Hasil Pencarian  ::  Simpan CSV :: Kembali

"ABSTRAKBatubara semi-antrasit, bituminus dan sub-bituminus dari Tanjung Enim,Sumatera Selatan, telah diproses dengan metode aglomerasi menggunakanmedia campuran air dan minyak goreng sawit atau minyak sawit mentah (CPO).Kadar karbon masing-masing batubara yang mengalami proses aglomerasimenurun, tetapi nilai kalorinya meningkat. Minyak goreng sawit sebagai mediaaglomerasi dapat meningkatkan nilai kalori batubara semi-antrasit, bituminusdan sub-bituminus masing-masing sampai 4,5%, 5,6% dan 11,1%. Sedangkankadar sulfur dapat diturunkan masing-masing sebesar 13,4% dan 18,75%.Minyak sawit mentah dapat meningkatkan nilai kalori masing-masing jenisbatubara tersebut sampai 4,2%, 8,3% dan 7,1% relatif terhadap nilai kaloribatubara yang tidak mengalami proses aglomerasi. Pengujian dengan TGAmenunjukkan bahwa terjadi dekomposisi baik untuk batubara yang belumdiproses aglomerasi maupun yang telah mengalami proses aglomerasi. Sawitmentah telah dapat meningkatkan nilai kalori batubara yang telah diprosesaglomerasi akibat persenyawaan kimia antara sawit mentah dengan batubara..Sementara SEM memperlihatkan bahwa cairan sawit mentah telah dapatmengisi celah antara butiran batubara sehingga terjadi ikatan yang baik

---

AbstractThe semi-anthracite, bituminous and sub-bituminous coals from Tanjung Enim,South of Sumatera, were processed by using palm oil or crude palm oil (CPO)as agglomerating oil. As a result, the carbon content decreased, while thecaloritic value increased. By adding palm oil, the calorific values of semi-anthracite, bituminous and sub-bituminous coal increased up to 4.5, 5.6 and11.1%. The ash content decreased to 57.28 % and 57.8 % for bituminous andsub bituminous coals. The sulfur content decreased to 13.4% and 18.75%. Onthe other hand, by adding crude palm oil, the crude palm oil, the calorific valueincreased up to 4.2%, 8.3% and 7.1% for semi anthracite, bituminous and subbituminous coals. Thermogravimetry Analysis (TGA) showed some peaks ofcoal decompotition. The CPO has influenced to increase the calorific value ofcoals due to the chemical reaction between the CPO and the coals. The SEMresult showed that CPO has filled the space between the grain coal."

"Boron Karbida (B4C) dapat disintesis dari berbagai macam bahan dan metode. Dalam penelitian ini dipilih pembuatan boron karbida dengan metode reduksi karbotermik dari bahan asam borat, karbon aktif dan asam sitrat. Boron karbida hasil sintesis kemudian digunakan sebagai fasa penguat komposit material tahan peluru alumina-titania. Proses sintesis dilakukan dengan beberapa komposisi (F 1-F8) dan beberapa teknik pencampuran. Secara garis besarnya asam sitrat dan asam borat dicampur kemudian ditambahkan karbon aktif. Selanjutnya dilakukan teknik mixing yang berbeda, yaitu milling dengan potmill dan milling dengan vibrator ballmill, untuk memperoleh ukuran butiran yang berbeda. Campuran reaktan hasil mixing kemudian dilakukan kalsinasi, di press sehingga berbentuk pelet, kaemudian dilakukan sintering pada kondisi argon dengan temperatur yang bervariasi. Hasil sintesis dikarakterisasi dengan menggunakan difraksi sinar-X (XRD), Fourier Transformator Infra Red (FTIR), uji mikrostruktur dengan Scanning-Electron Microscope (SEM), Ialu dibandingkan dengan karakteristik boron karbida produk Aldrich sebagai standar. Proses sintering pembuatan komposit alumina-titania berpenguat B4C dilakukan pada temperatur 1600 °C. Plate basil sintering diuji hardness dan fracture toughness-nya, lalu dilakukan nilai D balistik.Dari hasil sintesis didapat komposisi optimal pada F2 yaitu pada komposisi asam sitrat 1/6 mol, hal ini dapat dilihat dari hasil pembentukkan B4C pada temperatur 1450 °C dan 1560 °C pada Metode-I (milling dengan potmill dengan ukuran butir reaktan ± 300 mesh). Pembentukkan B4C terbanyak terjadi pada temperatur 1560 °C yaitu terbentuk fasa ± 83,96 % B4C (R3m) dengan struktur kristal rombohedral, 2.56 % B203 (P31) struktur kristal heksagonal dan 13,48 % C (P63/mmc) struktur kristal heksagonal. Dari hasil sintesis Metode-II (milling dengan vibrator ballmill ukuran butir reaktan ± 87 % dibawah 1 mikron) pembentukan B4C dapat terjadi pada temperatur lebih rendah yaitu 1300 ºC terbentuk ± 75,11 % B6C (R3m) dengan struktur kristal rombohedral, 0,165 % C (P63/mmc) struktur mm helsagonal, 12,78 % Fe2O3 (R3c) struktur kristal trigonal, 10,45 % B60 (R3mH) struktur kristal rombohedral, 1,64 % B203 (P3121) struktur kristal trigonal/rombohedral. Hasil karakterisasi dengan FTIR fasa B4C dari hasil sintesis menunjukkan finger print (1087,65 cm-1) yang identik dengan standar B4C produk Aldrich (l079,64 cm-1); hal ini memperkuat hasil XRD. Sedangkan hasil SEM belum terlihat jelas karena adanya agregat dan masih bercampur dengan fasa lain. B4C hasil sintesis yang digunakan sebagai fasa penguat pada alumina-titania menunjukkan peningkatan nilai D balistik yang signifikan. Pada temperatur sintering 1600 °C penambahan 3% berat B4C pada alumina-titania menghasilkan nilai kekerasan 10,6118 GPa dan fracture toughness 3,08 MPa m½, nilai D (Balistik) 127,658.(c). Alumina-titania tanpa B4C menghasilkan nilai kekerasan 10,4474 GPa, fracture toughness 3.12 MPa m½, nilai D (Balistik) 122,641.(c). Dapat disimpulkan bahwa B4C hasil sintesis sudah dapat dipakai sebagai material tahan peluru, walaupun dalam hal ini hasil sintesis belum dimurnikan.Boron carbide (B4C) can be synthesized by various materials and methods. In this research, boron carbide was synthesized from boric acid, active carbon and citric acid by using carbothermic reduction method. Boron carbide from this synthesis was used as reinforced material for body armor composite alumina-titania. The synthesis was conducted through several methods. In general, citric acid and boric acid were mixed and added with active carbon. In this case, two different mixing were used, pottmill and vibrator ballmill mixing. The mixing result was then encrusted at 450 °C and pressed to form a pellet, afterward it was sintered in argon condition with various temperatures. The synthesis results were characterized by using X-Ray Diffraction (XRD), the microstructure of synthesis result was characterized by Scanning Electron Microscope (SEM) and Fourier Transformator Infra Red (FTIR), and then it was compared to the boron carbide standard from Aldrich.

The synthesis result was used as a reinforced in alumina-titania in several composition at sintering temperature of 1600 ?C and 2 hours of holding time. A plate resulted from the sintering was tested for the hardness and fracture toughness and its D ballistic-value was calculated. The optimal composition F2 of the synthesis result was obtained at 1/6 mol of citric acid at 1450 °C and 1560 °C by using Method-I (pottmill milling grain size ± 300 mesh). The highest percentage of B4C occurred at 1560 °C in which the reaction yielded in ± 83.96 % B4C (R3m) rhombohedral, 2.56 % B2O3 (P31) hexagonal and 13.48 % C (P63/mmc) hexagonal. The Synthesis result from Method-II (milled by vibrator ballmill mixing, grain size ± 87% below 1 micron) the B4C formation is obtained at a lower temperature (1300 °C), consisted of ± 75.11 % B4C (R3m) rhombohedral, 0.165 % C (P63/mmc) hexagonal, 12.18 % Fe2O3, (R3c) trigonal, 10.45 % B60 (R3mH) rhombohedral and 1.64 % B203 (P3121) in trigonal/rhombohedral. FTIR analysis showed B4C?s linger print ( 1087.65 cm") that identical with B4C standard from Aldrich (1079.64 cm-1) which comformed fhe XRD result, whereas the SEM result was still unclear due to the formation of aggregate that mingled with other phases. The synthesis result of B4C, which is used as a reinforced on alumina-titania composite showed a significant increase in D ballistic value. Using 3% weight of B4C as a reinforced in alumina-titania composite and sintering at 1600 ºC resulted in 10.6118 GPa of hardness and 3,08 MPa m½ of fracture toughness, and 127.658.(c) of D Balisstic value. It can be concluded that the B4C from this synthesis can be used as a body armor material, regardless its purity. A re-synthesis process yielded in better B4C proven by XRD end FTIR result, however, in this research, the re-synthesis result sample was not further tested as a reinforced in alumina-titania composite."

"Material SBA-15 merupakan salah satu material mesopori dengan ukuran pori antara 2-50 nm. Material ini dapat diaplikasikan dalam berbagai penggunaan seperti dalam proses adsorpsi, katalis, filtrasi dan membran. Proses sintesis material SBA-15 dilakukan melalui jalur sol-gel. Bahan dasar yang digunakan ialah tetraethylorthosilicate (TEOS, Si(OC2H5)4) sebagai prekursor (sumber atom Si), surfaktan kopolimer triblok Pluronik P123 (EO20PO20EO20) sabagai cetakan/template dan air yang nanti akan bereaksi dengan TEOS. Kemudian ditambahkan juga bahan aditif yaitu etanol sebagi pelarut antara air dan TEOS dan HCI sebagai katalis.Penelitian ini bertujuan untuk mengetahui pengaruh peningkatan konsentrasi surfaktan terhadap karakteristik pori material mesopori SBA-15, serta memprediksi luas spesifik permukaan material SBA-15 sehlngga bisa diketahui nilai optimum penambahan konsentrasi sulfaktan terhadap luas spesifik permukaan. Variasi peningkatan konsentrasi surfaktan mulai dari 0,007 M hingga 0,066 M, sedangkan konsentrasi TEOS, air, etanol dan HCI dibuat tetap. Proses sintesis material SBA-15 terjadi dalam dua tahap yaitu proses pembentukan gel dan kemudian dilanjutkan dengan proses kalsinasi (400°C). Material SBA-15 kemudian dikarakterisasi dengan particle size; picnometer; SAXD, Adsorpsi-Desorpsi N2, SEM EDS, AFM, FESEM dan TEM.Hasil penelitian menunjukkan bahwa konsentrasi surfaktan tidak mempengaruhi struktur Kristal SBA-15, tetapi semakin tinggi konsentrasi surfaktan akan menurunkan derajat kristalisasi dari struktur heksagonal seperti terlihat dari hasil SAXD. Hasil pengujian luas spesifk permukan dengan adsorpsi-desorpsi N2 memperlihatkan peningkatan luas spesifik permukaan dari 482,20 m²/g menjadi 746,70 m²/g, dengan persentase kenaikan sebesar 54%. Peningkatan luas spesifik permukaan tersebut secara umum disebabkan oleh terbentuknya pori utama.Dengan metode perhitungan luas spesifik permukaan teoritis, diprediksi bahwa konsentrasi surfaktan optimum adalah sebesar 0,054 M, dimana nilai eksperimental luas spesifik permukaannya memiliki kesesuaian dengan nilai teoritis. Pada konsentrasi ini diperkirakan sebagai kontribusi maksimum dari pori utama. Pada konsentrasi surfaktan sebesar 0, 060 M dan 0,066 M dengan persentase kenaikan 11,11% dan 22,20% dari konsentrasi surfaktan 0,054 M akan lerjadi peningkatan luas spesifik permukaan dari 598,50 m²/g menjadi 702,10 m²/g dan 746,70 m²/g dengan persentase kenaikan 17,30% dan 24, 76%. Peningkatan luas spesifik permukaan ini bukan Iagi disebabkan oleh terbentuknya pori utama, melainkan pori antar dinding (intrawall pores). Pori intrawall tersebut terbentuk akibat kecenderungan kemampuan self assembly dari surfaktan pada daerah di antara pori-pori utama.

---

SBA-15 belongs to mesoporous material having pore size ranging from 2 to 50 nm. This material can be applied in many application such as in adsoption process, catalist, filtration and membrane. SBA-15 was synthesized via sol-gel technique from tetraethylorthosilicate (TEOS, Si(OC2H5)4) as Si source/precursor surfactant triblok copolimer Pluronik P123 (EO20PO70EO20) and water which will react with TEOS. To enhance dissolution of TEOS in water; ethanol and HCl catalyst were added.

This study was focused on the effect of surfactant concentration on the pore characteristics and optimization of the specific surface area of SBA-15. Surfactant concentration was varied from 0.007 to 0.066 M while TEOS, water, ethanol and HCl concentration were held constant. The synthesis was divided into two stage i.e gel formation and calcination at 400°C. Characterization of the product was performed using particle sizer; picnometer, SAXD, N2 adsorption-desorption, SEM, EDS, AFM, FESEM and TEM.

The SAXD result shows that surfactant concentration can not effect crystal formation, but it will decrease the degree of hexagonal crystal formation. Measurement of specific surface area using N2 adsorption-desorption technique indicates an increase from 482.20 m²/g became 746.70 m²/g which in percentage was 54%. This increasing of specific surface area were mainly caused by main pore formation.

It was theoritically calculated that optimum surfactant concentration was 0,054 M where the experimental value of specific surface area was close to its theoritical one. This concentration is considered the maximum specific surface area which is contributed by the main pores. In surfactant concentration 0.060 M and 0.066 M where in percentage are 11.11% and 22.20% from surfactant concentration 0.064 M, the specific surface area from 598.50 m²/g will increase became 702.10 m²/g and 746.70 m²/g, which are 17.30% and 24, 76% respectively. This increasing of specific surface area are not caused by main pore formation, but it was contribution of intrawall pores. These intrawall pores were formed as a result of surfactant tendency for self assembly in areas between the main pores."

"ABSTRAKTelah berhasil disintesis dan dipelajari material karbon nanopori yang diperoleh dari interaksi antara padatan silikon karbida dan HCl menggunakan metode variasi ultrasonik dan pemanasan. Silion karbida dengan kemurnian lebih dari 98% dari Aldrich digunakan sebagai sumber karbon, sedangkan larutan HCl berfungsi sebagai sumber gas klor yang akan bereaksi dan mengambil silikon (Si) dari silikon karbida. Dalam penelitian ini diadakan lima variasi yang berbeda yaitu disebut sebagai CDC1, CDC2, CDC3, CDC4 dan CDC5. Metode ultrasonik dan pemanasan terhadap material CDC1, CDC2, CDC3, CDC4, CDC5 didapatkan stabil pada suhu pemanasan 1000 o C dengan perbandingan berat wt% antara silikon karbida dan pori karbon hasil sintesis adalah CDC1 wt% = SiC : C = 75% : 25%, CDC2 wt% = SiC : C = 35% : 65%, CDC3 wt% = SiC : C = 34,5% : 65,5%, CDC4 wt% = SiC : C = 30% : 70% dan CDC5 wt% = SiC : C = 25% : 75%. Pembentukan pori dan pertumbuhan kristal hanya muncul setelah proses pemanasan. Material CDC1, CDC2, CDC3, CDC4, CDC5 hasil sintesis masing-masing memiliki struktur heksagonal dengan grup ruang P6 3 mc dan parameter kisi berturut-turut yaitu a = b = 2,456 Å dan c = 12,350 Å. Pembuktian berdasarkan analisis GSAS refine Fourier memperlihatkan bahwa material CDC1, CDC2, CDC3, CDC4, CDC5 memiliki struktur rentang panjang arah sumbu c untuk CDC1 = 15Å, CDC2 = 15Å, CDC3 = 20Å, CDC4 = 30Å, CDC5 = 35Å terhadap pemanjangan parameter kisi c masing -masing CDC1 = 12,35Å, CDC2 = 15,1Å, CDC3 = 18Å, CDC4 = 20,4Å dan CDC5 = 24,1Å dan mengalami penurunan nilai densitas CDC1= 3 gr/cm 3 , CDC2 = 2,45 gr/cm 3 , CDC3 = 1,5 gr/cm 3 , CDC4 = 1,4 gr/cm 3 dan CDC5 = 1,2 gr/cm 3 . Struktur karbon m akropori - nanopori rentang panjang heksagonal tipe pori silinder memiliki ukuran pori 200 nm - 35 nm, luas permukaan 55 m 2 /gram-1250 m 2 /gram dan sangat khas muncul pada bilangan gelombang 1095, 57 cm -1 dan karenanya material tersebut diharapkan dapat digunakan sebagai media penyimpan gas.

---

ABSTRACTNanopores carbide derived carbon synthesized from silicon carbide and HCl by using ultrasonic and sintering at high temperature has been investigated. Silicon carbide with a purity better than 98% from Aldrich was used as a carbon source while HCl was used as a leaching agent.. In this investigation, five different processes were carried out, i.e. CDC1, CDC2, CDC3, CDC4 and CDC5. Ultrasonik process and sintering on these five CDC1, CDC2, CDC3, CDC4 and CDC5 materials were found to be stable at 1000 o C with the weight ratio between silicon carbide and the derived carbon CDC1 wt% = SiC : C = 75% : 25%, CDC2 wt% = SiC : C = 35% : 65%, CDC3 wt% = SiC : C = 34,5% : 65,5%, CDC4 wt% = SiC : C = 30% : 70% dan CDC5 wt% = SiC : C = 25% : 75%. Pores formation and crystal growth occur after sintering process. Each derived carbon material has the hexagonal structure and a space group of P6 3 mc and lattice parameters a = b = 2.456 Å and c = 12.350 Å. Fourier analysis by using a package program of GSAS showed that CDC1, CDC2, CDC3, CDC4 and CDC5 have an expansion on the c direction in which CDC1 = 15 Å, CDC2 = 15 Å, CDC3 = 20 Å, CDC4 = 30 Å, and CDC5 = 35 Å from the original values of CDC1 = 12.35 Å, CDC2 = 15. 1 Å, CDC3 = 18 Å, CDC4 = 20. 4 Å and CDC5 = 24.1 Å. Furthermore, the elektronic density was found to be CDC1= 3 gr/cm 3 , CDC2 = 2.45 gr/cm 3 , CDC3 = 1.5 gr/cm 3 , CDC4 = 1.4 gr/cm 3 and CDC5 = 1.2 gr/cm 3 . The long hexagonal ribbon of the derived carbon has the size of 200 nm ? 35 nm, surface area of 55 m 2 /g ? 1250 m 2 /g and occur at a wave number of 1095. 57 cm -1 . This material has the potential application as a gas storage."

"ABSTRAKPengerasan permukaan baja karbon rendah St41 telah dilakukan melalui proses boronisasi padat dengan tekanan mekanik. Sampel baja St41 dimasukkan kedalam wadah, ditimbun dengan serbuk boronisasi dalam bentuk campuran 5% boron karbida (B4C), 90% silicon karbida (SiC), 5% kalium borofluoride (KBF4), dan diberi tekanan 10 kN. Sampel yang telah dimasukkan dalam wadah, dipanaskan pada temperature 600, 700, 800, 900,dan 10000C selama 2, 4, 6, dan 8 jam pada masing-masing temperature. Pendinginan sampel dilakukan secara alamiah pada suhu kamar. Setelah dipanaskan, sampel dikarakterisasi dengan mikroskop optic, uji kekerasan mikro, X-RD, dan ketahanan aus. Morfologi dan ketebalan lapisan boride yang terjadi diamati dan diukur pada potongan melintang sampel. Untuk menentukan fase yang terjadi dilakukan pencocokan kurva dengan software Match berdasarkan data kristalografi. Untuk menganalisis fase secara kuantitatif digunakan software GSAS untuk menentukan ukuran kristalit rata-rata, dan parameter kisi, pada masing-masing fase yang terbentuk. Hasil penelitian menunjukkan bahwa dengan menambahkan tekanan mekanik untuk mencegah terjadinya oksidasi pada proses boronisasi padat dapat membentuk larutan padat intertisi lapisan besi boride pada permukaan baja St41. Dari hasil pengujian diperoleh kekerasan mikro pada permukaan lapisan besi boride sebesar 1703 HV dengan ketebalan 309 μm, dan ketahanan aus 36 kali ketahanan aus sampel semula. Harga kekerasan mikro dan ketebalan tersebut lebih besar jika dibandingkan dengan hasil-hasil penelitian terdahulu dan meningkat menjadi lebih dari 10 kali lipat harga kekerasan sampel semula. Dari hasil perhitungan diperoleh persamaan difusi D = D0 exp (-168,25 kJ/RT) dengan energi aktivasi sebesar 168,25 kJ.

---

ABSTRACT

Surface hardening of low carbon steel St41 has been done through the pack boronizing combining with mechanical pressure. The sample of St41 steel was inserted into the container, containing boronizing powder with a mixture of 5% in the form of boron carbide (B4C), 90% silicon carbide (SiC), 5% potassium borofluoride (KBF4), and given the mechanical pressure of 10 kN. Samples were heated at temperatures of 600, 700, 800, 900, and 10000C for 2, 4, 6, and 8 hours at each temperature. After heating, the samples were characterized by optical microscop, micro-hardness, X-RD, and wear resistance. Morphology and boride layer thicknes is observed and measured on a cross section of the sample. Quantitative phase analysis software GSAS used to determine phase, the average crystallite size, and lattice parameters of each phase formed. It is also obtained the surface layer hardness of iron boride was 1703 HV with a thickness of 309 μm, and wear resistance about 36 times than the wear resistance of the untreated sample. The hardness and the thickness is greater when compared with the results of previous studies 10 times to the hardness of untreated sample. Energy activation and diffusion equation have value 168,255 kJ and D = D0 exp (-168.25 kJ/RT)."

"Barium hexaferrite (BaFe12O19) dan strontium titanate (SrTiO3) telah luas dikenal masing masing sebagai material magnet permanen dan piezoelektrik. Kedua jenis material tersebut sangat potensial untuk diaplikasikan pada pembuatan komponen produk magnet dan elektronik. Sifat ekstrinsik kedua jenis material tergantung kepada mikrostrukturnya yang sangat ditentukan pula oleh metode sintesis material yang diterapkan. Kajian literatur menunjukkan bahwa telah banyak dikembangkan berbagai macam metode sintesis senyawa magnetik BaFe12O19 dan dielektrik SrTiO3 dalam bentuk partikel halus dengan ukuran berskala nanometer. Kegiatan penelitian ini lebih difokuskan kepada sintesis dan karakterisasi material sistem nanokomposit BaFe12O19/SrTiO3, dimana senyawa BaFe12O19 (kode BHF) memiliki fasa feromagnetik dan senyawa SrTiO3 (kode STO) memiliki fasa feroelektrik dipersiapkan melalui metode pemaduan mekanik (mechanical alloying). Sedangkan pembuatan nanopartikel kedua senyawa diperoleh melalui penghalusan mekanik dan destruksi ultrasonik daya tinggi. Material BHF dipersiapkan dari campuran prekursornya berupa serbuk BaCO3 dan Fe2O3. Sedangkan material STO menggunakan prekursor SrCO3 dan TiO2. Aparatus yang digunakan adalah planetary ball mill dengan perbandingan berat antara material dan ball mill adalah 1 : 10. Ukuran rata-rata partikel dievaluasi menggunakan particle-size analyzer (PSA) dan ukuran rata-rata kristalit dihitung menggunakan metode Williamson Hall Plot dengan software High Score Plus dari data pola difaksi x-ray masing-masing senyawa. Adapun sampel berupa material kristalin diperoleh setelah kompaksi serbuk hasil pemaduan mekanik dan pemanasan pada temperatur 1100°C selama 3 jam dimana kemudian sampel material kristalin tersebut dihaluskan kembali menggunakan ball mill selama 20 jam. Serbuk halus BHF dan STO tersebut masing-masing menjalani destruksi lanjut secara ultrasonik daya tinggi untuk menghasilkan nanopartikel. Hasil evaluasi dengan PSA dan Williamson Hall Plot data XRD terhadap material BHF memperlihatkan nanopartikel dicapai setelah destruksi ultrasonik selama 14 jam. Dalam hal ini hasil PSA menunjukkan ukuran partikel rata-rata BHF adalah 28 nm sedangkan hasil evaluasi ukuran rata-rata kristalit adalah 26 nm. Untuk STO diperoleh hasil evaluasi ukuran rata-rata partikel sebesar 144 nm dan ukuran rata-rata kristalit adalah 30 nm. Kedua jenis material dalam bentuk nanopartikel ini digunakan sebagai komponen nanokomposit sistem BHF-STO. Berdasarkan hasil karakterisasi material komposit baik melalui pengujian XRD maupun permagraph bahwa sampel komposit tersusun dari dua fasa yaitu BaO.6(Fe2O3) dan SrTiO3 yang dipastikan dari pola difraksi dan sifat kemagnetannya. Dari kajian efek destruksi ultrasonik terhadap partikel STO dapat disimpulkan bahwa ukuran partikel rata rata dapat direduksi 8 kalinya yaitu dari ukuran 797 nm menjadi 144 nm setelah durasi watuk destruksi 14 jam. Sedangkan untuk partikel BHF tereduksi 100 kalinya yaitu dari 2931 nm menjadi 26 nm pasca durasi waktu destruksi yang sama. Penelitian ini juga mempelajari perilaku kinetika pertumbuhan ukuran kristalit fasa-fasa material penyusun material komposit dalam sistem komposit yang mengikuti persamaan Avrami. Berdasarkan kajian kinetika dapat diketahui energi aktivasi pertumbuhan kristalit fasa material STO dan BHF masing masing adalah 16 kJ.mol-1 dan 4 kJ.mol-1. Dapat disimpulkan bahwa kombinasi antara teknik penghalusan mekanik dan destruksi sonikasi daya tinggi terhadap partikel kristalin BHF dan STO dapat dijadikan metode alternatif yang efektif untuk menghasilkan nanopartikel.

---

Barium hexaferrite (BaFe12O19) and strontium titanate (SrTiO3) are well established permanent magnet and piezoelectric materials which are technologically and scientifically attractive due to their potential for various applications in the field of magnetic electronics functional materials. The extrinsic properties of these materials depend largely on the microstructure, which in turn depends on the method of synthesis. Different methods have been developed for the preparation of ultrafine BaFe12O19 and SrTiO3 particles in nanometer scale. In this work, research activivities were focused on synthesis and characterization of BaFe12O19/SrTiO3 nanocomposites in which feromagnetic materials of BaFe12O19 phase (coded BHF) and a ferroelectric materials of SrTiO3 phase (coded STO) were prepared by a mechanical alloying technique. In addition, nanoparticles of BHF and STO were obtained by physical destruction through a combined method between mechanical milling and high power ultrasonication.

BHF materials were made of their precursors which consisted of the mixture between BaCO3 and Fe2O3. Whereas for STO materials the precursors were SrCO3 and TiO2. The process of mixing and alloying was caried out under the used of a planetary ball mill apparatus with a weight ratio between mixture and ball mill was 1:10. The mean particle size of milled powders was further characterized by Particle Size Analyzer (PSA). Whereas the mean crystallite size was derived from Williamson Hall Plots using the High Score Plus software to evaluate data of x-ray diffraction patterns for each materials. The crystalline materials were obtained after sintering step at 1100°C for 3 hours to the green compact samples which further followed by remilling the sintered samples for 20 hours. Further refining the powders for BHF and STO was carried out under the use of a high power sonicator for 14 hours to produce nanoparticles.

Results of evaluation indicated that the mean particle size of BHF and STO was respectively 28 nm and 144 nm which refer to results of particles characterization by PSA whereas for their mean crystallite size were respectively 26 nm and 30 nm. Those nanoparticles of BHF and STO were then used as component materials in BHF-STO nanocomposite system. According to results of characterization for composite materials by XRD and permagraph, it was found that the composites consisted of two phases which were identified as BaO.6(Fe2O3) and SrTiO3 based on their diffraction pattern and magnetic properties.

Further to the characterization results, it was also found that the mean particle size of STO was reduced 8 times in which the mean size of 797 nm was brought down to 144 after ultrasonically destruction for 14 hours. However, much larger reduction in particle sizes were obtained in BHF in which the initial mean particle size of 2931 nm was reduced 100 times downed to 26 nm after the same duration periode of ultrasonic destruction.

Crystallite growth kinetics behavior of BHF and STO phases in the composite system was also studied in which data of mean crystallite sizes at different sintering temperatures and time were fitted into the Avrami equation. It was found that the activation energy for crystallite growth kinetics of BHF and STO is 16 kJ.mol-1 and 4 kJ.mol-1 respectively.

We conclude that mechanical alloying coupled with ultrasonication can be used as an effective alternative tools for the preparation of fine and homogeneous powder materials leading to nanoparticle-based materials."

"[ABSTRAKMaterial 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 elektronikTelah 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.;

---

ABSTRACTSolder 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 phenomenaThe 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 phenomenaThe 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 phenomenaThe 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.]"

"[ABSTRAKPada penelitian Disertasi ini telah dilakukan rekayasa material untuk pembuatan nano komposit magnetoelectric yang merupakan material multifungsi dengan menggabungkan antara material berfasa ferromagnetik dan material berfasa ferroelektrik Rekayasa material dilakukan dengan menggunakan metoda mechanical alloying yang dilanjutkan dengan penghalusan secara mekanik dan destruksi ultrasonik daya tinggi untuk mendapatkan ukuran partikel dalam skala nanometer Material nanokomposit dipersiapkan dalam bentuk pellet Komponen komponen komposit baik itu Ba0 7Sr0 3O 6 Fe2O3 B7S3HF dan Ba0 7Sr0 3TiO3 B7S3T mengunakan material nanopartikel yang merupakan hasil subsitusi parsial ion Ba dengan Sr pada senyawa BHF dan BT sehingga meningkatkan volume sel satuan Hasil pengujian X Ray Diffraction XRD menunjukan bahwa sampel yang dihasilkan merupakan material fasa tunggal untuk senyawa Ba0 7Sr0 3O 6 Fe2O3 BSHF dan Ba0 7Sr0 3TiO3 BST Pengujian kemagnetan material dilakukan dengan Permagraph sedangkan sifat elektrik material dilakukan dengan electrometer Hasil pengujian ini menaikkan nilai magnetisasi remanen untuk BSHF dari BHF masing masing adalah 0 180 T dan dan 0 16 T menurunkan nilai koersivitas masing masing adalah 275 54 kA m 1 dan 322 14 kA m 1 Nilai ini sesuai dengan nilai yang dipublikasikan dalam berbagai literatur dan dengan demikian sintesis material berbasis BSHF dan BHF dengan metode yang diterapkan dipastikan menghasilkan material berfasa tungal Demikian juga halnya dengan hasil karakterisasi material BST dengan electrometer diperoleh nilai polarisasi total untuk BaTiO3 dan Ba0 7Sr0 3TiO3 masing masing adalah 42 8 C cm 2 dan 40 7 C cm 2 Hasil pengujian dengan menggunakan Particle Size Analyzer PSA terhadap material komponen komposit menunjukkan ukuran rata rata partikel Ba0 7Sr0 3TiO3 atau B7S3T adalah 78 nm dan Ba0 7Sr0 3O 6 Fe2O3 atau B7S3HF adalah 44 nm yang diperoleh pasca penghalusan mekanik yang dilanjutkan dengan destruksi ultrasonik selama 12 jam Sedangkan sifat kemagnetan material B7S3HF adalah 0 180 T untuk magnetisasi remanen dan 275 54 kA m 1 untuk nilai koersivitas Nilai magnetisasi remanen mengalami peningkatan menjadi 0 249 T karena efek induksi anisotropi oleh medan magnet luar sebesar 5 mT tanpa penurunan nilai koersivitas Dalam bentuk nanokomposit B7S3T B7S3HF dengan komposisi 1 1 dalam fraksi massa diperoleh hasil 0 115 T untuk nilai remanen dan 282 14 kA m 1 untuk nilai koersivitas tanpa induksi anisotropi Nilai magnetisai remanen ini adalah 46 nilai remanen B7S3HF tanpa induksi anisotropi Nilai remanen sampel nanokomposit meningkat menjadi 0 148 T tanpa perubahan nilai koersivitas setelah induksi anisotropi Maka dapat disimpulkan bahwa ada peningkatan sebesar 0 010 T atau 8 berasal dari efek kopling antara kristalit B7S3HF dan B7S3T merupakan salah satu sifat magnetoelektric Hasil inspeksi nilai remanen terhadap material B7S3HF baik dalam jaringan komposit B7S3T B7S3HF memperlihatkan bahwa efek induksi anisotropi telah meningkat nilai magnetisasi remanen serta memperlihatkan munculnya sifat magnetoelektrik dalam sistem komposit;

---

ABSTRACTIn this Dissertation research synthesize of magnetoelectric nanocomposite which is multifunctional materials was carried out by combining ferromagnetic and ferroelectric components Nanocomposites were made of barium strontium hexaferrite Ba0 7Sr0 3O 6 Fe2O3 B7S3HF as ferromagnetic and barium strontium titanate dan Ba0 7Sr0 3TiO3 B7S3T as ferroelectric components Materials preparation was carried out trough mechanical alloying route which followed by mechanical refinement and high power ultrasonic destruction to obtain particle sizes in the nanometer scales Nanocomposite materials were prepared in pellet form In this case components of composite which are B7S3T and B7S3HF made of nanoparticles Phase identification by X Ray Diffraction XRD method showed that all samples B7S3T and B7S3HF are respectively single phase materials As to the characterization it was found that partial substitution of Ba ions by Sr ions in BT and BHF has increased the volume of their respective unit cell The magnetic properties of magnetic materials which evaluated by a Permagraph have derived values for remanent magnetization of B7S3HF and BHF were respectively 0 18 T and 0 16 T with their corresponding coercivity 275 54 kA m 1 and 322 14 kA m 1 respectively These values are almost similar to the values published elsewhere for BHF and BT which then confirmed once again that the synthesized BHF and BT based materials material are single phase Similarly results of material characterization for B7S3T with an electrometer has derived total polarization values obtained for BaTiO3 and B7S3T were 42 8 C cm 2 and 40 7 C cm 2 respectively Test results using Particle Size Analyzer PSA of the material components for the composites showed that the mean particle size of Ba0 7Sr0 3TiO3 or B7S3T is 78 nm and that of Ba0 7Sr0 3O 6 Fe2O3 or B7S3HF is 44 nm which were obtained after further refining under mechanical milling followed by high power ultrasonic destruction for 12 hours Whereas the remanent magnetization of B7S3HF is 0 180 T and 275 54 kA m 1 for the coercivity The remanent magnetization value increased to 0 249 T with no changing in the coercivity value after anisotropy induced by an external magnetic field of 5 mT In addition the isotropic B7S3T B7S3HF nanocomposite with a composition 1 1 mass fraction has a remanent magnetization value of 0 115 T with a corresponding coercivity of 282 14 kA m 1 The remanence value of 0 115 T is about 46 of that of an isotropic B7S3HF However the remanent magnetization value for nanocomposite samples increased to 0 148 T with no change in coercivity after induced anisotropy It then can be concluded that there was an increase of 0 010 T or 8 in a remanent value which rose from coupling effects between crystallites of B7S3HF and B7S3T Results of inspection in remanent values for a ferromagnetic B7S3HF material present alone as well as in B7S3T B7S3HF composites showed that the all samples have shown an increased in remanent magnetization values which rose from magneto electric properties , In this Dissertation research synthesize of magnetoelectric nanocomposite which is multifunctional materials was carried out by combining ferromagnetic and ferroelectric components Nanocomposites were made of barium strontium hexaferrite Ba0 7Sr0 3O 6 Fe2O3 B7S3HF as ferromagnetic and barium strontium titanate dan Ba0 7Sr0 3TiO3 B7S3T as ferroelectric components Materials preparation was carried out trough mechanical alloying route which followed by mechanical refinement and high power ultrasonic destruction to obtain particle sizes in the nanometer scales Nanocomposite materials were prepared in pellet form In this case components of composite which are B7S3T and B7S3HF made of nanoparticles Phase identification by X Ray Diffraction XRD method showed that all samples B7S3T and B7S3HF are respectively single phase materials As to the characterization it was found that partial substitution of Ba ions by Sr ions in BT and BHF has increased the volume of their respective unit cell The magnetic properties of magnetic materials which evaluated by a Permagraph have derived values for remanent magnetization of B7S3HF and BHF were respectively 0 18 T and 0 16 T with their corresponding coercivity 275 54 kA m 1 and 322 14 kA m 1 respectively These values are almost similar to the values published elsewhere for BHF and BT which then confirmed once again that the synthesized BHF and BT based materials material are single phase Similarly results of material characterization for B7S3T with an electrometer has derived total polarization values obtained for BaTiO3 and B7S3T were 42 8 C cm 2 and 40 7 C cm 2 respectively Test results using Particle Size Analyzer PSA of the material components for the composites showed that the mean particle size of Ba0 7Sr0 3TiO3 or B7S3T is 78 nm and that of Ba0 7Sr0 3O 6 Fe2O3 or B7S3HF is 44 nm which were obtained after further refining under mechanical milling followed by high power ultrasonic destruction for 12 hours Whereas the remanent magnetization of B7S3HF is 0 180 T and 275 54 kA m 1 for the coercivity The remanent magnetization value increased to 0 249 T with no changing in the coercivity value after anisotropy induced by an external magnetic field of 5 mT In addition the isotropic B7S3T B7S3HF nanocomposite with a composition 1 1 mass fraction has a remanent magnetization value of 0 115 T with a corresponding coercivity of 282 14 kA m 1 The remanence value of 0 115 T is about 46 of that of an isotropic B7S3HF However the remanent magnetization value for nanocomposite samples increased to 0 148 T with no change in coercivity after induced anisotropy It then can be concluded that there was an increase of 0 010 T or 8 in a remanent value which rose from coupling effects between crystallites of B7S3HF and B7S3T Results of inspection in remanent values for a ferromagnetic B7S3HF material present alone as well as in B7S3T B7S3HF composites showed that the all samples have shown an increased in remanent magnetization values which rose from magneto electric properties ]"