•Thermal fatigue damage depends on power density and pulse numbers.•Shear bands were observed in damaged areas.•The extruded flake structures on shear bands were formed.•Shear bands are generally parallel to the traces of {112} slip planes with the surface.Thermal fatigue resistance of plasma facing materials (PFMs) is an inevitable concern for component lifetime and plasma operations, since the temperature fluctuations will always exist in future nuclear fusion facilities and reactors. Accordingly, experiments were performed in the electron beam facility to investigate the thermal fatigue behavior under operational loading conditions. The tungsten is investigated in its stress relieved and fully recrystallized state for a better understanding of the thermal fatigue process when exposed to cyclic heat loads. The heat loads range from 24 to 48 MW/m2 and the number of cycles increases from 100 to 1000 times. The results indicate that the thermal fatigue damage (surface roughening) due to plastic deformation strongly depends on the loading conditions and the cycle index. As the power density and the number of cycles increase, the density of the intragranular shear bands in each grain becomes higher and the swelling of grain boundaries becomes more pronounced. The shear bands are generally parallel to different directions for varying grains, showing strong grain orientation dependence. Additionally, extruded flake structures on shear bands were observed in these damaged areas. It found that the shear bands are generally parallel to the traces of {112} slip planes with the surface. The results suggest that slip plastic deformation represent the predominant mechanism for thermal fatigue and a set of schematic diagram is presented to explain the formation of thermal fatigue damage morphology (extrusion and intrusion structures).

Large-scale uniform nanostructured surface with superwettability is crucial in both fundamental research and engineering applications. A facile and controllable approach was employed to fabricate a superwetting tilted silicon nanowires (TSNWs) surface through metal-assisted chemical etching and modification with low-surface-energy material. The contact angle (CA) measurements of the nanostructured surface show a large range from the superhydrophilicity (the CA approximate to 0°) to superhydrophobicity (the CA up to 160°). The surface becomes antiadhesion to water upon nanostructuring with a measured sliding angle (α) close to 0°. Moreover, the fluorinated TSNWs surface exhibits excellent stability and durability because strong chemical bonding has been formed on the surface.

•Superhydrophobic copper films were grown on Si substrates using DC sputtering.•The substrate temperature plays a key role in the development of the surface morphology.•The behavior of water in contact with the film at different static pressures was studied.•A model is proposed to explain the change of the surface wettability.Superhydrophobic copper films with hierarchically sandbeach-like morphologies were grown on Si substrates using direct current (DC) sputtering. After the surfaces were hydrophobized with 1-Octadecanethiol (ODT), the surfaces became superhydrophobic. The substrate temperature during sputtering played a key role in the formation of the surface morphology. The films exhibited long-term stability in the temperature range of 25 to 100 °C. The underwater stability of the surfaces was also characterized by studying the water contact behavior on the immersed surfaces under different static pressures. After immersion in different depth in water, the film surfaces changed from superhydrophobic even to superhydrophilic, due to the water trapped in the surface structures. A model was proposed to explain such change in the surface wettability.

A super-hydrophilic surface was prepared on the molybdenum substrate via a hydrothermal method. The scanning electron microscope (SEM) images show that many crystal grains with the size of about a hundred nanometers grown on the surface, which look like the seeds on the strawberry surface. The analysis by energy dispersive spectrometer (EDS) and X-ray diffraction (XRD) proves that the seeds are MoO2 crystals. The results of wetting test reveal that the water contact angle is nearly 0° and the super-hydrophilicity can stably keep for more than 105 days. The mechanism of the super-hydrophilicity was discussed according to the Wenzel theory.Graphical abstractHighlights► A super-hydrophilic surface was prepared on Mo substrate via a hydrothermal method. ► MoO2 grains with the size of about a hundred nanometers grown on the surface. ► MoO2 crystal grains look like the seeds on the strawberry surface. ► The stability of the contact angle of the post-reacted surface was studied. ► The super-hydrophilicity can steadily keep for more than 105 days.

Stable and easily controllable wettability of a solid surface is of great significance in many applications. In the present studies, a-C films with special nano-structured surfaces were deposited on silicon and glass substrates with magnetron sputtering method. The morphologies of the surfaces vary with the deposition parameters. Therefore, these a-C surfaces can be controlled to exhibit different wettability in a wide range from the hydrophilicity to the super-hydrophobicity. The studies also prove that the CF4 plasma treatment will remarkably enhance the hydrophobicity of the a-C films. And the fluorinated a-C surfaces show an excellent super-hydrophobic property for all the pH values of the aqueous solution. Moreover, a super-hydrophobic surface of the non-fluorinated a-C film can be reversed to being very hydrophilic by the plasma treatment of H2 or N2, while the fluorinated super-hydrophobic a-C films show a good stability.

A two-step method to synthesize metal–semiconductor heterostructure photocatalyst is presented in this research. Based on the tetrapod-like zinc oxide (T-ZnO) deposited by thermal evaporation, Ag/T-ZnO heterostructure is synthesized by RF magnetron sputtering method in this two-step preparation technique. The structure and the photocatalytic properties of the Ag/T-ZnO were studied in detail. The Ag/T-ZnO heterostructure exhibits better photocatalytic activity than that of the pure T-ZnO and there is an optimum sputtering time and sputtering power for the heterostructure's photocatalytic activity. The essential photocatalytic mechanism of this heterostructure have been discussed and the enhanced photocatalytic activity indicates the feasibility of this novel two-step method which may be developed to a promising synthesis technique.

Using RF magnetron sputtering, we have successfully grown (1 1 0) orientated La0.7Sr0.3MnO3 (LSMO) films on Si(0 0 1) wafers using SrMnO3 (SMO) as a template layer. The X-ray diffraction (XRD) patterns of the SMO/Si heterostructures indicate that SMO grows along the (1 1 0) orientation, the orientation relationship between the SMO thin film and the Si (0 0 1) substrate being given by (0 1 1)SMO∣∣(0 0 1)Si and [011¯]SMO∣∣[0 1 0]Si. From the XRD patterns of the LSMO/SMO/Si heterostructures, we find that with an increase of substrate temperature, the required thickness of SMO, which plays an effective role of tuning the preferential orientation of LSMO, will decrease at first and then increase. It is thought that this originates from the fact that the crystallization of SMO is not perfect at low temperatures whereas too high a temperature results in reaction and diffusion at the interface of the two layers.

In this work, crystalline AlN films were successfully synthesized on Si (100) by bias-enhanced catalytic chemical vapor deposition (Cat-CVD) at a low substrate temperature of 400 °C. The films were characterized by Fourier Transformation Infrared (FTIR) spectroscopy and X-ray diffraction (XRD). The results indicate that the bias plays an important role in enhancing the crystallinity of the AlN films. Furthermore, it was observed that the crystalline AlN films with small grains of 20 nm could be obtained under the negative bias of 400 V. The effects of the bias on the growth of the crystalline films and the grain size are discussed in detail.