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All Journal TEKNIK Journal of Engineering and Technological Sciences Science and Technology Indonesia INDONESIAN JOURNAL OF APPLIED PHYSICS Makara Journal of Science
Anawati, Anawati
Departemen Fisika, FMIPA, Universitas Indonesia, Jakarta
Astronomy Biochemistry, Genetics & Molecular Biology Chemical Engineering, Chemistry & Bioengineering Energy Engineering Environmental Science Materials Science & Nanotechnology Physics

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Creep and Electrochemical Corrosion Behavior of Heat-treated Mg-9Al-1Zn Alloy Ravi Naldi; Anawati - Anawati
Journal of Engineering and Technological Sciences Vol. 52 No. 5 (2020)
Publisher : Institute for Research and Community Services, Institut Teknologi Bandung

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.5614/j.eng.technol.sci.2020.52.5.1

Abstract

The high-strength Mg-9Al-1Zn alloy has been extensively investigated due to its potential application as a structural material in the automotive industry. The main challenges for its use are the low creep and corrosion resistance. In this work, heat treatment at 415 °C for 2 h was conducted on as-cast Mg-9Al-1Zn to improve its creep resistance. The corrosion behavior of the alloy was studied by the electrochemical method in an NaCl solution. The creep test results under 66.5 MPa load at 200 °C indicated one order of magnitude higher creep resistance of the heat-treated alloy relative to the as-cast one. The heat-treated specimen was ruptured after 6.5 h while the as-cast one was ruptured within 0.6 h. Creep occurred locally following the β phase in the alloy as evident from the cavities observed after the test. Reduction in the density of the discontinuous β precipitates resulting from heat treatment of the alloy lowered the susceptibility to creep. The smaller volume fraction of β precipitates suppressed the cathodic reaction during the polarization test and raised the electrochemical impedance spectra during the EIS test. The heat treatment improved not only the creep resistance but also the corrosion resistance of the Mg-9Al-1Zn alloy.
Kajian Literatur Karakteristik Lapisan Keramik Oksida yang Ditumbuhkan Diatas Paduan Zirkonium dengan Metode Plasma Electrolytic Oxidation Maman Kartaman Ajiriyanto; Anawati Anawati
INDONESIAN JOURNAL OF APPLIED PHYSICS Vol 12, No 1 (2022): April
Publisher : Department of Physics, Sebelas Maret University

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.13057/ijap.v12i1.49853

Abstract

Bahan Zircaloy-4 telah digunakan sebagai bahan kelongsong elemen bakar reaktor nuklir tipe pressurized water reactor, PWR. Kelongsong Zr-4 tersebut menghadapi kondisi temperatur dan tekanan tinggi, iradiasi neutron, dan penyerapan gas (hidrogen, oksigen).  Pada suhu dan tekanan tinggi, paduan Zr-4 mudah mengalami oksidasi dan kecepatan oksidasi meningkat pada suhu 800-1200°C. Upaya untuk meningkatkan ketahanan oksidasi kelongsong Zr-4 adalah pelapisan permukaan dengan metode seperti thermal spray, physical vapor deposition, cladding, heat treatment, dan chemical vapor deposition. Pada artikel review ini menggambarkan dan menjelaskan metode pelapisan alternatif yaitu plasma electrolytic oxidation (PEO) yang secara khusus diaplikasikan pada substrat zirkonium. Aspek lain yang dibahas adalah parameter proses yang mempengaruhi kualitas lapisan, dan karakteristik yang khas dari lapisan yang dihasilkan dengan metode PEO. Plasma electrolytic oxidation (PEO) merupakan metode pelapisan yang menjanjikan untuk menghasilkan lapisan oksida keramik dengan kekuatan mekanik dan termal yang tinggi. Proses PEO menggunakan peralatan yang sederhana dan bahan yang ramah lingkungan. Lapisan oksida zirkonium (ZrO2) yang terbentuk pada permukaan substrat Zr-4 mempunyai titik lebur sangat tinggi yaitu 2715°C dan tampang lintang neutron termal sangat rendah yaitu 0,18 barn. Karakteristik lapisan oksida keramik yang dihasilkan dipengaruhi oleh parameter proses PEO yaitu rapat arus, jenis dan konsentrasi elektrolit, bahan aditif pada elektrolit dll. Hingga saat ini, proses pelapisan metode PEO pada paduan Zirkonium (Zr) relatif belum banyak dibahas secara mendalam jika dibandingkan dengan logam lainnya seperti Al, Mg, dan Ti. Salah satu permasalahan yang masih dihadapi dalam pelapisan PEO terhadap substrat Zr-4 adalah porositas relatif tinggi dan jumlah fasa t-ZrO2 pada inner dan outer layer yang relatif rendah yang dapat mengurangi kekuatan mekanik dan ketahanan korosinya. Penyelesaian masalah untuk meningkatkan kualitas lapisan PEO adalah dengan optimasi parameter proses PEO yaitu rapat arus ,dan jenis dan konsentrasi elektrolit. Dalam kajian literatur ini didiskusikan strategi optimasi rapat arus, penggunaan variasi elektrolit, dan penambahan aditif pada proses PEO  untuk meningkatkan sifat mekanik dan korosi lapisan Modifikasi permukaan dengan proses PEO dapat diaplikasikan pada paduan zirkonium termasuk paduan Zr-4 sebagai komponen atau kelongsong bahan bakar reaktor nuklir tipe PWR. Metode PEO ini sangat potensial digunakan pada kelongsong Zr-4 untuk meningkatkan ketahanan oksidasi suhu tinggi dan meningkatkan efisiensi bahan bakar didalam reaktor nuklir.
Improving the Surface Corrosion Resistance of AMX601 Magnesium Alloy by Acid–Alkaline Treatment Anawati, Anawati; Asoh, Hidetaka; Ono, Sachiko
Makara Journal of Science Vol. 24, No. 2
Publisher : UI Scholars Hub

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Abstract

A drawback of acid cleaning as surface finishing of magnesium (Mg) surface is the absence of a protective oxide film on its surface. Acid–alkaline treatment is proposed to enhance the surface corrosion resistance of AMX601 Mg alloy. Acid–alkaline treatment was conducted by first dipping the alloy in HNO3–H3PO4 solution and then immersing the al-loy in NaOH solution. The potentiodynamic polarization test in 0.9% NaCl solution at 37 °C revealed a nobler corro-sion potential of −1.36 VAg/AgCl and a lower corrosion current density of 36.0 µA•cm−2 of the acid–alkaline-treated spec-imen than the acid-treated (−1.44 VAg/AgCl, 89.7 µA•cm−2) and untreated (−1.52 VAg/AgCl, 40.0 µA•cm−2) specimens. Acid treatment induced a significantly higher surface roughness (20 µm) than acid–alkaline (10 µm) and grinding (0.5 µm) treatments because of the selective dissolution of the Mg matrix and the accumulation of intermetallic precipitates. The film formed on the acid–alkaline-treated specimen was thick and free of cracks, whereas that formed on the acid-treated specimen was thin and cleaved. The formation of a protective oxide film and the enrichment of cathodic intermetallic particles on the acid–alkaline-treated specimen enhanced the corrosion resistance of the surface.
Kajian Komposit Berbasis Paduan Logam Magnesium Berpenguat Keramik untuk Aplikasi Ortopedi Franciska Pramuji Lestari; Ika Kartika; Ariadne Lakshmidevi Juwono; Anawati Anawati
TEKNIK Vol. 43, No. 3 (2022): December 2022
Publisher : Diponegoro University

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.14710/teknik.v43i3.46575

Abstract

Komposit berbasis logam Magnesium (Mg) merupakan material maju yang potensial diaplikasikan untuk implan biodegradabel yang bersifat sementara. Mg memiliki sifat biodegradabel, biokompatibel serta memiliki densitas yang mendekati tulang sehingga dapat mengurangi stress shielding antara tulang dan implan. Namun, Mg memiliki laju degradasi yang relatif cepat yang dapat menurunkan sifat mekaniknya di dalam lingkungan fisiologis dan kurangnya sifat bioaktivitas. Di sisi lain, biokeramik yang kerap digunakan sebagai bahan implan tulang dan gigi bersifat bioaktif dan bioinert. Penggabungan Mg dan keramik dapat menjadi sebuah material komposit untuk aplikasi biomedis dengan peningkatan sifat mekanik dan biokompatibilitas serta laju degradasi yang imbang. Dalam kajian ini, dibahas secara komprehensif kemajuan riset material komposit berbasis Mg dengan paduan logam Mg sebagai matriks, berbagai material keramik yang umum digunakan sebagai penguat, fasa-fasa penguatan pada komposit, proses manufaktur serta perlakuan panas pada komposit berbasis magesium. Komposit berbasis Mg menjadi material yang menjanjikan untuk aplikasi biomedis karena kombinasi sifat mekanik yang baik, berat jenis yang rendah, dan kemungkinan untuk mencapai laju korosi yang lebih lambat serta meningkatkan penyembuhan dengan adanya material bioaktif.
Carbon dioxide-Induced Corrosion of AISI 4140 Steel in Acidified Artificial Geothermal Brine Anawati, Anawati; Izzat, Rayhan; Pragitta, Riene Kaelamanda; Hernandi, Rafli Ihsan
Makara Journal of Science Vol. 27, No. 1
Publisher : UI Scholars Hub

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Abstract

Carbon dioxide (CO2)-induced corrosion often occurs in the structural materials of geothermal industry. The presence of CO2 influences the formation of various corrosion products. This research investigates the effect of dissolved CO2 in acidic brines on the corrosion behavior of AISI 4140 steel at atmospheric pressure. The brines were the standard brine, Ca-free brine, and high-salinity brine. The corrosion behavior was studied using electrochemical and immersion tests. A cyclic polarization test showed that the corrosion rate was higher in dissolved CO2 brine than in non-CO2 brine, and an immersion test demonstrated a similar result. In the absence of CO2, the presence of Ca ions in the brine reduced the corrosion rate of the alloy from 26.8 to 24.6 mmpy and further to 20.7 mmpy in the high-salinity brine. A similar trend was demonstrated during immersion in the CO2-containing brine, with higher rates of 37.1, 30.9, and 24.9 mmpy for the Ca-free, standard, and high-salinity brines, respectively. However, the Ca ions and high-salinity brines induced a more localized corrosion as pit and filiform. A surface analysis using an optical microscope revealed that immersion in CO2 brines generated 4–10-fold higher surface roughness than the non-CO2 brines. In all specimens, a protective layer was not established during the tests. No new phase was detected using X-Ray diffractometer after the immersion test. Moreover, no tendency of passivation was observed in the reverse scan of the cyclic polarization test.
Enhanced Crack Resistance of Porous Anodic Aluminum Oxide Grown on a Tubular Substrate with the Additive Ethylene Glycol Sianturi, Manogari; Juwono, Ariadne Laksmidevi; Anawati, Anawati
Makara Journal of Science Vol. 29, No. 2
Publisher : UI Scholars Hub

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Abstract

The growth of a porous anodic aluminum oxide (PAAO) layer with fewer cracks on a tubular substrate is quite challenging. The PAAO layer on a curved surface grows slower than that on a flat surface and is susceptible to cracking. This study aims to improve the crack resistance of the PAAO layer grown on a tubular aluminum substrate by adding ethylene glycol (EG). Each bath contained additive concentrations of 0, 5, 10, and 15 vol% EG. Anodization proceeded for 4 h at a temperature of 10 ℃ using the potentiostatic mode at 25 V in a sulfuric acid bath and 40 V in an oxalic acid bath. The crack and pore structure were investigated using a field emission scanning electron microscope (FE-SEM). The kinetic curve and FE-SEM investigation indicated that the addition of EG in the bath slowed the growth rate of the PAAO layer in both anodization baths. The lower oxidation rate drastically improved the crack resistance, as revealed by the significant reduction in the crack population and narrower crack width. The additive EG presumably enhanced the electrolyte viscosity and reduced the heating effect released during oxide growth. Consequently, the layer thickness and pore size decreased with the increase in the EG concentration.
Precision Engineered Graphene Oxide Membranes Optimizing Thin Film Composite Layers for Solvent and Dye Separation Widakdo, Januar; Fadly Azril Priodani; Hannah Faye M. Austria; Tsung Han-Huang; Aditya Rianjanu; Canggih Setya Budi; Anawati Anawati; Wei-Song Hung
Science and Technology Indonesia Vol. 10 No. 4 (2025): October
Publisher : Research Center of Inorganic Materials and Coordination Complexes, FMIPA Universitas Sriwijaya

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.26554/sti.2025.10.4.1031-1048

Abstract

Organic solvent nanofiltration (OSN) is a promising separation technology with low energy consumption and environmental benefits. However, membrane stability in harsh organic solvents remains a challenge. Graphene oxide (GO) is widely explored due to its exceptional mechanical strength and selective permeability; however, further modifications are necessary to optimize its performance. This study investigates the enhancement of GO membranes by incorporating a thin-film composite (TFC) layer through interfacial polymerization using polyethyleneimine (PEI) and trimethyl chloride (TMC). The fabricated membranes were characterized for theirmorphology, chemical structure, and filtration performance using scanning electron microscopy (SEM), Fourier-transform infrared spectroscopy (FTIR), X-ray Photoelectron Spectroscopy (XPS), and contact angle measurements. Filtration tests were conducted with ethanol and Congo red dye solutions. The optimized membrane, composed of 0.1 wt% PEI 800 Mw and 0.05 wt% TMC, exhibited superior performance, demonstrating a permeance of 8.06 ± 2.31 L L m-2 h-1 bar-1 and a rejection rate of 95.20 ± 1.54% for Congo red dye. Additionally, the membrane exhibited a charge-dependent separation mechanism, achieving a 98.64 ± 0.38% rejection of methyl green due to both affinity and Donnan effects. These findings provide insights into developing advanced OSN membranes for efficient solvent purification and dye separation.
Co-Authors Asoh, Hidetaka Canggih Setya Budi Fadly Azril Priodani Franciska Pramuji Lestari Hannah Faye M. Austria Hernandi, Rafli Ihsan Ika Kartika Izzat, Rayhan Januar Widakdo Juwono, Ariadne Lakshmidevi Juwono, Ariadne Laksmidevi Maman Kartaman Ajiriyanto Manogari Sianturi Ono, Sachiko Pragitta, Riene Kaelamanda Ravi Naldi Rianjanu, Aditya Tsung Han-Huang Wei-Song Hung