Activation/Inhibition Effects during the Coelectrodeposition of PtAg Nanoparticles: Application for ORR in Alkaline Media

PtAg bimetallic nanoparticles for oxygen reduction reaction (ORR) in alkaline media were prepared by pulse electrodeposition (PED). During PED the reduction of Ag⁺ ions predominates, thus an increased Ag content in the co‐deposit is accomplished. The mechanism for this anomalous co‐deposition was elucidated by potential pulse experiments, which revealed that nuclei formation mainly occurs via the reduction of Pt²⁺ ions. The growth of the particles is diffusion controlled leading to the formation of a Ag shell covering a PtAg alloyed region. However, the shell is not growing homogeneously on the PtAg alloy. Hence, regions of the PtAg alloy are exposed, which exhibit an enhanced ORR activity compared to a pure Ag surface.     

铝板带冷轧过程中磨损影响因素 及磨损作用机制研究

轧后铝材表面磨损量是影响铝材轧制过程的重要因素,脱落的铝粉恶化产品表面质量、影响轧制效率。本文选用不同的添加剂配制轧制油,对铝板材进行冷轧试验,重点研究添加剂种类、铝材原始表面质量、轧制压下率三方面对铝材表面磨损性能及磨损机制的影响。结果表明：双组分添加剂轧制油中油性剂在金属表面吸附成膜,犁削磨损现象较无润滑和纯基础油轧制有明显改善,轧后铝材表面磨损量小;轧件轧前表面粗糙度大,轧辊对轧件微凸体的碾压作用加剧,被碾压下来的大量铝粉成为轧辊和轧件外的“第三体”,造成磨粒磨损加剧;化学磨损和犁削磨损同时存在于轧制过程中,油膜厚度较大时,前者是主要磨损机制;反之,后者起主导作用。