SINTESIS DAN KARAKTERISASI KERNEL URANIUM KARBIDA OKSIDA (UCO)

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ABSTRAK

SINTESIS DAN KARAKTERISASI KERNEL URANIUM KARBIDA OKSIDA (UCO). Sintesis dan karakterisasi kernel uranium karbida oksida (UCO) telah dipelajari. Pertama kali dibuat gel uranium karbida bulat seperti bola yang mengandung uranium 1M, PVA 8% dan karbon dengan rasio C/U = 1,67 - 8,33 dengan proses gelasi ekternal dalam medium NH₄OH 8M. Setelah itu, gel dikalsinasikan pada 350 °C selama 4 jam, menghasilkan kernel UCO. Kernel UCO mengalami sintering secara fluidisasi di dalam medium gas argon dengan laju alir 33,3 ml/menit menggunakan fluidized bed. Suhu sinter divariasi pada 1000 - 1150 °C dengan waktu sintering 2 jam dan waktu sinter divariasi,
1 - 4 jam pada 1100 °C. Hasil sintering adalah kernel UCO sinter. Karakter kernel UCO hasil kalsinasi dan sintering ditentukan dari sifat kimia dan fisika. Sifat kimia meliputi analisis struktur molekul UCO dengan metode spektroskopi FTIR dari pita serapan infra merah ikatan O-U-O, U-O, U-C atau C-U-C, karbida C-C pada bilangan gelombang
400 - 4000 cm^-1. Sifat fisis meliputi analisis kerapatan dengan menggunakan piknometer dan larutan CCl₄ sebagai pelarut, luas muka spesifik dan jari-jari pori rerata dengan metode adsorpsi gas menggunakan surface area meter NOVA-1000 dan N₂ sebagai absorbat serta diameter butiran menggunakan mikroskopi optik dengan pembesaran 50´. Hasil percobaan menunjukkan bahwa kernel UCO sinter dapat disintesis dari kernel UCO hasil kalsinasi seperti diatas. Kondisi yang relatif baik adalah pada suhu 1100^oC,waktu sinter 2 jam dan rasio C/U = 4,17. Analisis sifat kimia menunjukkan bahwa pada proses sintering terjadi perubahan struktur molekul kernel UCO, diikuti pergeseran pita serapan infra merah ikatan O-U-O dari 740,6 cm^-1 ke 650,0 cm^-1 dan pita serapan ikatan C-C yang terkonyugasi dengan ikatan O-U-O membentuk ikatan C-C-U dari 1319,12 - 123,70 cm^-1 ke
1339,82 cm^-1, dan hilangnya pita serapan infra merah ikatan rangkap dua dan tiga, ikatan hidrogen dan hidroksi pada kernel UCO sinter. Analisis sifat fisis ditunjukkan bahwa terjadi perubahan struktur kristal pada kernel UCO sinter diikuti peningkatan kerapatan, perubahan luas muka spesifik, jari-jari pori rerata dan diameter butiran. Kernel UCO sinter yang dihasilkan pada kondisi relatif baik terdiri dari campuran UO₂ dan UC₂, berbentuk bulat, permukaan halus dan diameter padatan sebesar 836 - 954 µm.

KATA KUNCI: Sintesis, Karakterisasi, Kernel uranium karbida oksida sinter, Proses sintering, Fluidized bed, FTIR, Mikroskop optik

ABSTRACT

SYNTHESIS AND CHARACTERIZATION OF SINTERABLE URANIUM CARBIDE OXIDE (UCO). Synthesis and characterization of sinterable uranium carbide oxide (UCO) have been carried out. First of all, spherical form of uranium carbide gel which contained 1 M uranium, 8% PVA and 1.67 - 83 of C/U ratio was prepared using external gelation process in 8M NH₄OH medium. After that, the gel was calcinated at 350 ^oC for 4 hours to produce UCO kernel. The UCO kernel was sintered using fluidization method in argon medium with a flow rate of 33.3 ml/min using a fluidized bed. The sintering temperature was varied from 1000 - 1150 ^oC with sintering time of 2 hours, and at 1100 ^oC temperature the sintering time was varied from 1 - 4 hours. The sintering product obtained was sinterable UCO kernel. The characteristics of the UCO kernel from calcination process and sinterable UCO kernel from sintering process were defined from their chemical and physical properties. The chemical properties included structure analysis of UCO molecule using FTIR spectroscopy method from infrared absorption band of O-U-O, U-O, U-C or C-U-C and carbide of C-C bond at wave number 400 - 4000 cm^-1. The physical properties included density analysis using picnometer and CCl₄ solution as the solvent, specific surface area, mean pore radius using surface area meter NOVA-1000 and N₂ gas as absorbents, as well as grain diameter of UCO kernel using optical microscopy with a magnification of 50´. The experiment results showed that sinterable UCO kernel can be synthesized from UCO kernel produced from calcination above. The relatively good condition was at temperature of 1100 ^oC, sintering time of 2 hours and C/U ratio of 4.17. The analysis of the chemical properties showed changes of UCO molecular structure during sintering process followed by shifting of the absorption band of O-U-O bond from 740.6 cm^-1 to 650 cm^-1 and the absorption band of C-C bond that was conjugated with O-U-O bond forming C-C-U bond from 1319.12 - 1543.90 cm^-1 to 1359.82 cm^-1, and the disappearance of infrared absorption band of double bond and triple bond, hydrogen bond and hydroxyl bond in sinterable UCO kernel. The analysis of the physical properties showed changes in the crystal structure of sinterable UCO, accompanied with an increase of the density, changes of the specific surface area, the mean pore radius and grain diameter. The sintered UCO kernel produced at relatively good condition consisted of mixture of UO₂ and UC₂, spherical in form, with fine surface and solid grain diameter of 836 - 954 µm.

FREE TERMS: Synthesis, Characterization, Sinterable uranium carbide oxide, Sintering process, Fluidization bed, FTIR, Optical microscopy