acid cleaning
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2022 ◽  
Vol 17 (1) ◽  
Author(s):  
Wei He ◽  
Jian Li ◽  
Zeliang Liao ◽  
Feng Lin ◽  
Junye Wu ◽  
...  

AbstractIn this work, a vertical gallium nitride (GaN)-based trench MOSFET on 4-inch free-standing GaN substrate is presented with threshold voltage of 3.15 V, specific on-resistance of 1.93 mΩ·cm2, breakdown voltage of 1306 V, and figure of merit of 0.88 GW/cm2. High-quality and stable MOS interface is obtained through two-step process, including simple acid cleaning and a following (NH4)2S passivation. Based on the calibration with experiment, the simulation results of physical model are consistent well with the experiment data in transfer, output, and breakdown characteristic curves, which demonstrate the validity of the simulation data obtained by Silvaco technology computer aided design (Silvaco TCAD). The mechanisms of on-state and breakdown are thoroughly studied using Silvaco TCAD physical model. The device parameters, including n−-GaN drift layer, p-GaN channel layer and gate dielectric layer, are systematically designed for optimization. This comprehensive analysis and optimization on the vertical GaN-based trench MOSFETs provide significant guide for vertical GaN-based high power applications.


2021 ◽  
Vol 0 (0) ◽  
Author(s):  
Mohamed A. Deyab ◽  
Mohsen Mohammed Al-Qhatani

Abstract The purpose of this study was to see if Cymbopogon schoenanthus aerial extract (CSA extract) could reduce the corrosion of aluminum brass in acid cleaning solutions in the distillation plant. For this assessment, measurements of weight loss and polarization technique have all been used. We discovered that at 250 ppm, the efficiency of CSA extract was excellent (97%). Polarization assessments confirmed that the organic compounds in CSA extract were effective mixed-type corrosion inhibitors. HPLC and FTIR analysis were used to explore the key chemical components of CSA extract. CSA extract caused the corrosion process to have a higher energy barrier. Observations of SEM and FT-IR spectra confirmed that CSA extract prevents corrosion attacks at the aluminum brass’s surface.


Materials ◽  
2021 ◽  
Vol 14 (4) ◽  
pp. 1048
Author(s):  
Belén Díaz ◽  
X. Ramón Nóvoa ◽  
Carmen Pérez ◽  
Sheila Silva-Fernández

This research emphasizes the importance of the acid cleaning prior to the phosphate development on high-strength steel rods. It compares the phosphate properties achieved after different acid-pickling conditions. The most common inorganic acids were considered in this study. Additionally, taking into account the environmental and safety concerns of these acids, the assessment of a less harmful organic acid is presented. This study revealed significant differences in the coating morphology and chemical composition whereas no great changes were found in terms of the coating weight or porosity. Thus, hydrochloric and sulfuric acid promote the growth of a Fe-enriched phosphate layer with a less conductive character that is not developed after the pickling with phosphoric acid. The phosphate developed after the citric acid pickling is comparable to that developed after the inorganic acids although with a porosity slightly higher. The temperature of the citric acid bath is an important parameter that affects to the phosphate appearance, composition, and porosity.


Metals ◽  
2021 ◽  
Vol 11 (2) ◽  
pp. 343
Author(s):  
Abdullah M. Al-Mayouf ◽  
Matar N. Al-Shalwi

A simple galvanic sensor was developed to determine the onset of iron corrosion under conditions similar to those used for removing the iron oxide (magnetite) layer from steam boilers with a hy-drochloric acid solution. Since the potentials of magnetite and iron are different, the initiation of the dissolution of the magnetite layer without corroding the base metal can be determined by moni-toring the potential of a sensor made of magnetite layers of different thicknesses that can be placed directly on the iron surface. Moreover, the time at which the addition of corrosion inhibitors is required to protect the base metal can be specified using this sensor. It has been shown that the time required for the iron base metal to start was dependent on the magnetite layer thickness in the sensor. With this sensor, the onset of the steel corrosion during the cleaning can be detected in re-al-time which makes the oxide removal process less harmful to the base metal.


2021 ◽  
Vol 0 (0) ◽  
Author(s):  
Mohamed A. Deyab ◽  
Mohsen Mohammed Al-Qhatani

Abstract To strengthen the thermal desalination units and sustainability of their performance and reduce their corrosion during acid cleaning processes to remove the scale layers, economy and nontoxic strategies are needed. Here we clarify how Bladder wrack extract (BWE) can reduce the corrosion mitigations for thermal units (carbon steel part) during the acid cleaning (1.0 M HCl). We find that the performance of BWE extract reached an excellent value (94.2%) at 500 ppm. The rate of electrochemical reactions is very low in the presence of BWE extract, and is consistent with the mass loss method. The activity of BWE extract as a corrosion inhibitor is due to the presence of mixture of organic compounds inside the extract. These compounds were identified by HPLC, SEM and FT-IR analysis.


2021 ◽  
Vol 45 (6) ◽  
pp. 2967-2973
Author(s):  
Wenbin Qiu ◽  
Yongqiang Wei ◽  
Aijun Chen ◽  
Hao Deng ◽  
Lvjun Zhou ◽  
...  

The specific microstructural features and phase composition lead to different corrosion behaviors of SPS and additive manufactured Ti-6Al-4V alloys.


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