Production of Silicon Nitride from Rice Husk

Rice milling industry generates a lot of rice husk during milling of paddy which comes from the fields. This rice husk is mostly used as a fuel in the boilers for processing of paddy and is a carbon neutral green product. Rice Husk is burnt at controlled temperatures below 700 degrees centigrade to generate ash which is amorphous in nature . The transformation of this amorphous state to crystalline state takes place if the ash is exposed to high temperatures of above 850 degrees centigrade. Rice husk has a great potential as a raw material for the production of Si3N4. Prof. Concepción Real and others of Universidad de Sevilla, Spain report that silicon nitride (Si3N4) can be obtained from rice husks by the carbothermal reduction by applying the constant-rate-thermal-analysis (CRTA) method. In this method, the reaction rate of carbothermal reduction is controlled and while maintaining constant level of CO concentration generated during the process. By using this synthesis technique it has been possible to obtain ceramic powder from rice husks with a determined phase composition and a controlled microstructure.