Investigation of the production of silicon nitride from Turkish rice husks

Thesis Type: Post Graduate

Institution Of The Thesis: Orta Doğu Teknik Üniversitesi, Faculty of Engineering, Department of Metallurgical and Materials Engineering, Turkey

Approval Date: 2014




Production of silicon nitride by the carbothermal reduction and nitridation of silicon dioxide in rice husk was investigated. For this purpose, rice husks from the Black Sea region (Bafra) of Turkey was obtained. The husks were subjected to a pretreatment step involving water washing, acid leaching and pyrolysis at 600C. Pyrolyzed rice husks were found to have a Carbon:Silicon Dioxide molar ratio of about 5.2. Pyrolyzed rice husks were used as the starting material for the carbothermal reduction and nitridation experiments. Temperatures between 1300-1500C were studied for 1 h to determine the optimum temperature for the process. Then, the reaction duration, nitrogen flow rate and starting pyrolyzed rice husk amount was studied in order to examine their effect on the products of the process. Three different silicon nitride containing products were distinguished. Upon XRD analyses, it was seen that silicon carbide was formed along with silicon nitride in all conditions. Silicon nitride weight percentage was found to be increasing with the increasing reaction duration, increasing nitrogen flow rate and decreasing pyrolyzed rice husk amount. SEM analyses showed that silicon nitride was mainly formed as nano/micro-fibers.