Biomimetic Textures Research Articles

Construction of biomimetic textures and modification of self-lubrication mechanisms on the surface of sulfonated polyether ether ketone films

Construction of biomimetic textures and modification of self-lubrication mechanisms on the surface of sulfonated polyether ether ketone films

Biomimetic Slippery Surface with Exclusive Liquid-Repellent and Self-Cleaning Properties for Antifouling.

The nature always offers amazing inspiration, where it is highly desirable to endow coatings on marine equipment with powerful functions. An excellent example is slippery zone of Nepenthes pitcher, which possesses novel liquid-repellent and self-cleaning performance. Therefore, this study presents an efficient fabrication method to prepare a novel coating. The coatings were fabricated by designing biomimetic textures extracted from the lunate bodies of slippery zone on polydimethylsiloxane (PDMS) and then grafting Dictyophora indusiata polysaccharide (DIP) modifier. The as-prepared slippery coatings exhibited outstanding antifouling properties against kinds of daily life pollutants such as Chlorella and coffee. This synergistic strategy was proposed combined with environmentally friendly modifier grafting and heterogeneous microstructure on the surface to broaden new probabilities for manufacturing slippery coatings with incredible protective functionality.

Biomimetic papilla texture by femtosecond laser for high-strength CFRTP/A6061-T6 FSSW hybrid structures

The lightweight design concept in structural applications has generated interest in hybrid structures of carbon-fiber-reinforced thermoplastics (CFRTP) and metals as attractive structure components. However, these hybrid structures face challenges due to the significant differences in physical and chemical properties between CFRTP and metals, resulting in limited strength and rendering them unsuitable for advanced transportation. To address these limitations, the current research focuses on creating a biomimetic texture on A6061-T6 (6061) surfaces using femtosecond laser to manufacture high-strength hybrid structures, inspired by organismal body surfaces. The CFRTP and 6061 were joined by friction stir spot welding (FSSW). The femtosecond laser treatment produces double-scale roughness on 6061 surfaces and causes carbon to absorb into alumina. These changes in physical and chemical structures enhance the compatibility between 6061 and CFRTP. The biomimetic rough aluminum surface creates effective mechanical interlock at the interface with CFRTP, preventing the initiation and propagation of fracture cracks. The presence of absorbed carbon enhances the Al-O covalency, which influences the bonding behavior at CFRTP/6061 interfaces. The improved compatibility, mechanical interlock, and enhanced bonding behavior synergistically strengthen the joint strength of CFRTP/6061 hybrid structure modified by the biomimetic papilla structure. Current biomimetic design strategy inherits the remarkable natural wisdom and is expected to provide valuable insights for the development and application of CFRTP/metal hybrid structures.

Effects and optimization of bionic texture parameters on the tribological behavior of line contacts under starved lubrication conditions

PurposeGears are prone to instantaneous failure when operating under extreme conditions, affecting the machinery’s service life. With numerous types of gear meshing and complex operating conditions, this study focuses on the gear–rack mechanism. This study aims to analyze the effects and optimization of biomimetic texture parameters on the line contact tribological behavior of gear–rack mechanisms under starvation lubrication conditions.Design/methodology/approachInspired by the microstructure of shark skin surface, a diamond-shaped biomimetic texture was designed to improve the tribological performance of gear–rack mechanism under starved lubrication conditions. The line contact meshing process of gear–rack mechanisms under lubrication-deficient conditions was simulated by using a block-on-ring test. Using the response surface method, this paper analyzed the effects of bionic texture parameters (width, depth and spacing) on the tribological performance (friction coefficient and wear amount) of tested samples under line contact and starved lubrication conditions.FindingsThe experimental results show an optimal proportional relationship between the texture parameters, which made the tribological performance of the tested samples the best. The texture parameters were optimized by using the main objective function method, and the preferred combination of parameters was a width of 69 µm, depth of 24 µm and spacing of 1,162 µm.Originality/valueThe research results have practical guiding significance for designing line contact motion pairs surface texture and provide a theoretical basis for optimizing line contact motion pairs tribological performance under extreme working conditions.

Subnanometer Nanowire‐Reinforced Construction of COF‐Based Membranes with Engineering Biomimetic Texture for Efficient and Stable Proton Conduction

AbstractAchieving rapid ion transport through nanochannels is essential for both biological and artificial membrane systems. Covalent organic frameworks (COFs) with well‐defined nanostructures hold great promise for addressing the above challenge. However, due to the limited processability and inadequate interlamellar interaction of COF materials, it is extremely difficult to integrate them to prepare high‐performance proton conductors. Herein, inspired by the ingenious bio‐adhesion strategy in nature, ultrafast proton conduction is achieved by taking advantage of COF membranes where TP‐COF nanosheets are linked by subnanometer nanowires/lignocellulosic nanofibrils composites (SNWs/LCNFs) through electrostatic and π‐π interactions to form an ordered and robust structure. Notably, the synthesized SNWs exhibited impressive proton conductivity and adhesion capacity due to their inbuilt phosphotungstic acid (HPW) molecules and multidimensional interactions. Therefore, attributed to the synergistic contribution of TP‐COFs and SNWs, the composite membrane achieves ultrahigh proton conductivity (0.395 S cm−1 at 80 °C and 100% RH), superior mechanical property (109.8 MPa), exceptional fuel cell performance (71.6 mW cm−2), and superior operational stability (OCV decay rate is about 1.5 mV h−1), demonstrating outstanding competitiveness. More importantly, the proposed design concept has the potential to be applied in membranes for various electrochemical devices and molecular separations.

Thick-film printing of TaS2 soft films on the textured surface to enhance wear life

As an additive manufacturing technology, 3D printing has become the new trend of film preparation in the future. Electrohydrodynamic atomization (EHDA), a new additive manufacturing technique, can produce films with a wide range of thicknesses. Although the synergistic effect of soft films and textured surfaces can effectively improve the tribological properties of the substrate, there are still problems such as poor interface bonding and short film life. Research into new microtextured and soft film materials is an important part of expanding the use of ceramic cutting tools in metal cutting applications. Herein, biomimetic Nepenthe convex textures and TaS2 soft films were prepared on the surface of Al2O3/TiC ceramic using nanosecond laser and EHDA processes, respectively. The results reveal that TaS2 films printed on biomimetic textured substrates had a longer wear life and lower wear rate. The synergistic effect of TaS2 films and biomimetic textures exhibits the best effect in reducing wear and improving the wear life of the substrate, which are expected to become a promising way to improve the tribological properties of Al2O3/TiC ceramic.

Effect of femtosecond laser bionic texture on anti-wear properties of medical Ti-6Al-4 V

Ti-6Al-4 V (TC4) is used as a medical implant material. However, its wear resistance is poor, which is not conducive to the use of implants. In this study, three biomimetic textures were designed on the surface of materials by femtosecond pulsed laser processing technology. The wear resistance of the textured surface was studied by rotating dry friction. The results demonstrate that the textured surface effectively reduces and captures the generation of wear particles, leading to enhanced stability of TC4 during wear and reduced surface wear. Compared with the untextured surface, the wear of the textured surface is reduced by 73.68%. These results indicate that bionic texture can improve the wear resistance of TC4.

Coupling Effects of Biomimetic Texture with Solid Lubricants to Improve Tribological Properties of TC4 under Dry Sliding Conditions

Coupling Effects of Biomimetic Texture with Solid Lubricants to Improve Tribological Properties of TC4 under Dry Sliding Conditions

The impact of bio-inspired micro-textures on turbulence and implications for bio-fouling settlement

Biomimetic textures originally developed as an anti-fouling strategy for static immersion, have been studied for application on marine hydro-turbines. Turbulent flow Simulations have been performed to characterize hydrodynamic stresses in area where micro-organisms are expected to settle. The study relies on Large Eddy Simulations of fully developed channel flow in the transitionally rough regime to study the fluid flow interaction around the texture prisms. The analysis focusses on the sensitivity to the texture layout and orientation and considers three different gap sizes S+=10,40,80, scaled in inner units, where the smallest gap S+=10 corresponds to the physical gap between textures at full scale when applied over a turbine blade operating under nominal conditions. Results indicate that the smallest gap which has been shown previously to be most effective at hindering micro-organism attachment also creates an effective shelter against mean turbulent stresses. Interestingly, however, strong infrequent turbulent fluctuations are predicted within the gap. These may be sufficient to avoid unwanted accumulation of the smallest organisms and passive particles. Exposed surfaces including within groves between textures, where organisms would be most expected to settle in static immersions, are also found to experience significant stresses as the gap size is increased.

Experimental study of adhesion, friction, and peeling of biomimetic combined micro-mushroom and micro-spatulae textures

Although adhesive biomimetic textures have been extensively studied during the last decades, the natural combination of different micro-textures in some insects is still of interest due to the unique ability to optimize their adhesion and friction in different environmental conditions. This study presents a unique manufacturing method for creating combined textures of microfibril adhesive terminals of different shapes. Using DLP (Digital Light Processing), 3D printing, and unique design, isotropic samples containing a combination of micro-spatulae, and micro-mushroom textures were created. This work examines the tribological performances of combined micro-textures under different traction velocities and normal loads. Different power laws are proposed to link the loading/unloading velocities with the generated detachment force and the friction coefficient. The behavior of the combined textures can be approximated by merging existing models that describe the boundary cases of 0° and 90° between the load and unload directions.

Numerical Simulation and Experimental Investigation on Tribological Properties of Gear Alloy Surface Biomimetic Texture

A biomimetic microtexture was constructed on the surface of gear alloys, and the stress distribution and oil film pressure of the textured tooth surface were evaluated by numerical simulation. The tribological test of the textured gear alloy was carried out using a "reciprocating ball-on-flat" tribotester, and the friction mechanism was analyzed. The influence of microtexture on the tribological properties of gear alloys was analyzed by cross-checking between the simulation and experiment. The simulation results show that all three biomimetic textures can change the stress contact state of the tooth surface. The oil film pressure of the textured tooth surface is higher than that of the untextured tooth surface. The experimental results show that the textured alloy has excellent tribological properties. Among these, the crescent texture has the best comprehensive performance, and the friction coefficient and wear rate can be reduced by more than 30% and 95%, which is the result of the dynamic pressure effect of the texture and debris storage. In the analysis of wear marks and debris, it is found that the small size of debris wrapped by thick carbon material is helpful to improve the tribological properties of gear alloy. Large-size debris is the main cause of plowing and wear.

An effective encapsulation method for highly stable perovskite solar cells by introducing a UV absorber with biomimetic textures and heat sinker with a reduced graphene oxide composite layer

A UV-absorbing layer with micro-/nano hierarchical structures effectively cuts UV light while increasing the transmittance of visible light, resulting in enhanced device stability without sacrificing the photocurrent.

Tribological behavior of CoCrMo artificial knee joint with symmetrically biomimetic textured surfaces on PEEK

CoCrMo alloys are extensively used in the field of artificial knee joints. However, wear performance is one of the most important problems of artificial knee joints, limiting service life. In this paper, symmetrically biomimetic textures with the spacing of 200 μm, the width of 45 μm, and the depth of 45 μm are fabricated on the surfaces of CoCrMo artificial knee joints to improve its tribological properties. Friction tests are conducted under the following conditions: frequency 1.5 Hz, sliding time 30 min, load (5 ∼ 15 N), lubricant concentration (15 ∼ 55 mg/ml). Results show that textures, lubricating condition, load and surface wettability have significant influence of friction properties, and textured CoCrMo artificial knee joints show the better friction performances compared STT-0, and samples with scaly textured structure (STT-3) own best friction performances with the lowest coefficients of friction. The responsible mechanisms on the enhancement of friction properties of textured joint are explained as follows: micro-texture plays the role of storing the wear debris and lubricating fluid, preventing the wear debris from entering between the friction pairs and forming hydrodynamic pressure to generate hydrodynamic lubrication effect. Derivative-cutting behavior of the lower edge of biomimetic textures can act as “another cutting tool” to remove the wear debris which adhered on the bottom of the PEEK balls.

Wear-triggered self-repairing behavior of bionic textured AISI 4140 steel filled with multi-solid lubricants

The wear fatigue of slewing bearings at the contact areas of raceways (AISI 4140 steel (AS)) and rollers (AISI 52100 steel) seriously reduces the service life of equipment. AS-SnAgCu-TiC composites (AS-SACT) were prepared by filling multi-solid lubricants into surface biomimetic textures of AS to improve the wear resistance. Tribological properties were tested using a block-on-ring tribometer. The materials of block and ring were AS and AISI 52100 steel, respectively. Compared with that of AS, coefficient of friction of AS-SACT was decreased by 67.93%, and wear height was reduced by 42.19%. Wear triggered the diffusion of SnAgCu from the bionic textures to worn surface. The hard phase of nano-TiC was wrapped by a cluster of multi-layer lubricants to form spherical particles, which not only converted sliding to rolling contact, but also repaired pits and furrows on worn surface. Hence, AS-SACT with self-repairing behavior had excellent properties of antifriction and wear resistance.

Analysis of Biomimetic Texture Surface on Dynamic Compression Lubrication and Friction Reduction of Artificial Hip Pair

Analysis of Biomimetic Texture Surface on Dynamic Compression Lubrication and Friction Reduction of Artificial Hip Pair

Fabrication of WS2/C composite coatings via electrohydrodynamic atomization and their tribology behaviours

WS2 coatings were prepared by electrohydrodynamic atomization method, and graphite was introduced in order to improve their mechanical properties and oxidation resistance. The influence of graphite on the microstructure, anti-oxidation capability, mechanical performances and tribological properties of the composite coatings were systematically analysed. The sharkskin-like biomimetic textures were fabricated on the substrates by laser machining. The results showed that the sharkskin-like biomimetic textures increased the compressive stresses and surface energies of substrates, resulting in improved adhesion strength between deposited coatings and substrates. The improved adhesion strength and oxidation resistance of the WS2/C coatings as well as the antifriction capability of micro/nano-textures aided in keeping a low stabilized friction coefficient down to 0.05 for a long sliding time. The WS2/C (4:1) composite coatings deposited on the sharkskin-like biomimetic textured substrates presented the longest wear life of ~2800 s, which was ~2.3 times longer than that of the pure WS2 coatings on the polished substrates. The wear rate of WS2/C (4: 1) coating deposited on the textured substrate was ~3.1 × 10−7 mm3/N mm, which was about three-fifths of that of the pure WS2 coating deposited on the polished substrate. The micro/nano-grooves, which acted as reservoirs for WS2 lubricating material, could support the formation of the low-friction tribo-films.

Simple and low-cost interferogram projection system for small-size automotive parts profilometry: benchmarking with a commercial apparatus

Three-dimensional (3D) contouring has become very important in industry and in many other production systems. The optical techniques provide many attractive properties for such measurement due to their precision, reliability, accuracy and ability to measure small and fragile objects. In this work we report the study, the development and the performance of a low-cost optical device based on interferogram projection in order to measure the sub-millimetric relief of polymeric plates containing biomimetic textures used in the automotive industry. The interferogram was generated by a Twyman-Green interferometer illuminated by a 532-nm green laser. The measurement was performed by means of phase-shifting and phase-unwrapping procedures and the results were benchmarked with the ones obtained by a commercial device.

Optimization of Performance Parameters and Mechanism of Bionic Texture on Friction Surface

In this paper, a variety of micro-textures made by imitating the biological body surface are mentioned, and four common biomimetic texture types—convex hull, pit, groove and corrugation—are summarized by referring to a large number of literatures. These texture types that are widely used are those of the grooves and the pits of non-smooth surface because their viscosity drag reduction effects are relatively optimal for wear-resistance; in view of these two types of textures (with others including pit diameter, groove width, depth and area of share, and morphology spacing), we use data analysis and comparisons to find optimal parameter values in order to find the optimal effect of drag reduction and anti-sticking wear-resistance. Several texture processing methods are briefly introduced through case analysis and an illustration of the viscosity drag reduction mechanism of wear-resistance, and general fluid dynamic pressure is deduced from a theory formula in order to facilitate future research work on the basis of the optimal parameters to further improve the friction, wear lubrication, and hydrophobic properties, thus improving the bionic texture surface efficiency of saving energy and reducing consumption in industrial applications.

Electrochemical corrosion and anisotropic tribological properties of bioinspired hierarchical morphologies on Ti-6Al-4V fabricated by laser texturing

Abstract Biomimetic texture could widen the application of titanium alloys materials in biological fields. In this work, the electrochemical corrosion and unidirectional tribological properties of Ti-6Al-4V substrate textured with three types of bionic hierarchical morphologies in the modified simulated body fluids (m-SBF) have been evaluated. The experimental results reveal that the corrosion resistance of textured surfaces is improved by reducing the βphase/αphase volume ratio on the substrate and increasing the texture density. Moreover, the effect of friction-reducing of 79% and friction-increasing of 47% in unidirectional sliding can be easily tuned with laser processing parameters. Interestingly, the textured surface displays anisotropic tribological behaviour in m-SBF solution, with reducing friction along the stacked ring direction and increasing friction in other directions.

Multiscale Patterning of a Metallic Glass using Sacrificial Imprint Lithography

Bulk metallic glasses (BMGs) have been developed as a means to achieve durable multiscale, nanotextured surfaces with desirable properties dictated by topography for a multitude of applications. One barrier to this achievement is the lack of a bridging technique between macroscale thermoplastic forming and nanoimprint lithography, which arises from the difficulty and cost of generating controlled nanostructures on complex geometries using conventional top-down approaches. This difficulty is compounded by the necessary destruction of any resulting reentrant structures during rigid demolding. We have developed a generalized method to overcome this limitation by sacrificial template imprinting using zinc oxide (ZnO) nanostructures. It is established that such structures can be grown inexpensively and quickly with tunable morphologies on a wide variety of substrates out of solution, which we exploit to generate the nanoscale portion of the multiscale pattern through this bottom-up approach. In this way, we achieve metallic structures that simultaneously demonstrate features from the macroscale down to the nanoscale, requiring only the top-down fabrication of macro/microstructured molds. Upon detachment of the formed part from the multiscale molds, the ZnO remains embedded in the surface and can be removed by etching in mild conditions to both regenerate the mold and render the surface of the BMGs nanoporous. The ability to pattern metallic surfaces in a single step on length scales from centimeters down to nanometers is a critical step toward fabricating devices with complex shapes that rely on multiscale topography for their intended functions, such as biomedical and electrochemical applications. Biomedical and optical devices stand to benefit from a multiscale patterning technique developed by researchers in the USA. Bulk metallic glasses (BMGs) are extremely strong and corrosion-resistant alloys that can be thermoplastically molded with features spanning centimeter to nanometer dimensions. The generation of multiscale molds with conventional lithography, however, requires several costly steps. To simplify BMG patterning from the bottom-up, Chinedum Osuji from Yale University and co-workers from Yale and Rutgers grew tunably packed nanowires and nanosheets of zinc oxide (ZnO) directly onto mold surfaces. When a BMG is formed then detached from this modified mold, the nanostructures embed themselves into the metallic surface. A subsequent mild etching procedure removes the ZnO and gives the BMG a nanoporous surface—an economical route to biomimetic textures for applications ranging from biomanipulation to fuel cells.