Hongjin Liu

Cu, Ni and Al powders mixed in a certain stoichiometric proportion were ground via ball milling and deposited as coatings using low pressure cold spraying (LPCS) technology. The effect of particle morphology on the powder structure as well as the microstructure, composition and mechanical properties of the coatings was studied. The results revealed a core–shell structure of ball-milled powders. Compared with a mechanically mixed (MM) coating, coatings after ball milling at a rotation speed of 200 rpm exhibited the most uniform composition distribution and a lower degree of porosity (by 0.29%). Moreover, ball milling at 200 rpm was conducive to a significant increase in the deposition efficiency of the sprayed powder (by 10.89%), thereby improving the microhardness distribution uniformity. The ball milling treatment improved the adhesion of the coatings, and the adhesion of the composite coating increased to 40.29 MPa with the increase in ball milling speed. The dry sliding wear tests indicated that ball milling treatment of sprayed powder significantly improved the wear properties of the coatings. The coating after ball milling at a speed of 250 rpm showed the lowest friction coefficient and wear rate, with values of 0.41 and 2.47 × 10⁻¹² m³/m, respectively. The wear mechanism of coatings changed from abrasive wear to adhesive wear with the increase in ball milling speed.

The carboxyl-terminated 3-aminopropyltrimethoxysilane (APTMS) self-assembled monolayer (SAM) diffusion barrier was prepared onto a Si substrate via molecular self-assembly and graft modification technology. The SAM was afterward coated with a copper film via radio-frequency (RF) magnetron sputtering. In order to study the thermal stability of the diffusion barrier, the sample was subsequently annealed for 60 min in an Ar environment at the temperatures of 350 °C, 400 °C, 450 °C, 500 °C, and 550 °C. The results revealed that carboxyl modification enabled one to increase the barrier breakdown temperature of the APTMS diffusion barrier layer by about 100 °C, which was sufficient to effectively inhibit the copper diffusion at 500 °C.

α-Fe₂O₃ fusiform nanorods were prepared by a simple hydrothermal method employing the mixture of FeCl₃·6H₂O and urea as raw materials. The samples were examined by X-ray diffraction (XRD), high-resolution transmission electron microscopy (HRTEM), scanning electron microscopy (SEM), Fourier transform infrared (FTIR) spectroscopy and UV–vis diffuse reflectance spectra (UV–DRS). Its visible-light photocatalytic performances were evaluated by photocatalytic decolorization methylene blue (MB) in visible light irradiation. It was found that pure phase α-Fe₂O₃ nanorods with a length of about 125 nm and a diameter of 50 nm were successfully synthesized. The photocatalytic decolorization of MB results indicated that α-Fe₂O₃ nanorods showed higher photocatalytic activity than that of commercial Fe₂O₃ nanoparticles—these are attributed to its unique three-dimensional structure and lower electron-hole recombination rate.