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"Phase transformation studies have been carried out for pure iron and iron-carbon compounds of composition 0.1wt%C (low carbon), 0.4wt%C (hypo-eutectoid), and 0.8wt%C (nominal eutectoid) respectively. The samples were produced by powder metallurgy method. In this case Fe-C alloys were prepared by mixing both Fe and C powder prior to loading into a cylinder die and subsequently pressed using uniaxial force of 5 tons. The pressed samples (grain compact) were inserted into the quartz tube and air was evacuated by vacum to the level of 1.5x1 ff2mbar and then heated to 1100°C for 6 hours toward fully dense samples. Sintered samples were cooled in the furnace to room temperature. Results of OTA experiment indicated that ferromagnetic transition of pure iron taking place at temperature of 774°C and phase transformation of ferrite-austenite at temperature of 929°C. For 0.1wt%C alloy was occured pearlite-austenite transition at temperature of - 723°C with entalphy of formation of 17. 14J/g, and pro-eutectoid ferriteaustenite transition at temperature of 930°C. For 0.4wt%C alloy was occured entalphy of formation increasing of pearlite-austenite to 41.1 SJ/g. For nominal composition of 0.8wt%C was occured entalphy of formation increasing of pearlite-austenite to 72.0SJ/g at temperature of -723°C. From this study, it is found that the microstructure of pearlite consisted of ferrite and cementite in the lamelar structure. The volume fraction of pearlite consistently increased to -100% as the carbon content increased to the eutectoid composition."

"Telah dilakukan pengamatan transformasi fasa pada sistem besi-karbon (Fe-C) melalui pengamatan penganalisa perubah panas (Differential Thermal Analyzer, DTA). Sampel Fe-C dipersiapkan dengan metode metalurgi serbuk menggunakan serbuk besi dan karbon murni (> 99 %), meliputi komposisi nominal paduan karbon rendah (0,1 wt.%), hypoeutectoid (0,4 wt.%), dan eutectoid (0,8 wt.%). Hasil pengukuran DTA dalam jangkau temperatur antara 25 0C-1100 0C menunjukkan bahwa pada sampel Fe murni diamati dua temperatur transisi endotermik masing-masing pada 773,8 0C berkaitan dengan transformasi feromagnet (α) menjadi paramagnet (β) dan pada temperatur 930 0C berkaitan dengan transformasi fasa β menjadi fasa austenit (γ). Kedua temperatur transisi ini juga secara konsisten teramati untuk kesemua sampel Fe-C yang dipelajari, namun dengan penambahan satu temperatur transisi sekitar 753 0C. Temperatur transisi tambahan ini berasal dari transformasi fasa pearlit menjadi austenit. Data pengukuran perubahan panas dalam jangkau temperatur 25 0C-1100 0C digunakan untuk menentukan nilai kapasitas panas, Cp sampel untuk jangkau temperatur tersebut. Hasil regresi polinomial terhadap kurva Cp sebagai fungsi T menghasilkan koefi sien regresi yang cukup baik berkisar di antara 0,8 dan 1,0.

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Phase Transformation Studies of Fe-C System with Differential Thermal Analyzer: Phase transformation studies for ironcarbon (Fe-C) system have been done by means of Differential Thermal Analyzer, DTA. Fe-C samples of nominal compositions for respectively low carbon containing alloy (0.1 wt.%), hypo eutectoid (0.4 wt.%), and eutectoid (0.8 wt.%) were prepared by powder metallurgy process using pure Fe and C powder materials (>99 %) as the feed stock. Measurement by DTA in the temperature range 25 oC?1100 oC for the samples indicated that there are two endothermic temperatures transition in pure Fe sample respectively at 773.8 oC associated with phase transformation of ferromagnetic (α) to paramagnetic (β) and at 930 oC due to a phase transformation of β-ferrite to austenite (γ). The two transition temperature was also consistently observed in all Fe-C samples but with one additional temperature transition at about 753 oC associated with a phase transformation of pearlite to austenite. Data of heat change measurement in the temperature range 25 oC-1100 oC were subsequently used for determination of heat capacity, Cp for the Fe-C samples as the function of T. Cp (T) curves when fi tted by polynomial regression have resulted in regression coeffi cients between 0.8 and 1.0."

"Banyaknya bijih besi cadangan lateritik di Indonesia menimbulkan potensuial yang besar untuk memperkaya produksi besi dan besi baja untuk sektor industri Indonesia. Metode yang digunakan dalam mengekstraksi bijih besi lateritik tersebut umumnya adalah Direct reduction. Namun terdapat beberapa fasa slag yang terbentuk pada Direct reduction. Skripsi ini membahas tentang transformasi fasa yang dialami oleh bijih Goethite (FeOOH) dari Sebuku yang di proseskan dalam Direct Reduction dengan temperatur 1000-1200oC selama waktu tahan 30 menit – 60 menit dengan variabel batubara sub-bituminous 24% dan 16% pada campurannya. Hasil dari sponge iron yang didapatkan akan di-analisa menggunakan SEM-EDS dan XRD, untuk mendapatkan hasil yang akurat mengenai transformasi fasa yang terjadi pada bijih Goethite. Hasil yang didapatkan adalah terbentuknya fasa Fe metal, Spinel – Fe Metal + Spinel ,dan Wustit. Dengan hasil recovery terbaik diraih pada temperatur 1000oC pada komposisi batubara 24%. Fasa slag yang terbentuk adalah spinel dan Fe Metal + Spinel.

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Abundance of lateritic iron ore in Indonesia opens big potentials for Indonesia to intensify the production of ironworks and steelworks. The method to extract the lateritic ores is by Direct reduction. But in the process of Direct reduction there is some slags to be expected. The focus of this thesis is about phase transformation that occurs in Goethite ore (FeOOH) from Sebuku Mines that been processed in a Direct Reduction of 1000-1200oC with the holding time of 30 minutes – 60 minutes in a mixture of 24% and 16% sub-bituminous coal. The sponge iron that been resulted from the process is characterized with SEM-EDS and XRD, to acquire a precise and accurate data of phase transformation from the Goethite ore. The result of phase identification are Fe Metal, Spinels, Fe Metal + Spinels , and Wustites in all composition. The most high recovery value is from temperature 1000oC with the coal mixture of 24%. The slags are identified as spinels and Fe Metal + Spinels."

"ABSTRACTThe phase equilibria study of the Cu-Fe-O-Si-Ca system in equilibrium with metallic copper and iron aimed to determine the limit of removal of copper from copper smelting slag (Slag cleaning process). A literature review on information of phase equilibria of related systems at high temperature has been conducted and it is important basis for determining expected phase in the system and for the copper slag cleaning process.The experimental methodology used in the present study involves high temperature equilibration, rapid cooling of the samples, and microanalysis on the chemical compositions of all phases using Electron Probe X-ray Microanalysis (EPMA). The influence of temperature, Fe/SiO2 ration in slag, and CaO additive on the phase equilibria have been experimentally investigated. The selected experimental parameters are expected to influence the liquidus composition, major elements distributions between phases, and the activity of residual metal in the slag. All of these will influence the overall removal of metal from the slag phase. The experimental data are compared with the prediction results from the FactSage thermochemical software with public database. The slag system investigated in the present study is highly important for high-temperature copper smelting, converting and recycling processes.   

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ABSTRAKStudi kesetimbangan fase sistem Cu-Fe-O-Si-Ca dalam kesetimbangan dengan logam tembaga dan besi bertujuan untuk menentukan batas pembersihan tembaga dari slag peleburan tembaga (proses pembersihan slag). Tinjauan literatur tentang informasi kesetimbangan fasa sistem terkait pada suhu tinggi telah dilakukan dan merupakan dasar penting untuk menentukan fase yang diharapkan dalam sistem dan untuk proses pembersihan slag tembaga. Metodologi eksperimental yang digunakan dalam penelitian ini melibatkan kesetimbangan suhu tinggi, pendinginan sampel yang cepat, dan analisis mikro pada komposisi kimia dari semua fase menggunakan Analisis Elektron X-ray Mikroanalisis (EPMA). Pengaruh suhu, rasio Fe/SiO2 dalam slag, dan aditif CaO pada kesetimbangan fase telah diteliti secara eksperimental. Parameter eksperimental yang dipilih diharapkan untuk mempengaruhi komposisi liquidus, distribusi elemen utama antara fase, dan aktivitas logam sisa dalam slag. Semua ini akan mempengaruhi penghapusan logam secara keseluruhan dari fase slag. Data eksperimental dibandingkan dengan hasil prediksi dari perangkat lunak termokimia FactSage dengan database publik. Sistem slag yang diselidiki dalam penelitian ini sangat penting untuk proses peleburan, konversi, dan daur ulang tembaga suhu tinggi. "

"Telah dilakukan proses reduksi-difusi neodimium dari serbuk sintesis neodimium oksida karbonat Nd2O CO3 2 . Pada bahan ini, proses reduksi-difusi diawali dengan melakukan preparasi dengan mencampur serbuk sintesis Nd2O CO3 2 dengan CaH2 sebagai reduktor dengan penggerusan manual. Sampel awal lalu dikarakterisasi menggunakan XRD dan STA untuk mengetahui senyawa apa saja yang ada pada Nd2O CO3 2 dan dapat mengetahui perilaku sampel terhadap temperatur. Hasil dari uji STA memperlihatkan bahwa proses reduksi terjadi secara eksotermis dan mengalami tiga kali proses dekomposisi, yaitu dekomposisi molekul air, dekomposisi Nd2O CO3 2 menjadi Nd2O2CO3 dan dekomposisi Nd2O2CO3 menjadi Nd2O3. Sampel kemudian dipanaskan hingga 800oC dengan kecepatan 5oC/menit lalu di-holding pada temperatur 800oC selama 2 jam. Hasil reduksi lalu dikarakterisasi dengan XRD. Hasilnya memperlihatkan bahwa logam neodimium dengan fase alpha banyak terdeteksi di kedua sampel, diikuti dengan masih terdapatnya senyawa Nd2O3 dan CaCO3. Terbentuknya CaCO3 ini disebabkan oleh terbentuknya CaO dari reaksi antara CaH2 dengan oksigen yang ada di lingkungan tempat uji. Jumlah puncak logam neodimium sama untuk kedua sampel, namun jumlah puncak Nd2O3 terbanyak adalah sampel perbandingan 1:2.

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Reduction Diffusion process R D for Neodymium from synthetic powder Nd2O CO3 2 has been carried out. In the process, it was begun by mixing synthetic powder Nd2O CO3 2 with CaH2 as reductor by manual milling. The mixture was characterized using XRD and STA to analyze every compound that contained on Nd2O CO3 2 synthetic powder and determine the behavior of sample towards temperature. The result showed that the R D process occured as an exoterm reaction and three steps of decomposition was performed decomposition of water, decomposition of Nd2O CO3 2 into Nd2O2CO3 and decomposition of Nd2O2CO3 into Nd2O3. The reduction was heated with 5oC minute up to 800oC and was holding for 2 hours. XRD was performed after the reduction process had been done. The result showed that alpha phase of neodymium metal is detected in both sampels, followed by the presence of Nd2O3 and CaCO3 compounds. The formation of CaCO3 is caused by the formation of CaO from the reaction between CaH2 with oxygen present in the test site environment. The number of neodymium metal peaks is the same for both samples, but the highest number of Nd2O3 peaks is the 1 2 ratio."