Jusami | Indonesian Journal of Materials Science
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NOVEL MAGNETISM IN PERMANENT MAGNETS
No full textAn overview on the physics of hard magnetic materials is given. The basic considerations leading to hard magnetic properties are discussed. All groups of industrial permanent magnets such as: Al-Ni-Co, ferrites. Sm-Co based, Nd-Fe-B are presented. The most important production methods are described. The advantage and disadvantages of each magnet group is given
PREPARATION OF BARIUM HEXAFERRITE BY SOL GEL SELF COMBUSTION USING POLYVINYL ALCOHOL
Get PDFPREPARATION OF BARIUM HEXAFERRITE BY SOL GEL SELF COMBUSTION USING POLYVINYL ALCOHOL. Barium hexaferrite powders were produced by sol-gel auto-combustion. Ferric and barium nitrate in the molar ratio of 1:2, and Poly Vinyl Alcohol (PVA) are used as starting materials. After gelation with ammonium hydroxide, dehydration and subsequent mechanical milling, auto combustion and calcination at temperature from 300 oC to 1250 oC were performed to produce barium ferrite powder. XRD pattern showed barium ferrite phase started to form at temperature of 500 oC and grew to single phase at 1000 oC, with hexagonal structure. At this stage, the powder has saturation and remanence magnetization of 50.9 emu/g and 33.6 emu/g, respectively, and coercivity of 2.94 kOe
THE EFFECT OF CALCINATION ON MICROWAVE ABSORBING PROPERTIES OF Fe3O4/TiO2 COMPOSITE
Get PDFTHE EFFECT OF CALCINATION ON MICROWAVE ABSORBING PROPERTIES OF Fe3O4/TiO2 COMPOSITE. The Fe3O4/TiO2 composites have been fabricated by simple precipitation method for microwave absorbing. The obtained powder of Fe3O4/TiO2 which 10 % iron oxide containing were calcinated from 300oC – 700oC for 3 hours. The characteristic of samples was investigated by various techniques. The TEM image showed the composites form agglomeration with particles size of around 20 nm. The all sample contents most of the anatase phase. The increasing of calcination temperature is the bigger of crystallite size. The Raman bands shift towards lower wavenumber and their full-widths at half-maximum (FWHM) of the bands decreases as the particles size increase. The measurement of the magnetic properties illustrated that the Fe3O4/TiO2 exhibited paramagnetic behavior at room temperature. The microwave absorbing properties of the sample was measured by VNA using frequency microwave filter in X-band range (8-12 GHz). The reflection loss (RL) values were calculated for thickness 1 mm of the sample. The minimum reflectivity peak value tends to decrease with the increase of the calcination temperature due to increasing the crystallite size of the particles. The lowest reflectivity value of Fe3O4/TiO2 was occurred calcinated at 600oC with -13.4 dB loss at 10.9 GHz, that is more 80% absorbed of the electromagnetic wave in thickness 1 mm of the sample. The microwave absorption properties the calcinated 700oC the sample decrease due to the loss of magnetic properties of the sample. This study concluded that increase in average crystalline size, microwave absorption properties increased. However, the decrease dratisly of magnetic properties of the sample causes microwave absorption properties to decrease
DEVELOPMENT OF LOCAL COMPONENTS FOR FUEL CELL TECHNOLOGY
Get PDFDEVELOPMENT OF LOCAL COMPONENTS FOR FUEL CELL TECHNOLOGY. The limitation of oil and gas, dependence of system using energy besides oil fuel, and also awareness of environmental friendly policy have become urgency of fuel cell research. Alternative energy becomes main priority development in the world. Not only in developed countries such as US, Japan, Europe and Canada, many developing countries in Asia are running up to catch the hydrogen used technology. Furthermore, Indonesian policy of energy are shown a requirement to develop on renewable energy and the primary energy mix (Perpres 5/2006, 25 Januari 2006, Kepmen ESDM No. 0983 K/16/MEM/2004, Kepmen ESDM No. 0002/2004, PP No. 03/2005 about change to PP No.89/1989). According to national research strategy, especially of hydrogen and fuel cell technology in 2009, manufacture and production technology, distribution, security of hydrogen and PEMFC technologies is needed. Indeed, in 2025 Indonesia must have national attached PEMFCs 50 kW and capacities goals of 250 MW. On the other hand, vehicle of fuel cell will step into market in the year 2010-2015. The market for mobile fuel cells, with DMFC technologies expected to account for a large portion, is projected to reach US$ 2.6 billion by 2012. Therefore, fuel cell technology is become a crucial technology including of opportunity of local component to contribute in manufacturing fuel cell technology and also a hydrogen storage technology systems. Herein we described the development of various components of fuel cell along with the process such as polyelectrolyte membrane of PEMFC and DMFC, bipolar plate and steam reforming methane with inorganic membrane in BPPT
PENGUJIAN KEKERASAN PRODUK LOGAM FEROMAGNETIK DENGAN PENGUKURAN DERAU BARKHA USEN MAGNETIK
No full textPENGUJIAN KEKERASAN PRODUK LOGAM FEROMAGNETIK DENGAN PENGUKURAN DERAU BARKHA USEN MAGNETIK. Untuk menjamin kualitas dari produk-produk manufaktur massal, diperlukan pengujian secara tidak merusak (Nondestructive Testing) yang memiliki kecepatan pengujian serta ketelitian yang tinggi. Untuk produk-produk yang telah mengalami perlakuan panas, untuk mendapatkan nilai kekerasan tertentu, misalnya komponen-komponen otomotif, perlu diuji untuk menjamin kualitas yang diinginkan. Beberapa parameter seperti koersivitas dan permeabilitas dapat digunakan untuk karakterisasi bentuk kurva histerisis. Sifat-sifat ketergantungan bentuk kurva histeresis pada kekerasan mekanik, pengerjaan panas dan keberadaan tegangan sisa, dapat dimanfaatkan untuk pengukuran kekerasan produk yang bersifat feromagnetik. Khusus untuk pengukuran kekerasan ini, parameter yang diukur hanyalah koersivitas. Nilai koersivitas diperoleh dengan pengukuran derau Barkhausen magnetik. Dalam tulisan ini akan dipaparkan bagaimana pengukuran harga koersivitas dapat dilakukan dengan menggunakan efek Barkhausen, serta kajian tentang korelasi antara harga koersivitas dengan kekerasan suatu material feromagnetik dengan menggunakan metoda analisis regresi
AC MAGNETIC RESPONSE IN (Bi-2223+SrCO3)/Ag SUPERCONDUCTING TAPES
No full textAC MAGNETIC RESPONSE IN (Bi-2223+SrCO3)/Ag SUPERCONDUCTING TAPES. A Bi-22231 Ag superconducting tape has been fabricated by means of conventional PIT, followed by eccentric and two axial rolling and heat treatment were introducing an oxide additive (SrCO3) as a barrier. Temperature dependent of AC magnetic susceptibility measurements have been conducted at various external field Ba. The resulted data were analyzed on the basis of strip model using the wills bandfoiitizilation. It was found that the imaginary part ofthe critical current density at O K (Jco) is consistently larger than its real part, but both of them tend to decrease with increasing Ba
PENGARUH MILLING TERHADAP STRUKTURMIKRO, FASA DAN SIFAT MAGNETIK SISTEM KOMPOSIT Co-Al
Get PDFPENGARUH MILLING TERHADAP STRUKTURMIKRO, FASA DAN SIFAT MAGNETIK SISTEM KOMPOSIT Co-Al. Telah dilakukan penelitian tentang pengaruh waktu milling terhadap sifat magnetik bahan komposit Co-Al. Penelitian dilakukan dengan mencampur serbuk Co dan Al di dalam vial stainless steel menggunakan High Energy Milling (HEM). Komposisi yang digunakan adalah Co73Al27 wt% dengan rasio perbandingan berat campuran serbuk Co-Al terhadap bola-bola baja 1:2,7. Waktu milling divariasikan pada 4,5 jam, 12 jam dan 20 jam. Hasil pengamatan dari pola difraksi sinar-x menunjukkan terjadi penurunan ukuran kristalit dari 103,04 Å menjadi 71,536 Å dan 18,576 Å. Pengamatan sifat magnetik bahan dilakukan menggunakan VSM model OXFORD versi 2.1, hasil pengukuran menunjukkan harga Ms mengalami penurunan dari 156 emu/g, 113 emu/g dan 107 emu/g. Hal ini menunjukkan bahwa proses miling berpengaruh terhadap sifat magnetik bahan
PERANAN BAHAN MAGNET DAN KEMAGNETAN UNTUK PENGOLAHAN LIMBAH NUKLIR DAN NON NUKLIR
Get PDFPERANAN BAHAN MAGNET DAN KEMAGNETAN UNTUK PENGOLAHAN LIMBAH NUKLIR DAN NON NUKLIR. Sistem magnet dan elektromagnet telah ditemukan lebih dari satu abad yang lalu. Pada awalnya sistem ini diaplikasikan pada pembuatan generator untuk menghasilkan energi listrik. Dalam perkembangannya berbagai bidang seperti industri, kedokteran, pertambangan, perminyakan dan lingkungan juga memanfaatkan sistemini.Manajemen limbah pada umumnya telah banyak dipresentasikan dengan berbagai prosedur alternatif penanganan limbah dan sistem magnet dan elektromagnet banyak dikembangkan untuk berbagai keperluan seperti : separasi komponen, pencegahan korosi,menurunkan tegangan muka, pembentukan kristal, meningkatkan fungsi desinfektan dan pertumbuhan kecambah. Walaupun belum diketahui secara pasti bagaimana mekanisme efek sistem magnet dan elektromagnet berfungsi untuk beberapa tujuan, terutama pada teknik separasi atau bioteknologi, namun alat komersial yangmenggunakan sistemmagnet dan elektromagnet telah beredar luas, misalnya unit pengolahan air, pengolahan limbah (gas, cairan, dan padatan), berbagai alat medis, dan alat industri terutama pertambangan dan perminyakan. Sejak tiga dasa warsa ini, sistem magnet dan elektromagnet banyak diteliti dan dikembangkan, untuk pengolahan limbah berbahaya termasuk bahan radioaktif atau nuklir. Dimana polemik tentang limbah terutama bahan nuklir dewasa ini makin terasa. Di satu sisi manfaat bahan nuklir untuk berbagai bidang seperti industri energi, medis, dan pertanian telah dapat dibuktikan, disisi lain masyarakat masih trauma dengan resiko dan akibat yang ditimbulkan pada limbah yang dihasilkan dan ketika terjadi insiden kecelakaan
THE USE OF POLYMER GEL ELECTROLYTE CONTAINING I-/I3- REDOX COUPLE TO ASSEMBLY A SOLID STATE DYE SENSITIZED TiO2 SOLAR CELL
Get PDFTHE USE OF POLYMER GEL ELECTROLYTE CONTAINING I-/I3- REDOX COUPLE TO ASSEMBLY A SOLID STATE DYE SENSITIZED TiO2 SOLAR CELL. A solid state dye sensitized TiO2 nanocrystalline solar cells was assembled employing a polymer gel electrolyte contains of iodide/triiodide (I-/I3-) redox couple. The use of solid electrolyte based on polymer matrix for redox ‘couples is aimed to overcome several problems of liquid cell, such as leaks of electrolyte that result in degradation of solar cell. TiO2 nanocrystalline layer was grown on TCO glass substrate by doctor blade technique was stained by synthetic dye Ruthenium 535 for a day. To complete the cell, a polymer gel based on poly(ethylene glycol) (PEG) containing I-/I3- redox couple was sandwiched between a working electrode (nanoporous TiO2 layer on conductive glass substrate) and a counter electrode (graphite sheet). The solid-state cell does not need a clipp, so the gel polymer electrolyte also acts as a glue to join the electrodes. Two cells assembled with different amount of I-/I3- redox couple used in each cell, one of cell use 20 drops of Iodolyte (contains (I-/I3- redox couple) and another cell use 30 drops of Iodolyte solution (purchased fromSolaronix, SA). The cells were characterized their photovoltaic performances included: open-circuit voltage (Voc), short-circuit current (Isc),maximum power (Pmax), fill factor (FF) and energy conversion efficiency