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In order to obtain films with better mechanical properties and fracture toughness, the (TiAlCrZrNb)- Six-N (x=0, 4%, 8%, 12% and 16%) high entropy ceramic nanocomposite films with different Si contents were deposited on Si substrate by magnetron sputtering technology. The effects of Si doping on the microstructure, mechanical properties! and fracture toughness of the films were investigated by X-ray diffractometry, scanning electron microscopy, high-resolution transmission electron microscopy and Nano indentation apparatus. The results show that the mechanical properties and fracture toughness of the films increase first and then decrease with the addition of Si element, which can be attributed to the formation of nanocomposite structures. When Si content is 4%, (TiAlCrZrNb)-Six-N film has the best comprehensive mechanical properties, and Us maximum hardness and elastic modulus are 22.7 GPa and 192.0 GPa, respectively. In this case, the fracture toughness reaches the best, and the radial crack length C as 6.760 µm, The K1C was 1.77 MPa • m1/2. [ABSTRACT FROM AUTHOR]

• 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. [ABSTRACT FROM AUTHOR]

In order to explore the influence of the thickness of Ni-P transition layer on the preparation of Ni-P-PTFE coating on stainless steel surface. Ni /N-P /Ni-P-PTFE three-layers structure gradient coating was prepared on stainless steel by electroplating combined with electroless plating. Scanning electron microscopy (SEM), X-ray diffraction (XRD), nano indentation, friction and wear tester, scratch tester and contact angle tester were used to characterize and test the microstructure, mechanical properties, adhesion and anti-adhesion property of the gradient coating. The results showed that, with the increased of N-P transition layer deposition time, the transition layer gradually thickened, the PTFE content in N-P-PTFE first decreased and then increased, the hardness and adhesion of N-PTFE coating first increased and then decreased. The maximum values of hardness and adhesion reach to 4.18 GPa and 13.49 N respectively when the N-P deposition time was 20 min. When the N-P deposition time was 25 min,the friction coefficient reached the minimum value of 0.17, and the contact angle between the surface of Ni-P-PTFE coating with water-based and oil-based liquid reached the maximum value of 101.1° and 60.06° respectively. At this time, the Ni-P-PTFE coating showed excellent adhesion resistance. [ABSTRACT FROM AUTHOR]

• The (AlCrTiZrV)N/SiC nanomultilayers films with various SiC thicknesses were prepared. • The SiC can be transformed into crystal structure under the effect of (AlCrTiZrV)N. • The SiC layer can grow coherent epitaxially with (AlCrTiZrV)N crystallites layer. • The strengthening of (AlCrTiZrV)N/SiC films can be explained by coherent-interface. High-entropy alloy nano-multilayers film have been increasingly used in protective coatings due to the excellent performance. Among the many factors that affect the performance of the nano-multilayers film, the thickness of the modulation layer has a significant effect on the performance of the high-entropy alloy nano-multilayers film. In this work, the microstructure and mechanical properties of (AlCrTiZrV)N/SiC nano-multilayers films with different thicknesses of the SiC layers prepared by using reactive magnetron sputtering are studied systematically. The results show that under the influence of the template layer, the amorphous SiC layer undergoes crystallization transformation and grows co-epitaxially with the template layer, resulting in the enhancement in the hardness. The maximum hardness and modulus of elasticity of (AlCrTiZrV)N/SiC nano-multilayers film reach 31.5 GPa and 290.6 GPa when the thickness of SiC is 0.5 nm, which are significantly improved compared to the single layer (AlCrTiZrV)N. As the thickness of the SiC layer further increases, the cubic steady-state structure of the SiC layer returns to the amorphous state and the coherent epitaxial growth of the multilayers film is destroyed, resulting in a decrease in the hardness of the nano-multilayers film. [ABSTRACT FROM AUTHOR]

The (TiTaCrMoNb)N x films with nitrogen content were prepared on the surfaces of TC4 by magnetron sputtering. The effects of nitrogen content on the microstructures and mechanical properties of (TiTaCrMoNb)N x films were investigated by x-ray diffractometer (XRD), scanning electron microscope (SEM), nanoindentation, high-resolution transmission electron microscope (HRTEM), electron probe microanalysis (EPMA), and laser confocal microscope. The results show that the deposition rates of the films decrease with the increase of the nitrogen flow. Besides, when N element is intoduced, the structures of the films change from the body-centered-cubic (BCC) to face-centered-cubic (FCC) phase composed of Me–N (metal nitride), which are preferentially oriented in the (111) crystal plane. Meanwhile, with increasing nitrogen flow, the hardness of the films shows a trend of first increasing and then decreasing. When the ratio of Ar and N 2 flows is 25:25, the hardness and elastic modulus reaches the maximum value of 26.1 GPa and 311.8 GPa, respectively. The increase of hardness is mainly attributed to the formation of saturated Me–N and the solid solution strengthening. Meanwhile, the film behaves the best tribological performance, which presents a lowest friction coefficient and excellent wear resistance. [ABSTRACT FROM AUTHOR]

High-entropy (AlCrTiZrNb)N/WS 2 nano-multilayers with different thicknesses of WS 2 layers were synthesized by reactive magnetron sputtering. The influence of MoS 2 layers on the microstructure of the nano-multilayered films was studied by X-ray diffraction (XRD), scanning electron microscope (SEM), and high-resolution transmission electron microscope (HRTEM). Mechanical properties were examined through nanoindentation, HSR-2M coating friction and wear tester. The results show that when the thickness of the WS 2 layer is less than 1.2 nm, the WS 2 layer can be transformed into a cubic phase under the action of the (AlCrTiZrNb)N layer template, and a coherent epitaxial interface layer is formed between the two layers, resulting in an increase in hardness. The maximum values of hardness and elastic modulus of the high-entropy (AlCrTiZrNb)N/WS 2 film are 22.5 GPa and 300.6 GPa, respectively, when the WS 2 layer thickness reaches 1.2 nm. As the thickness of the WS 2 layer further increases, the WS 2 layer cannot maintain the cubic structure and the epitaxial growth interface is destroyed, resulting in a decrease in the hardness. The friction coefficient of the (AlCrTiZrNb)N/WS 2 nano-multilayered film is lower than that of the (AlCrTiZrNb)N monolithic film. • The (AlCrTiZrNb)N/WS 2 nano-multilayered films with FCC structure are produced. • When the WS 2 layer thickness is less than 1.2 nm, a co-epitaxial structure forms. • The maximal hardness reaches 22.5 GPa with the WS 2 layer thickness of 1.2 nm. • The friction coefficients of (AlCrTiZrNb)N/WS 2 films are between 0.20 and 0.55. • The (AlCrTiZrNb)N/WS 2 nano-multilayered films present superior wear resistance. [ABSTRACT FROM AUTHOR]