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Abstrak :
Noise (derau) merupakan masalah serius bagi masyarakat di kota-kota besar dan daerah industri karena berdampak merugikan terhadap kesehatan baik jasmani maupun rohani. Penelitian ini bertujuan untuk mensintesis beberapa Komposit Akustik sebagai bahan bangunan pengendali noise berbentuk pelat padat yang terbuat dari variasi bahan-bahan Magnesium Sulfate (MgSO4), Limbah Kertas, Glass Wool,Pumice, Alumina (Al2O3) dengan binder Polyvinyl Acetate (PVAc) serta melakukan uji akustik terhadap salah satu komposit yang dilengkapi dengan Resonator Helmholtz dan Resonator Quarter Wavelength. Karakterisasi terhadap komposit-komposit uji dilakukan menggunakan XRD, FTIR, EDAC, SEM, BET-Quantachrome, Universal Testing Machine dan Impedance Tube untuk mengetahui sifat sifat fisis dan kimiawi serta kemampuan pengendalian masing-masing komposit terhadap noise. Hasil menunjukkan bahwa komposit yang disintesis dari MgSO4, Limbah Kertas dengan binder PVAc dan Semen mempunyai harga rugi transmisi bunyi (Sound Transmission Loss) dengan harga maksimum 9 dB diatas kurva STC standar pada daerah frekwensi antara 315 Hz sampai 4000 Hz. Kemudian pada uji koefisien serapan terhadap komposit jenis ini diperoleh harga koefisien serapan bunyi tertinggi sebesar 0,52 pada daerah frekwensi antara 350 Hz?800 Hz. Adapun pengujian terhadap komposit berbasis Pumice dan Alumia (Al2O3) dengan binder PVAc maka harga koefisien serapannya jika tanpa resonator hanya berada dibawah 0,12 saja pada hampir seluruh frekwensi terukur, dan pengujian setelah dilengkapi dengan Resonator Quarter Wavelength mempunyai harga koefisien serapan tertinggi 0,28 pada daerah frekwensi antara 1000 Hz sampai 4500 Hz, sedang dengan Resonator Helmholtz harga koefisien serapan maksimum mencapai 0,9 pada daerah frekwensi rendah dibawah 1000 Hz. Disimpulkan bahwa komposit hasil uji berbasis MgSO4 dan Limbah Kertas mempunyai kemampuan menyerap noise diatas komposit berbasis MgSO4 dan Glass Wool pada daerah frekwensi 350 ? 800 Hz, sedang komposit uji berbasis Pumice dan Alumina (Al2O3) yang dilengkapi dengan Resonator merupakan bahan alternatif yang baik sebagai komponen bahan bangunan untuk penyerap noise pada daerah frekwensi rendah dan menengah karena berkekuatan tinggi, tahan api setelah dilakukan pembakaran dan tahan air setelah dilakukan uji rendam dalam air selama 1 bulan, ekonomis, serta mudah diproduksi. ......Noise (unwanted sound) is a kind of pollution that hits public community in many cities and industrial areas, harms human health both physically and psychologically. The aim of the investigation is producing an Acoustical Composite as building material component for controlling noise. The method was conducted by synthesizing and characterizing various composites made from crushed materials: MgSO4, Paper Waste, Glass Wool, Pumice and Alumina (Al2O3) by mechanical mixing with Polyvinyl Acetate (C4H6O2)n as binder without resonator, and one kind of the composite that equipped by Quarter Wavelength Resonator and Helmholtz Resonator. The Physical and Chemical Properties of each sample has been characterized by XRD, FTIR, EDAC, SEM, BET-Quantachrome Nova,Universal Testing Machine and Impedance Tube. The experiment results show that the composite synthesized by MgSO4 and Paper Waste has value of maximum sound transmission loss about 9 dB at the frequency range between 315 Hz - 4000 Hz, and maximum sound absorption coefficient is 0,52 at the frequency range between 350 Hz - 800 Hz. While the composite fabricated by pumice and Alumina(Al2O3) with Polyvinyl Acetate as binder without resonator has absorption coefficient below 0,12 at all measured frequencies area. It so happens the value of absorbtion coefficient of this composite that equipped by Quarter Wavelength Resonator has value about 0,28 at frequency range between 1000 Hz - 4500 Hz, and the composite that equipped by Helmholtz Resonator inside the synthesized composite has maximum value about 0,9, it effectively absorbs noise especially at low frequencies area below 1000 Hz. It is concluded that the tested composite based on MgSO4 and Paper Waste has better ability in absorbing noise than the composite based on MgSO4 and Glass Wool at the frequency range between 350 ? 800 Hz, while the composite based on Pumice dan Alumina (Al2O3) which bound by Polyvinyl Acetate and equipped by Resonator is a good alternative as a building material component for noise absorber at low and medium frequencies area because has high strength, fire resistant, water proof, low in cost and easy to produce.

Abstrak :
[ABSTRAK
Material solder saat ini banyak menggunakan Sn-Pb. Saat ini ada permasalahan lingkungan yaitu Pb yang bersifat racun. Selain itu terjadi fenomena Whiskers yang dapat menyebabkan hubungan pendek pada peralatan elektronik Telah dilakukan sintesa material solder bebastimbal Sn-0.7Cu-xBi/Zn. Pada sampel dilakukan karakterisasi x-ray difraksi. Dilakukan analisis Rietveld untukm emperoleh parameter kristalografidant eksturpa daarah bidang tertentu untuk melihat fenomena whisker. Hasilanilisa Rietveld memperlihatkan penambahan unsurBismut dengan konsentrs i tertentu pada paduan Sn-0.7Cu-xBi dapat merubah teksturpada bidang kristalografi tertentu ditandai dengant ingginya kerapatan pole figure yang dapat diartik antingginya keseragaman orientasikristalit yang dapat menja di penghambat whiskers dibidangtersebut.;

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ABSTRACT
Solder material is using Lead (Pb) recently. Toxity of lead was creating environtment issue now. Beside of that whiskers phenomena could make short at electronics circuits. Synthesis of Sn-0.7Cu-xBi/Zn lead free solder materials have been conducted. These alloys were being characterized by using XRD diffractometer. Crystallographic paratemeters and texture of certain plane have been extracted to observe whiskers phenomena The result from Rietveld refinement show that adding certain Bismuth concentration could change texture of Sn-0.7Cu-xBi alloy at certain crystall plane. This condition was being show by high density of pole figure, means crystallite orientation more uniform. High density of pole figure at certain crystall plane could become whisker inhibitor. ;Solder material is using Lead (Pb) recently. Toxity of lead was creating environtment issue now. Beside of that whiskers phenomena could make short at electronics circuits. Synthesis of Sn-0.7Cu-xBi/Zn lead free solder materials have been conducted. These alloys were being characterized by using XRD diffractometer. Crystallographic paratemeters and texture of certain plane have been extracted to observe whiskers phenomena The result from Rietveld refinement show that adding certain Bismuth concentration could change texture of Sn-0.7Cu-xBi alloy at certain crystall plane. This condition was being show by high density of pole figure, means crystallite orientation more uniform. High density of pole figure at certain crystall plane could become whisker inhibitor. , Solder material is using Lead (Pb) recently. Toxity of lead was creating environtment issue now. Beside of that whiskers phenomena could make short at electronics circuits. Synthesis of Sn-0.7Cu-xBi/Zn lead free solder materials have been conducted. These alloys were being characterized by using XRD diffractometer. Crystallographic paratemeters and texture of certain plane have been extracted to observe whiskers phenomena The result from Rietveld refinement show that adding certain Bismuth concentration could change texture of Sn-0.7Cu-xBi alloy at certain crystall plane. This condition was being show by high density of pole figure, means crystallite orientation more uniform. High density of pole figure at certain crystall plane could become whisker inhibitor. ]

Abstrak :
[ABSTRAK
Pembuatan bahan Cu-ZnFerrite dapat dilakukan dengan teknik Flow Injection Synthesis-FIS, dimana proses pembentukan bahan dilakukan secara reaksi kimia basah yang mengh asilkan pengendapan ?yield, dengan bahan baku FeCl2.4H2O, FeCl2.6H2O, CuCl2.2H2O, dan ZnCl2. Teknik FIS merupakan metode ko-presipitasi yang dilakukan secara terstruktur sehingga kecepatan reaksi, temperatur, dan pH bahan baku dapat diatur, direkam dengan skala produksi dapat dikembangkan dalam jumlah yang relatif besar. Fraksi yield merupakan fungsi dari pH larutan dan temperatur reagent yang berada dalam reaktor FIS. Parameter proses seperti; pH, temperatur (T), dan waktu proses(t) dapat direkam dengan memori elektronik SD-Card pH datalogger. Pengolahan data parameter proses pH dapat dilakukan relatif cepat sehingga diperoleh estimasi nilai entalpi dan kinetika pembentukan partikel bahan dengan teori dasar Avrami-Ozawa dan Kissinger. Salah satu macam produk yang diteliti adalah Bahan Cu-ZnFerrite. Karakteristik dasar bahan uji tersebut mampu menghsilkan nilai validitas dan reliabilitas tinggi yang direpresentasikan dalam bentuk nilai kesalahan pada rata rata atom. Dari 6 sampel berbeda tingkat krsalahan pembentuk senyawa Cu-ZnFerrite 0.85% dengan reliabilitas >0.9. Hal ini menunjukkan sistem FIS sebagai sistem alat ukur dan pemrosesan bahan Cu-Znferrite memiliki kemampuan ukur dan proses yang sahih-valid dan konsistensi-reliability, sehingga memungkinkan dapat digunakan untuk estimasi energi pembentukan pembentukan Cu-ZnFerrite dengan formulasi Cu(1-x) ZnxFe2O4 pada rentang x antara 0.35 sampai 0.45. Hasil estimasi nilai entalpi rata rata Cu-ZnFerrite 0.65[kcal/mol]. Secara kinetik bentuk partikel adalah batang berukuran paling besar 1,53 um dengan laju pembentukan 50 [nm/sec]. Uji Karakterisasi Difraksi SinarX, Ukuran partikel-Particle Size Analyser, dan Permagraf memperlihatkan partikel bahan Cu-ZnFerrite mudah dipengaruhi oleh atom yang berada baik pada sisi tetrahedral maupun sisi oktahedral Kristal spinel bahan.;

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ABSTRACT
The manufacture of Cu-ZnFerrite can be done by using the Technical of Flow Injection Synthesis-FIS, where the material forming process carried out by wet chemical reactions that produce the precipitation matter ?yield. The raw materials were; FeCl2.4H2O, FeCl3.6H2O, CuCl3.2H2O, and ZnCl2. The FIS technique developed by major reactor components such as; adiabatic reactor, peristaltic pumps and pH datalogger, where a co-precipitation synthesis method is done in a structured so that the reaction speed, temperature, and pH of the raw material can be arranged, recorded and scale of production can be developed in a relatively large amount. The process parameters such of pH, temperature (T), and the processing time (t) were recorded with an electronic memory SD-Card Datalogger and it can be performed in order to obtain both the enthalpy value and the kinetics of the material formation. The particle kinetic can be analyzed with the basic theory of Avrami-Ozawa and Kissinger. The baseline characteristics of the test material capable to result of both the instruments validity and reliability parameter values, which are represented in the form of a low error rate on the average atomic-forming compounds Cu-ZnFerrite a rounds 0.85% and reliability value more than 0.9 .The FIS system as a system of measuring and processing of Cu-Znferrite have ability to measure the parameter process as valid and consistency with high-reliability. In the estimation process of the formation energy of formation of Cu-ZnFerrite or as Cu (1-x) ZnxFe2O4 where x in the range of 0:35 to 0:45. the formation enthalpy of the Cu-ZnFerrite is 0.65 [kcal / mol], the particle shape is rod with a 1.53 um size and the growth formation rate is 50 [nm / sec]. The characterization of either X-ray Diffraction, Particle Size Analyser, or Permagraf show the Cu-ZnFerrite materials are easily become unstable particles by atomic both in the tetrahedral or octahedral spinel crystal sides; The manufacture of Cu-ZnFerrite can be done by using the Technical of Flow Injection Synthesis-FIS, where the material forming process carried out by wet chemical reactions that produce the precipitation matter ?yield. The raw materials were; FeCl2.4H2O, FeCl3.6H2O, CuCl3.2H2O, and ZnCl2. The FIS technique developed by major reactor components such as; adiabatic reactor, peristaltic pumps and pH datalogger, where a co-precipitation synthesis method is done in a structured so that the reaction speed, temperature, and pH of the raw material can be arranged, recorded and scale of production can be developed in a relatively large amount. The process parameters such of pH, temperature (T), and the processing time (t) were recorded with an electronic memory SD-Card Datalogger and it can be performed in order to obtain both the enthalpy value and the kinetics of the material formation. The particle kinetic can be analyzed with the basic theory of Avrami-Ozawa and Kissinger. The baseline characteristics of the test material capable to result of both the instruments validity and reliability parameter values, which are represented in the form of a low error rate on the average atomic-forming compounds Cu-ZnFerrite a rounds 0.85% and reliability value more than 0.9 .The FIS system as a system of measuring and processing of Cu-Znferrite have ability to measure the parameter process as valid and consistency with high-reliability. In the estimation process of the formation energy of formation of Cu-ZnFerrite or as Cu (1-x) ZnxFe2O4 where x in the range of 0:35 to 0:45. the formation enthalpy of the Cu-ZnFerrite is 0.65 [kcal / mol], the particle shape is rod with a 1.53 um size and the growth formation rate is 50 [nm / sec]. The characterization of either X-ray Diffraction, Particle Size Analyser, or Permagraf show the Cu-ZnFerrite materials are easily become unstable particles by atomic both in the tetrahedral or octahedral spinel crystal sides, The manufacture of Cu-ZnFerrite can be done by using the Technical of Flow Injection Synthesis-FIS, where the material forming process carried out by wet chemical reactions that produce the precipitation matter –yield. The raw materials were; FeCl2.4H2O, FeCl3.6H2O, CuCl3.2H2O, and ZnCl2. The FIS technique developed by major reactor components such as; adiabatic reactor, peristaltic pumps and pH datalogger, where a co-precipitation synthesis method is done in a structured so that the reaction speed, temperature, and pH of the raw material can be arranged, recorded and scale of production can be developed in a relatively large amount. The process parameters such of pH, temperature (T), and the processing time (t) were recorded with an electronic memory SD-Card Datalogger and it can be performed in order to obtain both the enthalpy value and the kinetics of the material formation. The particle kinetic can be analyzed with the basic theory of Avrami-Ozawa and Kissinger. The baseline characteristics of the test material capable to result of both the instruments validity and reliability parameter values, which are represented in the form of a low error rate on the average atomic-forming compounds Cu-ZnFerrite a rounds 0.85% and reliability value more than 0.9 .The FIS system as a system of measuring and processing of Cu-Znferrite have ability to measure the parameter process as valid and consistency with high-reliability. In the estimation process of the formation energy of formation of Cu-ZnFerrite or as Cu (1-x) ZnxFe2O4 where x in the range of 0:35 to 0:45. the formation enthalpy of the Cu-ZnFerrite is 0.65 [kcal / mol], the particle shape is rod with a 1.53 um size and the growth formation rate is 50 [nm / sec]. The characterization of either X-ray Diffraction, Particle Size Analyser, or Permagraf show the Cu-ZnFerrite materials are easily become unstable particles by atomic both in the tetrahedral or octahedral spinel crystal sides]

Abstrak :
Perkembangan industri elektronik di Indonesia semakin maju pesat dan tentunya membutuhkan tingkat akurasi produksi yang tinggi serta proses yang ramah terhadap lingkungan. Paduan solder SnPb perlu ditinjau karena sudah dilarang pengunaanya mulai 1 juli 2006 di negara maju mengingat sifat toxic Pb yang sangat berbahaya. Sebagai salah satu alternatif untuk mengganti unsur Pb maka dilakukan modifikasi unsur Zn yang dipadukan dengan unsur timah (Sn) dan tembaga(Cu) untuk memperoleh sifat fisik dan mekanik yang mendekati sifat SnPb. Metoda penggabungan secara metalurgi pada proses pembasahan dengan dasar sudut kontak dan pencapaian suhu solidus juga sebagai bentuk karakterisasi yang diperlukan. Pengujian dilakukan terhadap paduan terner Sn-0.7Cu-xZn dengan metoda peleburan Sn dan Cu yang dilanjutkan dengan penambahan variasi unsur Zn 22,24;19,37;16,47,15,14;14,29 dan 9,08 % dan dilakukan pengujian temperatur leleh (DSC test) serta pengujian pemanasan diatas tembaga,, mampu basah (wettability), tegangan geser (shear stress),kerapatan massa(density), kekerasan mikro dan makro(Micro and Macro hardness), dan pengamatan struktur mikro. Hasil pengujian menunjukkan bahwa penambahan kandungan Zn pada paduan terner berbasis Sn-0.7Cu-xZn akan menurunkan temperatur leleh secara signifikan. Kekuatan geser paduan terner terbesar diperoleh pada penambahan 9,08% Zn serta terkecil diperoleh pada penambahan 22,24 % Zn. Tingkat kekerasan paduan terner Sn0.7CuxZn terbesar diperoleh pada prosentase 22,24 % Zn dan terkecil diperoleh pada prosentase 9,08% Zn. Adapun dari pengamatan struktur mikro terlihat bahwa sebaran fasa intermetalik Cu3Sn dan fasa eutektik Sn cukup signifikan terjadi pada paduan Sn0.7CuxZn;

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Electronic industrial has developed rapidly as customer consumption. So that for an accuracy level and environmentally friendly is needed as base on production process. SnPb soldering is banned in developed country since july 2006, then the aim is to explore the material which have to eliminate Pb by using other free lead element to void toxic of lead solder as human health and environment protection. One of the potential element was studied is Zinc alloyed Tin and Copper on variety composition of Zinc. The method was carried out by using XRD measurement, microstructure observation and melting point tested to analyses hardness, shear strength and wettability behavior. Experimentally as shown that increasing of Zn (22,24;19,37;16,47;15,14;14,29 and 9,08) has effect to physically and mechanical properties. Shear stress on terner alloys has higher value in 22,24%Zn, and lower value in 14,29%Zn. Hardness level on terner alloys has higher value in 14,29%Zn and lower value in 12%Zn. Melting point has decreasing in increasing of Zinc content. Metallography observation has identified that intermetalic Cu3Sn and eutectic Sn are scattered in Sn0.7CuxZn alloy.

Abstrak :
Bahan yang memiliki sifat ferroelektrik dan ferromagnetik berpotensi sebagai absorber gelombang mikro dan memiliki peranan penting pada dunia militer. BiFeO3 merupakan salah satu bahan multiferroik yang memiliki sifat ferroelektrik dan ferromagnetik. Pada penelitian ini dilakukan rekayasa sintesa BiFeO3 dengan doping Yttrium dan Seng dengan variasi konsentrasi (%wt) 6, 12, dan 18%. Sintesa BiFeO3 telah berhasil disintesis dengan metode sol-gel autocombustion. Melalui uji XRD, fasa BiFeO3 diperoleh pada temperatur 750°C selama 5 jam. Hasil refinement menunjukkan bahwa BiFeO3 memiliki struktur kristal rhombohedral space grup R3c. BiFeO3 doping Yttrium dan Seng di atas 12% (%wt) terjadi perubahan struktur kristal dari rhombohedral ke orthorombic. Kurva hysterisis menunjukkan bahwa BiFeO3 memiliki saturasi magnetik 3.04 emu/g, remanen magnetik 0.26 emu/g, dan medan koersivitas 0.0013 T. BiFeO3 doping Yttrium dengan konsentrasi (%wt) 12% terjadi peningkatan nilai saturasi magnetik, remanen magnetik, dan medan koersivitas namun BiFeO3 doping Seng dengan konsentrasi (%wt) 12% terjadi penurunan nilai saturasi magnetik, remanen magnetik, dan medan koersivitas. BiFeO3 doping Yttrium 12% (%wt) dan Seng 12% (%wt) memiliki nilai saturasi magnetik 8.18 emu/g, remanen magnetik 2.92 emu/g, medan koersivitas 0.0036 T. Pada frekuensi 1 kHz BiFeO3 memiliki konstanta dielektrik sebesar 239.12 dan adanya doping Yttrium dan Seng terjadi penurunan nilai konstanta dielektrik. Hasil pengujian sifat penyerapan gelombang mikro pada frekuensi X band (8.2 ? 12.4 GHz) diperoleh bahwa bahan Bi0.88Y0.12FeO3/C memiliki refleksi loss -39.42 dB pada frekuensi resonansi 11.47 GHz. Dengan demikian bahan Bi0.88Y0.12FeO3/C dapat dijadikan bahan penyerap gelombang mikro pada frekuensi X band. ...... Materials with both ferroelectric and ferromagnetic properties are potential candidate for microwave absorbers and play important role in military world. One of them is BiFeO3, a multiferroic material with both ferroelectric and ferromagnetic properties. In this research, BiFeO3 has been synthesized successfully via auto-combustion sol-gel method. To improve its properties, yttrium- and zinc-doped BiFeO3 has been synthesized with various doping concentrations, i.e. 6, 12, and 18 wt.%. X-ray diffraction patterns showed that BiFeO3 phase was obtained after heating at 750ᵒC for 5 hours with rhombohedral crystal structure and space group of R3c. The hysteresis curve of BiFeO3 showed a magnetic saturation of 3.04 emu/g, magnetic remnant 0.26 emu/g and coercive field 0.0013 T. Yttrium- and zinc-doped BiFeO3 over 12wt.% showed a structural change from rhombohedral to orthorhombic with magnetic saturation of 8.18 emu/g, the magnetic remnant of 2.92 emu/g and coercive field of 0.0036 T. Yttrium-doped BiFeO3 showed an increase in the magnetic saturation, the magnetic remnant and the coercive field; however zinc-doped BiFeO3 showed a decrease in the magnetic saturation, the magnetic remnant and coercive field. At a frequency of 1 kHz, the dielectric constant of BiFeO3 was 239.12, and this value will decrease when it was doped by yttrium and zinc. Further investigation on the application of this material, composites Bi0.88Y0.12FeO3/C has also been synthesized. The composites showed a reflection loss of -39.32 dB within the frequency range of 8.2-12.4 GHz (X-band) particularly at the frequency of 11.47 GHz with the absorptivity of 98.60%. Based on this results, composite Bi0.88Y0.12FeO3/C material could be used as a potential microwave absorber in the X-band frequency.

Abstrak :
ABSTRAK
Telah dilakukan sintesa material BiFeO3, Bi 1-x MgxFeO3 x = 0,07 dan x = 0,1 dan BiFe 1-y ZnyO3 y = 0,07 dan y = 0,1 dengan metoda sol-gel autocombustion. Material Precursor yang digunakan adalah Bi5O O 9 NO3 4 dan Fe NO3 3.9H2O dan Asam sitrat sebagai bahan bakar. Sebagai dopant Mg digunakan Mg NO3 2.6 H2O dan sebagai dopant Zn digunakan Zn NO3 2.4 H2O. Temperatur proses sol-gel dijaga antara 80-90oC. Proses autocombustion dilakukan pada temperature 150oC selama 2 jam. Proses kalsinasi dilakukan pada temperature 550oC selama 10 jam. Semua material hasil sintesa berupa material multifasa. Material yang dihasilkan memiliki rumus molekul BiFeO3, Bi0,93Mg0,07FeO3, Bi0,91Mg0,09FeO3, BiFe0,97Zn0,03O3 dan BiFe0,92Zn0,08O3. Semua material hasil sintesa bersifat soft ferromagnetic dan ferroelektrik. Intersisi Mg pada BiFeO3, menyebabkan peningkatkan magnetisasi saturasi dan magnetisasi remanen, penurunan medan magnet koersif, penurunan polarisasi saturasi dan polarisasi remanen dan menaikan medan listrik koersif BiFeO3. Substitusi Zn2 terhadap Fe3 , menyebabkan penurunan nilai magnetisasi saturasi dan magnetisasi remanen, menaikan medan magnet koersif, menurunkan polarisasi saturasi dan polarisasi remanen dan menurunkan medan listrik koersif BiFeO3

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ABSTRACT
BiFeO3, Bi 1-x MgxFeO3 x = 0.07 and x = 0.1 and BiFe 1-y ZnyO3 y = 0.07 and y = 0.1 materials have been synthesised, using sol-gel auto combustion method. Bi5O OH 9 NO3 4 and Fe NO3 3.9H2O as precursor materials and citric acid as fuel. Mg dopants use Mg NO3 2.6H2O and Zn dopants use Zn NO3 2.4 H2O. Sol-gel process temperature is maintained between 80-90oC. Auto combustion process rsquo;s temperature is 150oC for 2 hours. The calcination process is performed at temperature 550oC for 10 hours. all material synthesis results are multiphase materials. The resulting materials have molecular formula BiFeO3, Bi0,93Mg0,07FeO3, Bi0,91Mg0,09FeO3, BiFe0,97Zn0,03O3 and BiFe0,92Zn0,08O3. All synthesis results materials are soft ferromagnetic and ferroelectric. Interstitial Mg in BiFeO3 causing increasing saturation and remanent magnetization, decreasing coercive magnetic field, decreasing saturation and remanent polarization, and increasing coercive electric field of BiFeO3. Substitution of Zn2 to Fe3 reducing the value of saturation and remanent magnetization, increasing coercive magnetic field, decreasing saturation and remanent polarization, decreasing coercive electric field of BiFeO

Abstrak :
ABSTRAK
Telah dilakukan penelitian pengaruh penambahan Fe dan Sr berhadap perubahan struktur mikro paduan hipoeutektik Al-7% Si dan paduan eutektik Al-11% Si terutama terhadap pembentukan fasa intermetalik dan nilai fluiditas paduan dengan metode vakum (vacum suction test). Perancangan dan pembuatan alat uji fluiditas metode vakum ini dilakukan untuk meminimalisasi kekurangan-kekurangan yang didapat dari pengujian fluiditas metode spiral dan metode lainnya. Hasil perancangan dan pembuatan alat ini untuk mendapatkan pengukuran temperatur dan kecepatan tuang yang lebih presisi pada saat melakukan pengujian fluiditas. Penelitian yang telah dilakukan oleh para peneliti sebelumnya, beberapa telah meneliti penggunaan Sr sebagai modifier, akan tetapi belum ada penelitian yang memfokuskan pada keterkaitan antara Sr sebagai modifier dan nilai fluditas dari paduan hipoeutektik Al-7% Si dan paduan eutektik Al-11% Si menggunakan metode vakum. Penelitian yang dilakukan pada prinsipnya dibagi ke dalam beberapa bagian, yaitu pembuatan peralatan uji fluiditas metode vakum dan validitasnya, pembuatan master alloy hipoeutektik dan eutektik serta karakterisasinya, dan rekayasa penambahan unsur Fe dan Sr pada kedua paduan untuk melihat pengaruh penambahan Fe dan Sr terhadap pembentukan fasa intermetalik dan nilai fluiditas kedua paduan. Karakterisasi yang dilakukan adalah analisis struktur mikro, terutama fasa intermetalik yang terbentuk pada paduan Al-7% Si dan Al-11% Si secara kuantitatif dan kualitatif, menggunakan mikrosokop elektron yang dilengkapi spektroskopi sinar-X (SEM/EDX) dan difraksi sinar-X (XRD). Dalam pembuatan peralatan uji fluiditas metode vakum, pengujian validasi dengan menambahkan modifier Sr dan grain refiner Al5TiB pada paduan komersial ADC12 didapatkan hasil yang sesuai dengan literatur. Penambahan 0,03% Sr memberikan nilai fluiditas yang paling baik, sedangkan penambahan 0,15% Al5TiB menghasilkan butir yang halus dan nilai fluiditas yang paling baik. Sementara itu, waktu proses degassing sangat menentukan nilai fluiditas, karena semakin lama waktu degassing yang diberikan akan meningkatkan nilai fluiditas paduan komersial ADC12. Hal ini dapat dipahami karena proses degassing akan menarik gas hidrogen yang ada dalam logam cair, dimana keberadaan gas ini akan menyebabkan cacat pada produk cor. Dari hasil pengujian dan validasi variasi jenis pipa dan tekanan didapatkan bahwa, dalam penelitian ini, pipa tembaga dengan tekanan 8 inHg yang paling baik untuk digunakan. Dari hasil pengujian fluiditas pada paduan Al-7% Si yang ditambahkan Fe, didapatkan bahwa semakin tinggi kadar Fe yang ditambahkan maka nilai fluiditas semakin turun. Hal ini dapat dipahami karena Fe akan membentuk senyawa intermetalik Al-Fe-Si yang mengganggu proses mampu alir paduan aluminium dimana semakin banyaknya fasa intermetalik yang terbentuk akan semakin menurunkan fluiditasnya. Pengujian fluiditas paduan Al-7% Si yang ditambahkan 1,2% Fe; 1,4% Fe; dan 1,6% Fe serta 0,015% Sr- 0,045% Sr memberikan hasil bahwa dengan semakin tingginya temperatur tuang maka nilai fluiditas akan semakin tinggi pada semua komposisi. Pada penambahan 0,03% Sr didapatkan nilai fluiditas yang paling tinggi pada setiap komposisi; dalam hal ini penambahan 0,03% Sr akan memodifikasi silikon primer menjadi lebih bulat dan mengubah morfologi fasa intermetalik menjadi lebih pendek. Dengan bertambahnya kadar Fe maka ukuran panjang dan lebar maupun fraksi luas intermetalik fasa intermetalik ?-Al5FeSi akan semakin meningkat. Pada paduan Al-7% Si didapatkan fasa intermetalik yang paling panjang pada penambahan 1,6% Fe yaitu 22,21 ?m dan yang paling pendek pada penambahan 1,2% Fe yaitu 9,66 _m. Untuk fraksi luas intermetalik yang terbentuk, dengan penambahan Fe yang semakin tinggi, akan menghasilkan fraksi luas intermetalik yang semakin besar. Pada penambahan 1,2% Fe menghasilkan fraksi luas intermetalik 3,67%, sedangkan pada penambahan 1,4% Fe dan1,6% Fe masing-masingnya menghasilkan fraksi luas 4,03% dan 5,23%. Dari hasil pengujian fluiditas pada paduan Al-11% Si yang ditambahkan Fe, juga didapatkan bahwa semakin tinggi kadar Fe yang ditambahkan maka nilai fluiditas semakin turun. Sedangkan pengujian fluiditas paduan Al-11%Si yang ditambahkan Fe dan Sr yang bervariasi juga memberikan hasil yang sama seperti pada paduan Al-7% Si, dimana dengan semakin tinggi kadar Fe yang ditambahkan maka nilai fluiditas paduan akan turun, sedangkan nilai fluiditas yang paling tinggi diberikan oleh penambahan Sr sebesar 0,03%. Pada penambahan 1% Fe memberikan fasa intermetalik yang paling panjang yaitu 50,25 _m, sedangkan fasa intermetalik yang paling pendek diberikan oleh penambahan 0,6 % Fe yaitu 21,3 _m. Pada paduan Al-11% Si umumnya dengan penambahan Fe yang semakin tinggi, akan menghasilkan fraksi luas intermetalik yang semakin besar. Pada penambahan 0,6% Fe menghasilkan fraksi luas intermetalik 1,01%, sedangkan pada penambahan 0,8% Fe dan 1% Fe masing-masingnya menghasilkan fraksi luas 1,16% dan 2,26%. Hasil pengujian fluiditas, baik pada paduan Al-7% Si maupun pada paduan Al-11 %Si memperlihatkan adanya kecendrungan bahwa dengan bertambahnya kadar Fe, akan semakin menurunkan nilai fluiditasnya; akan tetapi apabila ditambahkan dengan Sr, nilai fluiditasnya akan kembali naik. Perubahan nilai fluiditas ini didukung oleh morfologi struktur mikro dari hasil pengujian SEM yang memperlihatkan adanya matrik aluminium, struktur silikon, dan fasa intermetalik. Komposisi yang didapatkan melalui perkiraan hasil EDX diperkuat dengan data dari hasil pengujian XRD yang kemudian mengidentifikasi akan adanya fasa intermetalik ?dan ? . Akan tetapi, jika pada kedua paduan ini ditambahkan modifier Sr maka terjadi perubahan morfologi fasa intermetalik. Dari hal ini dapat disimpulkan bahwa Sr berfungsi mengubah struktur mikro fasa intermetalik yang panjang menjadi lebih pendek dan bulat sehingga akan menaikkan nilai fluiditas dari kedua paduan ini. Pada penambahan 0,03% Sr didapatkan nilai fluiditas paling baik pada setiap komposisi , dalam hal ini penambahan 0,03% Sr akan memodifikasi silikon primer menjadi lebih bulat dan mengubah morfologi fasa intermetalik menjadi lebih pendek.

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ABSTRACT
The effect of Fe and Sr addition on the intermetallic phase(s) formation and fluidity of the hypoeutectic Al-7% Si and eutectic Al-11% Si alloys has been investigated. Vacuum suction test equipment development for fluidity test was designed to minimize the disadvantages from spiral and other fluidity test methods. This fluidity test design was aiming at obtaining a precise temperature measurement and pouring rate in the fluidity test. Many researchers have investigated the role of Sr as a modifier but none of them focused in the relationship of Sr as a modifier and its effect on the fluidity of the hypoeutectic Al-7% Si and eutectic Al-11% Si alloys by using vacuum suction test. In this investigation, the work is divided into several sections, i.e. vacuum suction test equipment designing and development for fluidity test and its validity, synthesis of the hypoeutectic Al-7% Si and eutectic Al-11% Si alloys (master alloys) and their characterization, and effect of Fe and Sr elements addition into the master alloys on the intermetalic phase(s) formation and fluidity. The characterization that has been carried out including microstructure by using electron microscope (SEM/EDX) and X-ray diffraction (XRD). In the test equipment designing and development for fluidity test, validation test on the addition of Sr and grain refiner Al5TiB into commercial ADC12 alloy gives the same result as in literatures, in which the addition of 0.03% Sr gives the best performance while addition of 0.15% Al5TiB results in fine grain and the best fluidity. At the same time, degassing time affects the flowability greatly in which the more time for degassing the better the fluidity of the commercial ADC12 alloy. This can be understood since the degassing process will reduce the hydrogen gas in the melt, which may cause defect in the casting product. The validation test on the vacuum suction equipment also shows that, in this investigation, copper tube with a pressure of 8 inHg provides the best performance. The fluidity test on the Al-7% Si alloy with the addition of Fe shows that the increasing of Fe content results in decreasing of the fluidity. This can be understood since Fe will form an intermetalic phase of Al-Fe-Si, which will interfere and further slow down the flowability of aluminum alloys. At the same time, addition of 1.2% Fe; 1.4% Fe and 1.6% Fe, and 0.015% Sr ? 0.045% Sr shows that the flowability of the alloy increases with the increasing of temperature at all compositions. In this investigation, addition of 0.03% Sr results in the highest fluidity; in this instance, addition of 0.03% Sr will modify lath primary silicon intermetallic phase to become more round and changes the intermetallic phase morphology shorter than that of without Sr addition. The formation of intermetallic phase ?-Al5FeSi within Al-7% Si alloy increase with Fe content. This can be understood since the ability of Sr to modify the intermetallic phase decreases with the increase of Fe content. With the increase of Fe content, the fraction of ?-Al5FeSi increases both in length and area fraction of the intermetallic phase. In this investigation, the intermetallic phase with the maximum length of 22.2 _m occurs at the addition of 1.6% Fe while the intermetallic phase with the shortest length of 9.66 _m occurs at the addition of 1.2% Fe. In the event that Sr element is added into the alloys containing these Fe contents, the size of the intermetallic phases changes with the average length of 11.3 _m. In general, the increasing content of Fe results in the increasing area fraction of the intermetallic phase. Addition of 1.2% Fe results in intermetallic area fraction of 3.67%, whilst addition of 1.4% Fe and 1.6% Fe results in the intermetallic area fractions of 4.03% and 5.23% respectively. Fluidity test on the Al-11 % Si alloy with the addition of Fe also shows that the more Fe content the less the fluidity of the alloy. At the same time, fluidity test on the Al-11% Si alloy with the addition of various Fe and Sr compositions also results in the same way as that of Al-7% Si alloy, in which the increasing of Fe content results in decreasing of the fluidity, while the highest fluidity is given by the addition of 0.03% Sr. The formation of intermetallic phase ?-Al5FeSi within Al-11% Si alloy also increase with Fe content. With the increase of Fe content, the fraction of ?-Al5FeSi increases both in length and area fraction of the intermetallic phase, in which the intermetallic phase with the maximum length of 50,25 _m occurs at the addition of 1.0% Fe while the intermetallic phase with the shortest length of 21,3 _m occurs at the addition of 0.6% Fe. Addition of 0.6% of Fe results in intermetallic area fraction of 1,01%; while addition of 0.8% and 1.0% results in area fractions of 1.16% and 2.26%, respectively. The fluidity tests of both Al-7% Si and Al-11% Si alloys show the same trend in which the more Fe content the less the fluidity, while addition of Sr increases the fluidity. The change in this fluidity result is supported by morphology and microstructure of the alloys taken from the SEM, which shows an aluminum matrix, silicon structure, and intermetallic phases. The predicted compositions from EDX analysis are supported by XRD data analysis, which identifies the presence of the intermetallic phases of ? and ?. However, in the event that Sr is added into these two alloys, the intermetallic phases will be change. It can be concluded that Sr has an effect on the microstructure of the intermetallic phases, in which the addition of 0.03% Sr gives the best fluidity at all compositions; in this instance, addition of 0.03% Sr modifies primary lath silicon into more round and changes the intermetallic phases morphology to become shorter than that of without Sr addition.