Pemanfaatan Scaling Silika Dari Lapangan Panas Bumi Dieng Untuk Sintesis/Pembuatan Bahan Keramik Maju Silikon Nitrida Dengan (Si3N4) Metode Carbothermal Reduction Nitridation

WISHNU RAHARDY, Ir. M. Waziz Wildan, M.Sc., Ph.D.

2014 | Skripsi | TEKNIK MESIN

Scaling silika sering menjadi masalah yang serius dalam pengoperasian lapangan panas bumi. Scaling Silika dalam produksi pipa menyebabkan dalam mengurangi diameter pipa, sehingga mengurangi tingkat air dan bahkan dapat menyumbat pipa dan harus diganti. Selain itu, Scaling silika dalam bidang panas bumi dapat menyebabkan masalah lingkungan. Oleh karena itu, ada dua hal penting yang harus diselesaikan, yaitu mengurangi atau mengendalikan scaling silika dalam bidang panas bumi untuk meningkatkan PLTU kinerja dan mengurangi efek lingkungan dari limbah scaling silika. Penelitian ini bertujuan untuk memanfaatkan scaling silika dari lapangan panas bumi Dieng untuk menghasilkan/mensintesis Silikon Nitrida (Si3N4) sebagai rekayasa bahan keramik maju dengan metode carbothermal reduction nitridation. Scaling Silica diperoleh dari lapangan panas bumi Dieng. Itu kering di atmosfer udara dan kemudian diayak/sieving untuk mendapatkan ukuran partikel � 37 µm. Scaling silika dikalsinasi pada 800 °C selama 1 jam. XRD digunakan untuk mengkarakterisasi scaling silika. Scaling silika yang telah diayak/sieving kemudian dicampur dengan bubuk karbon aktif (dengan ukuran partikel � 37 µm) (dengan komposisi stoikiometri) menggunakan Turbula Mixer. Setiap campuran kemudian dipanaskan pada suhu 1400 ° C dengan 4 perlakuan: pemanasan 2 jam di lingkungan gas nitrogen teknis, pemanasan 5 jam di lingkungan gas nitrogen teknis, pemanasan 2 jam di lingkungan gas nitrogen ultra high purity UHP, dan pemanasan 10 jam di lingkungan gas nitrogen ultra high purity (UHP). XRD digunakan untuk mengkarakterisasi spesimen. pemanasan pada suhu 1400 °C selama 10 jam di lingkungan gas nitrogen UHP menunjukkan bahwa silikon nitrida mulai terbentuk. Untuk meningkatkan hasil sintesis silikon nitrida, hasil dari pemanasan digerus dan diikuti dengan pemanasan kembali pada 1400 °C selama 10 jam di lingkungan gas nitrogen UHP. Proses ini (penggerusan dan re-heating) dilakukan sampai dua kali. Setiap kali setelah penggerusan dan pemanasan kembali, spesimen ditandai menggunakan XRD. Hasil menunjukkan bahwa spesimen yang telah dipanaskan, digerus dan re-heated (dua kali) menunjukkan peak Si3N4 meningkat. SEM-EDX dan TEM juga digunakan untuk mengamati spesimen.

Silica scaling is often a serious problem in the operation of a geothermal field. Silica scaling in the pipe production causes in reducing the diameter of the pipe, thereby reducing the rate of water and can even clog the pipe and should be replaced. In addition, silica scaling in the geothermal field may cause enviromental problems. Therefore, there are two important things should be solved, i.e. reducing or controlling the silica scaling in the geothermal field to improve the performance geothermal plant and reducing the environmental effect of the silica scaling waste. This research aims to utilize the silica scaling from Dieng geothermal field to produce / to synthesize Silicon Nitride (Si3N4) as an advanced engineering ceramic material using carbothermal reduction nittridation method. Silica scaling was obtained from Dieng geothermal field. It was dried in air atmosphere and then sieved to get particle size � 37 µm. Two treatments were performed on it, in order to get two different types of silica scaling, i.e. without calcination and calcination at 800 oC. XRD were used to characterize the silica scaling. Each type was mixed with activated carbon powder (with particle size � 37 µm)(with stoichiometric composition) using a turbula mixer. Each mixture was then heated up in 1400 °C at various heating time of 2 hour, 5 hour, and 10 hour in technical nitrogen and ultra high purity nitrogen gas atmosphere. XRD was used to characterize the results. The result shows that the heating up the mixture at 1400 oC for 10 hour in ultra high purity nitrogen atmosphere yielding the optimum silicon nitride (Si3N4). To improve the silicon nitride synthesize reaction, the results from the heating was milled and followed by a re-heating at 1400 oC for 10 hours in ultra high purity nitrogen gas atmosphere. This process (milling and re-heating) was performed until two times. Each times after milling and re-heating, the specimen was characterized using XRD. The results show that the specimen which have been heated, milled and re-heated (two times) yielded the best Si3N4. SEM-EDX and TEM were also used to observe the specimens. From SEM and TEM observation, it was found that the Si3N4 phase was in the form of whiskers.

Kata Kunci : scaling silika, sintesis, silikon nitrida, karbon aktif, carbothermal reduction nitridation.