success rates of the first dental implant treatments were low (75%). Nowadays, oral rehabilitation with titanium dental implants has a high success rate (95%–98%). The success rate significantly increases due to increased scientific knowledge about osseointegration, changes in surgical techniques, and the development of implant surface treatments. Despite the high success rate of implants, there are no protocols to define the time for the prosthesis to be installed, the insertion torque, and the prosthesis loaded after surgery. This work compares a new dental implant’s primary (mechanical) and secondary (osseointegration) stability. Dental implants with micro- and nano-roughness surfaces were placed in 24 patients with a minimum of 35 N·cm and a maximum of 60 N·cm. Primary stability was quantified with a torque wrench and an Ostell Mentor Device. The secondary stability 45 and 60 days after surgery was measured with Ostell. The results showed no statistical difference in secondary stability at 45 and 60 days postoperatively among implants. The success rate of dental implants can be associated with the surface morphology with micro- and nano-roughness, the insertion torque value, and the shape of the implant threads. When the manufacturer’s guidelines are followed, it is possible to prosthetically rehabilitate the patient with an implant 45 days after surgery. Full article

Preparing elastic substrates as a carrier for dual-end supported nickel chromium thin film strain sensors is crucial. Wet etching is a vital microfabrication process widely used in producing microelectronic components for various applications. This article combines lithography and wet etching methods to microprocess the external dimensions and rectangular grooves of 304 stainless steel substrates. The single-factor variable method was used to explore the influence mechanism of FeCl₃, HCl, HNO₃, and temperature on the etching rate, etching factor, and etching surface roughness. The optimal etching parameter combination was summarized: an FeCl₃ concentration of 350 g/L, HCl concentration of 150 mL/L, HNO₃ concentration of 100 mL/L, and temperature of 40 °C. In addition, by comparing the surface morphology, microstructure, and chemical and mechanical properties of a 304 stainless steel substrate before and after etching treatment, it can be seen that the height difference of the substrate surface before and after etching is between 160 μm and −70 μm, which is basically consistent with the initial design of 0.2 mm. The results of an XPS analysis and Raman spectroscopy analysis both indicate that the surface C content increases after etching, and the corrosion resistance of the surface after etching decreases. The nano-hardness after etching increased by 26.4% compared to before, and the ζ value decreased by 7%. The combined XPS and Raman results indicate that the changes in surface mechanical properties of 304 stainless steel substrates after etching are mainly caused by the formation of micro-nanostructures, grain boundary density, and dislocations after wet etching. Compared with the initial rectangular substrate, the strain of the I-shaped substrate after wet etching increased by 3.5–4 times. The results of this study provide the preliminary process parameters for the wet etching of a 304 stainless steel substrate of a strain measuring force sensor and have certain guiding significance for the realization of simple steps and low cost of 304 stainless steel substrate micro-nano-processing. Full article

Electrical Discharge Machining (EDM) is a non-conventional machining technique, capable of processing any kind of conductive material. Recently, it has been successfully utilized for producing hydrophobic characteristics in inherently hydrophilic metallic materials. In this work, Wire Electrical Discharge Machining (WEDM) was utilized for producing hydrophobic characteristics on the surface of the aluminum alloy 6082, and various parameters that can affect wettability were investigated. Adopting an orthogonal Taguchi approach, the effects of the process parameter values of peak current, pulse-on time, and gap voltage on the contact angles of the machined surfaces were investigated. After machining, all samples were observed to have obtained hydrophobic properties, reaching contact angles up to 132°. The peak current was identified as the most influential parameter regarding the contact angle, while the gap voltage was the less influential parameter. A contact angle variation of 30° was observed throughout different combinations of machining parameters. Each combination of the machining parameters resulted in a distinct surface morphology. The samples with moderate roughness values (3.4 μm > Sa > 5.7 μm) were found to be more hydrophobic than the samples with high or low values, where the contact angle was measured under 115°. In addition, the finite element modeling of the experimental setup, with parametric surfaces of uniform random and Perlin noise types of roughness, was implemented. Time dependent simulations coupling phase field and laminar flow for the modelingof the wetting of surfaces with different surface roughness characteristics showed that an increase in the Sa roughness and total wetted area can lead to an increase in the contact angle. The combination of experimental and computational results suggests that the complexity of the wettability outcomes of aluminum alloy surfaces processed with WEDM lies in the interplay between variations of the surface chemical composition, roughness, micro/nano morphology, and the surface capability of forming a composite air/water interface. Full article

When describing the tribological behaviour of technical surfaces, the need for full-length scale microtopographic characterization often arises. The self-affine of surfaces and the characterisation of self-affine using a fractal dimension and its implantation into tribological models are commonly used. The goal of our present work was to determine the frequency range of fractal behaviour of surfaces by analysing the microtopographic measurements of an anodised aluminium brake plunger. We also wanted to know if bifractal and multifractal behaviour can be detected in real machine parts. As a result, we developed a new methodology for determining the fractal range boundaries to separate the nano- and micro-roughness. To reach our goals, we used an atomic force microscope (AFM) and a stylus instrument to obtain measurements in a wide frequency range (19 nm–3 mm). Power spectral density (PSD)-based fractal evaluation found that the examined surface could not be characterised by a single fractal dimension. A new method capable of separating nano- and micro-roughness has been developed for investigating multifractal behaviour. The presented procedure separates nano- and micro-roughness based on the geometric characteristics of surfaces. In this way, it becomes possible to specifically examine the relationship between the micro-geometry that can be measured in each wavelength range and the effects of cutting technology and the material structure that creates them. Full article

Wettability, as a vital tool for analyzing and describing oil flow, plays a significant role in determining oil/water relative permeability, residual oil distribution, and on–site recovery efficiency. Although the contact angle method is widely used for measuring wetting behavior, it is susceptible to the effects of surface roughness, oil–water saturation, and the distribution of mixed wetting within the range of droplet sizes. Additionally, millimeter–scale droplets fail to accurately represent the wetting distribution and the influencing factors at the micro/nano–scale. Therefore, this study presents a comprehensive investigation of the microstructure and wettability of shale samples. The characterization of the samples was performed using scanning electron microscopy (SEM) and atomic force microscopy (AFM) techniques to gain insights into their microscopic features, surface properties, and wettability. Results demonstrate the following: (1) Quartz and clay minerals tended to exhibit rough surface topography, appearing as darker areas (DA) under scanning electron microscopy (SEM). It is worth noting that plagioclase minerals exhibited brighter areas (BA) under SEM. (2) An increase in the content of minerals such as quartz and clay minerals was observed to decrease the surface oil wetting behavior. In contrast, plagioclase feldspar exhibited an opposite trend. (3) Based on the adhesive forces of the samples towards oil or water, a wetting index, I, was established to evaluate the wettability of shale at a microscale. The dimensionless contact angle W, obtained by normalizing the contact angle measurement, also consistently indicated oil wetting behavior. (4) By comparing the differences between I and W, it was observed that surface roughness significantly affected the behavior of water droplets. The presence of roughness impeded the contact between the solid and liquid phases, thus influencing the accuracy of the wetting results. Organic matter also plays a significant role in influencing surface wettability, and its distribution within the shale samples can lead to localized variations in wettability. Full article

Due to the expansion of the use of powder bed fusion metal additive technologies in the medical field, especially for the realization of dental prostheses, in this paper, the authors propose a comparative experimental study of the mechanical characteristics and the state of their microscale surfaces. The comparison was made from material considerations starting from two dental alloys commonly used to realize dental prostheses: Ni-Cr and Co-Cr, but also technologies for obtaining selective laser melting (SLM) and conventional casting. In addition, to compare the performances with the classical casting technology, for the dental prostheses obtained through SLM, the post-processing stage in which they are in a preliminary finishing and polished state was considered. Therefore, for the determination of important mechanical characteristics and the comparative study of dental prostheses, the indentation test was used, after which the hardness, penetration depths (maximum, permanent, and contact depth), contact stiffness, and contact surface were established, and for the determination of the microtopography of the surfaces, atomic force microscopy (AFM) was used, obtaining the local areal roughness parameters at the miniaturized scale—surface average roughness, root-mean-square roughness (RMS), and peak-to-peak values. Following the research carried out, several interesting conclusions were drawn, and the superiority of the SLM technology over the classic casting method for the production of dental prostheses in terms of some mechanical properties was highlighted. At the same time, the degree of finishing of dental prostheses made by SLM has a significant impact on the mechanical characteristics and especially the local roughness parameters on a miniaturized scale, and if we consider the same degree of finishing, no major differences are observed in the roughness parameters of the surfaces of the prostheses produced by different technologies. Full article

The current work seeks to discover and choose the proper friction stir processing (FSP) settings for aluminum alloy 7075 surface composites enhanced by adding three unique nanoparticles of titanium dioxide (TiO₂), B₄C, and graphene for superior performance. FSP is the only method that produces higher amounts of particle distribution and nanoscale reinforcing. For the sample fabrication, a special relatively high rotational speed of 2000 rpm and feed rate of 45 mm/min were tested with a suitable range of processing parameters (800–2000 rpm, 25–45 mm/min). To measure the micro-hardness and surface roughness of three different surface nano composites, they were studied under various FSP conditions. The findings showed that surface composites produced at high rotational speeds of 1400 rpm and 45 mm/min decreased surface roughness and granule distributions by 39% and 73%, respectively, and increased surface micro-hardness by 54%. According to the microstructure investigations, good bonding was produced between the AA7075 substrate generated at 1200 rpm and the base metal and friction stir processed specimens at 800 and 2000 rpm. The AA7075/B₄C surface composite produced at 1200 rpm rotating speed had a higher micro-hardness than the other two surface composites. Full article

There are many cylinder–plane contacts in microaccelerators, microgyroscopes, and RF switches. Adhesion is one of the main factors affecting the manufacture and use of these micro–nano devices, but its research is insufficient. Graphene is expected to be used in these fields due to its excellent electrical and mechanical properties. Therefore, it is significant to research the adhesion force of graphene under cylinder–plane. Firstly, the meniscus formation process was introduced using the variable-water-contact-angle method. Secondly, the adhesion force of the graphene surface was measured with a cylindrical atomic-force-microscope probe. Finally, the contact area was considered as a number of nanoscale cylinders in contact with the plane, and the adhesion force of the cylinder–plane model was obtained. The results showed that there was a maximum adhesion force at a relative humidity of 65%. The adhesion force was evidently not time-dependent when the relative humidity was below 45%, because the meniscus cannot be formed on the graphene surface at low relative humidity. While the graphene contact surface formed a meniscus for higher relative humidity, and the adhesion force-versus-time curves first increased and then decreased to stability. Moreover, the relationship between adhesion force and substrate contact angle, roughness, relative humidity, and dwell time was established, and the number of cylinders was determined. The error between the modified theoretical model and the experimental values was only 6%. Full article