The influence of electrochemical iron deposition modes from the electrolyte-suspension flow on the adhesion strength, structure and microhardness of precipitation has been studied. The range of ...electrolysis regimes has been established, which make it possible to obtain deposits with an optimal microstructure and high adhesion strength of coating to the base. It is shown that the deposition of iron deposits (precipitation) in an electrolyte flow with simultaneous hydromechanical activation of the built-up surface makes it possible to increase the cathode current density and significantly increase the process productivity.
The present work investigates the effect of different process parameters on the production of low-density polyethylene (LDPE) coatings by flame spray technology. Previously, flame spraying of ...polymers has been successfully performed to obtain durable icephobic coatings, providing an interesting solution for applications facing icing problems, e.g. in marine, aviation, energy, and transportation industry. However, the fine tailoring of the process parameters represents a necessary strategy for optimising the coating production due to the unique thermal properties of each polymer. For this purpose, we vary the heat input of the process during flame spraying of the coating, by changing the transverse speed and the spraying distance. The results show that the variation in the process parameters strongly influenced the quality of the polymer coating, including its areal roughness, thickness, chemical composition, thermal stability, and degree of crystallinity. Furthermore, we demonstrate that these properties significantly affect the icephobic behaviour of the surface within the spray window of the chosen parameters. In conclusion, the relationship between the thermal degradation of the polymer and the icephobicity of the surface was defined. This highlights the importance of process parameter optimisation in order to achieve the desired icephobic performance of the LPDE coatings.
A thin layer of hydroxyapatite (HAp) coating has been developed on Ti
6
Al
4
V substrates using a dip-coating process. An intermediate layer of shellac (natural resin) was applied in between the ...substrate and the coating film to improve the adhesion strength without the need for any secondary annealing process. The adhesion strength was measured as 7.14 MPa. The surface of the developed coating was characterized using a scanning electron microscope. The total coating thickness was found to be 30 microns, and the surface roughness parameters were measured as 0.93 μm (
R
a
), 1.17 μm (
R
q
), and 6.67 μm (
R
z
). The dip-coated samples were also subjected to dissolution behavior study and in vitro study. The measured parameters of the coating suggest the use of this method as an alternative to other expensive and temperature-dependent coating methods for producing HAp coating with better adhesion strength.
In this work, sulfonated polyetheretherketone (S-PEEK)-based coatings, nanocrystalline ZnS and hydroxyapatite (n-HA) particles were developed on Zr-2.5Nb zirconium alloy substrates by electrophoretic ...deposition (EPD) combined with subsequent heat treatment. The properties of suspensions and deposition kinetics were studied. Cationic chitosan polyelectrolyte ensured the stabilization of the suspension and allowed for the co-deposition of all coating components on the cathode. The heating of the coated samples at a temperature of 450 °C and slow cooling resulted in sulfonation of the PEEK and the formation of dense coatings. The coatings were characterized by high roughness, hardness, modulus of elasticity and adhesion strength. The coatings revealed mild hydrophilicity, improved the electrochemical corrosion resistance of the alloy and induced the formation of hydroxyapatite with a cauliflower-like morphology on its surface during the Kokubo test. This work explored the great development potential of advanced sulfonated PEEK-based coatings, incorporating antibacterial and bioactive components by EPD combined with heat treatment to stimulate the surface properties of zirconium alloy for prospective dental and orthopedic applications. The antibacterial and osteoconductive properties of the obtained coatings should be further investigated.
Current attention has focused on the preparation of thick ceramic coating of nanostructured materials as feedstock material using the thermal spray process. The cold spray method has appeared as a ...promising process to form ceramic nanostructured coating without significantly changing the microstructure of the initial feedstock materials due to its low processing temperature. However, deposition of ceramic powders by cold spray is not easy due to the brittle characteristics of the material. In this study, TiO2 coatings were deposited on unannealed stainless steel substrates and substrates that were annealed from room temperature to 700 °C prior to spraying. The adhesion strength was evaluated to investigate the bonding mechanism. The influence of the remaining surface oxide layer of chromium oxide, Cr2O3, which is thermodynamically preferred for stainless steel, on the bonding mechanism involved was investigated. The results showed that by increasing the annealing substrate temperature of stainless steel, the adhesion strength of the coatings (thicker oxide) is also increased. As a result, the bonding between the cold-sprayed TiO2 particle and the steel substrate is given by the chemical bonding of an inter-oxide reaction.
We investigate the cold-spray additive manufacturing process of nanometric copper particles impacting a copper substrate using molecular dynamics (MD) and focus on the interplay between particle size ...(2–32 nm), particle velocity (100–2800 m/s), ensuing particle penetration depth and the impact bonding energy (IBE) binding the impinging particle with the substrate. It is observed, based on trends in the IBE, that even at low particle velocities (∼100 m/s) smaller sized particles (<8 nm) bind to the substrate, while there is a size-dependent critical velocity (≥200 m/s) for binding of larger particles (≥8 nm). At velocities near and above 500 m/s, material jetting and significant increase in particle penetration into the substrate are observed for larger particles. Rapid temperature increase, accompanied by adiabatic shear banding and instability (ASI), is observed, especially at the particle-substrate interface, resulting in particle-cratering at higher velocities in the range studied. Further, while jetting and ASI are observed together at high impact velocities, simulations show that ASI is not essential for jetting, consistent with recent investigations. In addition, both ASI and jetting are not prerequisites for particle binding to the substrate. A significant observation involves self-similar variations in particle penetration depth and IBE with particle kinetic energy across all particle sizes, which is captured by a quantitative constitutive relationship governing the particle's kinetic energy, penetration depth, and IBE.
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We have developed a thermo-compression soldering appliance for joining rare-earth barium copper oxide (REBCO) tapes with excellent control of process temperature and pressure. With this tool, we have ...systematically investigated the effects of soldering parameters and solder materials on the electrical and mechanical performances of soldered joints between REBCO superconducting tapes with laminated copper stabilizers. Low resistivity of about 30 nΩ·cm 2 at 77 K in self-field and high adhesion strength of about 5 N have been reproducibly achieved for lap joints with optimized process using InSn48 solder. The critical axial tensile stress of the joints was above 300 N, whereas the critical diameter for double bending of the joints was smaller than 20 mm. Lowering the temperature from 77 to 20 K reduced the joint resistance by 22%. However, applied magnetic fields up to 5 T showed little effect on the joint resistance. Increasing the overlapping joint length by N times dropped the joint resistance by a factor of about N -1 . A 3-m-long lap joint of 5-mm-wide REBCO tapes showed a resistance as low as 0.3 nΩ at 77 K and self-field, which is the lowest resistance for soldered joint so far as we know.
•The SiC films consist amorphous SiC, slight β-SiC and graphite phase.•The proportion of three components affects the value of the optical band gap.•AlN buffer layer improves the microstructure and ...adhesion strengthen of SiC films.•The films transmittance decreases during the increasing of power.•A denser and more homogeneous film tends to be formed at higher power.
SiC is widely used in various mechanical applications as a protective film because of its strength, thermal stability and good mechanical hardness. Here, amorphous SiC thin films with AlN as a buffer layer were deposited on glass and Si substrates through RF magnetron sputtering at different RF powers. The influence of the AlN buffer layer thickness on the morphological and the mechanical properties of the composite films was investigated. Results demonstrate that the AlN buffer layer can effectively improve the adhesion strength of SiC thin films, which has increased gradually from 26.78 N to 37.66 N. The transmittance of SiC thin films was measured using a UV–Vis–NIR spectrophotometer over a spectral range of 300–1200 nm. The average transmittance of SiC films decreases with increasing RF power, and their optical band gap values have varied from 3.31 eV to 3.50 eV.
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