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TiAlN film was deposited with Cr-CrN interlayer (Cr-(CrN/TiAlN)) on DAC-10 tool steel using cathodic arc deposition followed by annealing in vacuum chamber at 700°C temperature. Nanoindentation and nanoscratch test were conducted on as-deposited and annealed samples. The annealed samples showcased improved hardness (8.55 %) and elastic modulus (12.21 %) attributed to the formation of larger grain size (48 nm) and diffusion of Cr atoms from the interlayer. The XRD pattern of the annealed samples revealed Cr diffusion in the TiAlN top layer along with the formation of oxide such as Al2O3. The annealed samples registered lower pile up, indentation depth, higher strain hardening exponent (n = 0.41) and lower plastic work (0.25). Tribological properties such as scratch hardness was improved by 8.84%, whereas coefficient of friction and wear rate was reduced by 22.92% and 35.75%, respectively, after annealing of the coating. The relation between the nanomechanical and scratch properties was indicative of the influence of hardness and strain hardening exponent on the wear properties of the annealed Cr-(CrN/TiAlN) coating. [ABSTRACT FROM AUTHOR]

• The single crystal PdSe 2 maintained 83% of its original volume after undergoing abrasion, demonstrating the exceptional elasticity of its surface. • Thanks to its strain hardening and sensitivity to strain rate, PdSe2 exhibits ductility like aluminum, enabling it to withstand considerable deformation without compromising its structural integrity. • The examination of its creep behavior revealed size-dependent mechanical endurance under constant load. • Strain hardening measurements yielded n = 0.21 ± 0.07, highlighting the material's high ductility and elasticity, making it ideal for vibration-proof applications in flexible electronics. Palladium diselenide (PdSe 2), a transition-metal dichalcogenide (TMDC), has received interest for its intriguing optical and electrical characteristics. Despite its relevance for flexible electronics, its mechanical properties have been only scarcely investigated. In this work, we examined time-dependent mechanical response, wear, and nanoductility of PdSe 2 grown using chemical vapor transport. Specifically, we measured hardness, elastic modulus, creep characteristics, activation volume, strain rate sensitivity, and wear resistance using nanoindentation and nanoscratch experiments. The obtained values of Young's modulus and hardness are promising for flexible electronic applications. Due to its strain hardening and strain-rate sensitivity, PdSe 2 is ductile like aluminum and could endure significant deformation without losing structural integrity. The investigation of the creep behavior showed its size-dependent mechanical endurance under steady load, which is important for device dependability. Additionally, activation volume calculations indicate dislocation dynamics and processes during deformation, revealing the material's reaction to different mechanical loading conditions. Our nanoscratch experiments showed resilience to surface wear, confirming its suitability for durable flexible electronic devices. The significant elasticity of PdSe 2 , facilitating substantial recovery after deformation, renders it well-suited for flexible and wearable electronic devices requiring the maintenance of electrical continuity even under mechanical stress. The results of our mechanical characterization will open the door to the design and manufacturing of next generation PdSe 2 -based flexible electronic devices. [ABSTRACT FROM AUTHOR]

TiAlN film was deposited on Cr2O3‐coated plasma‐nitrided DAC‐10 tool steel to obtained multilayer Cr2O3/TiAlN coating layer using cathodic arc deposition technique. The structural make‐up of the coating was characterized using Atomic Force Microscopy (AFM) and X‐ray diffraction methods, and the mechanical properties were evaluated using nanoindentation and nanoscratch test. The structural phases of the coating indicated the presence of crystalline CrO structure and cubic TiAlN phases. The coating showcased improved hardness (38 GPa), elastic modulus (387 GPa), and adhesion along with appreciable H/E (0.09) and H3/E2 (0.366 GPa) attributes. Further, friction‐induced wear behavior of the coating was investigated against steel and Al2O3 counterbodies under dry sliding conditions. The wear behavior of the coating was greatly influenced by its hardness and deformation properties and frictional behavior of the counterbodies. More spikes and fluctuation were observed in the frictional curve against Al2O3 counterbody attributed to the emanation of TiO2, Cr2O3, and Al2O3 compounds due to dry sliding leading to the formation of flakes and delamination induced debris. Against the steel counterbody, the coating mainly formed a typical smooth glossy surface ascribed to the formation of Fe2O3 compound on the worn surface. [ABSTRACT FROM AUTHOR]

Current study deals with the effect of carbon nanotube (CNTs) and graphene nanoplatelets (GNPs) reinforcement on the mechanical properties and the adhesion strength of plasma sprayed alumina (Al 2 O 3) single splats, using in-situ picoindentation and nanoscratch test, respectively. The hardness of the Al 2 O 3 splat was measured as 18 ± 5.3 GPa which increased to 34.22 ± 8.44 GPa on 1 wt% CNTs addition and to 42.5 ± 9.06 GPa on 0.5 wt% GNPs addition. Hybrid addition of CNTs and GNPs provided the maximum hardness value of 51.25 ± 8.76 GPa to the Al 2 O 3 splat. Similar trend in the elastic modulus has been reported with a minimum value for Al 2 O 3 splat, i.e. 159 ± 35.40 GPa, and maximum for the Al 2 O 3 splat mixed synergistically with CNTs and GNPs (269 ± 43.12 GPa). Adhesion strength of the Al 2 O 3 splat (0.21 ± 0.11 MPa) also showed a nearly 5-fold increase on hybrid addition of CNTs and GNPs with a maximum value of 1.08 ± 0.38 MPa. This improvement in the properties were due to the extremely high mechanical properties of CNTs and GNPs and better melting of the splats, which not only improved the densification but also provided a better interlocking between the splat and the substrate. [ABSTRACT FROM AUTHOR]

Nanoindentation and nanoscratch tests of YAG single crystals were systematically performed. The mechanical properties including elastic recovery rate, elastic modulus, nano hardness and fracture toughness of YAG single crystals were obtained by the nanoindentation tests. The surface morphologies of the scratched grooves were analysed using scanning electron microscopy. The formation characteristics of YAG single crystals induced by varied-depth nanoscratch indicated that there was distinct brittle-to-ductile transition phenomenon during the scratching process. Surface radial cracks occurred prior to the edge-breaking phenomenon, and transverse cracks extending to the surface of the work material dominated the brittle removal of YAG single crystals. A theoretical model of the edge-breaking size during the nanoscratch process was developed by considering the stress intensity factor, elastic recovery rate, and residual force. This model indicated that the edge-breaking size increased as the normal force, average elastic recovery rate and elastic modulus increased, but decreased as the nanoindenter tip radius, fracture toughness and nano hardness increased. When the average elastic recovery rate was within 17.5%–20% (the maximum elastic recovery rate was within 35%–40%), the values predicted by the theoretical model agreed well with the experimental values, and the average error was less than 5%. The model could provide theoretical guidance for analysing the surface generation characteristics of brittle solid materials during the abrasive processing at brittle removal regime. [ABSTRACT FROM AUTHOR]

This research uses quasi-static nanoindentation and nanoscratching to quantify human tooth deformation as a function of enamel rod and dentin tubule orientations at the nanoscale. Nanoindentation tests were performed on enamel and dentin to determine elastic modulus, hardness, and observe fracture. Additionally, nanoscratch tests were performed to determine pileup geometry and parameters such as recovery, scratch hardness, and scratch roughness. In enamel, it was found that nanofiber orientation gives rise to unique microcrack propagation and nanofiber behavior that affect these properties. For dentin, densification and organic content affect these properties. [ABSTRACT FROM AUTHOR]

Abstract In materials employed in the marine oil extraction, a nitrided layer produced by plasma immersion ion implantation (PI3) can improve the surface resistance against abrasion and still work as a strengthened substructure for deposition of hard coatings. PI3-modified supermartensitic stainless steel (SMSS) surfaces consisted of an iron nitride-rich case followed by N-solid solution; thicknesses of both regions grew as the treatment temperature increased from 300 to 400 °C. The amount of nitrides scaled up with ion fluence/temperature. The thickest layer (25 μm) with the highest hardness profile (13 GPa) was produced at 400 °C, as a result of mixed iron nitrides precipitated in the matrix. Elastic recoveries after normal and tangential loadings were improved as well. Moreover, specific wear rates reduced up to two orders of magnitude and the coefficient of friction was 60% lower when compared with that of the untreated surface. Wear features varied from adhesive to abrasive as iron nitrides became the prevailing structure on the modified surfaces, from 300 °C to 400 °C. Even so, all the nitrided layers disclosed an overall ductile character under deformation. Nanomechanical analyses indicated that nitrides-containing top layers originated in the implantation and diffusion-based PI3 method were uniformly hardened in depth, in contrast with those from the conventional plasma nitriding. Highlights • SMSS surfaces were nitrided though the implantation and diffusion-based PI3 method. • Temperature and ion fluence rule the layer structure and mechanical strengthening. • N-PI3 produces uniformly hardened top nitride-rich layers and underneath α′ N cases. • Wear tests disclose abrasion features as prevailing phases vary from α′ N to γ′ + ε. • Friction is reduced in 60% and wear in 2 orders of magnitude in the 400 °C nitriding. [ABSTRACT FROM AUTHOR]

This paper reports a study on the mechanical and tribological properties of ab- and a (b) c−planes of YBa2Cu3O7−δ single crystals. The single crystals were grown using a CuO-BaO self-flux method. The oxygenation effect on the mechanical and tribological properties of ab- and a (b) c−planes is reported. For the ab- plane, the hardness and elastic modulus were around 6 and 50 GPa, respectively. In this case, significant differences were not observed among the hardness and elastic modulus at different oxygenation states. However, the hardness and elastic modulus for as-grown and oxygenated YBa2Cu3O7−δ single crystals were different from that of the a (b) c−plane, and were observed to be slightly higher for the as-grown than for the oxygenated samples. For as-grown and oxygenated samples, we observed hardness values around 4.7 and 2.0 GPa, respectively. Regarding the elastic modulus, the values were 75 and 40 GPa, respectively. The indentation fracture toughness values on the ab- plane for the as-grown and oxygenated YBa2Cu3O7−δ single crystal were 3.7 ± 1.2 and 2.9 ± 1.2 MPa m1/2, respectively. For the ab- plane, the scratch resistance of the as-grown sample was higher than that of the oxygenated sample and the scratches under load were deeper for the oxygenated sample. As regards the a (b) c−plane, the scar features were seemingly constant through all the scratch lengths and the scratches under load were deeper and larger for the oxygenated than that for the as-grown sample. [ABSTRACT FROM AUTHOR]

This paper reports a study on the mechanical and tribological properties of ab- and a (b) c−planes of YBa2Cu3O7−δ single crystals. The single crystals were grown using a CuO-BaO self-flux method. The oxygenation effect on the mechanical and tribological properties of ab- and a (b) c−planes is reported. For the ab- plane, the hardness and elastic modulus were around 6 and 50 GPa, respectively. In this case, significant differences were not observed among the hardness and elastic modulus at different oxygenation states. However, the hardness and elastic modulus for as-grown and oxygenated YBa2Cu3O7−δ single crystals were different from that of the a (b) c−plane, and were observed to be slightly higher for the as-grown than for the oxygenated samples. For as-grown and oxygenated samples, we observed hardness values around 4.7 and 2.0 GPa, respectively. Regarding the elastic modulus, the values were 75 and 40 GPa, respectively. The indentation fracture toughness values on the ab- plane for the as-grown and oxygenated YBa2Cu3O7−δ single crystal were 3.7 ± 1.2 and 2.9 ± 1.2 MPa m1/2, respectively. For the ab- plane, the scratch resistance of the as-grown sample was higher than that of the oxygenated sample and the scratches under load were deeper for the oxygenated sample. As regards the a (b) c−plane, the scar features were seemingly constant through all the scratch lengths and the scratches under load were deeper and larger for the oxygenated than that for the as-grown sample. [ABSTRACT FROM AUTHOR]

Objectives The local structures and mechanical properties within tooth dentin-enamel-junction (DEJ) regions have been focused for numerous studies. The reported results, however, remain inconsistent particularly on the functional width and gradient architecture of the DEJ. The current study aims at systematically determining the mechanical gradient of the DEJ at different intratooth locations such that a clearer understanding on the tooth properties and the potential correlations with the tooth function could be obtained. Methods We re-examined how mechanical properties such as elastic modulus and hardness transitioned from those of dentin to those of enamel using combined static and dynamic nanoindentation mapping techniques. A new mapping method and associated image processing procedures were developed to improve the measurement accuracy and resolution. Results A thin, sigmoidally-transitioned interphase layer of the DEJ was identified with an accurate functional width of 2–3 μm. The DEJ width and gradient architecture were found intratooth location-dependent, with the DEJ at the occlusal sites being wider and transitioning smoother than that at the cervical sites. Such different widths and architectures of the interphase layer at sites subjected to different types and magnitudes of loadings during mastication could promote more efficient stress transferring between enamel and dentin without compromising the overall stiffness of the tooth. Significance The presented study not only adds our understanding in the local mechanical properties within tooth DEJ regions, it could also further advance the development of DEJ-mimetic, functional gradient interphase for strong and ultra-durable jointing between dissimilar materials. [ABSTRACT FROM AUTHOR]

Vinyl ester is a thermoset matrix resin that is widely used in the coating industry. The presence of glass flakes further enhances the anti-corrosion performance of this coating. This paper reports the nanoscaled characterization of glass flake filled vinyl ester anti-corrosion coatings on mild steel. Bond strength properties of one uncoated and four coated samples with different thicknesses (300, 600, 900 and 1200 μm) were studied using nanoscratch technique and ASTM Standard Test. It was found that the bond strength of coating with thickness 900 μm was the highest. The frequency distributions of elastic modulus on coating with 900 μm thickness determined using nanoindentation indicated that only 20-25% of the coating is composed of glass flakes and the balance is vinyl ester matrix. The critical depth at which the material is subject to failure due to external load and abrasion, was found to be around 100 nm. [ABSTRACT FROM AUTHOR]

The wear behavior of two coatings (Fe49.7Cr18Mn1.9Mo7.4W1.6B15.2C3.8Si2.4 and Fe40Cr23Mo14C15B6Y2) sprayed by high-velocity air fuel technology was investigated through nanoscratch tests under ramping loads. Compared with the substrate, the Fe-based amorphous coatings exhibit lower penetration depth, higher elastic recovery, and lower wear volume, indicating the excellent wear resistance of the coatings. This behavior is related to the high hardness and high hardness/elastic modulus ratio (H/E) of the Fe-based amorphous coatings. From the scanning electron microscopy images of the scratch grooves, it is found out that ploughing governs the wear behavior of the coatings and substrate. In addition, spalling wear easily occurs in the pore regions of the coatings. [ABSTRACT FROM AUTHOR]

In this work, the differences in nanomechanical properties, topography and morphology of carbonpalladium (C-Pd) films were studied. These films were prepared with a Physical Vapour Deposition method on various substrates with different technological parameters. We show that duration of the PVD process is a crucial factor affecting the palladium content in these films. The differences in thickness of films depend on the distance between source boats and substrates. The nanomechanical properties of C-Pd films were studied with nanoindentation. Their topography and morphology was ascertained with Atomic Force Microscopy and Scanning Electron Microscopy. It was found that the mechanical properties of C-Pd films depend on the content of palladium and on the morphology and topography of these films. The various types of carbon-palladium films containing palladium nanograins incorporated in a carbon matrix that were, investigated in this paper, seem to be promising materials for numerous applications.

Bioactive layers produced on titanium to induce osseointegration may not be mechanically stable and/or attend to the requirement for the bone-matching elastic modulus. The previous surface modification by ion nitriding can eventually improve adhesion and mechanical properties of such bioactive coatings. Titanium samples were DC plasma nitrided in low conditions of temperature (673 K and 873 K) and time (1 h and 3 h). The surfaces were studied by grazing-incidence X-ray diffraction, micro-Raman spectroscopy, atomic force microscopy, scanning electron microscopy, instrumented indentation and nanoscratch tests. The treatments at 873 K produced a stratified surface containing δ-TiN, ε-Ti 2 N and N-solid solution Ti(N), whereas the 673 K samples presented Ti(N) and evidence of nitride precipitates at a very shallow depth, as suggested by micro-Raman (depth of analysis ≤ 25 nm). The asperity degree and distribution increased with the treatment temperature and time, whose effects on hardness and elastic modulus were corrected by the contact stiffness analysis. The most significant changes in the near surface hardness (5 to 15 GPa) and elastic modulus (170 to 200 GPa) profiles in respect to the pristine Ti were observed for 873 K treatments. However, the 673 K – 3 h sample presented scratch hardness twice as high as the substrate value, even if the ductile-like tribological response was preserved. Afterwards, Ca–P containing titania coatings were produced by anodic oxidation on selected samples. The layers presented reduced brittleness under normal loading if grown on the previously nitrided surfaces, whereas elastic modulus profiles (75–90 GPa) were kept lower than bulk Ti. We conclude that Ti surfaces can be tailored by plasma nitriding to improve their load bearing capacity for deposition of bioactive layers. [ABSTRACT FROM AUTHOR]

Abstract: The present study investigated the microstructure and nanomechanical properties on the cross and normal planes of cold sprayed pure Al and Al-based composite coatings. The inhomogeneous plastic deformation of Al particles took place with the occurrence of grain refinement along the particle boundaries. No preferred orientation distribution in the cold sprayed Al coating was observed because of the random impact direction of particles on the surface of substrate or the previously formed coating. The hammering effect of hard Al2O3 particles enhanced the plastic deformation of Al particles. Anisotropic mechanical properties were revealed, i.e., higher hardness and elastic modulus were obtained on the cross plane. Compared with pure Al bulk metals, both the cold sprayed pure Al and Al-based composite coatings demonstrated the improved tribological properties in terms of lower wear volume and reduced friction coefficient. [Copyright &y& Elsevier]

Abstract: Alkali-heat treatment (AHT) is a simple and practical method to make titanium surfaces bioactive. Hydroxyapatite nucleates on Ti when in contact with body fluids due to the presence of a thin sodium titanate film produced by the AHT. This method was proposed more than a decade ago and it has been widely investigated at varied scopes. However, there is still little information about the mechanical properties of this film. In this work, the tribo-mechanical behavior of films produced by alkali treatment (AT) and AHT on Ti is investigated using instrumented indentation technique. The films were also characterized by TF-XRD, SEM, EDS and in vitro bioactivity tests. Analytical methods were employed to obtain the mechanical properties of the film from instrumented indentation data. The heat treatment subsequent to the alkaline processing increased the film elastic modulus from 1.7 GPa to 2.8 GPa, the hardness from 12 MPa to 20 MPa and the critical load for scratch test from 1.5 mN to 5.5 mN. Despite the overall improvement in the film bioactivity and tribo-mechanical behavior, the AHT elastic modulus is only 2% of the pristine Ti whereas hardness is less than 1%. This information must be considered for implant design purposes. [Copyright &y& Elsevier]

The micromechanical and tribological properties of titanium matrix composites reinforced with graphene oxide (GO) were investigated by nanoindentation and nanoscratch methods. The effect of sintering temperature on the nanohardness and elastic modulus of the composite was also evaluated. The results indicate that as the GO content and sintering temperature of the composite were increased, the nanohardness and elastic modulus significantly increased, attributing to the high mechanical property of GO and TiC formation. The composite reinforced with 5 wt% GO exhibited the maximum nanohardness (4.79 GPa) and elastic modulus (163.7 GPa) at 1473 K. At high temperatures, the composite achieved high elastic recovery. The nanoscratch behavior of the composites revealed that increased GO content and sintering temperature led to enhanced elastic recovery and reduced coefficient of friction. [Display omitted] • Micromechanical properties of titanium matrix composite is studied by nanoindentation and nanoscratch methods. • The high GO and temperature the applied, the higher nanohardness and elastic modulus. • The friction-reduction performance is improved by increasing of GO and sintering temperature. • The Ti-5 wt.% GO sintered at 1473 K exhibited the maximum micromechanical property. [ABSTRACT FROM AUTHOR]

The nanohardness (H), reduced elastic modulus (E), and nanotribological properties including nanoscratch and nanowear resistance of tantalum/cobalt (Ta/Co) nanolaminates with varying individual layer thickness (h) were systematically studied using a nanoindenter. With decreasing individual layer thickness from 100 nm to 5 nm, the H of the nanolaminates increased gradually and reached a peak of ~7.20 GPa at h = 5 nm, while the E increased gradually with a sudden decrease at h = 25 nm. The critical point of delamination (P c), coefficient of friction (COF), and post-scratch microstructures of the nanolaminates were assessed via nanoscratch testing. The normal load at P c was increased gradually with a decrease in h under a ramped load. The post-scratch microstructures after delamination showed clear film chipping/crack formation and propagation of cracks/breakdown of grains at larger h , while no film chipping/cracking/breakdown of grains was observed in the nanolaminate with h = 5 nm. The wear rate of the nanolaminates increased with an increase in applied load irrespective of h and, interestingly, it started decreasing with increasing the numbers of wear cycles and became steady at higher numbers of wear cycles during nanowear tests. The nanolaminate with h = 5 nm showed the lowest wear rate with minimal plastic deformation. Nanoindentation of the worn surfaces of the nanolaminate with h = 5 nm after nanowear testing showed significant work hardening despite its negligible plastic deformation during nanowear tests. Overall, the Ta/Co nanolaminate with individual layer thickness at a few nanometers' length-scale exhibited high strength and excellent scratch and wear resistance with minimal plastic deformation. • Nanoindentation and nanotribological behaviors were studied for Ta/Co nanolaminates. • Wear rate decreased with reducing individual layer thickness (h) during nanowear test. • Critical load of delamination increased with decreasing h during nanoscratch test. • Minimal deformation observed at h = 5 nm during both nanoscratch and nanowear tests. • Ta/Co nanolaminate at h = 5 nm exhibited excellent scratch and wear resistance. [ABSTRACT FROM AUTHOR]

In this work, the effect of corrosion-induced damage on the mechanical response of hardmetals was evaluated at small length-scale by means of nanoindentation and nanoscratch techniques. Damage was introduced in a controlled way through immersion of samples in acidic solution. It was found that surface degradation associated with corrosion leads to strong reduction of elastic modulus and hardness, as compared to non-corroded samples. Similarly, significant differences were observed in nanoscratch response, regarding not only the width and depth of tracks but also the deformation mechanisms developed as contact load is progressively increased. Damage emergence and evolution were evidenced in corroded surfaces at scratching loads significantly lower than for non-corroded specimens. Changes in nanoindentation and nanoscratch response and damage scenario are discussed on the basis of the effective microstructural assemblage remnant after corrosion action. In this regard, dissolution of metallic phase becomes critical as it yields as a result a mechanically unsupported, contiguous and binderless/porous, carbide network. Consequently, cracking, fragmentation and easy removal of WC grains under contact loading is evidenced; and thus, mechanical integrity is effectively lessened. • Influence of corrosion-induced damage on the small length-scale mechanical response of hardmetals is studied • Significant changes are evidenced in nanoindentation and nanoscratch response of corroded cemented carbides • Lessening of mechanical integrity is due to effective microstructural assemblage remnant after corrosion action. • Dissolution of metallic phase becomes critical as it yields as a result a mechanically unsupported carbide network. [ABSTRACT FROM AUTHOR]