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All Journal Traksi : Majalah Ilmiah Teknik Mesin Jurnal Pendidikan Teknologi dan Kejuruan Jurnal Sains Materi Indonesia SINTEK JURNAL: Jurnal Ilmiah Teknik Mesin ROTOR: JURNAL ILMIAH TEKNIK MESIN Widyariset Jurnal METTEK (Jurnal Ilmiah Nasional Dalam Bidang Ilmu Teknik Mesin) Science and Technology Indonesia Majalah Ilmiah Material, Komponen dan Konstruksi Jurnal AUDI Jurnal Rekayasa Material, Manufaktur & Energi Indonesian Journal of Chemistry NUSANTARA : Jurnal Ilmu Pengetahuan Sosial Majalah Ilmiah Pengkajian Industri Metalurgi Jurnal Metalurgi dan Material Indonesia Journal of Engineering and Scientific Research (JESR) Piston: Journal of Technical Engineering Widyariset Teknomekanik Indonesian Journal of Engineering and Science (IJES) Journal of Materials Exploration and Findings (JMEF) Malcom: Indonesian Journal of Machine Learning and Computer Science Metalurgi Jurnal Sains Materi Indonesia Recent in Engineering Science and Technology
Rini Riastuti, Rini
Departemen Teknik Metalurgi Dan Material, Fakultas Teknik, Universitas Indonesia, Depok
Aerospace Engineering Astronomy Automotive Engineering Biochemistry, Genetics & Molecular Biology Chemical Engineering, Chemistry & Bioengineering Chemistry Civil Engineering, Building, Construction & Architecture Computer Science & IT Control & Systems Engineering Decision Sciences, Operations Research & Management Earth & Planetary Sciences Economics, Econometrics & Finance Education Electrical & Electronics Engineering Energy Engineering Environmental Science Immunology & microbiology Industrial & Manufacturing Engineering Library & Information Science Materials Science & Nanotechnology Mechanical Engineering Neuroscience Physics Transportation

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STUDY OF INFLUENCE TIME IN THE IMPROVEMENT OF NICKEL CONTENTS ON LIMONITE PROCESSING USING NAOH Rini Riastuti; Kautsar Muwahhid; Ahmad Maksum; Johny Wahyuadi Soedarsono; Mhd. Ibkar Yusran Asfar
ROTOR Vol 15 No 2 (2022)
Publisher : Jurusan Teknik Mesin Fakultas Teknik Universitas Jember

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.19184/rotor.v15i2.34326

Abstract

Logam nikel didominasi oleh bijih sulfida, namun 70% sumber nikel dunia adalah bijih laterit, yang hanya menyumbang 40% dari output nikel dunia. Menanggapi kenaikan permintaan dan penurunan deposit nikel sulfida, pemurnian nikel bijih laterit dan teknik produksi hidrometalurgi untuk bijih laterit semakin intensif. Silikon dapat diekstraksi dari bijih nikel laterit dengan NaOH. Berbagai penelitian menunjukkan bahwa metode ini dapat meningkatkan kandungan nikel dari residu pelindian, memungkinkan limbah sisa untuk digunakan kembali dan mengurangi dampak lingkungannya. Penelitian ini bertujuan untuk mengetahui apakah mekanisme pengendapan dapat secara efektif memisahkan nikel dan kobalt dari pengotor lainnya. Limonit dilindi menggunakan larutan NaOH dengan konsentrasi 60 g/L. Durasi pelindian bervariasi antara 30, 60, 90, dan 120 menit. Pengaruh NaOH sebagai larutan pelindian diselidiki dengan pengujian XRD dan AAS. Hasil dari analisis XRD menunjukkan proses pelindian menggunakan NaOH membentuk fasa nikel dan kobalt oksida dan hidroksida dari goetit dan NaOH, dengan fasa lain pada residu pelindian terbentuk seiring dengan bertambahnya waktu pelindian. Pengujian AAS menunjukkan nilai perolehan nikel negatif yang dapat dihasilkan oleh kontaminan pada sampel awal, pelarutan ion nikel, dan kopresipitasi, dimana ion nikel diserap ke dalam fase besi hidroksida. Selain itu, uji AAS juga menunjukkan nilai perolehan kembali kobalt pada waktu pelindian 30 menit adalah 1,41%, yang berarti bahwa waktu tersebut adalah waktu optimum untuk pelindian kobalt. Sedangkan waktu yang melebihi 30 menit dapat menurunkan kadar kobalt karena pengenceran ulang dan pengendapan bersama.
Pengaruh Anneal Hardening Dan % Reduksi Warm Rolling Terhadap Sifat Mekanik Paduan Cu-Zn 70/30 [Influence of Anneal Hardening And Warm Rolling % Reduction To Mechanical Properties of Cu-Zn 70/30] Eka Febriyanti; Dedi Priadi; Rini Riastuti
Metalurgi Vol 31, No 1 (2016): Metalurgi Vol. 31 No. 1 April 2016
Publisher : National Research and Innovation Agency (BRIN)

Show Abstract | Download Original | Original Source | Check in Google Scholar | Full PDF (1577.138 KB) | DOI: 10.14203/metalurgi.v31i1.93

Abstract

Copper alloy has many uses in industry. However, in its application requires high mechanical properties. Therefore, copper alloys has been hardened conventionally by solution and/or precipitation hardening and dispersion hardening then is experienced with anneal hardening mechanism through an annealing process at 150-300 °C. In this research, Cu-Zn 70/30 alloys was subjected to warm rolling with 50% and 60% in reduction percentage followed by annealing. Several examinations was done after warm rolling such as microhardness testing, tensile testing, metallography, and FESEM (field emission scanning electron microscope). The results show that anneal hardening was occured at 300 °C followed by increasing of hardness value, tensile strength, and decreasing of elongation. Anneal hardening mechanism in Cu-Zn 70/30 was obtained by increasing % reduction during warm rolling and anneal process. This is caused by Zn element which is segregated into dislocation and observed with FESEM analysis as deformation band. With increasing of % reduction to Cu-Zn 70/30 alloy will also results denser and thicker deformation bands.AbstrakPaduan tembaga memiliki banyak kegunaan dalam bidang industri. Namun, dalam aplikasinya membutuhkan sifat mekanis yang tinggi. Oleh karena paduan tembaga sulit dilakukan pengerasan secara konvensional seperti alloying, precipitation hardening, dan dispersion hardening maka yang dilakukan adalah dengan mekanisme anneal hardening melalui proses anil pada suhu 150-300 °C. Pada penelitian ini, paduan Cu-Zn 70/30 dilakukan warm rolling pada suhu 300 °C dengan presentase reduksi 50% dan 60%. Karakterisasi yang dilakukan setelah proses di atas adalah uji kekerasan secara mikro, uji tarik, pengamatan metalografi, dan analisa dengan FESEM (field emission scanning electron microscope). Hasil pemeriksaan menunjukkan bahwa efek anneal hardening muncul pada suhu 300 °C yang diikuti dengan peningkatan nilai kekerasan dan kekuatan tarik, namun persen elongasinya menurun. Dengan semakin besarnya % reduksi warm rolling diikuti dengan proses anneal yang dilakukan terhadap paduan Cu-Zn 70/30 mengakibatkan terjadinya anneal hardening. Hal ini disebabkan karena adanya unsur Zn yang tersegregasi dalam dislokasi dan teramati dengan FESEM sebagai pita-pita deformasi (deformation band). Dengan meningkatnya % reduksi yang diberikan pada paduan juga akan menghasilkan pita-pita deformasi yang semakin rapat dan tebal.
Pengaruh Waktu Tahan ketika Proses Thermo Mechanical Controlled Process (TMCP) terhadap Sifat Mekanik dan Fenomena Anneal Hardening Paduan Cu-Zn 70/30 Eka Febriyanti; Amin Suhadi; Ahmad Fadli; Rini Riastuti
Piston: Journal of Technical Engineering Vol 4, No 1 (2020)
Publisher : Prodi Teknik Mesin

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.32493/pjte.v4i1.7352

Abstract

Paduan Cu-Zn 70/30 memiliki sifat konduktivitas panas dan listrik yang sangat baik serta mampu bentuk yang baik. Cu-Zn 70/30 sangat luas digunakan sebagai core dan tank radiator otomotif, komponen amunisi, maupun perangkat bangunan dan arsitektur. Thermo-Mechanical Controlled Processing (TMCP) adalah salah satu metode rangkaian pengontrolan pemanasan dan pembentukan dengan tujuan meningkatkan kualitas sifat material. Oleh karena itu, pada penelitian ini digunakan metode TMCP dengan canai hangat untuk meningkatkan sifat mekanik paduan Cu-Zn 70/30. Proses canai dilakukan dengan metode bolak-balik dengan deformasi sebesar 60% (30%-30%) dimana pada setiap pass-nya paduan Cu-Zn dipanaskan terlebih dahulu pada temperatur 300°C dengan waktu tahan berbeda mulai dari 30, 60, dan 120 menit. Berdasarkan hasil penelitian didapatkan kesimpulan bahwa dengan semakin lamanya waktu pemanasan dan kemudian dideformasi lebih lanjut maka terjadi penurunan mencapai 36,5 μm yang berpengaruh pada peningkatan kekerasan sebesar 174,12 HV dan kekuatan tarik mencapai 525,4 MPa pada waktu tahan 120 menit. Ditambah lagi, terdapat indikasi adanya fenomena Anneal Hardening karena tersegregasinya atom terlarut pada dislokasi atau batas butir sehingga memberikan pengaruh yang cukup signifikan terhadap nilai kekerasan dan kekuatan tarik paduan Cu-Zn 70/30.
Prediksi Sisa Umur Layan dan Analisa Resiko pada Power Transformer Menggunakan pendekatan Distribusi Weibull dan Risk Priority Number: Prediction of Remaining Service Life and Risk Analysis on Power Transformers Using The Weibull Distribution and Risk Priority Number Approach Krisnandha Rahardian; Rini Riastuti; Ahmad Zakiyuddin
MALCOM: Indonesian Journal of Machine Learning and Computer Science Vol. 4 No. 1 (2024): MALCOM January 2024
Publisher : Institut Riset dan Publikasi Indonesia

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.57152/malcom.v4i1.1068

Abstract

Transformator adalah peralatan mahal dan krusial dalam sistem transmisi dan distribusi tenaga listrik. Berperan penting dalam menjaga keandalan dan efisiensi pasokan listrik, transformator terus menerima tekanan termal, listrik, mekanik, dan kimia selama operasinya. Oleh karena itu, penilaian penuaan transformator memerlukan parameter komprehensif, terutama karena panas terbuang menjadi faktor pembatas untuk beban maksimum. Kelangsungan operasional transformator menjadi isu penting, dan kegiatan pemantauan, inspeksi, dan pemeliharaan rutin diperlukan untuk mencegah pemadaman yang tidak diinginkan. Dalam penelitian ini, pendekatan dilakukan dengan mendekomposisi transformator menjadi bagian-bagian dan melakukan analisis risiko kuantitatif serta evaluasi prioritas. Lowest Replacable Unit (LRU) dievaluasi menggunakan Weibull++, Life Data Analisis, dan software reliasoft. Hasil analisis menunjukkan bahwa Power Transformer (TR-01) milik PT ABC di Area Integrated Terminal berada dalam kondisi baik dan layak beroperasi. Simulasi Weibull++ menunjukkan umur sisa 275 bulan (22.9 tahun), dengan reliabilitas 86% untuk 4 tahun ke depan dan nilai risk priority number Medium High (3D). Kesimpulan dari analisis ini memberikan keyakinan bahwa transformator berfungsi dengan baik dan dapat diandalkan dalam operasionalnya.
EFFECT OF THIOSULFATE CONCENTRATION AND LEACHING TEMPERATURE IN AMMONIACAL THIOSULFATE LEACHING OF REFRACTORY SULFIDE GOLD ORE Rini Riastuti
TRAKSI Vol 23, No 2 (2023): TRAKSI
Publisher : Universitas Muhammadiyah Semarang

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.26714/traksi.23.2.2023.152-161

Abstract

Thiosulfate as gold leach solution first studied in 1979 to found alternative of cyanide and mercury solution which are widely used in gold extraction industry although it’s negative impact for the environment. The ore sample is native ore from Bolaang Mongondow, North Sulawesi. According to Optical Microscope observation and LIBS characterization, there are pyrite compound which is one of the chacaracteristic of sulfide ore. According to X-ray fluorescence and Inductively Coupled Plasma, the ore contained about 14.62% Fe, 6.69% S, 0.15% Cu, and 0.27 ppm Au. This study aimed to determine the effect of thiosulfate concentration and leaching temperature in ammoniacal thiosulfate leaching of refractory gold sulfide ores on the solubility of gold. This research was conducted by laboratory scale of leaching method. The leaching result is then checked by Inductively Coupled Plasma (ICP). The concentration of thiosulfate (0.05M, 0.1M, and 0.2M) and the effect of temperature (250 C, 400 C, 600 C) were studied. Maximum gold extraction (62%) was obtained using 0.1M of thiosulfate concentrations at 400 C for 2 h with 20% of pulp density. Stirring speed and the pH of the aqueous solution were 400 rpm and 10, respectively. According to the results, it can be concluded that the concentration of Thiosulfate solution and leaching temperature will affect the dissolution of gold.
Risk Management of Carbon Steel Piping in Sweet Environment Multiphase Fluid Production Tiggor, Triadhi Panthun; Riastuti, Rini
Journal of Materials Exploration and Findings Vol. 1, No. 2
Publisher : UI Scholars Hub

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Abstract

As well reserved depleted and limited, it is necessary to lower the capital expenditure so that lifting SZ reservoir be more profitable. This article first contextualizes the effort done to increase the hydrocarbon lifting in a mature field. Despite the importance to sustain the production, and massive studies done to quantify the associate risk, no structured methodology proposed to manage the risk in respect to optimize the production expenditure by selection of carbon steel as alternative for corrosion resistance material piping. Hence, this article proposed a framework to support the decision-making process to operate in safely manner. Real case study proposed and evaluated shown 6.72-millimetre metal loss due to SEC and CO2 corrosion is expected to occur within 5 years’ design life. Hence, carbon steel pipe is allowed considering the risk mitigation define are provided and continuously monitored. Results shows the proposed framework increase the confidence level in putting the assessment results into proper decision-making process whilst improving the integrity management system.
Multi-Mode Total Focusing Method (MTFM) to Detect High-Temperature Hydrogen Attack (HTHA) – A Review Oktikawati, Anjar; Riastuti, Rini; Yuanto, Nursidi
Journal of Materials Exploration and Findings Vol. 2, No. 1
Publisher : UI Scholars Hub

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Abstract

High temperature hydrogen attack (HTHA) is a commonly observed harm component in carbon steels exposed to high temperature and pressure in a hydrogen-rich environment. Hydrogen together with carbon responds to produce methane. The formation of methane bubbles in steel can lead to loss of fracture toughness and lead to intergranular cracking. The main challenge of this problem lies in early warning systems that can detect these bubble clusters before they reach the advanced stage. Several advanced ultrasonic inspections have been developed over the years due to the challenges of inspecting materials for defects and discontinuities. These cover time-of-flight diffraction (ToFD), phased array ultrasonic testing (PAUT), total focusing method (TFM), multi-mode total focusing method (MTFM), and others. However, these ultrasonic techniques used are typically used to detect all possible material defects. This paper briefly discusses the advantages and disadvantages of these techniques. MTFM has been successfully applied to characterize isolated or clustered signs, whether tilted or not, using high-frequency probes. The defects grouped in this paper are believed to be methane bubbles or HTHA. ToFD defect screening before aims to save time and money.
Local Chlorhexidine Delivery for Periodontal Infection Therapy: A Short Review Najmudin, Muhammad Guruh; Pangesty, Azizah Intan; Riastuti, Rini; Sunarso, Sunarso; Abdullah, Abdul Halim
Journal of Materials Exploration and Findings Vol. 2, No. 2
Publisher : UI Scholars Hub

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Abstract

Oral diseases affected more than half of the world’s population. Periodontitis is the second biggest threat to oral health after dental caries. Periodontitis is an inflammation inside periodontal pockets caused by pathogenic microbial colonies which lead to destruction of bone tissue and soft tissue. Chlorhexidine gluconate is an antimicrobial agent that effective to destroy pathogenic microbial and cure periodontitis. Chlorhexidine gluconate is given locally using a carrier material to the infected area. There are several materials that can be used to deliver Chlorhexidine gluconate to the infected periodontal tissue such as gel, liquid (mouthwash), and chip. This short review aims to describe the current methods to deliver Chlorhexidine gluconate to the infected periodontal tissue, including the advantages, disadvantages, and the future trend of the carrier materials used for periodontitis treatment. Future research about materials that can help to optimize tissue restorative after cure periodontitis would be beneficial.
Analysis of the Effect of Different Surface Preparation Methods on Corrosion Resistance and Adhesion Strength of ASTM A36 Steel Substrate with Surface Tolerant Epoxy Paint as Coating Material Santoso, Irwan Wijaya; Aqila, Daffa; Riastuti, Rini; Ramadhani, Rizal Tresna
Journal of Materials Exploration and Findings Vol. 3, No. 1
Publisher : UI Scholars Hub

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Abstract

In the industrial world, to extend the service life of materials, protection methods are carried out to slow down the material's corrosion rate. The protection method that is often used is the coating method. The coating method is a protection method by coating the substrate material using a coating material to prevent contact between the substrate material and the environment. In this research, the substrate material used is ASTM A36 steel and the coating material used is Surface Tolerant Epoxy paint. The independent variable used in this study lies in the surface preparation method which consists of: solvent cleaning, hand tool cleaning, power tool cleaning, power tool to bare metal cleaning, and abrasive blast cleaning. Different preparation methods result in different roughness and cleanliness of the surface. This can affect changes in the mechanical properties of the coating material, such as corrosion resistance and adhesion strength. Based on the corrosion resistance test, it is found that the abrasive blast cleaning and power tool to bare metal cleaning methods produce the highest corrosion resistance properties because both have a rating number of 8 in the salt spray test results. Based on the adhesion strength test, it is found that the abrasive blast cleaning method also produces the highest adhesion strength. This conclusion refers to the results of the tape x-cut test where the sample produces a rating number 5A where the sample does not experience peeling after testing. In addition, the abrasive blast cleaning method produced the highest adhesion strength in the pull-off test, which was 7.16 MPa. Thus, the abrasive blast cleaning method is the most effective surface preparation method for ASTM A36 steel before being coated with the coating material. In addition, it can also be concluded that the higher the surface roughness of the sample, the better the corrosion resistance and adhesion strength. Whereas abrasive blast cleaning method have 122.95 µm roughness and 7.16 MPa adhesion strength which is the highest in roughness and adhesion strength.
Development of 485 MPa Class High Strength Low Alloy Steel for Power Plant Infrastructures Baskoro, Agung; Riastuti, Rini
Journal of Materials Exploration and Findings Vol. 3, No. 1
Publisher : UI Scholars Hub

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Abstract

Currently, Indonesia is progressing to build 35,000 MW of power plants, which will increase the demand for materials, especially steel. One of these power plants is fossil fuel-based, which generates not only electricity but also flue gas containing sulfur that may cause corrosion to power plant infrastructure such as chimney or boiler areas. In addition, apart from being resistant to corrosion in sulfuric and hydrochloric acid conditions, the steel used in power plant infrastructure must also have good strength, toughness, and weldability. Therefore, the present paper describes about steel development for power plant applications that has not only corrosion resistance in sulfuric and hydrochloric acid environments but also good mechanical properties through the addition of vanadium as micro alloy element combined with the implementation of a thermo-mechanical controlled process (TMCP) in hot rolling process. The results showed that chemical composition and mechanical properties of the product comply with the standards ASTM A588 Grade A for high strength low alloy steel with atmospheric corrosion resistance. The measured atmospheric corrosion index is 6.54. Thus, the mechanical properties of the steel produced are yield strength of 512-518 MPa, tensile strength of 662-664 MPa, and elongation of 40-42%. The microstructure of the product is ferrite and perlite, with an average grain size of ASTM No. 12.10 (5.2-5.5 µm) classified as very fine grain.
Co-Authors Abdullah, Abdul Halim Adam Hidana Yudo Saputro, Adam Hidana Yudo Adi Noer Syahid Adipurnama, Iman Agus Supriyanto Ahmad Fadli Ahmad Fadli Ahmad Maksum Ahmad Zakiyuddin Akhmad Faizal Alfian Alfian Amalia, Dinda Putri Amanda, Putri Amin Suhadi Amin Suhadi Amin Suhadi Amin Suhadi Amin Suhadi Amin Suhadi, Amin Andryansah Andryansah Anjar Oktikawati Aqila, Daffa Aulia, Hafiz Ayu Rizeki Ridhowati Ayu Rizeki Ridhowati Azizah Intan Pangesty Bashari R Roszardi Baskoro, Agung budiarto, wahyu Chalid, Muchamad Dedi Priadi Dedi Priadi Dedi Priadi Dedi Supriadi Diana Natalia Eka Febriyanti Eka Febriyanti Eka Febriyanti Eka Febriyanti Eka Febriyanti Eka Febriyanti Eka Febriyanti Eka Febriyanti Febi Dwi Antony febriyanti, eka febriyanti, eka Febriyanti, Eka Gadang Priyotomo Gadang Priyotomo Hari Eko Irianto Ifah Munifah Irawan, Januar IRWAN WIJAYA J.W. Soedarsono Jamal Basmal, Jamal Jamhari Jamhari Johny Wahyuadi Soedarsono Kaban, Agus S Kautsar Muwahhid Kautsar Muwahhid Krisnandha Rahardian Kusumaningrum, Wida Banar Manurung, Rizky Rama Putra Mega Herawati Arifiana Amanah Notonegoro, Mega Herawati Arifiana Amanah Mhd. Ibkar Yusran Asfar Mochamad Chalid Muhammad Refai Muslih Muhammad Rifai Muhammad Yunus Najmudin, Muhammad Guruh Nikitasari, Arini Nono Darsono Nono Darsono, Nono Nurhayati Nurhayati Nurhayati Putri Salsabila, Syanatha Rachmat Hermawan Ramadhani, Rizal T Ramadhani, Rizal Tresna Ramdhani, Rizal Tresna Riady, Rado Ridhowati, Ayu Rizeki Ridhowati, Ayu Rizeki Rinta Kusumawati, Rinta Rinush Fedrikdo Paltgor Rizal Tresna Ramdhani Roszardi, Bashari Rohululloh Roziafanto, Ahmad Nandang Santoso, Irwan Wijaya SATRIYAS ILYAS Sunarso Sunarso Syahid, Adi Noer Tiggor, Triadhi Panthun Tri Handayani Tri Hardi Priyanto Wahyu Budiarto Winarto Winarto Yuanto, Nursidi