Preparation And Properties Research Of Reaction-bonded Grouting Silicon Nitride

The study purpose is ceramic crucible,it is used to load silicon raw material in the process of solar silicon ingots.Currently,quartz ceramics crucible with Si3N4 coating is used in the production,it is proposed to make out silicon nitride ceramic crucibles directly to replace the existing quartz crucibles in this study. Combined with the slip casting method and reaction sintering method,it is aim to achieve low-cost preparation requirements of complex shaped silicon nitride ceramic material. Main contents and results are as follows:Silicon-based slurry of high solid content is prepared using silicon as the raw material, adding dispersant, binder, sintering additives. Study the rheological properties of silicon-based slurry in different size, different dispersants, different pH and find the optimal parameters. It has effect on the density and porosity of sintered body to increase different content of Si3N4 and Y2O3.And test bending strength and the thermal shock resistance and fracture toughness of sintered body.It is found that the 2nd Si-based slurry (including silicon nitride)had the best rheological properties in the alkaline environment, 60%high solid content, 63.6cP low viscosity, dispersed, to meet the requirements of grouting. Drying shrinkage is very small and change is less than 5% of the total volume. The highest density sintered body is founded adding 5% Si3N4 and 2% Y2O3,up to 2.30g/cm3.Reaction sintered Si3N4 of S and P have better density,the porosity of S is large than P,therefore, the flexural strength of P is better.Low porosity is favorable on the bending strength,but for thermal shock resistance, the appropriate porosity is favorable.Thermal shock resistance of S is better than P. Found that the discrete of fracture toughness of reaction sintered Si3N4 is in accordance with weibull distribution,through statistical analysis of the fracture toughness of S and P.For reaction sintered Si3N4 of P, the average fracture toughness up to 5.23 MPa·m1 /2, weibull modulus up to 6.88.