Nanoporous anodic aluminum oxide (AAO) layers were successfully fabricated on aluminum foil through an anodizing process in oxalic acid and mixed electrolytes of sulfuric and oxalic acid. The effect of electrolyte resistivity on the morphology of nanoporous AAO, such as pore diameter and pore density, was investigated. The nanoporous AAO layers"bmorphology was examined using field emission scanning electron microscopy (FE-SEM) and analyzed using image analysis software. The results showed that anodizing in mixed electrolytes (sulfuric and oxalic acid) produced a much smaller pore diameter and a much higher pore density at lower voltage compared to anodizing in a single oxalic acid. For the anodizing process in oxalic acid, the pore diameters ranged from 14 to 52 nm, and the pore density ranged from 34106 pores in 500×500 nm 2. The anodizing process in the mixed electrolytes resulted in pore diameters within the range of 714 nm, and the pore densities were within the range of 211779 pores in 500×500 nm 2. Overall, increasing the electrolyte resistivity within the same solution leads to decreased pore diameter.

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Corrosion in API 5L steel under 1M HCl is a common issue; hence, creating a more effective and naturally-based inhibitor is critical. In this research, Syzygium Cumini leaf extract (SCLE) was used as a new green corrosion inhibitor under acidic conditions. The inhibition properties of the novel cumini extract were thoroughly characterized using potentiodynamic polarization (PDP), electrochemical impedance spectroscopy (EIS), Fourier-transform infrared spectroscopy (FTIR), and atomic force microscope (AFM). The results show that the cumini inhibitor has excellent corrosion inhibition with 93 % inhibition efficiency. The adsorption behavior of the inhibitor follows the Langmuir Adsorption Isotherm due to the nearness of R2 to unity. The potentiodynamic and electrochemical measurements demonstrate the mixed type of corrosion inhibitor. Thermodynamic calculation of ΔGads is – 18.41 kJ mol-1 showing the physical adsorption process between the inhibitor and metals. Further inspection of ΔHads at ‒58.93 kJ mol-1 considers releasing energy during adsorption. The FTIR results agree with the increased growth of passive layers due to the adsorption of polyphenol and flavonoids on metals. Remarkably, the adsorption peak at 3266.59 cm-1 corresponds to the adsorption of –OH. The peak at 1612.56 and 1698.4 cm-1 is attributed to C=C and C=O functional groups. The above functional groups serve as adsorption centers to reduce the corrosion effect. The surface treatment of AFM indicated a good relationship with the functional group characterization and confirmed the significant corrosion rate reduction. This work can be used as a benchmark to develop a natural plant as a corrosion inhibitor.

AMC (Aluminum Matrix Composite) as a main material for automotive and aircraft applications has the keyadvantage that islighter thanaluminumalloys. So, it can be ascertained that fuel comsumption forthoseapplicationswill be reduced. However, AMC materials are generally suceptible to galvanic corrosion due to galvanic reaction between aluminum matrix and reinforcement, and the formation of microstructure at matrix/reinforcement interface as well. Anodizing is the most effective surface modification method in order to protect AMCs surfaces. This process produces porous anodic coating which has the characteristics of high corrosion resistance and hardness layer. However, the presence of reinforcement particles in AMC hinders the initiation and growth of the protective oxide layer by forming cavities and micro crack. Therefore cerium sealing has been done to remedy the poor anodic film in order to further enhance the corrosion resistance in aggressive circumstances. The material studied in this research was AMC Al7xxx/SiC. Anodizing process were conducted in H2SO4solution at current densities 15, 20, and 25 mA/cm2at 0°C for 30 minutes. Subsequently, continuedwithelectro lesssealinginCeCl3.6H2O+H2O2solutionat room temperature atpH9 for 30 minutes. The morphologies of anodic coating and sealing layer were examined by means of FE-SEM, the corrosion resistance of composites was estimated in a 3.5 wt.% NaCl solution by potentiodynamic polarization test. Coating process conducted by anodizing and cerium sealing in various of anodizing current densities at 0°C results in protective layers which lead to the decreasing of corrosion rate and current density up to four orders magnifications than that of bare and anodizedAl7xxx/SiCcomposite.

Abstract Anodizing of aluminum is an environmental friendly process and can be done with a relatively low cost, but the resulting product has a good surface appearance and a protective oxide layer. The purpose of this research is to produce alumina oxide layer in accordance with the criteria and the protective layer can be applied to coloring in the process further and to determine the effect of changes in temperature and voltage to the aluminum oxide layer formation and pore formation for dyeing in a solution of phosphoric acid (H3PO4). Preparation of porous anodic alumina layer is done through anodizing process with a set of processes and variables such as type and composition of electrolyte, voltage and current density, temperature process in order to obtain honeycomb structures with pore sizes in the scale of micrometers or nanometers. As an innovation, the process followed by a staining using inorganic dyeing with multicolored technique. Expectations from this research were obtained decorative aluminum coating method that can be applied practically. The results showed that the increasing dip temperature and the applied voltage will reduce the thickness of the oxide layer formed and then the higher the temperature applied to the anodizing process will result in larger pore sizes are formed on the oxide layer and the resulting pore size affects the intensity of color that occurs Keywords :Anodizing, Aluminum Oxide, Pore Diameter, Thickness --------------------------------------------------------------------- Abstrak Proses anodisasi aluminium merupakan proses yang ramah lingkungan dan dapat dilakukan dengan biaya yang relatif murah, namun produk yang dihasilkan mempunyai penampilan permukaan cukup baik serta memiliki lapisan oksida yang protektif. Tujuan penelitian ini adalah untuk menghasilkan produk lapisan oksida alumina yang sesuai dengan kriteria lapisan protektif dan dapat diaplikasikan untuk pewarnaan dalam proses lebih lanjut serta untuk mengetahui pengaruh perubahan temperatur dan tegangan terhadap pembentukan lapisan aluminum oxide dan pembentukan pori untuk pewarnaan hasil proses anodisasi dalam larutan asam fosfat (H3PO4). Pembuatan lapisan anodic porous alumina dilakukan melalui proses anodisasi dengan mengatur proses dan variable seperti jenis dan komposisi elektrolit, tegangan dan rapat arus, temperatur proses agar didapat struktur honeycomb dengan ukuran pori yang berskala mikrometer atau nanometer. Sebagai inovasi, proses dilanjutkan dengan pewarnaan menggunakan inorganic dyeing dengan teknik multiwarna. Diharapkan dari penelitian ini diperoleh metode pelapisan aluminium dekoratif yang dapat diterapkan secara praktis. Hasil penelitian menunjukan bahwa semakin meningkatnya temperatur celup dan tegangan yang diberikan akan menurunkan ketebalan lapisan oksida yang terbentuk. Kemudian semakin tinggi temperatur yang diaplikasikan pada proses anodisasi akan mengakibatkan ukuran pori yang semakin besar yang terbentuk pada lapisan oksida dan ukuran pori yang dihasilkan mempengaruhi intensitas warna yang terjadi. Kata kunci : Anodisasi, Aluminium Oksida, Diameter Pori, Tebal Lapisan