【摘要】 目的为了获得耐蚀性能更加优异的AZ91D镁合金。方法研究了铸态、半固态、成膜铸态及成膜半固态AZ91D,在模拟生理盐水(0.9%NaCl)和模拟海水(3.5%NaCl)中的腐蚀特征,并引入分形理论表征其腐蚀程度及均匀性。通过对不同状态AZ91D进行NaCl溶液腐蚀、电化学腐蚀,运用扫描形貌(SEM)和能谱(EDS)分析各状态AZ91D的腐蚀形貌,引入分形理论对各状态AZ91D的腐蚀形貌进行计算及分析。结果在同一腐蚀时间,各状态AZ91D在模拟海水中出现更多的腐蚀区域,成膜铸态及半固态的腐蚀最早出现于膜层组织的裂纹处。在电化学实验中,随着电解液NaCl质量分数升高至3.5%,未成膜铸态及半固态的腐蚀电位分别从–1.4111V和–1.4323V下降为–1.5066V和–1.5089V,电流密度分别从6.270×10–10A/m2和9.847×10–10 A/m2上升为4.863×10–9 A/m2和8.396×10–9 A/m2;成膜铸态及半固态的腐蚀电位分别从–1.3884 V和–1.3430 V下降为–1.4856 V和–1.4331 V,电流密度分别从5.854×10–10 A/m2和8.592×10–10 A/m2下降为2.050×10–11 A/m2和1.189×10–11 A/m2。结论在分形计算中,随着腐蚀液浓度或腐蚀时间的上升,铸态及半固态AZ91D的腐蚀倾向和腐蚀速率提高;膜层的腐蚀倾向提高,腐蚀速率降低。同时,各状态AZ91D的分形维数DH随腐蚀程度的增加而增大,Δa值随腐蚀均匀性的降低而增大。更多还原

【Abstract】 The work aims to obtain AZ91 D magnesium alloys with better corrosion resistance. The corrosion characteristics of as-cast, semi-solid, film-forming as-cast and film-forming semi-solid AZ91 D in simulated normal saline(0.9%NaCl) and simulated seawater(3.5%NaCl) were studied, and the fractal theory was introduced to characterize the corrosion degree and uniformity. Through NaCl solution corrosion and electrochemical corrosion of AZ91 D in different states, the corrosion morphologies were analyzed by SEM and energy spectrum(EDS). Meanwhile, fractal theory was introduced to calculate and analyze the corrosion morphologies of AZ91 D in various states. At the same corrosion time, more corrosion zones appeared on AZ91 D in each state in the simulated seawater. The corrosion of film forming state and semi-solid state firstly appeared at the crack of film structure. In electrochemical experiments, as the concentration of electrolyte increased to 3.5%, the corrosion potential of unformed film casting and semi-solid state decreased from –1.4111 V and –1.4323 V to –1.5066 V and –1.5089 V, and the current density increased from 6.270×10–10 A/m2 and 9.847×10–10 A/m2 to 4.863×10–9 A/m2 and 8.396×10–9 A/m2. The corrosion potential in the as-cast and semi-solid state decreased from –1.3884 V and –1.3430 V to –1.4856 V and –1.4331 V, and the current density decreased from 5.854×10–10 A/m2 and 8.592×10–10 A/m2 to 2.050×10–11 A/m2 and 1.189×10–11 A/m2. In the fractal calculation, with the increase of the concentration of corrosion solution or the corrosion time, the corrosion tendency and corrosion rate of as-cast and semi-solid AZ91 D increase, and the corrosion tendency of the film increases, but the corrosion rate decreases. At the same time, the DH fractal dimension of different AZ91 D increases with the increase of the corrosion degree, and Δvalue increases as the corrosion uniformity decreases.更多还原