Zhenbo Qin

Improving Corrosion Resistance of a Nickel-Aluminum Bronze Alloy via Nickel Ion Implantation

An as-cast nickel-aluminum bronze alloy was subjected to nickel ion implantation, modifying its surface structure. A nickel-rich layer was formed on the surface of the alloy and its corrosion resistance in salt spray environment was improved gradually with the increasing implantation fluence. The corrosion resistance enhancement after ion implantation is believed to stem from the more compact Cu2O film with the incorporation of nickel ions. Under the protection of this more compact film, selective phase corrosion was inhibited effectively.

Microstructure and nanoindentation behavior of Cu composites reinforced with graphene nanoplatelets by electroless co-deposition technique.

A reduced graphene oxide/copper (RGO/Cu) composite was fabricated by a surfactant free, electroless co-deposition technique. The graphene oxide (GO) sheets were reduced and RGO homogeneous distributed into the copper matrix. On the basis of nanoindentation, the presence of RGO and the increase of its content in matrix significantly raised the hardness of RGO/Cu composites. Here, the relevant strengthening effect and mechanisms involved in RGO-reinforced Cu composites were systematically evaluated. Especially, the addition of RGO in Cu matrix led to the compressive micro-strain, and the resulted distortion of the lattice parameter was calculated based on Cohen’s method. However, excessive addition of GO in the electrolyte could decrease the mechanical performance due to agglomeration of RGO. Apparently, the optimal concentration for GO dispersion in co-deposition solution was deserved to discuss. After a serious of relative experiments, we could get a conclusion that this method provided a new pathway for embedded graphene into the metal matrix to improve the mechanical properties of RGO-reinforced materials.

Self-Assembly of Graphene-Encapsulated Cu Composites for Nonenzymatic Glucose Sensing

Cu has recently received great interest as a potential candidate for glucose sensing to overcome the problems with noble metals. In this work, reduced graphene oxide-encapsulated Cu nanoparticles (Cu@RGO) have been prepared via an electrostatic self-assembly method. This core/shell composites were found to be more stable than conventional Cu-decorated graphene composites and bare copper nanoparticles in an air atmosphere because the graphene shell can effectively protect the Cu nanoparticles from oxidation. In addition, the obtained Cu@RGO composites also showed an outstanding electrocatalytic activity toward glucose oxidation with a wide linear detection range of 1 μM to 2 mM, low detection limit of 0.34 μM (S/N = 3), and a sensitivity of 150 μA mM–1 cm–2. Moreover, Cu@RGO composites exhibited a satisfactory reproducibility, selectivity, and long effective performance. These excellent properties indicated that Cu@RGO nanoparticles have great potential application in glucose detection.

Synthetic Effects of Frequency and Duty Ratio on Growth Characteristics, Energy Consumption and Corrosion Properties of Microarc Oxidized Coating Formed on Ti6Al4V

The synthetic effects of frequency and duty ratio on growth characteristics and corrosion properties of coating on Ti6Al4V fabricated by microarc oxidation are investigated comprehensively. Under the condition of uniform cumulating time of positive impulse width, the essence of altering frequency and duty ratio to determine the formation of coating is to vary the duration and interval time of positive pulse. The growth of coating is mainly controlled by duration time of positive pulse and hardly correlated to the interval time of positive pulse, while both duration and interval time of positive pulse have few influences on the morphology and phase structures of coating. The dynamic current is related to positive impulse width and the ratio of positive pulse on-time to pulse off-time. Regardless of uniform duration or interval time of positive pulse, the energy dissipation presents a descending tendency. The relationship between energy consumption and anticorrosion performance is contradictory, and obtaining excellent corrosion resistance is bound to sacrifice lots of energy. The duty ratio and frequency can be designed purposefully to realize the optimal process.