Special Surface Treatment Research Articles

High performance AlGaN/GaN MISHEMTs using N2O treated TiO2 as the gate dielectric

Abstract In this work, TiO2 thin films deposited by the atomic layer deposition (ALD) method were treated with a special N2O plasma surface treatment and used as the gate dielectric for AlGaN/GaN metal insulator semiconductor high electron mobility transistors (MISHEMTs). The N2O plasma surface treatment effectively reduces defects in the oxide during low-temperature ALD growth. In addition, it allows oxygen atoms to diffuse into the device cap layer to increase the barrier height and thus reduce the gate leakage current. These TiO2 films exhibit a dielectric constant of 54.8 and a two-terminal current of 1.96 × 10−10 A mm−1 in 2 μm distance. When applied as the gate dielectric, the AlGaN/GaN MISHEMT with a 2 μm-gate-length shows a high on/off ratio of 2.59 × 108 and a low subthreshold slope (SS) of 84 mV dec−1 among all GaN MISHEMTs using TiO2 as the gate dielectric. This work provides a feasible way to significantly improve the TiO2 film electrical property for gate dielectrics, and it suggests that the developed TiO2 dielectric is a promising high-κ gate oxide and a potential passivation layer for GaN-based MISHEMTs, which can be further extended to other transistors.

A microfluidic analyzer based on liquid waveguide capillary cells for the high-sensitivity determination of phosphate in seawater and its applications

BackgroundOptical detection is frequently performed on microfluidic chips for colorimetric analysis. Integrating liquid waveguide capillaries with total internal reflection with the microfluidic chip requires less procedures, which is suitable in the optical detection of microfluidic systems and is a practical alternative to increase the optical path length in the colorimetric assay of microfluidic devices for higher sensitivities and lower detection limit. However, this alternative has not been applied to the connection of PMMA chips or the microfluidic devices for the detection of phosphate in seawater. ReslutsHere, a lab-on-a-chip system integrating a microfluidic chip and an external liquid waveguide capillary cell was presented to detect the phosphate in seawater. The detachable total internal reflection capillary made of Teflon AF 2400 connected to the chip transports sample and transmits light, greatly reducing detection limit, eliminating the interference from stray light and widening the dynamic range of the system without specific surface treatment of the microchannel. By utilizing an internal 5-cm absorption cell and an external 20-cm liquid waveguide capillary cell, the system reaches detection limits of 59 nM and 8 nM, respectively, and can detect phosphate concentration from 0 to 23 μM. An online analyzer was developed based on the high-sensitivity system and was applied to shipboard underway analysis for two scientific cruises and to laboratory measurements for seawater samples from Xisha sea area. SignificanceCorrelation analyses between the shipboard and laboratory phosphate measurements and other physical and biochemical elements revealed the marine ecological characteristics of the corresponding areas, demonstrating the high-sensitivity of this method over slight variations and narrow ranges of phosphate and the ability to provide microfluidic systems for high spatiotemporal resolution phosphate determination a practical and cost-effective alternative.

Comparison of Friction Properties of GI Steel Plates with Various Surface Treatments

This article presents the improved properties of GI (hot-dip galvanized) steel plates in combination with a special permanent surface treatment. The substrate used was hot-dip galvanized deep-drawn steel sheets of grade DX56D + Z. Subsequently, various surface treatments were applied to their surface. The coefficient of friction of the metal sheets without surface treatment, with a temporary surface treatment called passivation, and a thin organic coating (TOC) based on hydroxyl resins dissolved in water, Ti and Cr3+ were determined by a cup test. The surface quality and corrosion resistance of all tested samples were also determined by exposing them for up to 288 h in an atmosphere of neutral salt spray. The surface microgeometry parameters Ra, RPc and Rz(I), which have a significant influence on the pressing process itself, were also determined. The TOC deposited on the Zn substrate was the only one to exhibit excellent lubrication and anticorrosion properties, resulting in the lowest surface microgeometry values owing to the uniform and continuous layer of the thin organic coating compared to the GI substrate and passivation surface treatment, respectively.

Static and impact performance of engineered cementitious composites with hybrid graphite nano platelets modified PVA and shape memory alloy fibres

Polyvinyl alcohol (PVA) fibre has been widely adopted to produce engineered cementitious composites (ECC), the overall performance of which is highly dependent on the fibre surface characteristics. The traditional approach to improve PVA fibre bridging ability is to tailor the surrounding matrix properties. However, this common practice need to do a lot of laborious experimental works, and thus it has limited efficiency and practicality. Therefore, special surface treatments on PVA fibres are required to create synergistic interactions between fibre and surrounding matrix to retain excellent tensile ductility and better mechanical performance. This paper proposes a novel treatment method for PVA fibres using nano graphite platelets to modify the PVA fibre surface and improve the mechanical properties of PVA fibre reinforced ECC. To evaluate the effectiveness of such treatment, a systematic experimental study was performed. Firstly, static contact angle measurements, scanning electron microscopy and atomic force microscopy were employed to monitor the wettability and physical changes on the fibre surface. Then, the static and dynamic mechanical properties as well as microstructural characteristics of ECC with hybrid modified PVA fibres (2 vol%) and shape memory alloy (SMA) fibres (0.25 vol%, 0.50 vol% and 1 vol%) were examined. The results indicate that the graphite nanoplatelets treated PVA fibres (GPVA) exhibit high hydrophobicity and surface roughness providing steady-state crack propagation, which is a necessary condition to ensure multiple cracking and improving the higher fibre bridging complementary energy. This is evidenced by significantly densified the transition zone between the graphite treated PVA fibres and the matrix, and improved the flexural tensile strength and the toughness. The calculated surface roughness of 28.86 μm and lots of peaks and valleys on the 3D topographical micrographs of the cracking faces confirmed that 1 SMA-2 GPVA specimen efficiently participated in transferring stress through the composite, leading to a greater vertical impact reaction force. Finally, the structure-property relation for flexural versus fracture behaviour and the effectiveness of SMA fibres on the crack-healing feature of the composites were studied by using digitized fractal analysis and through the heat treatment. The disseminated fracture energy (Ws/Gf) value reached 130 and the crack sizes the crack size decreased by 34 %, which were much better than that of the reference composites. The nano treatment of PVA fibres in ECC provides an innovative and sustainable solution for engineering structures with requirement of high tensile ductility and high impact resistance, e.g., military infrastructure and industrial floors.

How do different intraoral scanners and milling machines affect the fit and fatigue behavior of lithium disilicate and resin composite endocrowns?

The aim of this in vitro study was to evaluate the effect of the combinations of two different intraoral scanners (IOS), two milling machines, and two restorative materials on the marginal/internal fit and fatigue behavior of endocrowns produced by CAD-CAM. Eight groups (n= 10) were considered through the combination of TRIOS 3 (TR) or Primescan (PS) IOS; 4-axes (CR; CEREC MC XL) or 5-axes (PM; PrograMill PM7) milling machines; and lithium disilicate (LD; IPS e.max CAD) or resin composite (RC; Tetric CAD) restorative materials. Specific surface treatments were applied to each material, and the bonding to its corresponding Endocrown-shaped fiberglass-reinforced epoxy resin preparations was performed (Variolink Esthetic DC). Computed microtomography (μCT) was performed to assess the marginal/internal fit, as well as a mechanical fatigue test (20 Hz, initial load = 100 N/5000 cycles; step-size = 50 N/10,000 cycles until a threshold of 1500 N, then, the step-size was increased if needed to 100 N/10,000 cycles until failure or a threshold of 2800 N) to evaluate the restorations long-term behavior. Complementary analysis of the fracture features and surface topography in scanning electron microscopy was performed. Three-way ANOVA and Kaplan-Meier test (α = 0.05) were performed for marginal/internal fit, and fatigue behavior data, respectively. PS scanner, CR milling machine, and RC endocrowns resulted in a better marginal fit compared to their counterparts. Still, the PM machine resulted in a better pulpal space fit compared to the CR milling machine. Regardless of the scanner and milling machine, RC endocrowns exhibited superior fatigue behavior than LD ones. LD endocrowns presented margin chipping regardless of the milling machine used. Despite minor differences in terms of fit, the ‘IOS’ and ‘milling machine’ factors did not impair the fatigue behavior of endocrowns. Resin-composite restorations resulted in a higher survival rate compared to glass-ceramic ones, independently of the digital devices used in the workflow.

Using spherical indentation to determine creep behavior with considering empirical friction coefficient

Indentation testing is a common technique for characterizing the mechanical properties of materials. When it comes to assessing the yield behavior of metals, conical indentation is often favored due to its ability to induce significant plastic deformation at relatively shallow indentation depths. On the other hand, spherical indentation is typically chosen for evaluating metal creep behavior, as it helps minimize the influence of plastic deformation on creep measurements. In spherical indentation tests, the friction at the contact interface is particularly crucial, given the larger contact area and more pronounced slip zones. However, accurately determining the friction coefficient at the contact interface is a complex multi-scale challenge, with the exact coefficient varying based on specific testing conditions and surface treatments. Consequently, empirical friction coefficients are frequently employed, often without thorough justification. In this work, we proposed Bayesian inference method for obtaining the creep constitutive behavior of alloys through spherical indentation tests. Our model considers not only the complexity of creep law, but also the indentation friction, which is unable to consider in most spherical indentation tests with traditional treatment. By using experimental data of spherical indentation tests on 310S stainless steel and pure nickel alloy from literature, present study demonstrates the effectiveness of the Bayesian inference approach, with the inferred constitutive models exhibiting well agreement with uniaxial creep behavior. Furthermore, the method considers the friction coefficient as an extra factor in inferring creep constitutive behavior from indentation tests.

STRENGTHENING OF THE CARBIDE ALLOY OF WOOD CUTTING SAWS WITH COMPOSITE MATERIALS

The article covers issues related to the strengthening of solid tungsten-cobalt alloy plates of wood-cutting disc saws with new tungsten-free composite materials. It is shown that the domestic hard alloy is significantly inferior to the similar hard alloy of foreign production. This is primarily related to the technology of its production (the imperfection of the equipment for grinding tungsten, which does not make it possible to obtain the required dispersion and the method of sintering). It is noted that one of the ways to solve these problems is the development of a technology for strengthening hard alloy plates, which will make it possible to increase the stability indicators of the tool. Wear resistance can be increased by special surface treatment with the help of new composite materials, which changes such properties of the main material as hardness, corrosion and operational wear resistance, and strength. The problem of surface strengthening of wood-cutting tools with the use of wear-resistant coatings is quite urgent, as it opens wide opportunities for the creation of new special materials with fundamentally new physico-mechanical and physico-chemical properties. Advanced technologies for obtaining such coatings include the method of their formation under the action of concentrated energy flows with the use of electrospark alloying. The main advantage of the surface treatment of materials is that despite the high hardness and strength of the surface layer, the high plasticity and viscosity of the base is preserved. That is why research aimed at strengthening wood-cutting saws with new materials using the electrospark alloying method is relevant. The purpose of the research is to increase the service life of the wood-cutting tool by electrospark alloying of hard alloy with new composite materials and to reduce the shortage of hard alloys. The research results showed that dusts with strengthening treatment of teeth with a material based on titanium carbide КТФХ have the greatest resistance.

Waterdrop-assisted efficient fog collection on micro-fiber grids

Fog collectors can mitigate water scarcity by capturing droplets from fog streams. Previous research focuses on improving aerodynamic design and surface characteristics to enhance collection efficiency. However, limited attention has been given to micro-meter level fog-intercepting structures and the impact of waterdrop clogging. This study investigates the fog collection process on microfiber grids with varying fiber spacings and diameters. Waterdrops clog the grid openings with a pattern that small waterdrops satelliting large ones. Due to the small fiber diameter, the waterdrops are “visible” to incoming airflow and strongly affect fog droplet interception. The large waterdrops deflect incoming fog flow towards the small ones, and the small waterdrops efficiently capture the fog droplets. Consequently, the fog collectors based on microfiber grids demonstrated an exceptional water collection efficiency of up to 21.4%. The micro-fiber grids require minimal material usage and no special surface treatment, highlighting a great potential in fog water collection. Additionally, this work provides a novel design strategy of fog collector, i.e., reducing the size of the fog-intercepting structure to directly capture fog droplets by waterdrops.

Facile SERS substrates from Ag nanostructures chemically synthesized on glass surfaces

A quick one-step fabrication of efficient SERS substrates by a modified approach based on a silver-mirror reaction (using Tollens’ reagent) is reported. Commercially available microscope slides or cover glass (coverslips) were used as-received, without special surface treatment. In contrast to the commonly used two-step process, the composition of the Tollens reagent was modified to use a single-step process. The obtained rather homogeneous films of densely packed nanoislands are promising for application as substrates for Surface-Enhanced Raman Scattering (SERS), as demonstrated by several different kinds of molecules as analytes. In particular, the achieved level of detection of a standard dye analyte, down to 10-14 M of Rhodamine 6G, is in the range of best values reported in the literature. Low concentrations of some biomolecules are also detected, such as lysozyme (10-4 M), adenine (10-4 M), and salicylic acid (10-5 M). For some analytes, stronger SERS was observed in the drop, and for others after the solvent was dried. The possible reasons for this effect are described. By applying thermal annealing in the inert gas atmosphere, the Ag film morphology can be partially converted into a coral-like 3D structure that may be advantageous for the localization of the analyte in the “hot spots” and allow additional spectral tunability of the plasmon resonance.

Characterization of Molecular Interactions in the Bondline of Composites from Plasma-Treated Aluminum and Wood.

Wood and aluminum composites are becoming increasingly attractive due to their ability to combine the advantages of both materials: the lightweight nature of wood and the strength of aluminum. However, using conventional wood adhesives like polyvinyl acetate (PVAc) to bond these dissimilar materials is challenging and requires special surface treatments. Prior studies have demonstrated that applying a dielectric barrier discharge plasma treatment significantly enhances shear and bending strengths in beech wood/aluminum bonds. This study focuses on the molecular interactions between PVAc and aluminum or beech wood influenced by plasma surface modification. Surface-sensitive methods, including X-ray photoelectron spectroscopy, infrared reflection adsorption spectroscopy and atomic force microscopy, were employed to characterize the PVAc films on the corresponding surfaces and to identify possible interactions. The ultrathin PVAc films required for this purpose were deposited by spin coating on untreated and plasma-treated aluminum. The aluminum surface was cleaned and oxidized by plasma. Additionally, hydroxyl species could be detected on the surface. This can lead to the formation of hydrogen bonds between the aluminum and the carbonyl oxygen of PVAc after plasma treatment, presumably resulting in increased bond strength. Furthermore, the beech wood surface is activated with polar oxygen species.

Polyvinylidene fluoride/maghnite nanocomposites: fabrication and study of structural, thermal and mechanical properties

Abstract An in-depth study of polyvinylidene fluoride (PVDF) based nanocomposite systems will be the focus of this research. This polymer being hydrophobic and apolar, it will be unlikely to generate strong interactions with clay leaves called organophilic maghnite. The challenge of this study will therefore be to manage the load/polymer interfaces by using montmorillonite with specific surface treatments by adding a surfactant Cetyltrimethylammonium bromide. Therefore, a significant improvement in mechanical and thermal properties was observed. The properties of PVDFNC nanocomposites were evaluated using various physico-chemical techniques (XRD, FTIR, TGA, DSC, TEM, SEM). The results of the structural and thermal measurements carried out on these products reveal that the structural concept of the surfactant influences both the morphological profile, the thermal and mechanical properties of the nanocomposites obtained. Accelerated crystallization is observed in PVDNC nanocomposites as an effective nucleation agent, the crystals formed are predominantly β shaped and have a small number of polar α crystals. Measurements by X-ray diffraction, as well as transmission and scanning electron microscopy indicated that modified maghnite was perfectly distributed 3 % by weight in the polyvinylidene fluoride matrix. The mechanical properties of the nanocomposites were evaluated according to the filler material used and the polyvinylidene fluoride matrix.

Experimental investigation of typical surface treatment effect on velocity fluctuations in turbulent flow around an airfoil

Noise reduction of different airfoils is important because these sections are used in wind turbines, propellers, and aircraft wings. Several methods are used for passive noise reduction of sections. One of these methods is the use of surface treatment. In this research, the effect of the typical surface treatment element (finlets) on the vortex structure at different frequencies in the turbulent flow created on the NACA2412 section is investigated. For this purpose, one-dimensional hot wire probe is used. The used surface treatment in this research has a special geometry and the distance between two consecutive finlets is 6 mm (S = 6 mm). This study shows that this surface treatment element can be used for noise reduction in high frequencies. Another result of this research is the suggestion of the most suitable position to install this special surface treatment element to reduce vortex energy in all frequency ranges. This installation location is determined based on a dimensionless parameter (Xaft/h).

Corrosion Stiction in Automotive Braking Systems.

This review paper targets the corrosion-stiction phenomenon that can occur in automotive braking systems under static conditions in aggressive environments. The corrosion of gray cast iron discs can lead to a strong adhesion of the brake pad at the pad/disc interface that can impair the reliability and performance of the braking system. The main constituents of friction materials are initially reviewed in order to highlight the complexity of a brake pad. Corrosion-related phenomena, including stiction and stick-slip, are considered in detail to discuss the complex effect of the chemical and physical properties of friction materials on these phenomena. In addition, testing methods to evaluate the susceptibility to corrosion stiction are reviewed in this work. Electrochemical methods, including potentiodynamic polarization and electrochemical impedance spectroscopy, are useful tools for a better understanding of corrosion stiction. The development of friction materials with low susceptibility to stiction should follow a complementary approach targeting an accurate selection of the constituents, control of local conditions at the pad-disc interface, and the use of specific additives or surface treatments to reduce the corrosion susceptibility of gray cast-iron rotors.

Dynamic large strain measurement under high-temperature environment using a modified FBG sensor and plasma surface treatment.

Large strain measurement under high-temperature environment has been a hot but difficult research issue in the fields of measurement and metrology. However, conventional resistive strain gauges are susceptible to electromagnetic interference at high temperature, and typical fiber sensors will be invalid under high-temperature environment or fall off under large strain conditions. In this paper, aiming to achieve effective and precision measurement of large strain under high-temperature environment, a systematic scheme combining a well-designed encapsulation of a fiber Bragg grating (FBG) sensor and a special surface treatment method using plasma is presented. The encapsulation protects the sensor from damage while achieving partial thermal isolation and avoiding shear stress and creep, resulting in higher accuracy. And the plasma surface treatment provides a new bonding solution which can greatly improve the bonding strength and coupling efficiency without damaging the surface structure of the object under test. Suitable adhesive and temperature compensation method are also carefully analyzed. Consequently, large strain measurement up to 1500 µɛ under high-temperature (1000°C) environment is experimentally achieved in a cost-effective way.

Shear bond strength of orthodontic brackets bonded to a new version of zirconium all ceramic restoration: An in vitro comparative study

ObjectivesEsthetic restorations such as monolithic zirconia crowns are highly requested for adults nowadays. Bonding orthodontic braces on this type of material became a challenge for orthodontists, because of the special surface treatment needed. This study aims to assess the shear bond strength (SBS) of metal, and ceramic brackets bonded on two types of zirconia ceramics, surface roughness (SR) after different surface treatments for their surfaces, and adhesive remnant index (ARI). Materials and methodsBrackets’ base surface area (BSA) was scanned by an extra-oral scanner, then measured. The doubled labial surface of monolithic zirconia crowns (n = 30) and monolithic high translucent zirconia crowns (n = 30) were prepared and each was divided into three groups (n = 10) depending on surface treatment (hydrofluoric acid etching, no treatment, and rocatec airborne abrasion). Extracted lower central incisors (n = 20) were prepared. Each of them was divided into two subgroups depending on the type of bracket bonded on their surfaces (metal and ceramic). The SR, SBS, and ARI were assessed. Statistical analysis usedTests used are independent-samples t-test, Fisher's exact test, One-Way ANOVA, and Kruskal-Wallis test. ResultsThe highest SBS and SR were observed in Enamel/Metal and Zirconia/Metal/Rocatec subgroups, respectively. ConclusionAdequate bond strength could be obtained with the high translucent zirconia group if bonded with ceramic or metal brackets even if no treatment was used. Clinical significanceA proportion of simulation was done like practicing inside the dental clinic to reach the best results regarding the adhesion strength of orthodontic brackets.

Effect of hydrophobic aerosil dispersions on the Goldstone mode dynamics in ferroelectric liquid crystal near the point of polarisation sign reversal

ABSTRACTBroadband dielectric spectroscopy in the frequency range from 10−2 Hz to 107 Hz was used to study the effect of hydrophobic aerosil nanoparticles on the dynamics of the Goldstone mode in a ferroelectric liquid crystal near the point of spontaneous polarisation sign reversal. The obtained results show that an important role in the modification of the dynamics of the Goldstone mode and the phenomena at the point of spontaneous polarisation sign reversal is played not only by the presence of the nanoparticles themselves in the ferroelectric liquid crystal structure, but also the state of the surface of these nanoparticles. Similarly to the hydrophilic aerosil, the polarisation sign reversal temperature slightly decreases with the increase of the hydrophobic aerosil concentration. For small concentrations of hydrophobic aerosil, only slight changes in the dynamics of the Goldstone mode over the entire temperature range are detected. The observed deviations are due to the different influence of aerosil nanoparticles on the structure and dielectric properties of the tested composite caused by the specific surface treatment. The presence of the Goldstone mode above and below the point of polarisation sign reversal seems to confirm the model of two conformers with different structure and opposite dipole moments.

Insights into the characteristics of corrosion products formed on the contact and exposed regions of C1045 steel bolt and nut fasteners exposed to aqueous chloride environments

• Corrosion products on different regions of C1045 bolt are characterized for the first time. • Differential aeration/concentration effects induced heterogeneity in the corrosion products. • Reactive phases, γ-FeOOH and β-FeOOH dominated at the exposed and contact region, respectively. • Magnetite, Fe 3 O 4 was detected in both regions under low oxygen conditions. • Due to the low amount of α-FeOOH, the rusts in both regions lack stability and protectiveness. This study investigated the characteristics of corrosion products formed on the contact and exposed regions of C1045 steel bolt and nut fasteners used in structures exposed to aqueous chloride environments. The corroded surface morphology, rust compositions, and corrosion kinetics of the bolt specimen were studied by visual observation, optical microscopy (OM), scanning electron microscopy (SEM), X-Ray diffractometry (XRD), micro-Raman, electron probe micro-analyzer (EPMA), and potentiodynamic polarization techniques. Results obtained showed a variation in corrosion kinetics, morphology, and composition of the rust layer which were driven by differential aeration and concentration effects. Due to the availability of sufficient dissolved oxygen, the oxyhydroxide compound, lepidocrocite (γ-FeOOH) was detected in the outer rust layer in the exposed region, whereas the inner rust layer was composed of magnetite (Fe 3 O 4 ). However, the oxygen-deficient contact surface revealed the presence of akaganeite (β-FeOOH) and magnetite (Fe 3 O 4 ) as dominant oxide phases. The most stable phase, goethite (α-FeOOH) was also detected in the rust formed in both regions, though in significantly low amounts. Furthermore, owing to variation in environmental conditions, the amount and density of the rust layer varied in the different regions. The estimated corrosion stability values for the different regions revealed that the corrosion products formed on the steel surfaces were non-protective, suggesting the need for specific surface treatment as a protective measure.

Dual-Function Fibrous Co-Polypeptide Scaffolds for Neural Tissue Engineering.

This paper reports dual-function (high cell attachment and cell viability) fibrous scaffolds featuring aligned fibers, displaying good biocompatibility and no cytotoxicity. These scaffolds are fabricated through the electrospinning of a co-polypeptide comprising molar equivalents of N6 -carbobenzyloxy-l-lysine and γ-benzyl-l-glutamate, with the lysine moieties enhancing cell adhesion and the neural-stimulating glutamate moieties improving cell viability. These new scaffolds allow neural cells to attach and grow effectively without any special surface treatment or coating. Pheochromocytoma (PC-12) cells grown on these scaffolds exhibit better neuronal activity and longer neurite length, relative to those grown on scaffolds prepared from their respective homo-polypeptides. When the scaffolds are partially hydrolyzed such that they present net positive charge and increased hydrophilicity, the cell viability and neurite growth both increase further. Accordingly, these novel co-polypeptide fibrous scaffolds have potential applications in neural tissue engineering.

PDMS-PUA bi-directional replication technology and its applications.

Polydimethylsiloxane (PDMS) and polyurethane acrylate (PUA) are excellent pattern transfer materials. In this study, PDMS-PUA bi-directional replication technology is explored using the PDMS grating as a template, and relevant technical issues are discussed in detail. Special surface treatment and process optimization are applied to solve the problems of demolding, PDMS polymerization inhibition, and substrate flatness. Further experiments show that the technology can be employed to replicate nanoscale structures and has the potential value of prolonging the longevity of the original template. Additionally, utilizing the advantage of the high elasticity of PDMS materials, two applications of bi-directional replication technology are demonstrated. One is to increase the line-density of the grating by stretching, and the experimental results show that the line-density of the grating increased by 26.6%. The other one is to fabricate the convex grating. Compared with the original planar PDMS grating, the resolution of the first-order diffraction spectrum of the convex grating at the focal point has been greatly improved. Since this technology requires simple equipment, and PDMS and PUA are reusable, it has the advantages of low cost, simplicity, and rapid fabrication. The two application examples also indicate that the technology has good application value.

Assessment of force control for surface finishing – an experimental comparison between Universal Robots UR10e and FerRobotics active contact flange

Abstract. Robotic surface treatment is already broadly used in the manufacturing industry because it guarantees repeatable high-quality surfaces at short production time. Such a robotic solution, with an accurate control of the applied force on a surface, requires a robot that is either equipped with a force/torque sensor or, alternatively, with a force compliance device. However, without a direct performance comparison, it is hard to know which is the best option for a specific surface treatment operation. Compared to the evaluation of the robot positioning accuracy, using the ISO 9283 test, no standardized test for the quality assessment of robot force control exists yet. In trying to fill this gap, this paper introduces different test scenarios and a test set-up for such a force control quality assessment. As a start, the force control of a Universal Robots UR10e model and a FerRobotics ACF-K 109/04 model are experimentally evaluated. The latter is an external device with controlled force/compliance characteristics, which is referred to as an active contact flange (ACF). For the performance comparison, an ATI force/torque sensor, which is mounted below a work piece, measures the applied force either by the UR or by the ACF. The measured forces are further transformed to the UR tool centre point (TCP) frame. Then, only the z component of the force, or rather the normal force, is relevant for surface treatment and hence important for the evaluation. For each test case, the average value of five test runs with the same parameters is used for the assessment. Results for both the UR and ACF force control are presented for varying desired contact velocities and desired forces. These results indicate the advantage of the ACF-K 109/04 over the UR10e force control for highly dynamic force control scenarios.