Nanoscratch Method Research Articles

The impact of BBr3/TiCl4 ratios on the microstructural and mechanical characteristics of TiBN coatings deposited using a pulsed-PACVD technique

This study aimed to investigate the impact of precursor ratios on both the microstructural and tribological characteristics of TiBN coatings. Using the PACVD process, TiN, TiB2, and three variations of TiBN coatings with adjusted BBr3/TiCl4 ratios were applied onto H13 substrates. The coatings were characterized using XRD, FESEM, TEM, AFM, nanoindentation, and nanoscratch methods to analyze their microstructural properties, surface morphology, and mechanical behavior. The findings revealed that the TiBN coatings possessed a nanocomposite structure with TiN crystals dispersed within the BN matrix, which is amorphous. Moreover, the augmentation of the BBr3/TiCl4 ratio from 0 to 1/3 resulted in a significant rise in the hardness value, from 13.4 GPa to 25.7 GPa. However, a further increase in the ratio from 1/3 to 3/3 resulted in a decrease in hardness to 14.4 GPa because cracks were formed in the deposited coating. In comparison, the TiB2 coating exhibited a higher hardness of 19.7 GPa due to strong TiB bonds within the coating. The TiBN coating, applied with a BBr3/TiCl4 ratio of 1/3, demonstrated the lowest wear volume of 0.10 × 10−18 m3, attributed to its higher hardness and smoother surface texture.

Nanoscale Abrasive Wear of Polyethylene: A Novel Approach To Probe Nanoplastic Release at the Single Asperity Level.

There is a growing concern that nanoplastic pollution may pose planetary threats to human and ecosystem health. However, a quantitative and mechanistic understanding of nanoplastic release via nanoscale mechanical degradation of bulk plastics and its interplay with photoweathering remains elusive. We developed a lateral force microscope (LFM)-based nanoscratch method to investigate mechanisms of nanoscale abrasive wear of low-density polyethylene (LDPE) surfaces by a single sand particle (simulated by a 300 nm tip) under environmentally relevant load, sliding motion, and sand size. For virgin LDPE, we found plowing as the dominant wear mechanism (i.e., deformed material pushed around the perimeter of scratch). After UVA-weathering, the wear mechanism of LDPE distinctively shifted to cutting wear (i.e., deformed material detached and pushed to the end of scratch). The shift in the mechanism was quantitatively described by a new parameter, which can be incorporated into calculating the NP release rate. We determined a 10-fold higher wear rate due to UV weathering. We also observed an unexpected resistance to initiate wear for UV-aged LDPE, likely due to nanohardness increase induced by UV. For the first time, we report 0.4-4 × 10-3 μm3/μm sliding distance/μN applied load as an initial approximate nanoplastic release rate for LDPE. Our novel findings reveal nanoplastic release mechanisms in the environment, enabling physics-based prediction of the global environmental inventory of nanoplastics.

Ultralow‐Voltage Frequency Tunning of Liquid Crystal‐Based GHz Antenna via Nanoscratching Method

AbstractLiquid crystal (LC)‐based radio‐frequency (RF) tunable antennas garner attention because of their compact size and minimal heat generation. Exploiting the LC's property to alter the RF permittivity depending on its alignment, voltage‐induced orientational switching enables frequency modulation of the radiated wave. To ensure dependable antenna performance, precise control of the initial LC alignment is crucial, which is conventionally achieved by polyimide (PI) coating followed by the rubbing process (PI‐rubbing). However, this approach demands high temperature (200 °C) and prolonged processing time (2 h), while also necessitating high voltage for LC reorientation due to induced excessive surface polar anchoring strength. Here, a PI‐free‐nanoscratching method creating 1D channels is introduced that induces initial LC alignment in a desired direction. The initial orienting capability of the scratched metal surface is superior to that of the PI‐rubbed surface. Furthermore, the LC‐based antenna employing the nanoscratching method shows a remarkable resonance frequency shift of up to 3 GHz with a low voltage of 2 V. This driving voltage is five times lower than that of antennas using the conventional PI‐rubbing method, which can open a new era for the next generation LC‐antenna.

Statistically distributed nano-scratch testing of AlFeMnNb, AlFeMnNi, and TiN/Si3N4 thin films on silicon

For studying the damage tolerance of thin films, a novel randomly distributed nano-scratch test method was introduced and demonstrated as a promising characterization method. It is capable of more closely simulating the damage progression in abrasion, where material removal can be influenced by the interaction between damage produced by previous scratches in close proximity. In addition to studying how localized failure events affect subsequent damage progression, it is possible to monitor the evolution of the film degradation cycle-by-cycle using the mean depth and friction over the scratch. Randomly distributed nano-scratch tests were performed on the high entropy alloy AlFeMnNb, AlFeMnNi, and nanocomposite (nc-) TiN/Si3N4 thin films on silicon. Brittle fracture and film removal with extensive chipping of the Si substrate were observed over the entire scratched region on AlFeMnNi and nc-TiN/Si3N4 in distributed scratch tests at applied loads that were only ∼0.2–0.3 of the load needed to produce the chipping in ramped load nano-scratch tests due to film and substrate fatigue. In contrast, the softer AlFeMnNb deformed predominantly by ductile ploughing with significantly improved damage tolerance and crack resistance in the distributed scratch tests. The new method can be used to evaluate the performance of thin films in applications where they can be exposed to abrasive/sliding wear. It can provide a more direct measure of abrasion resistance than assuming high resistance to abrasive wear from coating hardness. In the thin film systems studied, higher hardness was associated with greater fracture and delamination in the distributed scratch tests.

Evaluation of Fracture Toughness of Plasma Electrolytic Oxidized Al2O3-ZrO2 Coatings Utilizing Nano-Scratch Technique

Al2O3 coatings, which can be produced by plasma electrolytic oxidation (PEO) on aluminum substrates, provide an excellent protection against corrosion and wear. However, due to the brittle nature of the oxide ceramic, the fracture toughness is limited. One approach to enhance the tolerance to fracture is the incorporation of ZrO2 to form zirconia toughened alumina (ZTA). In addition to its use as a bulk material, the application as a coating material enables a broader field of application. In this study, an Al2O3-ZrO2 composite coating was applied on a 6082 aluminum alloy using an aluminate-phosphate-based electrolytic solution containing a Zr-based salt. Polarization measurement as an indicator of the passivability of a given system revealed that Zr-based salt improves the passivation of the aluminum alloy. The coatings’ characteristics were evaluated by SEM, EDS, and XRD. ZrO2 incorporated into alumina as a metastable high-temperature modification led to a thicker coating with new morphologies including lamellar and dendritic structures. Nano-indentation showed that the incorporated Zr increase the average hardness of the compact layer from 16 GPa to 18 GPa. The fracture toughness of the coatings was investigated locally with nano-scratches applied on the compact outer layer of the coatings’ cross-sections. The Zr-containing electrolytic solution resulted in a coating with significantly higher fracture toughness (6.9 MPa∙m1/2) in comparison with the Zr-free electrolytic solution (4.6 MPa∙m1/2). Therefore, it is shown, that the PEO process stabilized a high-temperature allotrope of zirconia at room temperature without the need for rare-earth dopants such as Y2O3. Furthermore, it was demonstrated that the nano-scratch method is a suitable and accurate technique for the investigation of the fracture toughness of coatings with inherent cracks.

Micromechanical and tribological behavior of titanium matrix composites reinforced with graphene oxide

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.

Optimization mechanism of bonding strength of laser melting deposited tungsten/reduced activation steel heterogeneous interface via addition of Y2O3 by magnetron sputtering

• Y 2 O 3 amorphous layer is magnetron sputtered and W/Fe interface is prepared by laser melting deposition. • Non-crystal Y 2 O 3 by magnetron sputtering promotes nucleation and dispersion distribution of FeW phase. • The increase in thickness of Y 2 O 3 layer improve the bonding strength of the interface. In this study, magnetron sputtering Y 2 O 3 layer has been used as the nucleating agent at tungsten/reduced activation steel interface for solving the bonding difficulty between tungsten and reduced activation steels owing to the formation of FeW phase and the huge residual stress at tungsten/reduced activation steel interface fabricated by laser melting deposition. Moreover, SEM, EBSD and nanoscratch methods were applied to study the interfacial microstructure and mechanical properties of tungsten/reduced activation steel interface for exploring the action mechanism of Y 2 O 3 in solidification and nucleation processes of molten pool. The results showed that Y 2 O 3 as the nucleating agent could considerably promote FeW phase nucleation. With the increase in thickness of Y 2 O 3 layer, mutual diffusion of W and Fe was decreased consequently, making the distribution of precipitated FeW phase more dispersed to effectively inhibit the formation of cracks caused by coarse FeW phase precipitation. It was also proved that the bonding strength of interface increased with the increase of the thickness of magnetron sputtering Y 2 O 3 layer, which relieved the cracking phenomenon in the heterogeneous interface of tungsten/reduced activation steel.

Tribological behavior of an amorphous Zr20Ti20Cu20Ni20Be20 high-entropy alloy studied using a nanoscratch technique

In this study, friction and wear behaviors of an amorphous Zr20Ti20Cu20Ni20Be20 high-entropy alloy (a-HEA) were characterized using a nanoscratch method. Scratch tests were carried out under both ramping and constant loading conditions to measure the coefficient of friction (COF) and wear resistance of the amorphous alloy. The morphology of scratched surface and subsurface was further examined using scanning and transmission electron microscopes. It was found that friction behavior of the a-HEA can be divided into two regions: elastic and plastic. In the elastic region, the COF dramatically decreases with increasing normal force, however, it monotonically increases in the plastic region. Morphological observation indicated that brittle fracture dominated in the plastic region, which was consistent with the result that a series of load serrations were accompanied by the formation of brittle cracks along the scratched track. Wear performance of the a-HEA was also evaluated and compared with “conventional” metallic glasses and crystalline high-entropy alloys. As a result of high hardness and large elastic recovery, the current a-HEA exhibited good wear resistance and low COF, behaved more like brittle amorphous alloys rather than ductile high-entropy alloys.

Nanoscratching technique for highly oriented liquid crystal materials

A simple, fast, and cost-effective technique to obtain highly oriented thermotropic and lyotropic liquid crystal (LC) phases using a simple nanoscratching method is presented. Highly aligned linear nanogrooves are fabricated by scratching substrates such as normal, indium tin oxide (ITO), curved glasses, and ITO-coated polyethylene terephthalate (PET) film using diamond lapping films. To demonstrate the feasibility of the platform, typical thermotropic and lyotropic LC materials in the nematic phase are used to demonstrate the well-aligned domains along with the resulting scratched nanogrooves. The polarised optical microscopy (POM) images show excellent dark and bright states depending on the sample rotation, proving that the LC molecules are well aligned. The electro-optical performance of the twisted nematic (TN) mode LC display fabricated using the nanogrooves is also measured and indicates reliable results compared with that of the conventional device. Indeed, scratch-induced nanogrooves are well generated on the curved substrate and ITO-coated PET film to show versatility of our technique. Our platform can suggest a new nanofabrication way to make various electro-optical devices as well as other patterning applications.

Friction and wear behavior of a single-phase equiatomic TiZrHfNb high-entropy alloy studied using a nanoscratch technique

In this study, friction and wear of a body-centered cubic equiatomic TiZrHfNb high-entropy (HE) alloy were investigated using a nanoscratch method. Scratch tests, under both ramping and constant load modes, were conducted to evaluate the coefficient of friction (COF) and wear rate of the alloy. The effects of scratch rate on the friction and wear were also studied. The morphology such as the surface profile and depth of scratched tracks was examined using scanning electron microscopy (SEM) and scanning probe microscopy (SPM). It was found that, whilst wear behavior, including wear rate and wear resistance, could be described by Archard equation, friction of the alloy appeared to be more complicated. Experimental results revealed that the friction of the alloy could be divided into two distinct regimes - elastic and plastic. The COF decreased rapidly with increasing normal load in the elastic regime, but became essentially constant in the plastic regime, indicating a transition of friction mechanism. In this study, scratch tests were also performed on pure Nb and a solid-solution strengthened Nb-based C103 alloy to make a direct comparison. The TiZrHfNb HE alloy apparently exhibited an improved wear resistance and lower COF as compared to its traditional alloy counterparts. The better wear resistance and lower COF were discussed in lights of the acting plowing and adhesion mechanisms during wear.

Investigation on friction behavior and processing depth prediction of polymer in nanoscale using AFM probe-based nanoscratching method

The present work investigates the friction behavior and machined depth prediction when scratching on a polymer material using an atomic force microscopy (AFM) tip. According to the calculated results based on the experimental tests and the proposed model, the flow stress during machining is demonstrated to be a logarithmic increase with the scratching speed increasing, and the adhesive friction coefficient has little change with the variation of the normal load and scratching speed. Finally, several nanochannels with expected machined depth are achieved on the polymer surface using the prediction method presented in this study and the deviation between the experimental and desired values is mainly less than 10%.

Fiber-matrix interphase in applied short glass fiber composites determined by a nano-scratch method

Abstract The fiber-matrix interphase in composites is defined as the intersection region between fibers and the matrix material. It shows altered matrix material properties. In dependency of the matrix material or the fiber coating, this phase is created by interdiffusion processes at the macromolecular scale driven by thermodynamic forces. Especially for FE simulations of composites and the validation of multi-scale material modeling approaches, the information about the existing interphase becomes important. Thus, the present study analyses the interphase in applied short glass fiber reinforced thermoplastics. For the identification of the interphase thickness, the nano-scratch method provides admissible results. This methodology is improved and adapted to the use in short fiber composite specimens. Thereby, the measured range of interphase thickness represents the inhomogeneity of the interphase. To assure that the measured interphase is not mainly constituted by the sizing of the glass fiber, incineration tests are performed additionally. The comparison of the interphase and the sizing thickness shows a significant thicker interphase.

Fabrication of nanochannels with complex three‐dimensional structures based on a modified atomic force microscopy nanoscratching system

A novel manufacturing method of fabricating nanochannels with complex three-dimensional (3D) structures based on a modified atomic force microscopy (AFM) nanoscratching method is presented. By changing the moving trajectories of the AFM tip, arbitrary geometric patterns were obtained. Nanochannels consisting of the superposition of geometric figures could be fabricated through extensively controlling the scanning velocity of the AFM tip and combining the movement of the AFM tip with the high-precision stage. Machining experiments were performed to demonstrate the capability, validity and flexibility of the proposed approach. Finally, nanochannels with complex 3D structures were presented in an automated, flexible but cost-effective way.

Fabrication of nanochannels with ladder nanostructure at the bottom using AFM nanoscratching method.

This letter presents a novel atomic force microscopy (AFM)-based nanomanufacturing method combining the tip scanning with the high-precision stage movement to fabricate nanochannels with ladder nanostructure at the bottom by continuous scanning with a fixed scan size. Different structures can be obtained according to the matching relation of the tip feeding velocity and the precision stage moving velocity. This relationship was first studied in detail to achieve nanochannels with different ladder nanostructures at the bottom. Machining experiments were then performed to fabricate nanochannels on an aluminum alloy surface to demonstrate the capability of this AFM-based fabrication method presented in this study. Results show that the feed value and the tip orientation in the removing action play important roles in this method which has a significant effect on the machined surfaces. Finally, the capacity of this method to fabricate a large-scale nanochannel was also demonstrated. This method has the potential to advance the existing AFM tip-based nanomanufacturing technique of the formation these complex structures by increasing the removal speed, simplifying the processing procedure and achieving the large-scale nanofabrication.

Improvement of the scanning area positioning repeatability using nanomarkers developed with a nanoscratching method

A sophisticated experiment requiring multiple micrometer-scale scanning of the same area of a sample may be performed easily if special positioning features on the surface are available. A set of nanomarkers developed using a nanoscratching technique can provide an efficient, submicron-accurate solution allowing us to investigate various phenomena. In this paper, the analysis of the roughness estimation repeatability is presented in terms of defining the accuracy of the area of interest. The obtained results confirmed the possibility of the repeatable positioning of the sample in an atomic force microscope, providing area roughness determination repeatability with a standard distribution smaller than 3%. As an example, the observation of light-caused surface degradation is presented. Also, the utilization of nanomarkers in determining the magnetic domain's rearrangement angle with an accuracy better than 0.5° is shown.

Evaluation of Adhesion Strength of Er<sub>2</sub>O<sub>3 </sub>Coating Layer for an Advanced Breeding Blanket System Applied to Thermal Cycles using Nano-Scratch Method

The electrical insulator and hydrogen permeation barrier coatings are important materials to realize the liquid metal and molten-salt typed breeding blanket systems. We found that erbium oxide (Er2O3) is one of the promising materials as the electrical insulator and hydrogen permeation restraint coatings. Establishing the mechanical property evaluation method for these coating is extremely important to certify the durability of coating material in the blanket systems. The adhesion strength property, which is one of the key mechanical properties of coating materials, was investigated using the nano-scratch method. From the results, it was found that the nano-scratch test was able to evaluate the adhesion strength of the Er2O3 coating synthesized by the Metal Organic Chemical Vapor Deposition (MOCVD) process with high reproducibility. Furthermore, the adhesion strength of the Er2O3 coating before and after thermal cycling was evaluated using this method. The adhesion strength after 50 thermal cycles at 700 ◦ C was kept around 70% compared with that before thermal cycling.

Nanomechanical and tribological properties of carbon nanotube/polyvinyl butyral composites

The surface and subsurface mechanical and tribological properties of multiwall carbon nanotube (MWCNTs)/polyvinyl butyral (PVB) composites have been studied. Hardness and elastic modulus were obtained from nanoindentation, whereas the coefficient of friction of the composites was obtained using a nanoscratch method. The results show a clear impact of the percentage of CNTs filling on the monitored properties. Considerable improvement in the scratch resistance is obtained by the addition of CNTs and a maximum increase in nanomechanical properties is found at intermediate levels of CNTs filling. Creep studies revealed that a higher loading rate results in a greater primary creep deformation and leads to an increase of the total creep deformation, whereas the addition of MWCNTs affects the elastic recovery of the PVB matrix. POLYM. COMPOS., 34:1950–1959, 2013. © 2013 Society of Plastics Engineers

Material Removal Mechanism of Copper CMP from a Chemical–Mechanical Synergy Perspective

The material removal in chemical–mechanical planarization/polishing (CMP) of copper involves both chemical and mechanical effects. The roles of chemical corrosion, abrasive wear, and their synergistic effects on the material removal mechanism were studied by electrochemical analysis and nano-scratching method using atom force microscopy, respectively. Combining with the results of CMP experiments, dominant factors (chemistry and mechanics) in slurries within the range of pH 3.0–10.0 were assessed. Consequently, a removal mechanism map of copper CMP depending on pH values was constructed. In the alkaline slurry, the wear–corrosion effect predominated in the material removal at pH 8.0 and 9.0; while the copper removal mechanism changed to corrosion–wear action in the acidic slurry from pH 4.0 to 6.0, and good surface quality was also obtained. The results and the strategies provide thorough understanding of the material removal mechanism and further optimization of the CMP process.

Nanoindentation and nanoscratch investigations on graphene-based nanocomposites

The effect of graphene nano-platelets (GNPs) on mechanical properties of polymer nanocomposites were investigated using nanoindentation and nanoscratch methods. The GNPs at different weight fractions namely 0, 0.05, 0.1, 0.25 and 0.5% were dispersed in the polymer matrix using a mechanical stirrer and ultrasonic apparatus. A standard Berkovich indenter was used for indentation at three different normal loads, i.e., 400, 600 and 800 μN. Both elastic modulus and hardness increased with the addition of 0.05 wt% GNP. The tribological behavior of nanocomposites was investigated by a nanoscratch test in conjunction with atomic force microscopy (AFM); less pile ups and high wear resistance were observed in the nanocomposites. Based on this research, mechanical properties of pure polymer matrix are improved significantly with addition of low amounts of the graphene nano-platelets.

Investigation of mechanical and tribological properties of bone cement by nano-indentation and nano-scratch experiments

The mechanical and tribological properties of PMMA-based bone cement (CEMEX RX, TECRES Company, Italy) were measured using nano-indentation and nano-scratch tests. The polymer samples were prepared using two different mixing methods i.e., hand mixing and vacuum mixing. Cubic CEMEX RX specimens were produced and the nano-indentation and nano-scratch tests were performed on both the hand-mixed and the vacuum-mixed specimens by a nano-indenter setup and atomic force microscopy (AFM) observation.The values of Young's modulus, hardness and wear resistance obtained on the hand-mixed and the vacuum-mixed cements were compared. The results indicate that the vacuum-mixed cement has better mechanical and tribological properties compared with the hand-mixed one. Since the nano-indentation and the nano-scratch test methods need less sample material, decrease costs and obtain reliable results, they can be considered as suitable techniques for determination of the mechanical and tribological properties of bone cements.