Pembuatan Keramik Beta Alumina (Na2o - Al2o3) Dengan Aditif Mgo Dan Karakterisasi Sifat Fisis Serta Struktur Kristalnya

Keramik system Na2O-Al2O3 dibuat melalui reaksi padatan dari campuran bahan baku : serbuk Na2CO3, serbuk α-Al2O3, dan Mg(OH)2CO3 sebagai aditif MgO. Mole ratio antara Na2O dan Al2O3 adalah 1 : 11 , sedangkan aditif MgO divariasikan yaitu: 0, 1 %, 2 %, 3 % , dan 4 % berat. Preparasi sample dilakukan dua tahpan, tahap pertama pembuatan serbuk, ketiga macam bahan baku tersebut digiling menggunakan ball mill selama 24 jam, kemudian dikalsinasi pada suhu 1200oC selama 2 jam. Pada tahap kedua serbuk yang telah dikalsinasi digiling dan diayak hingga lolos ayakan 400 mesh, kemudian dicetak dengan cara tekan , dan disintering dengan variasi suhu yaitu 1400, 1450, 1500, 1550, dan 1600oC, serta ditahan selama 2 jam. Masing-masing sample setelah disinterringdikarakterisasi yang meliputi: sifat-sifat fisis (densitas, dan porositas), dan analisa fasa dengan difraksi sinar X. Hasil karakterisasi menunjukkan bahwa densitas tertinggi (2,34 g/cm3 ) dan porositas terendah (32 %) diperoleh pada sample dengan aditif 3 % MgO dan suhu sintering 1600oC. Hasil analisa dengan difraksi sinar X menunjukkan bahwa telah terbentuk fasa dominan Na-β″ Al2O3 dengan fasa minor Na-β′ Al2O3.Ceramic system of Na2O - Al2O3 has been made through solid-solid reaction from mixing of raw materials : powder Na2CO3, powder α-Al2O3, and Mg(OH)2CO3 as additive MgO. Mole ratio between Na2O dan Al2O3 was 1 : 11 , also additive MgO was varied such as : 0, 1 %, 2 %, 3 % , and 4 % wt. The sample preparation was done in two steps, first step was mixing of raw materials with using a ball mill for 24 hours, then it was calcined at temperature 1200oC for 2 hours. The second step was forming of calcined powder with using pressing, and then all samples were sintered at temperature: 1400, 1450, 1500, 1550, and 1600oC with holding time about 2 hours. The sintered samples were characterized such as : physical properties (density and porosity), also phases analysis by using XRD. The charachterization results show that highest density (2,34 g/cm3) and lowest porosity (32%) were found at sample with 3 % MgO and at sintering temperature1600oC. The XRD analysis show that it was obtained Na-β″ Al2O3 phase as dominat phase, and Na-β′ Al2O3 phase as minor phase