Cr–N coatings were deposited using the ion-beam-assisted magnetron sputtering technique. The microstructure and mechanical properties of Cr–N coatings were found to be dependent on the ion ...bombardment energy. The microstructure of the coatings changes from columnar structure to fine and dense grains when the ion bombardment energy increases from 0 to 800
eV and to equiaxial grains for an ion energy of 1200
eV. The coatings average grain size, which is determined by the Voigt profile function, decreases from 20.3
nm at an ion energy of 0
eV to 8.8
nm at 800
eV and further increases to 21.5
nm at 1200
eV. Both the hardness and fracture toughness of the coatings are improved when the ion energy increases from 0 to 800
eV, which is related to the decrease of grain size. The grain size of the coating grown at an energy of 1200
eV is close to that of 0
eV, but the hardness and fracture toughness at 1200
eV are higher. This suggests that the improvement of hardness and fracture toughness is also related to the increased densification of the coatings caused by ion bombardment.
The Mo–N, Mo–C, Mo–Cr modified layers on Ti-6Al-4V alloy were prepared using a double glow discharge plasma alloying technology. Repeated impact tests were performed to evaluate the fatigue behavior ...of the plasma modified Ti-6Al-4V alloys. Results show that the three surface modified layers exhibited a different depth distribution in microhardness and different failure mode in repeated impact tests. Among the three modified layers the Mo–N has the best matching of impact fatigue strength with hardness.
In this work, a duplex treatment of laser surface texturing (LST)-thermal oxidation (TO) was conducted on Ti6Al4V alloy to improve its mechanical property and wear performance. Microstructure, ...bonding strength, microhardness and nanoindentation behavior of the TO-Ti6Al4V were characterized. A comparative appraisal of wear performance for related samples of original Ti6Al4V, LST-Ti6Al4V, TO-Ti6Al4V and duplex treated-Ti6Al4V (DT-Ti6Al4V) were performed under dry sliding condition. The results revealed that gradient titanium oxide coatings with a thickness of 17 μm were in situ fabricated on the surface of Ti6Al4V and textured Ti6Al4V. The content of O displayed a gradient distribution across the TO-coating. TO treatment has improved the surface hardness and elasticity modulus of the Ti6Al4V. The specific wear rate of the samples was sorted in the following sequence: DT-Ti6Al4V < TO-Ti6Al4V < LST-Ti6Al4V < Ti6Al4V, which indicates that DT-Ti6Al4V exhibited the most excellent wear performance. It was confirmed that Ti6Al4V could obtain promisingly enhanced wear performance by taking advantages of LST and TO treatment.
•Laser surface texturing (LST) was conducted on Ti6Al4V.•Thermal oxidation (TO) coating was prepared on Ti6Al4V and textured Ti6Al4V.•LST-TO duplex treatment improved the mechanical property and wear performance.
•A molybdenized layer was prepared as a buffer layer under TiN film on Ti6Al4V.•The molybdenized layer can enhance adhesion strength of PVD coatings effectively.•The duplex treated samples increase ...elastic energy ratio in the impact tests.•The enhancement attributes to the hardness improvement and inverted-S shape elastic modulus profile of the modified layer.
Effect of molybdenized buffer layer on adhesion strength of TiN film on Ti6Al4V alloy was investigated. The buffer layer composed of a dense molybdenum deposition layer, a rapid drop zone and a slow fall zone was prepared using double glow plasma surface alloying technique. Scratch tests and low energy repeated impact tests were adopted to comparatively evaluate the duplex treated layers and the single TiN samples. The results show that the critical load was increased from 62N for the single TiN film to over 100N for the duplex treated layer. The volume of impact pit, formed in impact tests, of the single TiN samples is 9.15×106μm3, and about 1.5 times than that of the duplex treated samples. The Leeb hardness values reveal that about 70% impact energy was transferred to the single TiN samples to generate permanent deformation, while that was only about 47% for the duplex treated samples. The mechanism of improving adhesion strength is attributed to synergistic effect due to an inverted-S shape elastic modulus distribution produced by the molybdenized layer.
Recently, ultraviolet (UV) photodetectors based on TiO
2
semiconductors have attracted intensive attention, due to their wide applications in environmental and biological research, optical ...communication, astronomical investigations and missile launch detection. However, there still remain material- and fabrication-related obstacles in realizing highly efficient UV photodetectors. Here, we reported the exploration of the efficient UV photodetectors based on the highly ordered TiO
2
nanotube arrays (TNAs). The TNAs were prepared by a two-step anodic oxidation with tailored tube lengths and wall thicknesses, and then transplanted to a transparent FTO substrate to construct a front-illuminated photodetector. The as-assembled photodetectors exhibit a satisfactory stability and wavelength selectivity with a high photocurrent, photo-to-dark current ratio and responsivity up to 1395 μA, 10 730 and 176.3 A W
−1
under the UV illumination of 350 nm (45 μW cm
−1
) at a given bias of 2 V with TiO
2
tube length of 14.7 μm, respectively, suggesting their promising applications in efficient UV photodetectors.
We report the front-illuminated ultraviolet photodetectors based on TiO
2
nanotube arrays with efficient photodetecting activities.
The Mo-N surface modified layer on Ti6Al4V alloy was obtained by the plasma surface alloying technique. The structure and composition of the Mo-N modified Ti6Al4V alloy were investigated by X-ray ...diffraction （XRD） and glow discharge optical emission spectroscopy （GDOES）. The Mo-N modified layer contains Mo-N coating on subsurface and diffusion layers between the subsurface and substrate. The X- ray diffraction analysis of the Mo-N modified Ti6Al4V alloy reveals that the outmost surface of the Mo-N modified Ti6Al4V alloy is composed of phase Mo2N （fcc） and Mo2N （tetr）. The electrochemical corrosion performance of the Mo-N modified Ti6Al4V alloy in 0.5 mol/L HCl solution was investigated and compared with that of Ti6Al4V alloy. The chemical corrosion performance of the Mo-N modified Ti6Al4V alloy in boiling 37% HCl solution was investigated and compared with that of Ti6Al4V alloy. Results indicate that self-corroding electric potentials and corrosion-rate of the Mo-N modified Ti6Al4V alloy are higher than that of Ti6Al4V alloy in 0.5 mol/L HCl solution. The corrosion-rate of the Mo-N modified Ti6Al4V alloy is lower than that of Ti6Al4V alloy in boiling 37% HCl solution.
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•A W-Ta-V-Cr HEA coating has been successfully synthesized by DGPSA technology.•The alloy coating was a nanocrystalline structure composed of BCC phases.•The coating hardness reaches ...1130HV, which is 2 times that of the substrate.•The specific abrasion rate of the coating was 1/8.5 of the W substrate.
A W-Ta-V-Cr high entropy alloy (HEA) coating has been successfully synthesized on the tungsten-based surface by Double glow plasma surface alloying (DGPSA) technology. The effects of W-Ta-V-Cr on the microstructure and properties of the coating were systematically investigated. The results illustrated that a compact and homogeneous alloy coating with a thickness of 8.8 μm was formed on the surfaces of pure tungsten. The addition of four elements promoted the formation of BCC phase in the coating, refined the grain size and formed nanocrystalline materials. Thereby the microhardness and abrasion rate of the coating increased and decreased, respectively. The hardness value of the coating reaches 1130 HV, which is 2 times that of the substrate (∼551 HV) and the specific abrasion rate of the coating was only 1/8.5 of that of the W substrate, showing extremely excellent abrasion resistance performance. The coating effectively improves the mechanical of pure tungsten. Such high hardness and abrasion resistant can be attributed to the combined contribution from solid-solution hardening and grain refinement.
Fracture behavior of CrN coatings deposited on the surface of silicon and AISI52100 steel by different energy ion beam assisted magnetron sputtering technique （IBAMS） was studied using indentation ...and dynamic cycle impact. It is found that, for the coatings on silicon substrate, the cracks form in the indentation corners and then propagate outward under Vickers indentation. The coating prepared using ion assisted energy of 800 eV shows the highest fracture resistance due to its compact structure. Under Rockwell indentation, only finer radial cracks are found in the CrN coating on AISI 52100 steel without ion assisting while in the condition of ion assisting energy of 800 eV, radial, lateral cracks and spalling appear in the vicinity of indentation. The fracture of CrN coatings under dynamic cycle impact is similar to fatigue. The impact fracture resistance of CrN coatings increases with the increase of ion assisting energy.
The Mo surface modified layer on titanium was obtained by the plasma surface alloying technique. The structure and composition of the Mo modified titanium were investigated by X-ray diffraction （XRD） ...and glow discharge optical emission spectroscopy （GDOES）. The Mo modified layer contains Mo coating on subsurface and diffusion layers between the subsurface and substrate. The Xray diffraction analysis of the Mo modified titanium reveals that the outmost surface of the Mo modified titanium is composed of pure Mo. The electrochemical corrosion performance of the Mo modified titanium in saliva was investigated and compared with that of titanium. The chemical corrosion performance of the Mo modified titanium in 37 ℃ saliva was investigated and compared with that of titanium. The experimental results indicated that self-corroding electric potentials and corrosion-rate of the Mo modified titanium were higher than that of titanium in saliva. Corrosion-rate of the Mo modified titanium was lower than that of titanium in 37 ℃ saliva.
•Laser surface texturing (LST) was conducted on 304 SS.•Hexadecyltrimethoxysilane (HDTMS) was decorated on 304 SS and LST treated 304 SS.•The LST treated 304 SS showed super-hydrophobicity after ...decoration of HDTMS.•LST followed by decorating HDTMS improved the corrosion resistance of 304 SS.
Stainless steel (SS) has long been widely used in the outdoor environment as engineering material due to its excellent corrosion resistance. Recently it is found that super-hydrophobicity on the stainless steel surface also has significant effect on its corrosion resistance. In this work, laser surface texturing (LST) and decoration of hexadecyltrimethoxysilane (HDTMS) duplex treatment were carried out to improve the super-hydrophobicity and corrosion resistance of AISI 304 SS. Comparative appraisals of super-hydrophobicity and corrosion resistance for the related samples were conducted via wetting behavior with distilled water and electrochemical performance with simulated haze solution. The surface morphologies of ground 304 SS (G-304 SS), HDTMS + ground 304 SS (HG-304 SS), surface textured 304 SS (T-304 SS) and HDTMS + surface textured 304 SS (HT-304 SS) before and after electrochemical tests were obtained by scanning electron microscope (SEM). The results showed that micropores with different designed distances have distributed on the surfaces of 304 SS samples after LST treatment. When the micropore distance was 50 μm, this HT-304 SS exhibited a highest contact angle of 158.9°. Electrochemical experiments revealed that the HT-304 SS suggested better corrosion resistance in comparison to the G-304 SS, HG-304, and T-304 SS samples, which was mainly due to its outstanding super-hydrophobicity property.
