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Pengaruh Peningkatan Derajat Deformasi Canai Hangat Terhadap Karakteristik Deformation Band Paduan Cu-Zn 70/30 Eka Febriyanti; Dedi Priadi; Rini Riastuti
Jurnal Material Komponen dan Konstruksi Vol. 15 No. 2 (2015)
Publisher : Badan Pengkajian dan Penerapan Teknologi (BPPT)

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.29122/mkk.v15i2.3373

AbstractÂ Cu-Zn 70/30 alloyÂ has properties that is relatively soft, ductile, and easy to perform by cold working. However, cold working has the disadvantage that require equipment which has higher loading capacity to generate strength and higher density thus increasing of machining cost. In addition, strain hardening phenomenon due to cold working process resulted in decreasing of ductility material. Therefore, it is necessary alternative fabrication processes to optimize the mechanical properties of Cu-Zn alloy 70/30 that with the TMCP method. TMCP is metal forming material by providing large and controlled plastic strain to the material. TMCP using the deformation percentage variation that 32.25%, 35.48%, and 38.7% from hot rolled research at 500Â°C temperature in double pass reversible which performed on Cu-Zn 70/30 plate. By tensile testing using universal testing machine can be seen that the Cu-Zn 70/30 alloy on 32.25% degree of deformation, both of UTS and YS respectively are 505 MPa and 460 MPa. Whereas from examination of thickness and density deformation bands by FE-SEM shows denser and thicker deformation band proportional with increasing of deformation degree.Moreover, the values of tensile strength at the edge of the area and the center is directly proportional to the density and thickness of the deformation band.Â Paduan Cu-Zn 70/30 memiliki sifat yang relatif lunak, ulet, dan mudah dilakukan pengerjaan dingin. Namun, pengerjaan dingin memiliki kekurangan yaitu membutuhkan peralatan yang memiliki kapasitas pembebanan tinggi untuk menghasilkan kekuatan dan kepadatan tinggi sehingga meningkatkan biaya permesinan. Selain itu, fenomena pengerasan regang akibat proses pengerjaan dingin menghasilkan penurunan keuletan material. Oleh karena itu, diperlukan alternatif proses fabrikasi untuk mengoptimalkan sifat mekanik paduan Cu-Zn 70/30 salah satunya dengan metode TMCP. TMCP merupakan suatu proses perubahan bentuk suatu material dengan cara memberikan regangan plastis yang besar dan terkontrol terhadap material. TMCP dengan menggunakan variasi persentase deformasi sebanyak 32,25%, 35,48%, dan 38,70% dari penelitian canai hangat di suhu 500oC secara double pass reversible dilakukan pada pelat paduan Cu-Zn 70/30. Dengan melakukan pengujian tarik menggunakan mesin uji tarik universal testing machine dapat dilihat bahwa pada material paduan Cu-Zn 70/30 pada derajat deformasi 32,25% menghasilkan nilai UTS dan YS masing-masing sebesar 505 MPa dan 460 MPa. Sedangkan dari hasil pengamatan ketebalan dan kerapatan deformation band menggunakan FE-SEM menunjukkan deformation band yang lebih rapat dan lebih tebal sebanding dengan semakin meningkatnya derajat deformasi.Â Selain itu, nilai kekuatan tarik pada daerah tepi dan tengah berbanding lurus dengan kerapatan dan ketebalan deformation band.Â Keywords:Â 70/30 Cu-Zn alloy, warm rolled, deformation degree, deformation bandsÂ

DESAIN ALAT UJI NOSEL DENGAN MENGGUNAKAN PRINSIP TEROWONGAN ANGIN SUPERSONIK Bagus H. Jihad; Dedi Priadi
Jurnal Teknologi Dirgantara Vol 9, No. 1 Juni (2011)
Publisher : National Institute of Aeronautics and Space - LAPAN

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The accuracy of nozzle design can be improved by validation. Two methods of validation is software or hardware application. The software can be either CFD software or special software for the nozzle design, such as NOZZLE ® or Aerospike ®. The limitations of CFD software is on unsteady flow conditions. while the limitations of special software is the obscurity of assumptions used. Therefore, the flow validation experimental is important to be implemented. Lapan has three units of wind tunnels, namely subsonic, transonic and supersonic. They have the capability to measure the external flow of the body. While the nozzle design purpose is mostly to investigate the internal flow of the nozzle. Therefore, the nozzle flow testing system which is called a mini wind tunnel has been designed.This wind tunnel is designed to have speed of Mach 2.4, but the effective speed of 2 Mach. By using a calculation we obtain the run time of 46 seconds. If we assume the pressure drop is 40%, then actually the run time is 28 seconds.Keyword:Windtunnel, Nozzle, Supersonic, Run-time, Schlieren

THE COMPARATION OF TWO LAPAN'S PROPELLANTS OF DIFFERENT COMPOSITION Bagus H. Jihad; Tresna P. Soemardi; Dedi Priadi
Jurnal Teknologi Dirgantara Vol 5, No.1 Juni (2007)
Publisher : National Institute of Aeronautics and Space - LAPAN

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This paper compares two LAPAN'S propellant compositions. The A propellant has a composition of AP/AL/Binder with ratio of 70/10/20, and propellant B has ratio 75/7.5/17.5, both with HTPB base but different curing agent. As comparator of this simulation is RX-1512.01 rocket that has flight tested. The performances which compared are specific impulse and efficiency characteristic. Result shows that the propellant B gives higher specific impulse, however higher losses is, about 5.373 percent. One to be considered is that the propellant B produce combustion temperature higher than propellant A by 200 k, that may influence the rocket structures. Keywords: Impuls specific, characteristic efficiency, propellant, simulation.

EFFECT OF SULFUR IN THE REDUCTANTS ON SULFIDATION MECHANISM OF NICKEL LATERITE Fajar Nurjaman; Yuliana Sari; Anton Sapto Handoko; Fathan Bahfie; Ulin Herlina; Muhammad Miftahurrahman; Dedi Priadi; Deni Ferdian; Bambang Suharno
Indonesian Mining Journal Vol 24, No 2 (2021): INDONESIAN MINING JOURNAL, Vol. 24 No. 2, October 2021
Publisher : Puslitbang tekMIRA

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.30556/imj.Vol24.No2.2021.1216

Processing nickel laterite conventionally, namely by pyrometallurgy method, requires high temperature and energy, results in a costive process. Due to its lower temperature reduction process, selective reduction with additives could be an alternative in nickel ore processing. Additives such as sulfur/sulfate have a critical role in promoting the low melting point phase. Sulfur is also found in coal. Therefore, it is important to investigate the effect of sulfur content in reductant on selective reduction of lateritic nickel ore. In this work, the effect of sulfur content (2.68% and 5% S) in anthracite coal as a reductant on selective reduction of limonitic ore was studied clearly. Nickel ore, reductant and sodium sulfate were mixed homogenously and pelletized up to 10-15 mm in diameter. Pellets were reduced using a muffle furnace at 950 to 1150°C for 60 min. Reduced pellets were crushed into -200 mesh before separating the ferronickel and its impurities using a wet magnetic separation process. The result showed that the anthracite coal with 5% S produced concentrate containing 3.56% Ni with 95,97% recovery, which is higher than 2.68% S. The sulfur content in reductant could replace the addition of sulfur/sulfate as the additives in the selective reduction of lateritic nickel ore.

Effect of Calcium Carbonate Content on the Mechanical and Thermal Properties of Chitosan-Coated Poly(urethane) Foams Elvi Kustiyah; Achmad Nandang Roziafanto; Majid Amrullah; Dedi Priadi; Mochamad Chalid
Indonesian Journal of Chemistry Vol 22, No 3 (2022)
Publisher : Universitas Gadjah Mada

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.22146/ijc.72135

In this work, the effect of chitosan and CaCO3 coating on polyurethane (PU) foam on the mechanical and thermal properties was studied. PU-foams were soaked in a mixture of chitosan- calcium carbonate solution at different concentrations, i.e., 0.1–0.4%. The molecular behaviors due to the incorporation of chitosan/CaCO3 into the PU-foam matrix were investigated by Fourier-Transform Infrared (FTIR) spectroscopy. Field Emission Scanning Electron Microscope (FE-SEM) was utilized to study the effect of chitosan/CaCO3 coat on the pore structure of PU-foam. FTIR spectra show changes in the peak of 1446 and 1413 cm–1, which serve as evidence of molecular interaction between PU and chitosan/CaCO3. FE-SEM images show that the addition of chitosan/calcium carbonate cells was starting to close together, probably due to the increased dispersion of calcium carbonate on the entire surface of PU-foams/chitosan, which indicates that reducing the size of the cell will increase mechanical properties. From this study, it was found that PU-foam soaked in 0.4% CaCO3 had the highest tensile strength. Coating PU-foam with 0.4% CaCO3 also improved its thermal stability, indicated by an increase in its residual mass compared to neat PU-foam.

Analisa Gaya Penekanan pada Proses ECAP Batang Kuningan CuZn 70/30 Suryadi -; Amin Suhadi; Dedi Priadi; E. S. Siradj
Majalah Ilmiah Pengkajian Industri Vol. 8 No. 1 (2014): Majalah Ilmiah Pengkajian Industri
Publisher : BRIN

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.29122/mipi.v8i1.3646

Telah dilakukan percobaanÂ severe plastic deformationÂ (SPD) dengan metodeequal channel angular pressingÂ (ECAP) pada batang kuningan CuZn 70/30 diameter 10 mm sampai 5 pas. Gaya penekanan meningkat secara signifikan pada awal langkah penekanan dan mencapai nilai maksimum lalu melandai. Pada pas pertama gaya penekanan mencapai 115 kN, pas kedua 130 kN, pas ketiga mecapai 150 kN dan pada pas keempat 165 kN. Dari pengukuran luas area di bawah kurva gaya penekanan diperoleh energi total pembentukan pada proses ECAP batang kuningan persatuan panjang adalah 95 Joule/mm pada pas pertama, sampai 130 Joule/mm pada pas ketiga, dan turun 125 Juole/mm pada pas keempat. Secara kumulatif total energi persatuan panjang meningkat secara linier sesuai dengan peningkatan jumpah pas, dimana pada pas keempat mencapai 597 MPa. Peningkatan gaya penekanan dan energi penekanan sebanding dengan terjadinya peningkatan kekerasan pada batang kuningan dan terjadinya penghalusan butir.Kata kunci:Â ECAP, gaya penekanan, energi pembentukan, kekerasan, penghalusan butir, kuningan.AbstractExperiments of severe plastic deformation (SPD) have been carried out by the method of equal channel angular pressing (ECAP) on brass rods CuZn 70/30 diameter 10 mm to 5 pas. Pressing force significantly is increased emphasis on early steps and reaches a maximum value and then ramp. At the first pas the pressing force reached 115 kN, the second pass 130 kN, the third pass 150 kN and fouth pass is 165. From measurements of the area under the curve of pressing force, the total forming energy per unit length generated to form the brass rod in ECAP is 95 Joule / mm at the first pass, 130 Joules / mm at third pass and down to 125 Joule/mm at fouth pass. Cumulatively, the total forming energy per unit length increases linearly according to the increase in number of ECAP pass, where the fourth pass reach 597 Joule/mm. Increased emphasis pressing load and forming energy is proportional to the increase in hardness of the brass rod and the grain refinement.Keywords:Â ECAP, pressing load, forming energy, hardness, grain refinement, Brass

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)

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.

EFFECT OF SULFUR IN THE REDUCTANTS ON SULFIDATION MECHANISM OF NICKEL LATERITE Fajar Nurjaman; Yuliana Sari; Anton Sapto Handoko; Fathan Bahfie; Ulin Herlina; Muhammad Miftahurrahman; Dedi Priadi; Deni Ferdian; Bambang Suharno
Indonesian Mining Journal Vol 24 No 2 (2021): INDONESIAN MINING JOURNAL, Vol. 24 No. 2, October 2021
Publisher : Balai Besar Pengujian Mineral dan Batubara tekMIRA

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.30556/imj.Vol24.No2.2021.1216

Processing nickel laterite conventionally, namely by pyrometallurgy method, requires high temperature and energy, results in a costive process. Due to its lower temperature reduction process, selective reduction with additives could be an alternative in nickel ore processing. Additives such as sulfur/sulfate have a critical role in promoting the low melting point phase. Sulfur is also found in coal. Therefore, it is important to investigate the effect of sulfur content in reductant on selective reduction of lateritic nickel ore. In this work, the effect of sulfur content (2.68% and 5% S) in anthracite coal as a reductant on selective reduction of limonitic ore was studied clearly. Nickel ore, reductant and sodium sulfate were mixed homogenously and pelletized up to 10-15 mm in diameter. Pellets were reduced using a muffle furnace at 950 to 1150°C for 60 min. Reduced pellets were crushed into -200 mesh before separating the ferronickel and its impurities using a wet magnetic separation process. The result showed that the anthracite coal with 5% S produced concentrate containing 3.56% Ni with 95,97% recovery, which is higher than 2.68% S. The sulfur content in reductant could replace the addition of sulfur/sulfate as the additives in the selective reduction of lateritic nickel ore.

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