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"Plasma Electrolytic Oxidation (PEO) merupakan pelapisan permukaan logam dengan plasma anodisasi untuk menghasilkan lapisan tahan karat dan keras. Sifat lapisan yang dihasilkan dikendalikan oleh parameter proses seperti arus dan waktu pembentukan. Proses PEO dilakukan dengan 2 variasi yaitu variasi waktu dan variasi arus dalam larutan 0,5 M Na3PO4. Pada variasi waktu, arus yang digunakan adalah 0,5 A dengan waktu 1, 3, dan 5 menit. Sedangkan pada variasi arus digunakan arus 0,2; 0,3; 0,4 A dan dilakukan pada waktu konstan selama 3 menit. Temperatur elektrolit dijaga tetap 30°C dan diaduk dengan magnetic stirrer dengan kecepatan konstan 300 rpm. Perubahan morfologi sebagai fungsi arus dan waktu diamati menggunakan scanning electron microscope dan energy dispersive X-ray spectroscopy (SEM-EDS). Analisis fasa dilakukan dengan X-ray Diffraction (XRD). Perubahan kekerasan diamati melalui uji kekerasan micro-Vickers. Perubahan sifat korosi diuji dengan metode electrochemical impedance spectroscopy (EIS) dan potentiodynamic polarization (PDP). Hasil karakterisasi menunjukkan fasa kristal yang terbentuk pada lapisan PEO adalah fasa Mg3(PO4)2 yang diidentifikasikan pada puncak 35°, 37°, 49° dan 62° pada pola XRD. Nilai kekerasan lapisan PEO yang terbentuk pada 1, 3 dan 5 menit masing-masing adalah 315,67; 427,67; dan 382,67 HV sedangkan pada arus 0,2; 0,3; dan 0,4 A diperoleh nilai kekerasan lapisan masing-masing sebesar 355; 421,67; dan 459 HV. Hasil uji polarisasi menunjukkan peningkatan ketahanan korosi yang ditunjukkan dengan berkurangnya rapat arus korosi. Semakin kecil rapat arus korosinya maka laju pembentukkan korosi semakin berkurang. Pada variasi waktu 1, 3 dan 5 menit nilai rapat arus korosinya adalah 3,24 x 10-5; 7,76 x 10-7; dan 1,11 x 10-6 A/cm2 sedangkan pada variasi arus 0,2; 0,3; dan 0,4 A nilai rapatarus korosinya adalah 2,26 x 10-6; 3,12 x 10-6; dan 7,60 x 10-7 A/cm2. Hasil EIS menunjukkan bahwa nilai R1 semakin besar yang artinya ketahanan resistansi polarisasi semakin besar dengan meningkatnya waktu dan arus pembentukan. Pada variasi waktu 1, 3 dan 5 menit nilai R1 adalah 42,35; 564,7; dan 574,4 Ω.cm2 sedangkan pada variasi arus 0,2; 0,3; dan 0,4A nilai R1 adalah 254,5; 169; 627,5 Ω.cm2 setelah dicelupkan selama 3 jam.

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Plasma Electrolytic Oxidation (PEO) is a coating for metal surface by plasma anodization to produce corrosion resistant and hard coating. The resulting coating properties were controlled by process parameters such as formation current and time. The PEO process in this research uses 2 variation: time and current formation in 0,5 M Na3PO4 solution. At the time variation, the current used is 0,5 A with time of 1, 3 and 5 minutes. Whereas in the current variation used 0,2;0,3 and 0,4 A for 3 minutes. The electrolyte temperature was kept at 30 oC and stirred with a magnetic stirrer at 300 rpm. Morphological changes were investigated by using scanning electron microscope and energy dispersive X-ray spectroscopy (SEM-EDS). Phase analysis was performed by X-ray Diffraction (XRD). Hardness changes were observed using micro-Vickers hardness test. Changes in corrosion properties were investigated by electrochemical impedance spectroscopy (EIS) and potentiodynamic polarization (PDP). The phases formed in the PEO layer is Mg3(PO4)2 which identified at the peaks of 35°, 37°, 49° and 62° in the XRD pattern. Hardness of AZ31 alloys at 1, 3 and 5 minutes was 315,67 HV, 427,67 HV and 382,67 HV whilte at currents 0,2;0,3 and 0,4 A is 355 HV, 421,67 HV dan 459 HV. The polarization test results showed an increase in corrosion resistance which is approved by the reduced corrosion current density. The smaller the corrosion current, the rate of corrosion formation decreases. At the time variation of 1, 3 and 5 minutes the value of the corrosion current density is 3,24 x 10-5, 7,76 x 10-7, and 1,11 x 10-6 A/cm2 whereas in the variation of current 0,2; 0,3; and 0,4 A thecorrosion current density is 2,26 x 10-6; 3,12 x 10-6; and 7,60 x 10-7 A/cm2. EIS results showed that the higher value of R1 means the greater the polarization resistance. At the time variation of 1, 3 and 5 minutes the value of R1 are 42.35. 564.7, 574.4 Ω.cm2 whereas in the current variation of 0,2;0,3 and 0,4 A the value of R1 are 254.5, 169, 627.5 Ω.cm2 after being immersed for 3 hours."

"Penggunaan paduan magnesium sebagai material bio-metalik memiliki potensi untuk terurai secara alami dalam cairan tubuh dan berperan penting dalam struktur tulang. Dalam aplikasinya, modifikasi permukaan paduan magnesium diperlukan untuk meningkatkan sifat mekanik dan anti-korosinya. Salah satu metode pelapisan menjanjikan adalah Plasma Electrolytic Oxidation (PEO). Pada penelitian ini, dilakukan pelapisan paduan magnesium AZ31 dengan metode PEO menggunakan pendekatan one-step dan two-step. Parameter ditetapkan sama dalam penggunaan kedua metode ini yaitu meliputi waktu, rapat arus, sumber tegangan, dan suhu. Pada metode two-step PEO, lapisan HA (hidroksiapatit) disisipkan ke dalam lapisan oksida yang terbentuk. Hasil penelitian menunjukkan bahwa metode two-step PEO menghasilkan lapisan dengan karakteristik lebih baik dibandingkan metode one-step PEO. Lapisan two-step PEO memiliki persentase pori lebih kecil, ketebalan lapisan lebih besar, dan nilai spesifik abrasi lebih rendah. Selain itu, fasa kristalin baru, yaitu Ca5(PO4)3OH atau HA, terdeteksi dalam lapisan two-step PEO. Penggunaan metode two-step PEO dengan penambahan hidroksiapatit memberikan hasil lebih baik dalam hal karakterisasi morfologi dan sifat ketahanan aus. Dalam konteks aplikasi biomedis, hal ini menunjukkan potensi penggunaan paduan magnesium dengan metode pelapisan two-step PEO sebagai material cocok untuk aplikasi tulang dan gigi manusia.

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The use of magnesium alloy as a bio-metallic material has the potential to decompose naturally in body fluids and plays an essential role in bone structure. In its application, surface modification of magnesium alloy is required to improve its mechanical and anti-corrosion properties. One of the promising coating methods is Plasma Electrolytic Oxidation (PEO). In this study, the coating of magnesium alloy AZ31 was carried out using a one-step and two-step approach using the PEO method. The parameters used in both methods include the same time, current density, voltage source, and temperature. In the two-step PEO method, a HA (hydroxyapatite) layer is inserted into the formed oxide layer. The results showed that the two-step PEO method produced layers with better characteristics than the one-step PEO method. The PEO two-step coating has a smaller pore percentage, a larger layer thickness, and a lower abrasion-specific value. In addition, a new crystalline phase, namely Ca5(PO4)3OH or HA, was detected in the two-step PEO layer. The two-step PEO method with hydroxyapatite adds better morphology characterization and wear resistance properties. This demonstrates the potential use of magnesium alloys coated by the two-step PEO method as suitable materials for human bone and tooth applications in biomedical applications."

"Plasma electrolytic oxidation (PEO) digunakan untuk meningkatkan ketahanan korosi dan aus material kelongsong Pressurrized water reactor yaitu zircalloy-4 (Zr-4). Rapat arus merupakan salah satu parameter yang mempengaruhi sifat-sifat pelapisan PEO. Ada 3 rapat arus berbeda yang digunakan untuk proses PEO Zr-4 yaitu 30, 50 dan 70 mA/cm2 pada penelitian ini. Pengaruh rapat arus terhadap karakterisasi lapisan permukaan dan tampang lintang PEO, komposisi element dan fasa, evaluasi korosi dan ketahanan aus diamati. Hasil percobaan menunjukkan bahwa rapat arus 70 mA/cm2 memiliki ketahanan korosi terbaik dengan nilai Rcoating= 20 x106 Ω/cm2 karena memiliki komposisi element Si 27,74% sebagai pasif film. Namun rapat arus 70 mA/cm2 memiliki ketahanan aus yang paling baik yaitu laju keausan= 8,86 x 10-6 mm3/mm karena memiliki persentase pori terendah dibanding rapat arus lainnya yaitu 4,5%. Mempertimbangkan ketahanan aus yang lebih diperlukan dalam pengembangan pelapisan Zr-4, sehingga rapat arus 70 mA/cm2 adalah yang paling optimal dalam meningkatkan karakteristik Zr-4 dalam penelitian ini.

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Plasma Electrolytic Oxidation (PEO) is used to improve the corrosion and wear resistance of PWR cladding material, namely zircaloy-4. Current density is one of the parameters that affect the properties of the PEO coating. There are 3 different current densities used for the PEO Zr-4 process, namely 30, 50 and 70 mA/cm2 in this study. The effect of current density on the surface layer characterization and cross section of PEO, element and phase composition, evaluation of corrosion and wear resistance were observed. The experimental results show that the current density of 30 mA/cm2 has the best corrosion resistance Rcoating= 20 x106 Ω/cm2 because it has an elemental composition of 27.74% Si as a pasif film. However, the current density of 70 mA/cm2 has the best wear resistance because its surface porosity 4.5% is lowest than others. Considering that more wear resistance is needed in the development of Zr-4 coating, so that the current density of 70 mA is the most optimal in improving the characteristics of Zr-4 in this study."

"Magnesium (Mg) merupakan logam ringan. Namun, magnesium dan paduannya mengalami degradasi yang sangat cepat di dalam lingkungan yang basah. Selain itu sifat film alami pada paduan magnesium sangat tipis, sehingga paduan magnesium memiliki ketahanan korosi yang sangat rendah. Hal ini menyebabkan kekuatan mekanik pada paduan magnesium mengalami penurunan. Untuk menangani masalah tersebut maka dilakukan Plasma electrolytic Oxidation (PEO) untuk meningkatkan ketahanan korosi pada paduan magnesium. Lapisan film oksida yang dihasilkan dari proses PEO bersifat tebal dan keras, namun juga memiliki pori, retakan dan lapisan yang tidak rata. Proses PEO dilakukan dengan memvariasikan waktu PEO dan arus selama PEO yang berlangsung di dalam elektrolit 0.5 M Na3PO4 pada suhu 30°C ± 1°C. PEO dilakukan dengan variasi waktu 30, 60 dan 90 detik. Ketebalan yang dihasilkan untuk masing-masing variasi waktu adalah 16,23, 27,76 dan 33,11 μm. Sedangkan untuk variasi arus 0,2, 0,3 dan 0,4 A akan dihasilkan ketebalan film oksida 32,61, 55,65 dan 66,25 μm. Untuk mengetahui laju korosi paduan magnesium yang telah diberi perlakuan PEO dilakukan dengan uji polarisasi di dalam larutan 3,5% NaCl pada suhu 30°C. Hasil uji polarisasi untuk variasi waktu menunjukkan peningkatan ketahanan korosi yang ditandai dengan kenaikan potensial korosi pada substrat, 30, 60 dan 90 detik berturut-turut adalah -1.22, -1.26, -0.75 dan -1.03 VAg/AgCl dan penurunan arus korosi berturut-turut 94,79, 11.30, 0.36 dan 0,67 μA/cm2. Sedangkan untuk variasi arus 0,2, 0,3 san 0,4 A menunjukkan kenaikan potensial korosi berturut-turut  -1,24, -1,18 dan 0,41 VAg/AgCl dan penurunan arus korosi berturut-turut adalah 5,1, 4,6 dan 4,3 μA/cm2. Hasil tersebut menunjukkan bahwa PEO dapat meningkatkan ketahanan  korosi pada paduan magnesium AZ91.

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Magnesium (Mg) is a lightweight metal. However, Magnesium and its alloys experience very rapid degradation in wet environments. In addition, the natural film properties of magnesium alloys are very thin, so magnesium alloys have very low corrosion resistance. This causes the mechanical strength of the magnesium alloy to decrease. To deal with these problems, a Plasma Electrolytic Oxidation (PEO) was performed to improve corrosion resistance in magnesium alloys. The oxide film layer produced from the PEO process is thick and hard, but also has pores, cracks and uneven layers. The PEO process is carried out by varying the time of the PEO and the current during the PEO that takes place in a 0.5 M Na3PO4 electrolyte at a temperature of 30 °C ± 1 °C. PEO is done with a time variation of 30, 60 and 90 seconds. The thickness produced for each time variation is 16.23, 27.76 and 33.11 μm. As for the current variations of 0.2, 0.3 and 0.4 A, an oxide film thickness of 32.61, 55.65 and 66,25 μm  To determine the corrosion rate of magnesium alloys that have been treated with PEO is done by polarization testing in a solution of 3.5% NaCl at 30 °C. The polarization test results for time variation show an increase in corrosion resistance which is characterized by an increase in corrosion potential on the substrate, 30, 60 and 90 seconds respectively -1.22, -1.26, -0.75 and -1.03 VAg/AgCl and a decrease in corrosion currents respectively 94.79, 11.30, 0.36 and 0.67 μA/cm2. As for the current variations of 0.2, 0.3 and 0.4 A, it shows a increase in corrosion potential of -1.24, -1.18 and 0.41 VAg/AgCl and an decrease in corrosion current respectively 5,1, 4,6 dan 4,3 μA/cm2. These results indicate that PEO can increase corrosion resistance in AZ91 magnesium alloys."

"Logam ringan aluminium (Al) dan paduannya memiliki sifat mekanik yang cocok digunakan dalam industri penerbangan, perkapalan, dan otomotif. Proteksi terhadap permukaan logam Al diperlukan untuk meningkatkan ketahanan korosi dan aus. Plasma Electrolytic Oxidation (PEO) menghasilkanlapisan oksida tebal dan kristalin sehingga dapat meningkatkan ketahanan korosi dan ketahanan aus. Karakteristik mekanik dan korosi lapisan oksida hasil PEO sangat bergantung pada ketebalan dan morfologi lapisan yang ditentukan oleh waktu dan karakteristik plasma. Dalam penelitian ini, PEO dilakukan pada paduan Al seri 7075-T651 dengan menggunakan elektrolit campuran 30 g/lNa2SiO3, 30 g/l KOH, 30 g/l Na3PO4, dan 20 g/l TEA pada rapat arus konstan 200 A/m2dengan variasi waktu 10, 15, dan 20 menit. Lapisan PEO dikarakterisasi dengan menggunakan X-Ray Diffractometer (XRD) untuk menganalisis komposisi fasa kristal, Scanning Electron Microscopy-Energy Dispersive x-ray Spectroscopy (SEM-EDS) untuk menganalisis morfologi permukaan dan komposisi unsur. Perilaku korosi pada sampel dievaluasi melalui uji elektrokimia, yaitu Open Circuit Potential (OCP), Electrochemical Impedence Spectroscopy (EIS), dan juga Potentiodynamic Polarization (PDP). Sifat mekanik lapisan PEO diuji dengan metode Vickers microhardness, dan ketahanan aus diuji menggunakan metode Ogoshi. Unsur P, Si, O merupakan lapisan perlindungan terhadap korosi semakin meningkat seiring berjalannya waktu. Hasil XRD menunjukkan adanya lapisan Al2O3, SiO2, dan AlPO4. Hasil uji elektrokimia PDP dan EIS menunjukkan bahwa PEO 15 menit menunjukkan kinerja korosi yang paling baik, memiliki rapat arus korosi terendah sebesar 1,20 × 10-7 A.cm−2 dan hambatan tertinggi sebesar 706,8 Ω.cm2 dan 1,65 × 104 Ω.cm2. Tetapi, uji mekanik menunjukkan bahwa PEO 15 menitmemiliki tingkat keausan yang tinggi sebesar 20,8 mm3/mm dan kekerasan sebesar 143 HV. Sedangkan PEO 20 menit nilai keausan lebih rendah sekitar 8 mm3/mm dan kekerasan sebesar 159,4 HV serta sudut kontak sebesar 78˚.

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The lightweight metal aluminum (Al) and its alloys exhibit mechanical properties suitable for use in the aerospace, shipping, and automotive sectors. Surface protection of Al metal is necessary to enhance corrosion and wear resistance. Plasma Electrolysis Oxidation (PEO) produces thick and crystalline oxide layers, thus improving high corrosion resistance and high wear resistance. The mechanical and corrosion characteristics of PEO oxide layers greatly depend on the thickness and morphology of the layers determined by time and plasma characteristics. In this study, PEO was performed on 7075-T651 series Al alloy using a mixed electrolyte of 30 g/l Na2SiO3, 30 g/l KOH, 30 g/l Na3PO4, and 20 g/l TEA at a constant current density of 200 A/m2 with time variations of 10, 15, and 20 minutes. The PEO layers were characterized using X-Ray Diffractometer (XRD) to analyze the crystal phase composition, Scanning Electron Microscopy-Energy Dispersive x-ray Spectroscopy (SEM-EDS) to analyze surface morphology and elemental composition. Corrosion behavior on the samples was evaluated through electrochemical tests, namely Open Circuit Potential (OCP), Electrochemical Impedance Spectroscopy (EIS), and Potentiodynamic Polarization (PDP). The mechanical properties of PEO layers were tested using the Vickers microhardness method, and wear resistance was tested using the Ogoshi method. The protective layer against corrosion increases over time with elements P, Si, O. XRD results show the presence of Al2O3, SiO2, and AlPO4 layers. PDP and EIS electrochemical test results indicate that PEO for 15 minutes shows the best corrosion performance, with the lowest corrosion current density of 1.20 × 10-7 A.cm−2 and the highest impedance of 706.8 Ω.cm2 and 1,65 × 104 Ω.cm2. However, mechanical tests show that the 15-minute PEO has a high wear rate of 20.8 mm3/mm and a hardness of 143 HV. Meanwhile, the 20-minute PEO has a lower wear rate of about 8 mm3/mm and a hardness of 159.4 HV, as well as a contact angle of 78˚."

"Phosphate Sludge (PS) waste has been a problem in metal surface finishing industry. The waste cannot be dumped in landfill due to the metal content. Valorisation of the waste will be beneficial in a way that it conserves natural reserves and reduces energy consumption. This paper describes the attempt of utilization of PS by mixing it in kaolin in preparation of ceramic bricks. A series of experiments showed that mixtures containing between 25–50 mass % PS sintered at 1200oC attained the highest compressive strength of >25 MPa. X-ray diffractions (XRD) showed that the presence of PS hindered the formation of mullite, the phase that contribute to strength in Al2O3–SiO2 kaolin system. In the mixture of 1:1 kaolin: PS fired at 1200oC, cristobalite was formed, instead of mullite, as observed in the XRD patterns."

"This research was done to investigate influence of the base metal surface roughness on the BAg-8 spreading behavior and to get a proper surface roughness number for large area brazing. The filler metal was melted at 830o C for 15 minutes on a S50C surface for with various roughness levels. After solidified, the spreading area was observed and characterized in macro and micro scale. The results show that physically the filler spreading consists of two kinds of spreading forms: true and apparent filler spreading with composition of the both being almost same; 77% Ag and 23% Cu. For some roughness numbers, irregularities in uniformity of the heating and cooling process on the filler and dissolving of contaminant into the molten filler caused the true spreading that tend to separate became several parts and tend to flow out from initial placement. Increasing of the surface roughness tends to increase the capillarity effect and to decrease imbalance in the surface tension. Optimum surface roughness was obtained at Rz = 0.92. At this number, the ratio, as well as fitness of the true spreading with initial condition, was at the maximum. During the application process, this condition is predicted as being able to prevent or avoid weaknesses in the joint, thereby increasing the joint strength and its appearance quality."