In this study, ultrasonic bath and milling processes were used to synthesis epoxy resin-multiwalled carbon nanotubes (MWCNT) composite, and their effect on the absorption of magnetic waves was investigated using the Vector Network Analyzer (VNA) test. The effect of the concentration of MWCNT used to attract the wave's magnetic part in the epoxy resin matrix is also investigated. This study showed that the optimal amount of MWCNT in this epoxy resin-MWCNT composite was about 5 wt.% for the ultrasonic bath method, while it was around 15 wt% for the milling method. The ultrasonic bath caused the reflection losses (RL) value reaches to about -25 dB in the range of 9 to 11 GHz. The results of the VSM test showed that the composite produced from epoxy resin and MWCNT is a soft magnetic material. Also, the sample produced in the ultrasonic bath process has a higher magnetic saturation than the milling process, which causes it to absorb more electromagnetic waves. تفاصيل المقالة

The idea of smart inhibitors is based on the principle that an inhibitor is used where needed. This will reduce the use of inhibitors and protect materials in hostile environments. On the other hand, direct addition of the inhibitor within the coating can be harmful, resulting in the loss of inhibitors ability, deterioration in the coating or both of them. An appropriate method for solving these problems is the use of neutral host systems that act as a nanocontainer system or reservoir and are filled with arbitrary inhibitor. In this study, mesoporous silica with and without corrosion inhibitor (benzotriazole) were dispersed within an epoxy coating to protect the steel sheet. Then, the corrosion properties of these coatings with and without mesoporous silica particles were compared in a saline solution. Electrochemical studies showed that coatings containing particles could protect the surface of steel in the chloride environment. The impedance modulus (Z100 mHz) and corrosion resistance (Rcorr) regarding the coating embedded with mesoporous silica doped with inhibitor showed a value about one order of magnitude higher than that of a coating without inhibitor. This behavior could be due to the release of benzotriazole at the interface of the epoxy coating. In addition, the scratched coating with mesoporous silica doped with inhibitor exhibited less corrosion products compared to the coating without inhibitor which also confirmed the release of benzotriazole on demand of the corrosion process. تفاصيل المقالة

In this work, Zn-Co-Mo coatings were electrodeposited on mild steel substrate from a citrate solution at current densities of 5, 7.5 and 10 mA.cm-2 and pH values of 4.5, 5, and 5.5. The coated samples were studied by scanning electron microscope and potentiodynamic polarization. The corrosion behavior of the coatings was related to the molybdenum content and formation of local anodes and cathodes. According to the results, a distinct range of current and pH was recognized to provide high quality and corrosion resistant coatings. The percentage of molybdenum as an alloying element plays an important role in the improvement of the corrosion properties of the coating. The formed coating at pH of 5.5 with 13 wt. % Mo showed the lowest corrosion current density with a value of 0.5 µA.cm-2.The molybdenum coating also showed a passive-like behavior in the anodic region due to the presence of molybdenum in the coating composition. تفاصيل المقالة

The effect of hydrofluoric acid (HF) treatment on the corrosion performance of the Mg–Zn–Al–0.5Ca alloy was studied by immersing a specimen in HF solutions for varying lengths of time at room temperature. X-ray diffraction (XRD), scanning electron microscopy (SEM) and atomic force microscopy (AFM) were used to study the evolution of microstructures. In vitro corrosion resistance was assessed using potentiodynamic polarization and a room-temperature immersion test in Kokubo solution. The fluoride-treated Mg–Zn–Al–0.5Ca alloy formed by 24h immersion in HF exhibited a more homogeneous, compact, and thicker (2.1 μm) coating layer compared to the other HF treated specimens in 6, 12 and 18 hours. The corrosion resistance performance of the Mg–Zn–Al–0.5Ca alloy formed by 24h immersion in HF was the best, with a corrosion rate of 2.87 mm/y according to the electrochemical experiment. The mean weight loss of the untreated samples was more considerably higher (up to 2 times) than that of the fluoride-treated alloys, according to in vitro degradation assessments. According to the findings because of its low degradation kinetics and apatite formation ability, the fluoride-treated Mg–Zn–Al–0.5Ca alloy is a promising candidate for biodegradable implants. تفاصيل المقالة

در این تحقیق خواص مکانیکی نانوکامپوزیت پایه سیمانی تقویت شده با نانولوله های کربنی با روش میکرومکانیکال شبیه سازی شد. اثر پارامترهای مختلف مانند مدول سیمان، قطر داخلی نانولوله ها، قطر خارجی نانولوله ها، طول نانولوله ها، شکل المان انتخاب شده بر روی نتایج بدست آمده مورد بررسی قرار گرفت. در ادامه به منظور معتبر سازی این مدل، نتایج بدست آمده از مدل با نتایج تجربی محققان مختلف مقایسه شده است. نتایج نشان داد که با افزایش نسبت L/D، قطر خارجی نانولوله ها و طول نانو لوله ها، مدول بدست آمده برای نانوکامپوزیت افزایش می یابد. با این وجود قطر داخلی نانولوله ها چندان تاثیری بر روی مدول یانگ ندارد. مشاهده شد که نمودارهای مدول یانگ Ec بر حسب درصد حجمی نانولوله ها به صورت خطی می باشد. مقایسه نتایج تجربی با نتایج پیش بینی شده نشان داد که میزان E پیش بینی شده توسط مدل در بسیاری از موارد با نتایج تجربی بدست آمده توسط محققان مختلف نزدیک بوده و این نشان میدهد که مدل ارائه شده به خوبی می تواند خواص مکانیکی نانوکامپوزیت سیمان-نانولوله کربنی را پیش بینی نماید در حالی که مدل های رایج که برای پیش بینی خواص ماکروکامپوزیت های استفاده می شود از دقت کافی برای پیش بینی خواص نانوکامپوزیت پایه سیمانی برخوردار نیستند. تفاصيل المقالة