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In this thesis, ceramic crucible , it is used to mount the solar polysilicon ingot process polysilicon feedstock . Currently used in the production of quartz ceramic crucibles have Si the the 3 N 4 coating , the paper attempts to direct preparation of silicon nitride ceramic crucible replace existing quartz ceramic crucible . Experiments using slip casting method combined with the reaction sintering method , to achieve the requirements of the low cost silicon nitride ceramic material for the preparation of complex shapes . The main contents and results are as follows : Si powder as raw material , add dispersant , binder , sintering aids were prepared silicon slurry of high solid content . Different size , different dispersant at different pH values ??, the rheological properties of the silicon slurry , to find the optimal process parameters . Experiments add Si 3 N 4 and Y 2 O 3 , study its content on the density of the sintered body , porosity , testing and analysis of the bending strength of the sintered body , thermal shock resistance and fracture toughness . II Si substrate (including Si 3 N 4 ) slurry rheological properties in an alkaline environment , the best, the solid phase on the rheological properties of the study found that : content of 60% , a viscosity minimum 63.6cP slurry uniformly dispersed , to meet the requirements of the grouting . The volume of the preform in the molding before and after drying shrinkage is very small, the change amount is less than 5% of the total volume . Additive content : add 5 % Si 3 N 4 2% Y 2 O 3 , the reaction sintered silicon nitride highest density up 2.30g/cm 3 . Reaction sintered silicon nitride S and P , better density , S No. porosity is slightly larger than the P of S of flexural strength than P No. . The study found that low porosity is beneficial to the strength , for the thermal shock resistance , however , the appropriate porosity is advantageous , the S number of the thermal shock resistance than the P number . Found through statistical analysis of the fracture toughness the discrete fracture toughness reaction sintered silicon nitride ceramic also meet weibull distribution ; P No. reaction sintered silicon nitride ceramic materials fracture toughness was 5.23 MPa · m 1 / 2 , weibull modulus of 6.88.
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