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51.
研究了一种制备超细Ni/Cu包覆型复合粉的新工艺。以硫酸铜和硫酸镍为原料、酒石酸铵为络合剂、NaOH调节pH值、水合肼还原的化学共沉积法,制备了平均粒径为50nm的纳米级镍包铜(Ni/Cu)复合粉末。并从电化学、结晶学的角度阐述了制备粒度微细、包覆均匀的Ni/Cu复合粉末的基本原理。该方法利用液-液均相置换反应,采用温和的反应条件,直接制备纳米级复合粉末材料,具有方法简单、粉末粒度均匀、产品纯度高等优点。 相似文献
52.
Anomalous codeposition of Co and Ni onto a gold RDE was investigated in a solution containing simple sulfate salts with the addition of sodium citrate. It was shown that the dependence of the percentage of Co in the deposit on the percentage of Co in the bath follows the shape found in the literature, with the percentage of Co in the deposit being slightly higher than in electrolytes containing pure simple salts. Alloy layers of different composition, electrodeposited at constant charge Qdep = 1 C cm−2 (thickness 0.34 μm) were submitted to anodic dissolution at a sweep rate of 1 mV s−1 (ALSV technique) in a solution of 1 M NaCl, pH 2. All samples were found to dissolve through a single anodic peak, indicating that both constituents of the alloy dissolve simultaneously. Alloys with higher Ni content (above 40at.%) were found to dissolve at potentials more positive than the potential of pure Ni dissolution as a consequence of the Gibbs energy change of formation of electrodeposited solid solution type Co + Ni alloys. The composition of electrodeposited alloys was determined by the atomic absorption technique. An attempt was made to obtain a correlation between the peak potentials of anodic dissolution of alloy samples and the composition of alloys, to determine the composition of the alloy from the peak potential of its dissolution. It is found that such a correlation can be used only for strictly defined conditions of alloy deposition and dissolution, caused by the contribution of the Gibbs energy change of formation of electrodeposited alloys. Also, the presence of a CoNi3 ordered structure in the system is not detected as a separate ALSV peak, but its existence could be the cause of the shape of the Gibbs energy change with composition of the alloy for alloys electrodeposited at low current density. 相似文献
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