喷雾造粒粉制备ZTM陶瓷的结构缺陷与强度研究

STRUCTURE DEFECT AND STRENGTH OF ZTM CERAMICS MADE FROM SPRAY-DRIED POWDER

结合喷雾料浆、造粒颗粒的相关工艺控制 ,对喷雾造粒粉制备的ZTM陶瓷的结构缺陷及强度进行了研究 .结果发现 :较低固相含量的料浆易形成具有坚硬外壳的空心颗粒 ,这种颗粒在成型过程中难以破坏 ,在坯体中形成结构缺陷 ;颗粒的残余水分对颗粒的变形性具有重要作用 ,随残余水分的增加 ,坯体的断裂从沿颗粒向穿过颗粒的形式过渡 .研究还表明 :较大颗粒间的气孔 ,如在成型过程未被完全破坏和变形 ,则会遗留在烧结体中 ,导致材料强度的明显降低 .由尺寸均一、变形性好的造粒颗粒制备的材料具有较高的强度和Weibull模数 .

Structure defects of ZTM ceramics fabricated from spray_dried powder differing in granule morphology and deformability were determined. The effects of solid content of feed slurry and moisture content of granules on the granule character were discussed. It had been found that the lower solid content resulted in hard and hollow granules that resisted deformation during compaction, and that fracture mode of green bodies changed from inter_granular to trans_granular with increasing moisture content of granules. It had been also showed that relatively large inter_granular pores, due to the incomplete deformation of granules, which persisted during sintering, were the major structure defects in fired material. The sintered material pre_ssed from deformable and uniform granules had a significantly higher mean strength and Weibull modulus.