•Ni-P-PTFE gradient coatings were prepared by electroplating and electroless plating.•Gradient coatings can effectively improve the adhesion strength of the coating.•Gradient coatings have little ...effect on mechanical properties and wettability.•When the concentration is (25 + 50) mL/L, the gradient coatings show the best comprehensive performances.
Ni-P-PTFE (polytetrafluoroethylene) coatings were prepared on stainless steel surfaces to enhance their anti-fouling performance. However, the coatings face the challenge of low adhesion strength due to the complex deposition conditions. To address this issue, gradient Ni-P-PTFE coatings with varying concentrations of PTFE emulsion were fabricated on stainless steels, and non-gradient Ni-P-PTFE coatings were also synthesized for comparison purposes. The surface morphology, cross-sectional morphology, and element distribution in the vertical direction were characterized using Scanning Electron Microscopy (SEM) and Energy-Dispersive Spectroscopy (EDS). X-ray Diffraction (XRD) was employed to examine the microstructure of the coatings. Nanoindentation was conducted to evaluate hardness and elastic modulus, while a friction and wear tester was used to measure the coefficient of friction. A coating adhesion scratch tester was utilized for testing the adhesion strength, whereas a contact angle tester determined wetting property characteristics. The results demonstrate that an increase in PTFE emulsion content leads to a reduction in the hardness and elastic modulus of Ni-P-PTFE coatings while gradually enhancing their hydrophobicity. The overall performance of gradient coatings surpasses that of non-gradient coatings. Notably, when the PTFE concentration reaches (25 + 50) mL/L, the gradient coatings exhibit uniform particle distribution, superior friction and wear resistance, and the bonding strength is enhanced.
Display omitted
•A supramolecular strategy is reported to fabricate a soybean meal-based adhesive.•Cellulose nanofibrils act as templates to regulate biomineralization process.•Aminoclay is ...functionalized by tailor-made long alkyl chain quaternary salt.•The dry and wet shear strengths of the adhesive increase by 130% and 197%.•The adhesive has remarkably improved flame retardancy and antibacterial activity.
Plant-derived protein adhesives have received widespread attention as sustainable alternatives to formaldehyde-based engineered wood products, but their practical applications are severely limited by the poor mechanical and antibacterial properties. Inspired by the amphiphilic and ionic features of mussel chemistry, we have developed a facile and green strategy for fabricating a soybean meal-based biomass adhesive with high bonding strength and antibacterial activity. The strategy incorporates a supramolecular system of biomineralized cellulose nanofibril (MCF) and a cationic long-alkyl-chain quaternary salt (LAQ) functionalized aminoclay (LAQ@AC). The functional MCF was prepared by in situ biomineralization of inorganic particles regulated by a cellulose nanofibril biotemplate, thus constructing a rigid mineralized skeleton structure in the protein matrix. The cohesion and adhesion strength of the protein composites were significantly improved by the supramolecular crosslinking of MCF/LAQ@AC hybrids via hydrogen bonds and electrostatic interactions. The dry and wet shear strengths of the resultant adhesive increased to 2.58 and 1.87 MPa, respectively, 130% and 197% higher than the pristine soybean meal adhesive, and remarkably exceeded those of other protein-based adhesives. By establishing a biomineralized architecture and a positively charged surface, the incorporated MCF/LAQ@AC hybrids endow the adhesive with desirable flame retardation and antibacterial activity. This novel and sustainable strategy provides a strong and stable supramolecular network for fabricating high-performance environmentally friendly biomass adhesives in biological and engineering applications.
Display omitted
•Hydrate formed on soft and stiff solid surfaces shows distinct adhesion strengths.•Adhesion strength of hydrate on soft substrates is greatly dictated by the shear loading ...rate.•Adhesion strength of hydrate on stiff substrates is greatly affected by the elastic modulus of the substrates.
Hydrate formation and accumulation pose significant challenges in oil and gas pipelines, leading to flow assurance issues and safety hazards. It is crucial to understand hydrate adhesion to prevent the accretion of hydrate in petro-pipelines. In this study, the adhesion strength (AS) of tetrahydrofuran (THF) hydrate on various solid surfaces with different elastic moduli subjected to shear loading rates ranging from 10 to 10000 μm/s is comprehensively investigated by shear force experimental measurements and finite element (FE) simulations. The results reveal that the hydrate AS is primarily influenced by the elastic modulus of the substrates, and the shear-induced detachment properties are strongly dependent on the shear loading rate. Specifically, when the hydrate is synthesized on a soft polydimethylsiloxane (PDMS) substrate, the AS exhibits minimal changes at low and high shear loading rates. However, under intermediate shear loading rates, the AS rapidly increases by approximately 500 %. In contrast, when the hydrate is formed on stiff polytetrafluoroethylene (PTFE) and polyethylene (PE) substrates, the AS is increased by approximately 200 % and 230 %, respectively as shear loading rate increases. Interestingly, for the hydrate on a stiff hydrophobic coated glass slide (CG) substrate, the AS anomalously decreases with increasing shear loading rates. These findings provide valuable insights into the effects of substrate properties and shear loading rate on hydrate adhesion. The results are of significance for the design of optimal coatings that ensure flow assurance of oil and gas in pressure-variant petro-pipelines.
Display omitted
We designed and constructed a series of micro-cubic arrays on silicon surface by means of a selective plasma etching technology to explore the size effect of surface microstructure on ...anti-icing/icephobic performance in terms of ice adhesion strength and icing delay time in this work. It was confirmed that the micro-cubic array with the center-center spacing distance of 70μm could greatly delay the icing process to 1295s (∼two orders of magnitude comparing with that on the substrate surface). This type of micro-structures could entrap more air pockets underneath the water droplets to form the stable Cassie-Baxter wetting state, leading to lower actual solid/liquid contact areal fraction ∼8.15% and larger heat transfer barrier. Meanwhile, the special interface configuration is beneficial to the reduction in ice adhesion strength. As the temperature decreases, the wetting state with varied has shifted. The ice adhesion strength of the surface was as low as 16kPa with the center-center spacing distance of 30μm for the micro-cubic arrays. In this case, the entrapped air pockets act as the micro-cracks under the shear force, which leads to lower fracture critical stress. The understanding of the size effect of microstructures on the icing delay ability and ice adhesion strength will be beneficial to the design of ideal anti-icing/icephobic materials.
This study investigates the effects of varying bias voltages on the crystallographic orientation and properties of DCMS + HiPIMS-deposited chromium coatings. Under bias voltages varying from 100 to ...500 V, dense Cr coatings were obtained, and the deposition rate decreased by 13 %. The bias voltage significantly impacts the hardness, crystallographic orientation, electrical conductivity, and bonding strength of the coating. As the bias voltage increases, the hardness of the Cr coating gradually increases. The crystallographic orientation of the coating is governed collectively by surface energy, strain energy, and sputtering effects. The preferential crystallographic orientation of the Cr coating transitions from (222) to (110), subsequently changing to a mixed preferential crystallographic orientation of (110), (211), and (222). Under the combined influence of thermal effects and ion bombardment, a (110) preferential crystallographic orientation was obtained at a bias voltage of 300 V, featuring moderate hardness and optimal wear resistance. This study establishes that the electrical characteristics of the coatings have a significant correlation with bias voltage levels.
Display omitted
•By manipulating ion energy, DC/HiPIMS-Cr coatings with varied preferential orientations were achieved.•The mechanism of preferential orientation evolution of Cr coating under bias voltage.•The interrelationships between characteristics and preferential orientations.
The demand for high-performance interconnects in electronic devices has prompted extensive research on self-forming copper (Cu) interconnect metallization. However, the investigation of the ...self-forming process and the corresponding electromigration behaviors for cobalt (Co), a novel interconnect wiring material for next generation semiconductor device, is currently in its early stages. This study reports the fabrication of Co interconnect lines using an all-wet self-assembled nanoseeding and electroless deposition process, and investigates the electromigration reliability enhancement of the Co interconnects through 0.06 at.% of added tungsten (W). Electromigration-induced failure times and current density scaling factors were measured to evaluate the impact of the super-diluted W on electromigration reliability of the Co lines. Furthermore, an evaluation of adhesion properties was conducted, revealing the significant contribution of the added W to the marked improvement in electromigration performance. The incorporation of diluted W (only 0.06 at.%) into Co interconnects could potentially avoid causing a significant increase in residual electrical resistivity. Providing valuable insights into the practical application of Co as a new interconnect material.
Display omitted
•The super-diluted W into Co interconnects could maintain a low residual electrical resistivity.•All-wet surface modification/electroless-superfill process is used to fabricate Co(W) interconnect.•The Co(W) interconnect doubles lifetime in comparison to pure Co.•Co(W) yields much lower n values, signifying its elongated electromigration lifetime.•The enhanced adhesion strength by the added W contributes to the remarkable electromigration reliability.
In the present research, a composite layer of TiO₂-TiC-NbO-NbC was coated on the Ti-64 alloy using two different methods (i.e., the electric discharge coating (EDC) and electric discharge machining ...processes) while the Nb powder were mixed in dielectric fluid. The effect produced on the machined surfaces by both processes was reported. The influence of Nb-concentration along with the EDC key parameters (Ip and Ton) on the coated surface integrity such as surface topography, micro-cracks, coating layer thickness, coating deposition, micro-hardness has been evaluated as well. It has been noticed that in the EDC process the high peak current and high Nb-powder concentration allow improvement in the material migration, and a crack-free thick layer (215 μm) on the workpiece surface is deposited. The presence of various oxides and carbides on the coated surface further enhanced the mechanical properties, especially, the wear resistance, corrosion resistance and bioactivity. The surface hardness of the coated layer is increased from 365 HV to 1465 HV. Furthermore, the coated layer reveals a higher adhesion strength (~118 N), which permits to enhance the wear resistance of the Ti-64 alloy. This proposed technology allows modification of the mechanical properties and surface characteristics according to an orthopedic implant's requirements.
Display omitted
•Phase transformable slippery liquid infused porous surfaces (PTSLIPS) were introduced.•PTSLIPS showed low ice adhesion strength (4.45∼22.43 kPa) as well as excellent ...durability.•PTSLIPS indiscriminately adapt to porous substrates with various chemical compositions.•PTSLIPS also possessed self-repairing property that could repair the bulk damage.
Generally, the longevity and durability of slippery liquid infused porous surfaces (SLIPS) applied for anti-icing purpose are of great challenge. In this work, phase transformable slippery liquid infused porous surfaces (PTSLIPS) are fabricated to overcome this tough barrier. The underlying mechanism relies on the physical property of lubricant that enables the transformation to solid state before water freezing. Peanut oil infused porous PDMS substrates show low ice adhesion strength (4∼22 kPa) as well as excellent durability. For selected samples, low ice adhesion strength around ∼16 kPa maintains after 30 icing/de-icing cycles due to the phase transition property of the lubricant. In addition to the promising ice adhesion strength and durability, PTSLIPS also suit to various substrates with numerous chemical compositions (both hydrophobic and hydrophilic materials), wide pore size distributions and diverse pore morphologies. PTSLIPS with a variety of ice adhesion strength are demonstrated with substrates (wipers, foams and paper) that can be found easily from household garbage and lab supplies. Therefore, we show the possibility of creating anti-icing surfaces by Do-It-Yourself (DIY) with porous materials in hand. The PTSLIPS also possess self-repairing property with excellent physical damage resistance, and scratches on PTSLIPS have minor effects on their ice adhesion strength.
Interfacial mechanical properties of tetrahydrofuran (THF) hydrate and ice on solid substrates were investigated by force analysis based shearing measurements and molecular dynamics (MD) simulations. ...The adhesion strength of ice/THF hydrate on solid substrates decreases with increasing temperature and with decreasing work of adhesion. MD simulations uncovered that the ice adhesion strength on solid substrates was dominated by the quasi-liquid layers (QLLs), however, that of THF hydrate was governed not only by QLLs but also by newly formed unconventional clathrate cages.
Display omitted
Understanding the interfacial mechanical properties between hydrate and solids is vital to designing and fabricating surfaces for hydrate management. Herein, the role of the surface wettability, the type of solid substrate and temperature on the interfacial adhesion properties of tetrahydrofuran (THF) hydrate and ice were examined by force analysis based shearing measurements and molecular dynamics (MD) simulations. The results showed that the adhesion strength of THF hydrate and ice on silica varies with the compositions of coating, and the adhesion strength of ice is larger than that of THF hydrate for all investigated solid substrates. Particularly, in contrast to a linear relationship between 1 + cosθr and hydrate adhesion on organic silanes/thiols/polymer surfaces, the hydrate adhesion on the coated inorganic glass surfaces is enhanced as a function of 1 + cosθr, in which θr is the receding contact angle. MD simulations uncovered that the adhesion strength of ice on solid substrates is dominated by the quasi-liquid water layer, however, that of hydrate is governed not only by the quasi-liquid layer but also newly formed unconventional clathrate cages. This study provides new insights and perspectives into the hydrate adhesion on solid surfaces, which is of help to develop hydrate-phobic coatings for advanced hydrate management.
Display omitted
For waterborne coating, there is still inevitable defects (insufficient anti-corrosion performance). In this paper, the functional graphene oxide (TDPG) is prepared via self-prepared ...polymer (triethylene tetramine-polyethylene glycol diglycidyl ether). The TDPG is used to modify waterborne polyurethane (WPU) coating for improving anti-corrosion property. The electrochemical impedance spectroscopy and salt spray test are used to evaluate the corrosion resistance ability of composite coating. The WPU/ TDPG0.05 owns optimal corrosion resistance property. After 30 days immersion in 3.5 wt.% NaCl solution, the impedance modulus Zf = 10mHz of WPU decreases to 6.17 × 106 Ω·cm2 from 1.36 × 107 Ω·cm2, but the Zf = 10mHz of WPU/TDPG0.05 decreases to 9.48 × 106 Ω·cm2 from 2.39 × 107 Ω·cm2. By Tafel test, the corrosion potential of WPU/TDPG0.05 is -0.056 v, which is more positive than that of WPU (-0.224 v). The corrosion current and polarization resistance of WPU/TDPG0.05 are 1.30 × 10−8 A/cm2 and 3.4 × 106 Ω·cm2, respectively. Moreover, the adhesion strength of WPU/TDPG0.05 decreases to 5.89 MPa from 6.69 MPa, only losing 16.96 %.
PDF
