为分析镁合金表面膜的活性位置,建立起镁负极的点蚀破坏与电化学特性的关联性,本文采用循环伏安和电化学阻抗技术研究了AZ镁合金在MgSO_4溶液中的点蚀行为,从电解质浓度、电位扫描速度、阴极极化角度探讨腐蚀膜对镁合金点蚀的影响。电化学阻抗谱由两个连续容抗弧构成,其电荷转移电阻和膜电阻均随MgSO_4溶液浓度增大而减小,当MgSO_4溶液浓度为1.5 mol/L时,AZ31B合金表面膜阻抗最低,容易发生点蚀。扫描速率从3.3 m V/s下降至0.17 m V/s时,AZ63合金点蚀滞后环面积先增加后减小,击穿电位负移。控制阴极极化起始电位负移,则击穿电位降低,滞后环的面积增加,AZ镁合金的点蚀倾向变大;而在阴极过电位下停留可降低表面膜的腐蚀破坏程度,有利于抑制镁合金点腐蚀的发展。
There is a growing interest in designing more effective fuel cell cathode catalyst precursors.Here the partial pyrolysis of animal bloods has been used to produce the blood pyropolymers,which are an intermediate substance between a polymer and carbonaceous material.These pyropolymers were yielded by carbonization process below 600°C.The structural changes in the pyropolymers were characterized by X-ray diffraction,and their formation was checked by micro-IR spectra,thermogravimetric and differential thermal analysis.Their potential electrocatalytic properties were evaluated using the linear sweep voltammetry in the O2-saturated KOH solution.It is found that the process of pyropolymer formation began about 200°C and completed around500°C.The change of particle phase depends on the formation of the pyropolymers,but has no effect to their internal carbon structures which are controlled by pyrolysis process only.Meanwhile,it is confirmed that the crystalline phases in the pyropolymers can exist at the surface of heat-treated materials.It can be also found that the carbon materials are active toward oxygen reduction and their activity is associated with the carbonization level.Our study will stimulate the designers to design the highly active catalysts by using native blood pyropolymers as the precursors.
Research on magnesium battery has three primary fields as follows:changing the metallurgical factors of the magnesium electrode material to improve discharge performance,identifying inhibitors to form a protective film to reduce self-corrosion of magnesium alloys,and improving the electrochemical properties of the electrolyte to improve discharge continuity.During the research and development of the magnesium battery,the voltage delay that occurs in the discharge process is a critical issue because it limits the application of Mg/MnO2cells.This paper provides an overview of the relationship between the voltage delay of magnesium primary battery and magnesium anode corrosion.Furthermore,the factors affecting the voltage delay were analyzed,and the existing problems in the study of the voltage delay of magnesium battery were identified.
