Table of contents

The gecko exhibits remarkably swift and reliable climbing ability on most surfaces in nature. Numerous studies have been conducted to determine the underlying mechanisms of gecko adhesion in order to realise controllable gecko-inspired handling applications. This paper, reviews recent developments in the field of gecko-inspired dry adhesive surfaces from fabrication to application. First, the gecko adhesion progress, from the adhesive tools and the source of adhesion to the underlying mechanisms of tuning contact area and peeling behavior, is introduced. Then, the design and fabrication of gecko-inspired dry adhesive surfaces are comprehensively reviewed according to the three features of gecko adhesion, namely adaptability, controllability, and self-cleaning. Further, existing test methods for adhesion, friction and anisotropy are summarised, and the influences of test conditions such as the stiffness of test system, the area of the samples and the experimental environment are discussed. Finally, applications of robots and grippers based on the flexibly controllable adhesion and friction of gecko-inspired dry adhesive surfaces as well as novel controllable functional adhesive surfaces are introduced, and the associated control mechanisms are summarised.

A novel coating system of epoxy matrix containing aniline trimer modified silica conversion layer was prepared on Q235 steel surface. The conversion layer was obtained by electrodeposition on the basis of precursor solution, which contained ethyl silicate and modificatory aniline trimer (MAT). Hydrophobicity, electroactivity and corrosion resistance of as-prepared coating systems were detected. Result showed that the as-prepared MAT-including silica conversion layer (M-SiO₂) presented a super-hydrophobicity and excellent electroactivity. Meanwhile, the novel coating system displayed a stronger adhesion force compared with single epoxy coating and silica/epoxy coating system. By electrochemical impedance spectrum and salt spray test, the protective capability of epoxy matrix was largely improved by the coverage of electroactive M-SiO₂ conversion layer. This was attributed to the forceful hydrophobicity and self-healing ability of conversion layer. The synergistic effect of above-mention two functions promoted the perfection of corrosion performance for as-prepared novel coating system.

Graphene is extensively considered to be highly promising in the optimizing of the anticorrosive properties of organic coatings. However, the poor hydrophilicity of graphene impedes its application in waterborne coatings. In this work, attapulgite-graphene (ATP-G) nanocomposites were synthesized through a simple method. Graphene was well bonded with ATP via hydrogen bond interaction, thus improving its compatibility with water obviously. Susequently the ATP-G nanocomposites was incorporated into waterborne epoxy coating. It is indicated from the electrochemical measurement that the ATP-G nanocomposite could significantly improve the long-term anticorrosive property of waterborne epoxy coating, which was attributed to synergistic action of ATP nanofibers and graphene nanosheets on the barring for the penetration of water, O₂ and corrosive ions.

Alumina is a widely used anticorrosive coating material for protection of metal surfaces. The graphene oxide (GO)-alumina composite coatings can enhance the anticorrosion property of carbon steel surfaces used in an industrial scale. In the present work, the spray dried graphene oxide nanoplatelets of 0, 0.5, 1, 1.5 and 2 wt% reinforced alumina (α-Al₂O₃) were deposited on the low carbon steel substrate by Atmospheric Plasma Spray (APS) technique. The GO-alumina nanocomposite coatings are characterised using XRD, FE-SEM, HR-TEM and Raman Spectroscopy. The electrochemical corrosion behaviour of the coatings on carbon steel has been examined using three electrode electrochemical method in 3.5 wt% NaCl electrolyte. A remarkable improvement in the corrosion resistance (with a corrosion current density of 0.01 nAcm⁻²) of about six orders with respect to pristine alumina was observed. The wettability tests revealed that, with 1.5 and 2 wt% graphene oxide nanoplatelets addition, the surface coating turned out to be hydrophobic with contact angle of 127°, from hydrophilic with contact angle 36°, which complements the anticorrosion results. The in situ reduction of GO to r-GO by APS deposition and bridging of alumina splats by the GO sheets accounts for observing the superior performance of the composite coatings.

We report a simple oil-water separation technique using adhesively attached fluoropolymer coated cotton fabric prepared by the admicellar polymerization process. The modified cotton fabric shows hydrophobic/oleophilic properties with a high water contact angle of 126° ± 1 and an oil contact angle of ∼0°. For the oil-water separation, we used two techniques i.e. filtration-based and absorption-based separation. The modified cotton fabric can effectively separate a series of oil-water mixtures like kerosene/water (Gasoline), petrol/water, hexane/water, octane/water and decane/water with high efficiency. Among them, kerosene–water mixture shows approx ∼93% separation efficiency even after repeated use for 10 cycles through an ordinary filtering process, without any noticeable change in efficiency. More importantly, the as-prepared fabric shows good recyclability after several separations. Therefore, this modified cotton fabric has the advantages of scalable fabrication, cost-effective preparation, low-energy consumption, high separation efficiency, and excellent recyclability.

Atomically well-defined TiO₂ is the prerequisite for both interfacial-physics engineering and photocatalytic-mechanism understanding. Here, we report the preparation of atomically flat rutile TiO₂(100) over a centimeter scale by high-temperature annealing in ultrahigh vacuum and detailedly traced its microscopic evolution dynamics towards atomic smoothness. The reflection high-energy electron-diffraction pattern and the scanning topographic image both show an atomically flat surface over a sub–square-centimeter area. These results provide a microscopic understanding of the methodologies for obtaining atomically well-defined surfaces.

Surface topography modifications due to wear or other factors are usually investigated by visual and microscopic inspection, and—when quantitative assessment is required—through the computation of surface texture parameters. However, the current state-of-the-art areal topography measuring instruments produce detailed, areal reconstructions of surface topography which, in principle, may allow accurate comparison of the individual topographic formations before and after the modification event. The main obstacle to such an approach is registration, i.e. being able to accurately relocate the two topography datasets (measured before and after modification) in the same coordinate system. The challenge is related to the measurements being performed in independent coordinate systems, and on a surface which, having undergone modifications, may not feature easily-identifiable landmarks suitable for alignment. In this work, an algorithmic registration solution is proposed, based on the automated identification and alignment of matching topographic features. A shape descriptor (adapted from the scale invariant feature transform) is used to identify landmarks. Pairs of matching landmarks are identified by similarity of shape descriptor values. Registration is implemented by resolving the absolute orientation problem to align matched landmarks. The registration method is validated and discussed through application to simulated and real topographies selected as test cases.

Nanostructured tungsten/tungsten carbide (W/WC) coatings produced by chemical vapour deposition are promising WC based coatings for applications where galling wear is prevalent due to the high hardness, toughness and stacking fault energy which the coatings possess despite low hardness to elastic modulus ratio (H/E). In this work the galling resistance of W/WC coatings has been studied through tibometer tests using sliding speeds of 0.014 m s⁻¹ and contact pressures of up to 810 MPa. The study investigates the effects of surface finish and the use of similar and dissimilar material combinations on galling wear. Results show that self-mated stainless steel AISI 316 behave poorly under dry sliding wear conditions whilst uncoated stainless steel tested versus W/WC coating combinations are affected by galling due to material transfer forming a stainless steel on stainless steel tribosystem. The best performance was recorded for self-mated W/WC which did not develop any signs of galling even at the highest contact pressures (810 MPa) contradicting the common practice that the use of dissimilar materials can help prevent galling.

Self-assembly technique has been used to solve adhesion and friction problems in moving parts of micro-electro-mechanical systems (MEMS). In this paper, tetraethoxysilane/octadecyltrichlorosilane (TEOS/OTS) bilayer films were prepared by self-assembly on Si substrate. TEOS was firstly self-assembled on Si substrate as the interlayer and then OTS was grafted on the TEOS monolayers as the top layer. The morphology, chemical composition, wettability, and adhesion of the films were characterized. The prepared TEOS/OTS bilayer films were observed to be hydrophobic with uniform nanoclusters. The tribological properties of the films were performed on a ball-on-plate statnamic tribometer. Compared with Si substrate and OTS self-assembled monolayer (SAM), TEOS/OTS bilayer films exhibited reduced adhesion and improved tribological performance, which was attributed to the stable bilayer structure of TEOS as the interlayer and the transfer of the destroyed OTS SAM as the lubricating film. TEOS/OTS bilayer films are expected to improve the quality of the micro-parts in MEMS and reduce the abrasion of the micro-molds in microfabrication techniques.

Selectivity (maximum absorptivity/minimum emissivity) of a thin film has become the decisive parameter associated with the success of solar energy capturing coat. Accordingly, the issue of developing effectively solar energy absorbing coat is of great interest in research. This research studies the effect of changing the pH value of copper oxide based coats and monitors its effect on optical properties. Increasing the surfactant percentage has resulted in more enhanced coats. prepared coats with pH = 5.5 have selectivity of α/ε = 96.3/65 for 5 wt% surfactant and α/ε = 97/56.6 for 20 wt% surfactant. Moreover, optical bandgap was calculated to vary between 1.29 and 1.86 eV for different pH values. Through this work, optical properties, bandgap, coat thickness, surface topography, and existing phases are all investigated in details.

The paper solves the problem of modeling a machined workpiece surface after processing with a grinding wheel during flat grinding with the periphery of the tool. When scaling the simulation of the entire tool and the entire workpiece surface over a long period of processing, the task becomes much more complicated and requires large computational capacities. It is proposed to use spline surfaces when modeling a machined surface. This will allow reducing the computational volume of the solvable problem and implementing a model of this scale. The developed method of modeling of a scratch from single abrasive grain by creation of three guides curves and the forming curve moving on them is described. The suggested method of modeling of a surface of a scratch allows receiving values of depths of each of scratch topography points in the settlement way. The paper experimentally confirms the adequacy of the developed model for describing a single scratch by using specially developed tool design with single abrasive grain. Further, a virtual model of the grinding wheel is built for a transition from a single scratch to a machined surface, taking into account the fractional composition of abrasive grains, visual illustrations of the tool's surface are given. Further, based on the developed model for describing a grinding scratch in the form of a spline surface and based on the three-dimensional model of the tool, the machined surface of the workpiece is formed. The paper presents a procedure for calculating the roughness parameters for a virtual surface. In conclusion, the simulation results in the model are compared with experimental data and data from other researchers. It is shown that the model has a high accuracy of predicting real roughness parameters in the processes of flat grinding with the periphery of a wheel.

The speed and energy consumption are important indices to evaluate the performance of surface and underwater vehicles. The frictional drag is a key factor influencing the speed and energy consumption of vehicles. We studied the flow field and the drag reduction for different transverse microstructures and found that vortices could be formed in the transverse structures, which reduced the frictional drag. We fabricated different apertures of nanoporous TiO₂ films on smooth Ti foils by a two-step low-cost anodic oxidation process. Compared with smooth foils, the nanoporous with a depth of 100 nm and diameter 5.1 μm can decrease drag by 40% under the 1.5 m s⁻¹ velocity condition. The results showed that sliding friction changes to rolling friction at the solid-liquid interface in the transverse grooves. The technology has practical application in drag reduction.

Magnesium (Mg) and its alloys are promising materials for use in medical applications due to their good mechanical properties, biocompatibility, and biodegradability. However, the rapid corrosion of Mg alloys restricts their range of use in these applications. Fluoride conversion (HF) coating is one of the most effective and environmentally friendly surface modifications available to address this limitation. The formation of a thin, uniform, smooth, and adherent fluoride coating improves the corrosion and wear resistance of Mg alloys. However, this method is not suitable for long-term medical treatment. In previous research, we found that ultrasonically treated fluoride (HFU) coatings can increase the corrosion resistance of Mg alloys. The aim of this study, therefore, was to investigate in more detail the surface morphology, coating thickness, composition, and corrosion of ultrasonically treated fluoride-coated Mg alloys. The results indicated that the HF and HFU coatings were identical in terms of thickness and composition. However, unlike the HF-coated specimens, there were no pores and cracks on the surface of the HFU-coated specimens, which also exhibited significantly higher corrosion resistance in electrochemical corrosion and mass loss tests. As a result, HFU-coated Mg alloys may prove suitable for use in long-term medical treatment.

Graphene as a physical barrier in organic coating exhibits good anticorrosion property, whereas its agglomeration would greatly debase such performance. Here, functionalized graphene was prepared via a green/facile method with tea polyphenol as reductant and graphene oxide (GO) as precursor. The anticorrosion performance of polyphenol-reduced graphene oxide (T-rGO) in waterborne epoxy coating was evaluated according to the electrochemical impedance spectroscopy, polarization curve, water absorption and salt spray test. Results indicate that the T-rGO/epoxy coating has the largest impedance modulus and corrosion potential, and the corrosion current density is an order of magnitude lower than that of pure epoxy coating. The T-rGO/epoxy coating displays excellent corrosion protection under continuous high salt spray environment, with pure epoxy coating as a comparison. T-rGO greatly enhances the corrosion resistance of waterborne epoxy coating, which is attributed to its good dispersibility and intrinsic characteristics.

Diamond tool wear has been proven to strongly depend on the temperature at the cutting zone. This is because the elevated temperature so attained during machining not only lowers carbon cohesion energy thereby reducing the fracture toughness of diamond tool due to C–C bond weakening but also facilitates high rate of carbon diffusion from diamond tool into silicon workpiece leading to high tool wear. This research therefore studied the response of diamond tool wear path and mode to changing rake angle and $\tfrac{{d}_{uncut}}{{R}_{edge}}$ ratio during ultraprecision single point diamond turning of a monocrystalline silicon. It was observed from the study that the tool with larger rake angle and high $\tfrac{{d}_{uncut}}{{R}_{edge}}$ ratio experienced stronger cutting resistance from the workpiece thereby causing the kinetic friction to be high. Additionally, silicon carbide (Tribochemistry) formation was observed to be through both solid-state single phase and multiphase reaction which are in tandem with sp³–sp² disorder (graphitization) of diamond with bulk of the observed tool wear happening in the flank face which could be due to increasing rake angle influence on the changing $\tfrac{{d}_{uncut}}{{R}_{edge}}$ ratio.

Scratches, those usually generated during polishing the silicon wafer surface, are one of the major yield loss factors in semiconductor manufacturing industry. In order to determine the source of the scratches in real time and reduce the yield loss, it is critical for manufacturers to match and identify the same type of scratches automatically. In this paper, an improved K nearest neighbors (KNN) algorithm to address this issue is presented. Firstly, a skeleton extraction method is used to depict the main lines of scratches. Then the clustering protocol is applied as a preliminary step to group these main lines so that some essential endpoints features of main lines, such as distance, slope and curvature, can be extracted. During feature extraction, a dynamic coordinate system is introduced and this greatly reduces the distortions arise due to the magnitude of tangent difference. An intelligent matching of similar scratches MSML-KNN algorithm is formulated. The experimental results show that the proposed matching method for wafer scratches has a good adaptability and robustness.

Lack of monitoring and quality control of in situ forming process is a major bottleneck in Wire and Arc Additive Manufacturing (WAAM). Among various process control, the control of the geometric signatures is of high importance. This paper presents a method of in situ monitoring and closed-loop control of topography measurement. A laser-based areal topography measurement sensor is used to measure the surface geometric signatures of the formed layer. A topography control strategy is carried out by processing and analyzing the 3D surface profile data. To increase the computing speed and efficiency, a depth-image method is proposed to process the 3D surface point clouds data and extract the 3D contour signatures of the shaped layer. Experiments were designed to verify the feasibility and stability of the system and the experimental results indicate that the proposed method can adaptively deal with the surface topography quality and handle the concave and convex parts of the shaped layer.

For MoS₂-based films, mechanical performance has a significant influence on their tribological properties. In this work, Ti was doped into MoS₂ film to enhance the mechanical properties, and the tribological properties and contact voltages of the Ti/MoS₂ composite film sliding against Al balls were systemically investigated at different current conditions. It was found that the Ti/MoS₂ film exhibited amorphous structure with a dense morphology, and the hardness, elastic modulus and toughness as well as adhesion strength were effectively enhanced with the incorporation of Ti into MoS₂ film. It was also found that the Ti/MoS₂ film showed better tribological properties than the MoS₂ film under electric currents, which was attributed to the enhanced mechanical properties. What's more, the abrasive wear and adhesive wear were the main failure types of the Ti/MoS₂ film. When the currents were equal to or greater than 0.5 A, arc ablation appeared on the wear surfaces, and the main wear mechanisms were friction wear, arc erosion and the coupling effect. The contact voltages increased from low to high in the initial stage and dropped in the later stage.

Wear resistance and excellent mechanical properties are the main requirements in industrial applications of bimetal composites. The interfacial evolution of duplex stainless steel/low carbon steel (2205/AH36) bimetal composite after annealing and its tribological behaviour in a 3.5 wt% NaCl solution were investigated in this study. The bonding interface evolution between two layers plays a critical role in mechanical properties of composite, and the surface microstructure of stainless steel layer determines the wear and corrosion resistance. The hot-rolled composite samples were heat treated at temperatures ranging from 850 to 1150 °C in steps of 100 °C for 1 h. Optical microscopy (OM) and electron backscattered diffraction (EBSD) were employed to investigate the microstructural evolution of both component layers and bonding interface. The uniaxial tensile tests were used to investigate the tensile strength and elongation of composites after annealing at different temperatures. Ball-on-disc sliding tests were employed to study the tribological behaviour of bimetal composite, with sample discs being immersed in the solution. The variations of the coefficient of friction (COF) were recorded as a function of the sliding time, and the wear tracks of discs after tribological tests were observed by the laser scanning microscope and a scanning electron microscope (SEM). The results show that the annealing temperature significantly affects the width of bonding interface, and the total wear volume loss of duplex stainless steel of composite is dominated by the mechanical wear in the chloride solution.

A new approach for analysis of atomic-force microscopy (AFM) images of ultrasmooth surfaces is developed. Decomposition of AFM image into three components is the base of the approach. Each component represents a characteristic feature of the surface relief. It allows obtaining statistically reliable quantitative characterization of ultrasmooth surface topography. The decomposition makes it possible to predict the reflective properties of multilayer interference coating deposited onto a glass ceramics substrate as early as at the stage of the substrate treatment. The developed technique and direct measurements of integral light scattering showed that polishing glass ceramic substrate with gas cluster ions before the reflective coating deposition results in smoother surface. Consequently, we improved reflective properties of the mirrors.

Engineering surface shows fractal characteristics, and mechanical performance of electroless Ni–W–P coating with fractal parameters can avoid the effects of instrument resolution and sampling length. In the present work, the ternary Ni–W–P coatings were deposited on mild steel (1015) polished with various sandpapers. Surface morphology of coating and mechanical property, including matrix roughness, adhesion strength, friction behavior and elastic modulus were investigated by using scanning electron microscopy (SEM) and MFT-4000 multifunctional material surface performance instrument, respectively. The results present that the mechanical property of the electroless Ni–W–P coating is affected by the fractal features. The stress in the direction of matrix surface is considered to decrease due to the rougher matrix. Meanwhile, the elements are prone to be deposited and the adhesion strength between Ni–W–P coating and matrix is seen to increase. The experiments also indicate that the friction coefficient of coating reduces as the fractal dimension of coating increase. However, the regularity of the relationship between fractal dimension and elastic modulus of Ni–W–P coating is inconspicuous while the elastic modulus is mainly affected by its own chemical component. The work provides evidence that the fractal dimension has a significant influence on the mechanical property of the electroless Ni–W–P coating.

Micro-grooves were fabricated on GCr15 steel disc and filled by epoxy resin composites, formed hybrid laser surface texture. The tribological properties of textured disc sliding against ceramic ball were investigated. The friction tests were carried on a ball-on-disc tribometer. Three kinds of fibers, two kinds of particle and three kinds of polymer were selected to improve the epoxy resin-based material filled in the micro-grooves. Glass fiber (GF), graphite particle (GP) and PTFE shown better tribological performances, which were selected as additives for the optimized design of the epoxy resin composite. The specimen with fill ratio of 3:1:1 (PTFE: GF: GP) exhibits lower friction coefficient and better wear resistance. The worn surface of textured discs and balls were observed. It was found that this hybrid laser surface texture could form a transfer layer on the contact surface, which contribute to the friction and wear reduction of tribo-pairs under dry friction condition.

Ni₃Ti and Ni₃Ti + (Cr₃C₂ + 20NiCr) coatings were deposited on gas turbine based ASTM B265 titanium (Ti-15) and AISI 420 stainless steel (MDN-420) substrate materials using HVOF technique. Thermocyclic hot corrosion tests were carried out at 650 °C in molten salt environment of Na₂SO₄ − 40%V₂O₅ for about 50 cycles. Thermogravimetric analysis was carried out to study the hot corrosion kinetics of uncoated and coated titanium and stainless steel substrates. The weight gain per unit area showed that the coated substrate materials displayed better resistance to hot corrosion when compared with that of uncoated substrate materials. The surface morphology of uncoated and coated substrate materials were analysed using scanning electron microscopy and elemental analysis. The formation of different types of oxides and compounds were analysed using x-ray diffraction. The uncoated substrates surface showed microspalling at several regions while coated substrates surface were composed of protective oxide layers. The presence of ternary NiCr₂O₄ protective oxides on the surface of Ni₃Ti + (Cr₃C₂ + 20NiCr) coated substrates leads to reduction in the diffusion of corrosive species inside the coating.

Magnesium and its alloys have been identified as potential biodegradable implant materials for orthopaedic applications considering their bone equivalent density, biocompatibility, and biodegradability. However, the rapid corrosion rate of magnesium alloys in the physiological environment is a severe problem. This study attempts to simultaneously improve the microhardness and reduce the corrosion rate of AZ91D alloy by friction stir processing. Magnesium alloy AZ91D is friction stir processed by varying the process parameters namely tool rotation speed and tool traverse speed. The effects of friction stir processing parameters on the microstructural evolution, surface topography, microhardness, and corrosion rate of AZ91D alloy are investigated using the hybrid models, which are developed by integrating the quadratic function and radial basis function. The results indicate that the optimum process parameters for friction stir processing of AZ91D alloy is 750 rpm and 45 mm min⁻¹. Cytotoxicity test revealed that the biocompatibility of friction stir processed AZ91D alloy is in good agreement with the biocompatibility of the AZ91D alloy.

Contact is one of the main means to transmit force between bodies, and a detailed study of contact mechanics provides the required knowledge toward a realistic prediction of the behavior of contacting bodies. In this study, an approach based on the Greenwood-Williamson model is developed in which all of the contact points on the contacting surfaces are observed momentarily. The surface roughness is experimentally measured. The surface asperities are treated as spline functions, and their properties such as radius of curvature are obtained by differentiating these functions. The response of each individual contact point is evaluated by solving contact equations related to a specific asperity in elastic, elastoplastic, and plastic regimes. The method is therefore called spatially resolved Greenwood-Williamson (SRGW) model. To validate the model, a new technique is used which is based on indentation. A series of indentation experiments are conducted on two contacting surfaces, and the elastic and plastic deformations of the asperities under different loads are measured. The percentage error of the proposed approach is lower compared to other methods such as GW and ZMC, which shows the higher accuracy of this new method. The results show that the presented model can predict experimental results with reasonable accuracy under different contact conditions.

Titanium is frequently adopted in laser-induced forward transfer (LIFT) due to its unique industrial advantages (low density, high specific strength and good corrosion resistance). To understand the LIFT process assisted with Ti films, topographies of on Ti films with a thickness $435\,{\rm{nm}}\,\leqslant {\rm{d}}\leqslant 1250\,{\rm{nm}}$ irradiated by ultraviolet nanosecond laser pulses are investigated. Five different topographies (the pit, blister, bump, spray, and strip) are observed and classified, among which the pit, with a basin-like profile, is first addressed in this work. The probability distribution of these types with respect to laser fluence on 435 nm and 1250 nm Ti films is provided and an analytical model is developed to explain the driving mechanism of the ablation threshold and the formation of different topographies.

Structural and mechanical integrity, as well as friction and wear performance of a composite designed for tribological application (hereafter called as tribo-composite) depends on a precise selection and potent combination of fillers, fibers, and polymer matrix along with right processing technique. Modern day research is primarily focused on exploring the suitability and potential of new ingredients, which are better than the conventional ones, in enhancing the friction and wear performance of a tribo-composite. In-depth laboratory scale study on the tribo-performance evaluation of these ingredients is a key to explore their potential and use at an industrial level. Particles of potassium titanate (KT) is one of such ingredients which helps in reducing wear of friction materials. However, its role in influencing the wear performance of anti-friction materials is still unexplored. In the present work, the potential of KT particles (10 wt%) in two sizes (micron and a combination of micrometer and nanometer, 7 + 3 wt%) has been evaluated. In all, three tribo-composites based on two fixed ingredients viz. polyaryletherketone (PAEK) and short glass fibers (GF-30 wt%) were developed. The first composite contained 10 wt% graphite, while the other two composites contained additional 10 wt% KT particles. It was observed that KT particles acted as a solid lubricant despite not having a layer-lattice structure. Tribo-composites with nanoparticles of KT as a filler proved more effective at severe sliding conditions (PV_limit 168 MPa m s⁻¹) compared to that filled with micron-sized particles (PV_limit 112 MPa m s⁻¹ respectively). Based on this study, it was concluded that KT proved as a filler having the potential to enhance the tribo-performance of PAEK based composites and nano-sized particles proved more efficient compared to the micro-sized one.

A method for rapid measurement of large step heights is proposed. Owing to elimination of mechanical scanning processes, this method possesses a greatly reduced measurement time. The theory underlying the proposed method is described in detail. The single-shot spectral interferometric signal is recorded using a Linnik microscopic white-light spectral interferometer and phase information is retrieved using a windowed Fourier transform. The proposed method was used to measure a 10.083(±0.022) μm step height standard. The mean measured height and standard deviation obtained from ten measurements were 10.0827 μm and 2.1 nm, respectively, and the experimental results agreed well with the calibrated value.