| Currently,the vast majority of materials used in solar power generation in the world are multi-crystalline silicon wafers.Multi-crystalline has a great advantage in cost,production and technology development.However,to get rid of current higher photovoltaic electricity price and serious cases of relying on subsidies,reduce the production cost is still the primary task of research on multi-crystalline ingots.There are many ways to improve the quality and reduce the cost of multi-crystalline production.This paper focus on the two aspects of multi-crystalline production,one is the quartz ceramic crucible used in the production of polycrystalline silicon ingot,and the other silicon nitride coating process prior to use of crucible.The poly-silicon of 6N raw materials is used in the multi-crystalline production,it’s a big technical difficulty due to the raw materials used for quartz ceramic crucible contains more metals,III and V group element impurities,which has great impact on the lifetime and resistivity of the multi-crystalline.Silicon nitride powder coating is an important barrier layer isolated quartz crucible and silicon melt,which played a role of isolating impurities from the crucible into the melt in the process of directional solidification,and ensure a good separation of quartz crucible and ingot.Therefore,it’s necessary to research the silicon nitride powder coating on the quality of multi-crystalline product and the effective output of unit weight of raw materials.This paper focused on the preparation of silicon nitride powder coating,and research the different ratio of spraying liquid,different spraying process.The detection of metal elements,O content confirmed that the new process is more simplified than the traditional process,while has the best effect for silicon nitride coating in the industry,that is,reduced the rate of crucible stick,formed a dense layer of silicon nitride,and blocked the elements from quartz crucible into silicone melt,which resulting in better quality and higher purity of multi-crystalline product. |
