Selective laser melting (SLM) is an important method in additive manufacturing. SLM has obvious advantages for the fabrication of metal parts with complex structure that cannot be processed directly and are manufactured in relatively low amounts. However, the surfaces of the SLM-formed parts contain more adhesive particles and pores than those manufactured by traditional methods, leading to the poor corrosion resistance of the parts and preventing the widespread use of SLM. To solve these problems, jet electrochemical machining and jet electrodeposition combined processing techniques were investigated for the treatment of the substrate surface in this work. Jet electrochemical machining was used to remove the surface defects of the SLM-formed parts, and the results were compared with the traditional sandblasting and sandpaper grinding surface treatment methods. Then, the nickel coating was deposited on the surface of the SLM-formed parts using jet electrodeposition to protect the surface and extend the service life of the parts. The mechanisms of the different processing techniques were analyzed, and properties such as the substrate morphology, coating morphology, corrosion resistance of the coating, and adhesion of the coating were compared. The results show that holes, adhesive particles and other defects are still present on the substrate surface after sandpaper grinding and sandblasting and affect the quality of the nickel coating. After electrochemical machining, the SLM surface defects were almost completely removed, forming a uniform microporous structure that interlocked with the nickel coating. The coating was smooth and dense and showed the best corrosion resistance and binding force. In 3.5 wt% NaCl solution, the corrosion potential reached −0.196 V, and the maximum binding force reached 35 N.

No abstract

Graphene oxide (GO) is recognized as a promising antibacterial material that is expected to be used to prepare a new generation of high-efficiency antibacterial coatings. The propensity of GO to agglomeration makes it difficult to apply it effectively. A new method of preparing GO-loaded nickel (GNC) with excellent antibacterial property is proposed in this paper. In this work, GNC was prepared on a titanium sheet by magnetic field-assisted scanning jet electrodeposition. The massive introduction of GO on the coating was proven by energy disperse spectroscopy and Raman spectroscopy. The antibacterial performance of GNC was proven by agar plate assessment and cell living/dead staining. The detection of intracellular reactive oxygen species (ROS) and the concentration of nickel ions, indicate that the antibacterial property of GNC are not entirely derived from the nickel ions released by the coating and the intracellular ROS induced by nickel ions, but rather are due to the synergistic effect of nickel ions and GO.

No abstract

The oxygen-plasma-treated reduced graphene oxide films (RGOFs) are firstly used as the sensing membranes in extended-gate field-effect transistors (EGFETs) for the pH sensors. A large amount of oxygen-containing functional groups are effectively decorated on the RGOFs, resulting in increasing the sensing sites. Furthermore, the reverse pyramid (RP) structure is used as the substrate to increase surface roughness with fixed sensing window. The pH-EGFET current sensitivity of the plasma-treated RGOF on the RP structure can achieve as high as 1.09 uA 1/2 /pH with excellent linearity of 0.999, and a wide sensing range from pH 1 to 13.