Search Results (86)

Polishing pad conditioners are of critical importance in chemical mechanical polishing (CMP), acting as a key determinant of CMP efficiency and an indispensable consumable in the polishing process. In addition to acid–alkali resistance and outstanding stability, stringent requirements are also imposed on the physical properties of conditioners, including high hardness and wear resistance. Diamond films, with their exceptional comprehensive performance, can satisfactorily fulfill these demanding specifications. In this work, to investigate the bonding strength and wear resistance of diamond films deposited on a silicon carbide (SiC) substrate, four groups of diamond films with distinct processing parameters were synthesized via hot wire chemical vapor deposition (HWCVD) on SiC substrates. Nano-scratch tests were employed to characterize the bonding strength at the diamond film/SiC substrate interface, while wear tests under humid conditions with a 500 g load, accompanied by in-depth analysis of the associated wear mechanisms, were conducted. The results demonstrate that diamond films exhibit tremendous application potential as CMP pad conditioners in CMP processes. Full article

8Cr4Mo4V bearing steel is a critical material for main shaft bearings in aero-engine applications. However, the current understanding of the micro-mechanical properties of its matrix and primary carbide phases (vanadium-rich and molybdenum-rich carbides) remains insufficient. This knowledge gap readily induces various forms of deformation damage during grinding, severely compromising the surface integrity of the workpiece. To address this, nanoindentation and nano-scratch techniques were employed to systematically quantify the micro-mechanical properties of each phase and investigate the deformation damage behavior of the steel under load. Results showed that MC carbides exhibited the highest elastic modulus and microhardness, which made them more susceptible to becoming crack initiation sites during grinding. Nano-scratch testing further revealed that crack initiation at carbide edges and localized spalling were the primary damage mechanisms. This study provides a micro-mechanical foundation for controlling the grinding surface quality of 8Cr4Mo4V bearing steel, holding significant implications for optimizing grinding processes, suppressing crack initiation, and elucidating the grinding damage mechanism. Full article

This study aimed to examine the influence of sputtering temperature on the bonding structure and properties of non-hydrogenated chromium/nickel co-doped diamond-like carbon (DLC) films synthesized via direct current magnetron sputtering. The Cr/Ni doping levels in the coatings were regulated by varying the shield opening above a chromium-nickel (20/80 at.%) target, resulting in a total metal co-doping concentration ranging from 6.1 to 8.9 at.%. The thickness of the Cr/Ni-DLC films ranged from 160 to 180 nm. Meanwhile, the deposition temperatures of 185 °C and 235 °C were achieved by adjusting the substrate-to-target distance. The XPS and Raman spectroscopy results indicated enhanced graphitization of the Cr/Ni-DLC films with a decrease in the synthesis temperature. XPS results indicated the formation of carbon-oxide and metal-oxide bonds, with no evidence of metal carbide formation in the doped DLC films. Furthermore, both the nanohardness and Young’s modulus demonstrated significant improvement, while the friction coefficient was reduced more than twice as the deposition temperature increased. These findings provide valuable insights into the influence of deposition temperature on Cr/Ni co-doped DLC films, highlighting their potential as advanced functional coatings. Full article

This work reports on the effects of surface pre-treatment and EPD process parameters on the nanomechanical and adhesive performance of chitosan-based composite coatings fabricated on a Ti13Zr13Nb alloy. Three different coating systems were prepared: chitosan–Cu (series A), chitosan–HAp (series B), and HAp–Cu (series C). Coatings were deposited from suspensions at different voltages (10–30 V) and for various times (1–2 min) onto polished, anodized, and laser surface-treated titanium alloy substrates. Microstructural, nanomechanical, and adhesion properties were characterized by means of SEM, nanoindentation, and nanoscratch testing, respectively. Chitosan–Cu coatings exhibited the highest hardness (up to 8.2 GPa) and stiffness due to the homogeneous dispersion of Cu nanoparticles and strong interfacial bonding to the underlying anodized TiO₂ layer. Chitosan–HAp coatings were softer (0.05–0.13 GPa) and highly plastic, particularly after laser surface treatment due to their specific porous, polymer-dominated structure. HAp–Cu coatings exhibited an intermediate mechanical behavior with a hardness between 0.1 GPa and 2.9 GPa and enhanced elastic recovery (Wp/We ≈ 3.5–4.7), particularly for anodized substrates. The nanoscratch test results showed that the HAp–Cu coatings exhibited the highest adhesion Lc (≈150–173 mN), confirming a synergistic effect of hybrid composition and heat treatment on interfacial toughness. The present data demonstrate that the optimization of anodizing and EPD processing parameters allows for the manipulation of the mechanical integrity and adhesion of bioactive chitosan-based coatings for titanium biomedical applications. Full article

Cementitious materials are multiscale and multiphase composites whose frost resistance at the macroscale is closely governed by microstructural characteristics. However, the interfacial transition zone (ITZ) between clinker and hydrates, recognized as the weakest solid phase, plays a decisive role in the initiation and propagation of microcracks under freezing conditions. Understanding the frost damage mechanism of ITZ is therefore essential for improving the durability of concrete in cold regions. The motivation of this study lies in revealing how freezing affects the mechanical integrity and microstructure of ITZ in its early ages, which remains insufficiently understood in existing research. To address this, a nanoscratch technique was employed for its ability to quantify local fracture properties and interfacial adhesion at the submicronscale, providing a direct and high-resolution assessment of ITZ behavior under freeze–thaw action. The ITZ thickness and fracture properties were characterized in unfrozen cement paste and in cement paste frozen at 1 and 7 days of age to elucidate the microscale frost damage mechanism. Moreover, the enhancement effect of nano-silica modification on frozen ITZ was investigated through the combined use of nanoscratch and mercury intrusion porosimetry (MIP). The correlations among clinker particle size, ITZ thickness, and ITZ fracture properties were further established using nanoscratch coupled with scanning electron microscopy (SEM). This study provides a novel micromechanical insight into the frost deterioration of ITZ and demonstrates the innovative application of nanoscratch technology in characterizing freeze-induced damage in cementitious materials, offering theoretical guidance for designing durable concrete for cold environments. Full article

This study systematically investigates the effects of aging treatment (AT) on the microstructure and properties of Cr/DLC coatings deposited via cathodic arc ion plating onto the surface of ECAP-7075 aluminum alloy. Utilizing a comprehensive approach combining performance tests (nanoindentation, nanoscratch testing, dynamic polarization analysis) with characterization tests (scanning electron microscopy, energy dispersive spectroscopy, X-ray diffraction, and X-ray photoelectron spectroscopy), the synergistic effects of equal channel angular pressing (ECAP) and aging treatment(AT) were elucidated. The results demonstrate that the combined ECAP and AT significantly enhance the coating’s performance. Specifically, AT promotes the precipitation of η’ phase within the 7075 aluminum alloy substrate, increases the size of Cr₇C₃ crystallites in the Cr-based interlayer, improves the crystallinity of the Cr₇C₃ phase on the (060) or (242) crystal planes, and elevates the sp³-C/sp²-C ratio in the diamond-like carbon(DLC) top layer, leading to partial healing of defects and a denser overall coating structure. These microstructural transformations, induced by AT, result in substantial improvements in the mechanical properties (hardness reaching 5.2 GPa, bond strength achieving 15.1 N) and corrosion resistance (corrosion potential increasing to -0.698 V) of the Cr/DLC-coated ECAP-7075 aluminum alloy. This enhanced combination of properties makes these coatings particularly well-suited for high-performance aerospace components requiring both wear resistance and corrosion protection in demanding environments. Full article

This study investigates the anodization behavior and surface modification of Ti6Al4V (Ti64) alloy components fabricated via electron beam powder bed fusion (EB-PBF), aiming to enhance their performance in biomedical applications. Ti64 samples were manufactured using optimized EB-PBF parameters to produce a uniform microstructure and surface quality. Electrochemical anodization at 40 V and 60 V for 2 h generated self-organized TiO₂ nanotube layers, followed by a heat treatment at 550 °C to improve crystallinity while preserving the nanotube morphology. Characterization using scanning electron microscopy (SEM) and atomic force microscopy (AFM) revealed that a lower voltage produced uniform, compact nanotubes with moderate roughness and higher hardness, whereas a higher voltage generated thicker, less ordered nanotubes with larger diameters, increased roughness, and slightly reduced mechanical performance. X-ray diffraction (XRD) confirmed the presence of anatase TiO₂ phases, and energy-dispersive spectroscopy (EDS) analysis revealed a homogeneous distribution of Ti and O. Mechanical testing via nanoindentation and nanoscratch techniques demonstrated superior hardness and adhesion in nanotubes formed at lower voltage due to their compact structure. Electrochemical measurements indicated significantly enhanced corrosion resistance in anodized samples, attributed to the dense and chemically stable TiO₂ layer that acts as a barrier to aggressive ions and reduces active corrosion sites. In vitro bioactivity analysis further confirmed improved apatite formation on anodized surfaces. These results demonstrate the synergistic potential of EB-PBF and controlled anodization for modifying the surface properties of Ti64 implants, leading to improved mechanical behavior, corrosion resistance, and biological performance suitable for biomedical applications. Full article

This study investigates the mechanical and tribological behavior of a polydimethylsiloxane (PDMS)–silica nanocomposite coating over the temperature range extending from 24 °C to 120 °C. Nanoindentation tests revealed depth- and temperature-dependent variations in hardness and complex modulus. A time-dependent deformation model accurately captured the viscoelastic and viscoplastic behavior observed during sustained loading, providing predictive insight into the coating’s thermomechanical performance. Tribological evaluation through friction and nanoscratch testing demonstrated a temperature-induced increase in the coefficient of friction. The integration of mechanical and surface metrology and characterization techniques offers a comprehensive understanding of the coating’s behavior under thermal and mechanical stress. These findings support the design of robust nanocomposite coatings with superior functional performance for practical applications requiring enhanced mechanical stability, wear resistance, and thermal tolerance in challenging service environments. Full article

Single-crystal 4H silicon carbide (4H-SiC) is a key substrate material for third-generation semiconductor devices, where surface and subsurface integrity critically affect performance and reliability. This study systematically examined the evolution of surface morphology and subsurface damage (SSD) during nanoscratching of 4H-SiC under varying normal loads (0–100 mN) using a nanoindenter equipped with a diamond Berkovich tip. Scratch characteristics were assessed using scanning electron microscopy (SEM), while cross-sectional SSD was characterised via focused ion beam (FIB) slicing and transmission electron microscopy (TEM). The results revealed three distinct material removal regimes: ductile removal below 14.5 mN, a brittle-to-ductile transition between 14.5–59.3 mN, and brittle removal above 59.3 mN. Notably, substantial subsurface damage—including median cracks exceeding 4 μm and dislocation clusters—was observed even within the transition zone where the surface appeared smooth. A thin amorphous layer at the indenter-substrate interface suppressed immediate surface defects but promoted subsurface damage nucleation. Crack propagation followed slip lines or their intersections, demonstrating sensitivity to local stress states. These findings offer important insights into nanoscale damage mechanisms, which are essential for optimizing precision machining processes to minimise SSD in SiC substrates. Full article

Hastelloy is widely used in the manufacturing of high-temperature components in the aerospace industry because of its high strength and corrosion-resistant physical properties, as well as its ability to maintain excellent mechanical properties at high temperatures. However, with developments in science and technology, the amount of available components for use in high-temperature and corrosive environments is increasing, their structures are becoming more complex and varied, and requirements with regard to the surface quality of the components has also become more stringent. The integration of cold plasma (CP) and nano-lubricant minimum quantity lubrication (NMQL), within a multi-physics coupling-assisted micro-grinding process (CPNMQL), presents a promising strategy to overcome this bottleneck. In this paper, micro-grinding of Hastelloy C-276 was performed under dry, CP, NMQL, and CPNMQL conditions, respectively. Contact angle testing, X-ray photoelectron spectroscopy (XPS) analysis, and nano-scratch experiments were used to investigate the mechanism of CPNMQL and to compare the micro-milling performance under different cooling and lubrication conditions employing various characteristics such as grinding temperature, surface roughness, and 3D surface profile. The results showed that at different micro-grinding depths, the micro-grinding temperature and surface roughness were significantly reduced under CP, NMQL, and CPNMQL conditions compared to dry friction. Among them, CPNMQL showed the best performance, with 53.4% and 54.7% reductions in temperature and surface roughness, respectively, compared to the dry condition. Full article

Molecular dynamics (MD) simulation of nanoscratching with a spherical diamond abrasive was performed to investigate the role of water molecular film on the surface nanotribological characteristics and subsurface lattice damage of GaN (0001) at the atomic level. The simulation results indicate that the tangential and normal forces exhibited no significant variation trend with the increase in water film thickness. Inducing a water film can alleviate the material pile-up during scratching, and the GaN surface obtained the lowest friction coefficient and wear volume when the water film thickness reached 3 nm, primarily due to the enhanced lubrication and the heat absorption by the water film in this case. Water-film-covered GaN exhibited a thinner subsurface damage layer than the bare GaN, and the damage layer thickness decreased with the increase in water film thickness for various scratching depths of 1 to 4 nm. For each scratching depth, there was an optimal water film thickness causing the minimum number of amorphization atoms. Nevertheless, the water film failed to inhibit the formation and propagation of dislocations in the scratching process, and water-film-covered GaN exhibited more dislocations than the bare one. This research has the potential to expand the comprehension of water-mediated nanotribology and the ultra-precision machining procedures of GaN. Full article

The invasive presence of nanoplastics in various ecosystems makes them a significant environmental problem nowadays. One of the main production mechanisms of nanoplastics is mechanical wear. The combination of friction, abrasion, and shear forces can indeed lead to the progressive fragmentation of polymeric materials. The high surface area–volume ratio of the resulting nanoparticles not only alters the physicochemical properties of the polymers but also leads to increased interaction with biological systems, which raises questions about the persistence of nanoplastics in the environment and their potential toxicity. Despite the growing body of research on microplastics, studies specifically addressing the formation, characterization, and impact of wear-induced nanoplastics remain limited. This article describes current research on the formation mechanisms of nanoplastics generated by mechanical wear, highlighting the tribological processes underlying their release. Advanced characterization techniques used to identify the morphology and composition of these particles are also mentioned. The techniques include atomic force microscopy (AFM), scanning electron microscopy (SEM), and, to some extent, Raman spectroscopy. In the case of AFM, an example of application to the extrusion of nanoplastics from polystyrene surfaces subjected to repeated nanoscratching is also provided. Full article

TiN thin films are widely used as protective and decorative coatings for tools in industry. Previous studies have focused on the deposition of TiN coatings on substrates by reactive magnetron sputtering, whereas the use of TiN targets avoids problems such as ‘nitrogen contamination’ and ‘target poisoning’. TiN coatings were grown on silicon wafers and cemented carbide substrates by varying the parameters of the magnetron sputtering plasma source, operating Ar pressure and deposition temperature. The experimental results show the better mechanical properties of ceramic materials deposited using radio frequency (RF) magnetron sputtering. During RF magnetron sputtering, the hardness of the coating increased significantly to 17 Gpa when the deposition working pressure was reduced from 1.5 Pa to 0.5 Pa. The coefficient of friction tends to decrease as the deposition temperature increases, and at 400 °C the coefficient of friction between the deposited film and the friction pair made of Al₂O₃ material is only 0.36. The nano-scratch experimental tests concluded that the TiN coatings deposited at 300 °C conditions had the best adhesion to the substrate at an Ar pressure of 0.5 Pa under an RF source. Full article

Austenitic stainless steels are used widely in many fields due to their good mechanical properties and high resistance to corrosion. This work focuses on the reconstruction of the passive film after scratching. The purpose of the study was to compare changes in the rate of passive layer reconstruction and to discuss the effect of both the type of material and its electrochemical treatment on the reconstruction of the passive layer for two types of stainless steel: 304 and 316. The XPS tests performed indicate a significantly higher Cr/Fe ratio for the samples after the electropolishing process of 1.41–1.88 compared to the as-received samples of 0.82–0.86. After 2–3 min of sputtering the surface with Ar+ ions, a decrease in chromium content can be observed, with a simultaneous increase in nickel content, visible especially for the electropolished samples. A new approach in the conducted research was to scratch the test samples under controlled conditions, then evaluate the dynamics of the passive layer reconstruction using the AFM method, and then confront the obtained results with XPS measurements for the corresponding samples. For the as-received samples (2B finish) and those after surface treatment, regardless of the level of contamination of the electropolishing process bath, the reconstruction time was similar, which was approximately 2 h, although certain differences in the process dynamics were noticeable. Full article

The investigation of new composite materials possessing low weight but not at the expense of their mechanical performance is of great interest in terms of reducing energy consumption in many industrial applications. This study is focused on the nanomechanical characterization of high-density polyethylene (HDPE)-based composite specimens modified with equal loadings of graphene nanoplatelets (GNPs) and/or multiwall carbon nanotubes (MWCNTs). Quasi-static nanoindentation analysis revealed the impact of the carbon nanofillers on the receiving of nanocomposites with higher nanohardness and reduced modulus of elasticity, reaching values of 0.146 GPa and 3.57 GPa, respectively. The role of the indentation size effect in elastic polymer matrix was assessed by applying three distinct peak forces. Nanoscratch experiments depicted the tribological behavior of the composite samples and inferred the influence of the carbon nanofillers on the values of the coefficient of friction (COF). It seems that the incorporation of 4 wt% GNPs in the polymer structure improves the scratch resistance of the material, resulting in a higher value of the exerted lateral force and therefore leading to the detection of a higher coefficient of friction at scratch of 0.401. A considerable pile-up response of the scratched polymer specimens was observed by means of in-situ SPM imaging of the tested surface sample area. The sway of the carbon nanoparticles on the composite pile-up behavior and the effect of the pile-up on the measured friction coefficients have been explored. Full article