摘要 SiC具有高硬、高强、高热导率、优异的高温力学性能、抗氧化、耐酸耐碱等特点，在高性能陶瓷制备方面备受关注。越来越多的研究者通过对SiC进行表面改性和颗粒级配研究，以获得性能更优异的高性能陶瓷制品。与-SiC相比，β-SiC具有更优异的烧结活性，可以在更低的温度下实现材料的烧结和致密化。本文以β-SiC超细粉体为研究对象，通过对其进行物理改性和颗粒级配研究，制备出干压成型所要求的流动性好、均匀、成型性能好的粉料和注浆成型要求的高固相含量低粘度的浆料。 研究表明，干法成型中，β-SiC粉体的最佳表面改性剂为聚丙烯酸(PAA)，其最佳添加量为2wt%，改性后粉体的综合流动性指数从47提高到58.5，分散性、流动性得到改善；粉料的中粒径D50由原粉的0.92μm减小到0.79μm；改性与喷雾造粒结合，粘结剂PVA的最佳用量为2wt%，喷雾造粒使得粉体形成很好的球形度，综合流动性指数由原粉的47提高到93，优于法国圣戈班造粒粉的流动性。改性β-SiC粉体素坯密度为1.78g/cm3，喷雾造粒粉素坯密度为1.88g/cm3。粘结剂为酚醛树脂的喷雾造粒粉素坯密度为1.92g/cm3，法国圣戈班造粒粉素坯密度1.97g/cm3，可见，本文所制备的喷雾造粒粉流动性与国际一流水平接近。 注浆成型中，用于浆料的最佳改性剂为聚羧酸，添加量为0.5wt%时，可使浆料的最大固含量由原粉的39wt%提高到58wt%。粉料的中粒径D50由原粉的0.92μm减小到0.71μm；聚羧酸改性粉的Zeta电位绝对值在pH=8时，达到最大，由原粉的37.9mv(-37.9mv，pH=8)提高到49.9mv(-49.9mv，pH=8)；改性提高了β-SiC超细粉体在悬浮液中的悬浮稳定性，36小时沉降后，改性粉的沉降高度为96ml，比原料粉体提高了71%；在pH=10的条件下，采用β-SiC超细粉与α-SiC粗粉级配，优化出最佳级配为50wt%粗粉+50wt%改性超细粉，制备出了固含量为60vol.%，粘度为960mPa.s，符合注浆成型要求的高固低粘浆料。与圣戈班(53vol.%)以及河南易城(50vol.%)的浆料固含量相比，本实验所得浆料固含量较高。

ABSTRACT SiC has the characteristics of high hardness, high strength, high thermal conductivity, excellent mechanical behavior under high temperature, acid resistance, alkali resistance and so on, which take more attention in preparing high performance ceramics.More and more researchers try to obtain greater high performance ceramics by surface modification and gradation.Compared with -SiC, β-SiC has more excellent sintering activity, which make it sintered and densificated at lower temperature and easier process facility. However, recently many researches focus on -SiC, which make the report about β-SiC less. So β-SiC is as the object of the study, by physical modification and gradation, trying to solve the problem raised by ultrafine powder. Powder with good flow, uniformity and good formability was made which satisfied the requirement of dry pressing and slurry with high solid content and low viscosity satisfying the requirements of slip casting was fabricated. The study showed that the best surface modifier of the ultrafine β-SiC powder was PAA in the dry molding, of which the optimal dosage was 2wt%. The comprehensive liquidity index increased from 47 to 58.5 and the dispersion and liquidity was improved. The middle particle size D50 of the powder reduced from the original 0.92μm to 0.79μm, making the dispersibility improved. Combining modification with spray granulation, the optimum dosage of binder was 2wt%. Spray granulation made powder form a good sphericity and the fluidity index of the original powder increased from 47 to 93, which is better than Saint-Gobain granulation powder. After being molded, PAA modified β-SiC powder biscuit density was 1.78g/cm3. The spray granulation powder biscuit density was 1.88g/cm3. The spray granulated powder green density was 1.92g/cm3 whose binder is bakelite. Compared to the French Saint-Gobain SiC granulation powder whose compact density was 1.97g/cm3, the flowability of spray granulation powsder prepared in this paper is obviously close to the international level. In slip casting, polycarboxylic acid was an optimum modifier for slurry. When it’s addition amount is 0.5 wt%, it can make the maximum solids content of the slurry increase to 58 wt% from 39wt% of the original powder. The middle particle size D50 was reduced to 0.71μm from 0.94μm. The powder modified by polycarboxylate achieve a maximum potential absolute value in pH=8. The value are increased from the original 37.9mv(-37.9mv, pH=8)to 49.9mv(-49.9mv, pH=8). The modification improved the suspension stability of the β-SiC ultrafine powders in suspension. After a settlement of 36h, The sedimentation height of the original powder was 56ml, and the sedimentation height of the modified powder was 96ml increasing by 71%. Under the optimum condition in pH = 10, we use β-SiC ultrafine powder and alpha silicon carbide meal to make a gradation, we optimized the best gradation which is 50wt% +50wt%. Finally, we prepared a solid content of 60vol.%, the viscosity of 960mPa.s, high solid content low viscosity slurry which can meet the the requirements of slip casting. Compared with the slurry made by Saint-Gobain whose solid content was 53vol.% and Henan Yi city whose solid content was 50vol.%, the solid content of slurry made by us was higher.