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"Korosi kerap menjadi masalah dalam pemipaan untuk industri minyak dan gas bumi. Untuk mengatasi masalah tersebut diciptakanlah material yang dapat menahan laju korosi, salah satunya adalah baja tahan karat duplex. Namun, baja tahan karat duplex masih rentan terkena korosi lokal di lingkungan yang terdapat ion klorida. Selain itu, pipa-pipa yang digunakan untuk mengalirkan produk industri minyak dan gas bumi dirangkai menggunakan metode las yang dapat merubah konten ferit yang dapat mempengaruhi ketahanan pipa terhadap korosi. Penelitian ini dilakukan untuk mempelajari pengaruh konsentrasi NaCl dan pengaruh perubahan konten ferit terhadap korosi duplex 2205 menggunakan metode polarisasi siklik. Hasil penelitian menunjukkan bahwa baik konsentrasi NaCl dan perubahan konten ferit memberi pengaruh pada korosi duplex 2205. Konsentrasi NaCl yang memiliki korosi paling besar adalah konsentrasi 3,5% NaCl. Peningkatan fasa austenit pada baja akan memperkuat ketahanan korosi dari baja tahan karat duplex.

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Corrosion become the problem in pipeline for oil and gas industry. To handle this problem, materials that stainless was made, one of them is duplex stainless steel. However, duplex stainless steel can be corroded by localized corrosion in environment that contain chloride ion. More over, pipes which used to stream the product of oil and gas industry is joint by welding which can affect the ferric content that can change the pipe?s resistance of corrosion.

This study was conducted to study the effect of NaCl concentration and the effect of change of ferrite content to corrosion of duplex 2205. This study shows that both of NaCl concentration and change of ferrite content have affect the corrosion of duplex 22015. 3.5% NaCl is the most corrosive environment. The increase of austenite phase will increase the corrosion resistance of duplex stainless steel."

"[Logam merupakan kebutuhan utama dari infrastruktur pada industri. Korosi pada logam merupakan suatu hal yang tidak dapat dihindari, dan seringkali menjadi penyebab utama kegagalan dalam berbagai industri, terutama industri minyak dan gas yang berada di lepas pantai. Pemilihan material yang sesuai dapat mencegah terjadinya korosi pada industri, sehingga meminimalisir penggantian komponen dalam waktu yang singkat.Penelitian ini dilakukan untuk mempelajari perilaku korosi pada pipa baja tahan karat austenitik 316L pada lingkungan NaCl yang bervariasi. Parameter elektrokimia dievaluasi dengan menggunakan metode polarisasi siklik untuk mengetahui perilaku korosi yang terjadi pada lingkungan NaCl. Pemanasan dilakukan untuk mendapatkan perbedaan bentuk mikrostruktur dari keadaan awal. Kemudian diuji didalam lingkungan NaCl 3,5% yang memiliki kelarutan oksigen tertinggi dan bandingkan dengan logam yang tidak dipanaskan pada konsentrasi yang sama.Hasil penelitian menunjukkan bahwa ketahanan korosi berubah berdasarkan konsentrasi NaCl, logam paling tahan dengan korosi pada NaCl 1%, dan paling lemah ketahanannya pada NaCl 3,5%. Perubahan mikrostruktur yang menjadi lebih tidak seragam dan kemunculan sensitasi menurunkan ketahanan korosi. Dari hasil polarisasi siklik didapati bahwa mekanisme korosi pada lingkungan NaCl adalah korosi sumuran.

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Steels are basic needs for industrial infrastructure. Corrosion in steels can?t be avoided and often plays a role as a major cause of failure in industries, especially offshore oil and gas. Proper material selection is one of the best ways to prevent corrosion and minimize component replacement caused by corrosion.This study investigates corrosion behaviour of austenitic stainless steel 316L in various NaCl solutions. Electrochemical parameter is evaluated by cyclic polarization, and also to determine which corrosion behaviour has occurred. Heat is given to obtain different microstructure shapes from the initial one. Then tested in 3.5% NaCl solution and compared to the un-heated with the same solution concentration.The results shown that corrosion resistance affected by Chloride presence, with 1% concentration was the strongest, and 3.5% was the most susceptible. Microstructure transformation to more un-uniform than before heated, and presence of sensitization decreases the corrosion resistance. From the cyclic curve, it is known that the corrosion behaviour that occurred was pitting corrosion., Steels are basic needs for industrial infrastructure. Corrosion in steels can’t be avoided and often plays a role as a major cause of failure in industries, especially offshore oil and gas. Proper material selection is one of the best ways to prevent corrosion and minimize component replacement caused by corrosion.This study investigates corrosion behaviour of austenitic stainless steel 316L in various NaCl solutions. Electrochemical parameter is evaluated by cyclic polarization, and also to determine which corrosion behaviour has occurred. Heat is given to obtain different microstructure shapes from the initial one. Then tested in 3.5% NaCl solution and compared to the un-heated with the same solution concentration.The results shown that corrosion resistance affected by Chloride presence, with 1% concentration was the strongest, and 3.5% was the most susceptible. Microstructure transformation to more un-uniform than before heated, and presence of sensitization decreases the corrosion resistance. From the cyclic curve, it is known that the corrosion behaviour that occurred was pitting corrosion.]"

"[ABSTRAKKemampuan inhibitor Triazine dalam menginhibisi baja karbon API 5L X60 dalam lingkungan NaCl 3.5% diinvestigasi dengan menggunakan metode Polarisasi Tafel dalam berbagai variasi konsentrasi. Konsentrasi yang digunakan pada penelitian kali ini adalah 0 ppm, 50 ppm, 10 ppm, 150 ppm, 200 ppm, dan 250 ppm. Efisiensi optimum yang didapatkan adalah sebesar 50.28% dengan konsentrasi inhibitor triazine sebesar 150 ppm. Dengan pengujian FTIR, maka dibuktikan bahwa senyawa triazine mampu menginhibisi permukaan baja API 5L X60. Penelitian ini juga membuktikan bahwa inhibitor triazine merupakan inhibitor korosi karena mampu menurunkan laju korosi.Inhibitor triazine termasuk kedalam jenis inhibitor campuran.

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ABSTRACT

The corrosion rate from Triazine-based inhibitors on API 5-L X60 steel at NaCl 3,5% environtment were investigated using the Tafel Polarization method. The Triazine compounds that successfully absorbed onto steel surface were investigated using the Fourier Transform Infra Red (FTIR). Triazine?s efficiency depends on the concentration that given onto environtment. The highest efficiency of Triazine inhibitor is 50.28% with the optimize concentration 150 ppm. The investigated Triazine inhibitors were proven as the corrosion inhibitors because it can reduces the corrosion rate. Triazine inhibitors are also mixed type inhibitors.;The corrosion rate from Triazine-based inhibitors on API 5-L X60 steel at NaCl 3,5% environtment were investigated using the Tafel Polarization method. The Triazine compounds that successfully absorbed onto steel surface were investigated using the Fourier Transform Infra Red (FTIR). Triazine?s efficiency depends on the concentration that given onto environtment. The highest efficiency of Triazine inhibitor is 50.28% with the optimize concentration 150 ppm. The investigated Triazine inhibitors were proven as the corrosion inhibitors because it can reduces the corrosion rate. Triazine inhibitors are also mixed type inhibitors. , The corrosion rate from Triazine-based inhibitors on API 5-L X60 steel at NaCl 3,5% environtment were investigated using the Tafel Polarization method. The Triazine compounds that successfully absorbed onto steel surface were investigated using the Fourier Transform Infra Red (FTIR). Triazine’s efficiency depends on the concentration that given onto environtment. The highest efficiency of Triazine inhibitor is 50.28% with the optimize concentration 150 ppm. The investigated Triazine inhibitors were proven as the corrosion inhibitors because it can reduces the corrosion rate. Triazine inhibitors are also mixed type inhibitors. ]"

"Kebijakan sistem zonasi digunakan dalam proses penyeleksian penerimaan peserta didik baru (PPDB) untuk jenjang pendidikan SMP dan SMA yang diselenggarakan oleh negara. Tujuan kebijakan ini sebagai upaya pemerintah dalam melakukan pemerataan pendidikan di Indonesia untuk menghapus stigma eklusivitas sekolah unggulan dan sekolah non-unggulan. Dalam pelaksanaan penerimaan peserta didik baru tahun 2017 dan tahun 2018 masih ditemukan tindak kejahatan; tindak jual-beli kursi, kasus pungutan liar dan kasus pemalsuan Surat Keterangan Tidak Mampu (SKTM) yang baru muncul sejak diterapkan PPDB sistem zonasi. Dalam penulisan ini menggunakan Routine Activity Theory untuk mengidentifikasi dan menganalisis bagaimana peluang membentuk beberapa kasus kejahatan dalam proses pelaksanaan PPDB. Pengumpulan data diperoleh dari berbagai sumber laporan dan berita, serta wawancara. Hasil penelitian ditemukan bahwa peluang kejahatan terbentuk akibat rentannya target, para pelaku yang termotivasi untuk melakukan tindak kejahatan dan lemahnya pengawasan yang cakap.

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The school zoning system policy is applied in the process of selecting new student admissions (PPDB) for the level of junior and senior high school education held by the state. The purpose of the school zoning system is one of the government efforts inequitable education in Indonesia to eliminating the stigma of exclusivity in schools. In the implementation of new student admissions in 2017 and 2018, crimes are still found; seat purchases, extortion, and relief letter for students from disadvantaged families (SKTM) Forgery that has emerged since the PPDB zoning system were implemented.

This writing is using the Routine Activity Theory to identify and analyze how opportunities form several criminal cases in the process of implementing PPDB. Data collection is obtained from various sources of reports and news, as well as an interview. The result found that chances of crime formed are due to the vulnerability of the targets, the motivated offenders who willing to commit crimes and lack of capable guardians."

"[ABSTRAKPenggunaan baja tahan karat dua fasa austenitik-ferritik (Duplex) UNS32205 telah digunakan secara luas pada berbagai sektor perusahaan, khususnya industri Minyak dan Gas serta industri Petrokimia karena memiliki sifat mekanik dan ketahanan korosi yang sangat baik. Pada penelitian ini,yang diamati adalah pengaruh konsentrasi NaCl pada lingkungan kerja baja tahan karat ini, yang bertujuan mencari konsentrasi yang bersifat paling korosif, dan juga dilakukan pengamatan terhadap pengaruh perubahan Ferrite Content atau nilai rasio dari kedua fasa penyusun baja tahan karat UNS32205 yaitu Austenit dan Ferrit.Pada sampel awal yang diamati tanpa diberikan perlakuan panas apapun memiliki nilai rasio fasa 40% Austenit ? 60 Ferrit. Perubahan Ferrite Content atau perubahan rasio tersebut dilakukan dengan melakukan dua metode pemanasan sampel. Yaitu pemanasan menggunakan maffle furnace pada temperatur 11000C dan ditahan selama 20 menit, dengan hasil rasio 42% Austenit ? 58% Ferrit dan nilai ketahanan korosi paling rendah. Dan juga dilakukan pemanasan dengan cara mengambil sampel pada daerah HAZ dengan temperatur antara 4000C-12000C dan langsung quench, dengan hasil pengamatannya adalah memiliki ketahanan korosi paling tinggi karena memiliki rasio 50,3% Austenit ? 49,7% Ferrit.ABSTRACTThe use of Duplex Stainless Steel UNS32205 has been widely used in various sectors of the company, particularly the oil and Gas industry and the petrochemical industry because it has excellent mechanical properties and corrosion resistance. In this study, the effect of NaCl concentration was observed on the stainless steel working environment, which aims to find the most corrosive nature of concentrations, and also carried out observations on the influence of Ferrite Content or change the value of the ratio of the phase constituent of stainless steel UNS32205 i.e. Austenite and Ferrite. On the initial samples were observed without any heat treatment has given the value of the phase ratio 40% Austenite ? 60 Ferrite. Ferrite Content changes or changes the ratio by doing two sample heating method. I.e. the heating furnace temperature on maffle using 11000C and detained for 20 minutes, with a ratio of 42% Austenit ? 58% Ferrit and lowest corrosion resistance value. And also done warming up by taking samples at the HAZ with temperature between 4000C-12000C and direct quench, with the results of its observations is to have the highest corrosion resistance because it has a ratio of 50.3% Austenite ? 49.7% Ferrite., The use of Duplex Stainless Steel UNS32205 has been widely used in various sectors of the company, particularly the oil and Gas industry and the petrochemical industry because it has excellent mechanical properties and corrosion resistance. In this study, the effect of NaCl concentration was observed on the stainless steel working environment, which aims to find the most corrosive nature of concentrations, and also carried out observations on the influence of Ferrite Content or change the value of the ratio of the phase constituent of stainless steel UNS32205 i.e. Austenite and Ferrite.On the initial samples were observed without any heat treatment has given the value of the phase ratio 40% Austenite – 60 Ferrite. Ferrite Content changes or changes the ratio by doing two sample heating method. I.e. the heating furnace temperature on maffle using 11000C and detained for 20 minutes, with a ratio of 42% Austenit – 58% Ferrit and lowest corrosion resistance value. And also done warming up by taking samples at the HAZ with temperature between 4000C-12000C and direct quench, with the results of its observations is to have the highest corrosion resistance because it has a ratio of 50.3% Austenite – 49.7% Ferrite.]"

"Perilaku korosi dari baja tahan karat duplex 2205 dan feritik 410s diamati dalam berbagai konsentrasi larutan sodium klorida. Rangkaian pengujian dilakukan dengan menggunakan metode Electrochemical Impedance Spectroscopy pada suhu ruang. Metode ini dilakukan untuk mengamati impedansi dari material uji. Konsentrasi larutan klorida disiapkan dengan variasi 1, 2, 3, 4 dan 5 w.t. Hasil pengujian terhadap kedua sampel menyatakan bahwa sistem dengan ketahanan korosi paling rendah adalah sistem yang menggunakan 3,5 w.t sodium klorida, yang serupa dengan kandungan klorida air laut. Hasil pengujian juga menyatakan bahwa baja tahan karat duplex 2205 secara umum lebih tahan korosi dibandingkan dengan feritik 410s pada setiap konsentrasi klorida.

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Corrosion behaviour of SS 2205 and SS 410s were investigated in various concentrations of aqueous sodium chloride solutions. Experimental work was carried out by using electrochemical impedance spectroscopy method at room temperature to evaluate the impedance of the system. Sodium chloride solutions were prepared with various concentration i.e. 1, 2, 3.5, 4 and 5 w.t. The testing results were represented by Nyquist plot for both alloys. It was observed that the lowest corrosion resistance of both alloys was at 3,5 w.t NaCl which was similar to typical seawater solution. It was also observed that SS 2205 had better corrosion resistance along with greater impedance than the SS 410s in every NaCl concentration."

"Studi ini mempelajari tentang ketahanan korosi dari baja tahan karat duplex 2205 dan baja tahan karat feritik 410S terhadap konsentrasi larutan sodium klorida. Mekanisme korosi yang terjadi disebabkan oleh potensial breakdown Eb dan potensial proteksi Ep yang nilainya didapat selama pengujian polarisasi siklik. Variabel dari penelitian ini adalah konsentrasi dari larutan sodium klorida yang dipersiapkan pada konsentrasi 1 , 2 , 3,5 ,4 ,5 berat masa. Pengujian polarisasi siklik menghasilkan kurva untuk masing - masing material baja tahan karat pada setiap konsentrasi larutan NaCl dimana masing - masing kurva tersebut menunjukan nilai Eb dan Ep secara berurutan.Ketahanan korosi terbaik didapat pada konsentrasi 1 sodium klorida dan ketahanan korosi terburuk didapat pada larutan dengan konsentrasi 3,5 untuk kedua material baja tahan karat 2205 dan baja tahan karat 410S. Korosi sumuran terjadi pada baja tahan karat 410S namun tidak pada baja tahan karat 2205.

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Corrosion resistance of duplex stainless steels 2205 type and ferritic stainless steel 410S type were investigated due to the influence of the concentration of sodium chloride solution. The corrosion mechanism was caused by the breakdown potential Eb and protection potential Ep during the cyclic polarization testing. Aqueous sodium chloride solution with concentration of 1 , 2 , 3.5 , 4 , 5 w.t were prepared as the variable of the investigation. The cyclic polarization testing results the curves for both stainless steels in every concentration of NaCl solution which showed potential that indicate the onset of Eb and Ep respectively.The highest corrosion resistance was achieved in 1 sodium chloride solution and the lowest was in 3.5 sodium chloride solution for both 2205 ss and 410S ss. Pitting corrosion occurred in 410S SS but not in 2205 SS."

"Proses magmatisme berkaitan dengan jalur tektonik ring of fire, yang menyebabkan proses mineralisasi hidrotermal sehingga membentuk potensi sumber daya mineral di Indonesia. Salah satu endapan hidrotermal yaitu endapan epitermal sulfidasi rendah yang berada di Lapangan “RD”, Cibaliung. Struktur patahan menjadi pengontrol sistem epithermal sulfidasi rendah sebagai tempat terendapkannya mineral emas. Integrasi data geologi dengan geofisika diperlukan dalam menentukan struktur pengontrol dan zona potensi mineralisasi. Mineral bijih sulfida dapat dibedakan dari sifat kemagnetan dan kelistrikan dikarenakan mineral logam memiliki respon suseptibilitas, resistivitas dan chargeabilitas lebih tinggi dibandingkan dengan mineral non-logam. Zona potensi mineralisasi emas sulfidasi rendah berada pada zona struktur yang didominasi alterasi argilik dan kaya akan mineral sulfida pada alterasi argilik ilitik dengan nilai suseptibilitas menengah hingga tinggi kisaran -83.7 nT – 92.3 nT, resistivitas dengan nilai rendah hingga menengah 0 – 25 ohm.m dan chargeabilitas dengan nilai menengah hingga tinggi 15 - >75 msec. Dari ketiga parameter tersebut, diduga zona mineralisasi berada pada zona struktur patahan berorientasi Baratlaut-Tenggara. Struktur pengontrol zona potensi mineralisasi tersebut berada di lintasan 3 yaitu patahan D dip 62° ke arah NE dan patahan E dip 83° ke arah NE. Lintasan 4 yaitu patahan D dip 79° ke arah NE, patahan E dip 77° ke arah NE dan patahan F dip 73° ke arah NE. Lintasan 7 yaitu patahan D dip 80° ke arah SW dan patahan E dip 75° ke arah NE. Lintasan 8 yaitu patahan D dip 84° ke arah NE dan patahan E dip 66° ke arah NE. Lintasan 9 yaitu patahan A dip 70° ke arah SW dan patahan B dip 81° ke arah NE.

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The magmatism process is related to the Ring of Fire tectonic pathway, which causes a hydrothermal mineralization process to form potential mineral resources in Indonesia. One of the hydrothermal deposits is an epithermal low-sulfidation deposit in the "RD" Field, Cibaliung. The fault structure controls the epithermal low-sulfidation system as a place for gold mineral deposition. Integration of geological data with geophysical data is required in determining the controlling structure and potential mineralization zone. Sulfide ore minerals can be distinguished from their magnetic and electrical properties because metal minerals have a higher susceptibility, resistivity and chargeability response compared to non-metallic minerals. The potential zone of low sulfidation gold mineralization is located in the structure zone which is dominated by argillic alteration and rich in sulphide minerals in Illitic argillic alteration has medium to high susceptibility values ranging from -83.7 nT - 92.3 nT, resistivity with low to medium values 0 - 25 ohm.m and chargeability with medium to high values of 15 -> 75 msec. From those three parameters, it is assumed that the mineralization zone is located in the NW-SE oriented fault structure zone. The controlling structure for the zone of mineralization potential is in line 3 is fault D with dip 62° to the NE and the E fault with dip 83° to the NE. Line 4 is fault D with dip 79° to the NE, fault E with dip 77° to the NE and fault F with dip 73° to the NE. Line 7, is fault D with dip 80 ° to the SW and the E fault dip 75° to the NE. Line 8 is fault D with dip 84° to the NE and fault E with dip 66 ° to the NE. Line 9 is fault A with dip 70° SW and fault B with dip 81° to NE."

"PZT (PbZr1-xTixO3) merupakan bahan berbentuk kristal perovskite yang dapat dimanfaatkan sebagai sensor inframerah. Penambahan sedikit dopan (bahan pendoping) dapat mengubah secara drastis karakteristik spesifik dari bahan keramik-ferroelektrik seperti polarisasi spontan, sifat dielektrik, sifat elektromekanik, elektrooptik dan sifat lainnya. Hard doping dengan menggunakan ion In3+ diaplikasikan pada penelitian ini dan dilakukan penumbuhan lapisan tipis dari bubuk PIZT (PbInxZryTi1-x-yO3-x/2) pada substrat Si(100) dengan metode Chemical Solution Deposition (CSD) dengan konsentrasi 0,5 M dan kecepatan putar spin coating 3000 rpm. Karakteristik bahan PIZT baik bubuk maupun lapisan tipisnya diuji dengan difraksi sinar x. Analisis Rietveld dilakukan dengan menggunakan program GSAS-EXPGUI dan diperoleh parameter kisi dan komposisi fasa dari kristal. Polarisasi spontan (Ps) PIZT bubuk dan lapisan tipisnya mengalami penurunan dibandingkan dengan bahan asalnya (PZT). Polarisasi spontan yang optimum dari lapisan tipis PIZT dicapai pada rentang doping 0,5% - 1% In2O3. Momen quadrupol potensial listrik (�?�Q(r)) bahan PIZT pada suatu titik P (0,0,2a) mencapai kondisi optimum pada % doping 6% In2O3 dan dari hasil penelitian ini juga menunjukkan bentuk lapisan tipis PIZT memiliki nilai (�?�Q(r)) yang lebih baik daripada bentuk bubuknya untuk rentang doping > 1% In2O3.

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The Calculation Spontaneous Polarization and Quadrupole Moment of Electric Potential PIZT (PbInxZryTi1-x-yO3-x/2). PZT (PbZr1-xTixO3) is a perovskite crystal that can be used for IR sensor. Small amount of dopant can drastically change the specific characteristic of ferroelectric ceramic such as spontaneous polarization, dielectric constant, electromechanical and also electro-optic properties. The addition of In3+ ion (called as hard doping) has been applied in this research. Thin film of PIZT (PbInxZryTi1-x-yO3-x/2) has been deposited on Si(100) substrate with Chemical Solution Deposition (CSD) method. The concentration of solution is 0,5 M and the angular speed applied of spin coating is 3000 rpm. The PIZT sample has been analyzed with x-ray diffraction method. Rietveld analyses using GSAS-EXPGUI software resulted lattice parameter of crystal and phase compositions of PIZT samples. The values of all sample PIZT spontaneous polarization (Ps) have been calculated lower than PZT. The optimally Ps was reached at 0,5% to 1% In2O3 doping. Quadrupole moment of electric potential (�?�Q(r)) at point P (0,0,2a) reached optimum at 6% In2O3 doping and they also showed that PIZT thin film have �?�Q(r) higher value than their bulk form for In2O3 doping >1%."

"Sebagai biomaterial implan, salah satu sifat penting yang harus dimiliki paduan kobalt adalah ketahanan korosi dan biokompatibilitas yang sangat baik terhadap lingkungan biologis seperti Artificial Blood Plasma (ABP) Dalam penelitian ini digunakan spesimen paduan kobalt ASTM F 75 hasil metalurgi serbuk dalam bentuk kepingan (tablet) dengan variasi kandungan Si 0 - 1%. Untuk mengetahui kinetika korosi, dilakukan pengujian polarisasi potensiodinamik dan exposure (immersion) pada pH 7,4 dan temperatur 37 ºC dalam lingkungan Artificial Blood Plasma (ABP) dengan beberapa kondisi yang dipertahankan konstan. Pengujian dilakukan dengan mengikuti standar ASTM. Kenaikan potensial pengujian 3 mV/detik dengan rentang pemindaian mulai dari -0,25 Volt hingga 0,25 Volt. Elektroda bantu yang digunakan karbon dan elektroda acuan dipilih Kalomel jenuh (SCE). Untuk mengamati produk korosi, jenis korosi dan biokompatibilitas spesimen uji, dilakukan serangkaian penelitian lanjutan menggunakan SEM/EDX, foto penampang melintang dan AAS (Atomic Absorb Spectrometry). Hasil yang diperoleh dari pengujian polarisasi potensiodinamik dan exposure mengindikasikan ketahanan korosi yang berada pada level paling baik dengan laju korosi < 1 mpy dan memenuhi standar aplikasi medis untuk Eropa, yaitu dibawah 0,457 mpy. Laju korosi yang baik diperoleh melalui hadirnya lapisan pasif dalam lingkungan Artificial Blood Plasma (ABP). Spesimen yang memenuhi standar pengujian tersebut adalah spesimen uji nomor 6 berupa paduan kobalt ASTM F 75 hasil metalurgi serbuk dengan kandungan 1% Si. Untuk aspek biokompatibilitas, material ini masih memiliki kelemahan jika digunakan sebagai implan permanen. Pengujian dengan teknik exposure selama 1 minggu mengindikasikan jumlah ion Co dan Ni terlarut yang mendekati ambang batas maksimum, mengacu kepada standar aplikasi medis bahwa ambang batas maksimum ion Co adalah < 3,50 ppm sedangkan ion Ni adalah < 1,10 ppm. Peningkatan kandungan Si hingga 1% dalam spesimen paduan kobalt ASTM F 75 hasil metalurgi serbuk dapat memperbaiki ketahanan korosi dan biokompatibilitasnya.

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As a biomaterial implant, one of important properties that must be possessed by cobalt alloys is an outstanding corrosion resistant and good value of biocompatibility in biological environment such as Artificial Blood Plasma (ABP). The specimen used on this experiment was powder metallurgy cobalt alloy ASTM F 75 tablet shape with silicon content variation 0 ? 1%. To observe the corrosion kinetics of powder metallurgy cobalt alloy ASTM F 75, this experiment were carried out in Artificial Blood Plasma (ABP) by potentiodynamic polarization and exposure (immersion) test at pH 7,4 and 37 ºC under several constant conditions maintained. The experiment data processing was accorded to ASTM standard. Potential scan rate was 3mV/sec with range -0,25 Volt to 0,25 Volt. The counter electrode was carbon, while reference electrode was Saturated Calomel (SCE). Product corrosion, form corrosion and biocompatibility follow observed by SEM/EDX, cross sectional area and AAS (Atomic Absorb Spectrometry). The observation data achieved from potentiodynamic polarization and exposure test indicated an outstanding corrosion resistance by less than 1 mpy and less than 0,457 refer to Europe medical application standard. Outstanding corrosion resistance from the material have correlated by present of passive film in Artificial Blood Plasma . The specimen have passed standard requirements was specimen number 6 (1% silicon content). On biocompatibility aspect, this material still had weaknesses for permanent medical uses. Exposure test on 1 week period indicated that dissolved Co and Ni close to maximum limit. These referred to medical application standard that the maximum limit of dissolved Co and Ni were < 3,50 and < 1.10 ppm. Increasing silicon content till 1% on powder metallurgy cobalt alloy ASTM F 75 enhanced corrosion resistance and biocompatibility of material."